CLASS 123,	INTERNAL-COMBUSTION ENGINES
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SECTION I - CLASS DEFINITION

This class contains inventions relating to prime movers or engines in which a combustible material is burned within an inc losed space or chamber and the heat energy thus developed converted into work by permitting the resulting products of combustion to act upon and through mechanical powers, the engine in question including suitable mechanism whereby the functions above enumerated are continually and automatically carried out, and such engine being designed to communicate power to some machine or device exterior to itself.

The space or combustion chamber above referred to is ordinarily the interior of the working cylinder of the engine, the products of combustion acting immediately upon a reciprocating, rotating, or oscillating piston moving within the same chamber in which combustion takes place or in an extension thereof. Some types of internal-combustion engines, however, besides fulfilling the conditions above mentioned, have a transfer valve operated by and in unison therewith located between the combustion chamber and the elements upon and through which the products of combustion act to thereby control the flow of said products, in which case the above mentioned transfer valve is operated to establish communication between the combustion chamber and the working cylinder at the instant of ignition or prior thereto, so that the piston is driven by burning products of combustion.

The working fluid is ordinarily such as results from combustion alone; but in some of the engines in this class a small quantity of water is supplied to the engine, generally by injecting it directly into the interior of the combustion-chamber during or after the combustion of the combustible material; but in all engines using water the amount used is comparatively small, so that the resulting steam is necessarily in a superheated condition.

This class also includes separate parts of engines coming within the above definition and also subordinate elements designed for use with such engines, and incapable of use in the manner contemplated with other devices or in other relations.

From the above it will be seen that devices go into this class because of a function performed by a given element or combination of elements rather than because of any particular structure of such elements, and therefore, given structural features forming a machine adapted for use as an internal-combustion engine, may be found in any other classes having machines of like general structure. Thus probably any given structure adapted for use as an internal-combustion engine could generally with slight modification be used as steam or other heat engine, and often as an air, gas, or water pump, a hydraulic motor, a meter, etc. This would not ordinarily be the case with the subordinate or auxiliary devices included in this class, as from what appears above such subordinate elements as the class contains are adapted for use in the manner contemplated only with or forming a part of an internal-combustion engine.

It therefore follows that a search for a given general mechanical structure adapted for use as an internal-combustion engine will generally need to be continued in the classes above indicated.

Further fields of search for the various subordinate elements designed for and adapted to be used only with internal-combustion engines, and therefore included in this class, are indicated in the definitions hereinafter appearing of those various subclasses.

SECTION II - LINES WITH OTHER CLASSES AND WITHIN THIS CLASS

A compilation of all types of motors will be found in the Notes to the class definition of Class 60.

The following examples of terminology have been considered to be a nominal inclusion of an internal combustion engine and if so claimed would not preclude classification in Class 417:

(a) a cam driven pump; (b) a "crank (shaft)" driven pump; (c) a "gear" driven pump; (d) a "chain" driven pump; (e) a "belt" driven pump; (f) a "fluid" driven pump; (g) an "electrically" driven pump; (h) a pump and an "outlet" "tube" and "injector".

The following pump control parameters are separately appropriate for Class 417. Control by both of these parameters is appropriate for Class 123;

(a) engine speed control; (b) manifold vacuum.

The following examples have been considered to be significant inclusion of an engine and if so claimed would cause classification in Class 123 if otherwise appropriate.

(a) timing of the pump relative to the engine; (b) engine temperature control of the pump.

(1) Note. When the pump-engine combination is claimed broadly, it is properly classified in Class 123. When the output of the pump is not delivered to the engine, classification is proper in Class 417.

SECTION III - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

48,	Gas: Heating and Illuminating,   subclass 198.8 for a method of making a fuel gas from methane using an internal combustion engine.
60,	Power Plants,   subclasses 39.6+ , for engines of the external-combustion type.
92,	Expansible Chamber Devices,   appropriate subclasses. Class 123 takes an expansible chamber device or element thereof which is limited for use in an internal combustion engine. However, since Class 123, has not been cleared, many expansible chamber devices which are not limited for use in an internal combustion engine will be found in Class 123, without any stated line or perceptible distinction with the subject matter found in Class 92.
440,	Marine Propulsion,   subclass 45 , for devices utilizing an explosive jet to propel a vessel through the water.
417,	Pumps,   appropriate subclasses for pumps, per se, which may be disclosed as internal-combustion engine accessories and particularly subclass 34 for an internal-combustion engine driving a pump and having means for controlling the engine in response to a condition of the pump or pump fluid, subclasses 73+ for pumps in which one fluid is pumped by the ignition of another in direct contact therewith; subclass 364, for pumps driven by an internal-combustion engine; and subclass 380, for fluid motor driven pumps in which the motive fluid for the fluid motor is generated by an internal-combustion engine. Internal-combustion engine driven pumps are classified in Class 417 even though the pump may be solely disclosed as a mere accessory of or ancillary to the operation of the engine (e.g., cooling fluid pump, fuel pump, etc.). However, this class (123) takes those internal-combustion engine driven accessory pumps when the claims reflect a fluid connection between the pump and the engine, provided there is no additional pump fluid inlet or outlet claimed for supplying or exhausting fluid for use external of the engine.
477,	Interrelated Power Delivery Controls, Including Engine Control,   for interrelated controls between an engine and a transmission, clutch, or brake.
588,	Hazardous or Toxic Waste Destruction or Containment,   subclasses 313 through 320wherein the waste is destroyed by burning it in an internal - combustion engine. Also, see cross-reference art collection, subclass 900, for apparatus used to treat hazardous or toxic waste.

SUBCLASSES

1	MISCELLANEOUS:
	This subclass is indented under the class definition.  Internal combustion engines not coming within the terms of the definition of some one of the following internal-combustion engine subclasses. This subclass contains patents relating to cycles or modes of operation not hereinafter provided for or in which the cycle or mode of operation is not definitely determined by the structure disclosed and will not ordinarily contain patents relating to definite mechanical structure. (1) Note. Given mechanical structures not provided for in structural subclasses, but operating upon a definite and determined cycle of operation provided for in this classification, are classified in miscellaneous functional or cycle subclasses, such as 65, and subclasses indented thereunder, and 311+, and indented subclasses, etc. (2) Note. The use of unconventional fuels as found in this subclass are commonly hazardous and toxic waste and their chemical destruction or containment is found in Class 588, Hazardous or Toxic Waste Destruction or Containment.

2	COMBINED DEVICES:
	This subclass is indented under the class definition.  Combinations not coming within the terms of the following subclasses of combined devices in which an internal-combustion engine, is disclosed and claimed in combination with some other device not in itself classifiable in some appropriate subclass of internal-combustion engines and which combined device itself is not treated as a unitary machine in the general system of Office classification and as such classified in some appropriate class. SEE OR SEARCH CLASS: 290,  Prime-Mover Dynamo Plants,   for the combination of internal combustion engines and dynamoelectric machines. 368,  Horology: Time Measuring Systems or Devices,   subclass 5 for an horological device acted upon by an internal combustion engine.

3	Generating plants:
	This subclass is indented under subclass 2.  Combinations of an internal-combustion engine together with means for generating and supplying a combustible mixture thereto, the engine and generating apparatus being ordinarily capable of separation, but disclosed and claimed in combination, and the elements collectively forming a complete plant for developing and applying power. In the power plants occurring herein the various elements constituting the generating portion of the plant are of ordinary or commercial form and if presented by themselves would be classified in other classes or subclasses. Patents covering the engine and generating device together are classified in the class of internal-combustion engines, because all the elements of the plant are so correlated as to develop and apply power by means including an internal combustion engine. (1) Note. The devices occurring in this subclass differ from many of the engines in subclasses of oil engines in that in an oil-engine the source of power is always a liquid hydrocarbon and the elements concerned with the vaporization of the oil and those constituting the engine are so designed with reference to each other as to form a single unitary machine incapable of being separated into its component sets of elements without defeating the operation of the engine as a whole in the manner contemplated.

18	OSCILLATING PISTON:
	This subclass is indented under the class definition.  Internal-combustion engines irrespective of cycle or mode of operation, comprising a stationary inclosing casing, sections of which perpendicular to its axis are bounded by circular arcs concentric to said axis, and a movable member or piston therein moving in contact with the inner walls of the said casing, said piston partaking of an oscillating or swinging motion about the axis of the casing and, together with the walls thereof, inclosing a space or chamber within which the burned gases act expansively to impel the piston. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 223 and 339+ for cyclically operable expansible chamber motors of the oscillating piston type.

19	LIQUID PISTON:
	This subclass is indented under the class definition.  Internal-combustion engines in which a body of liquid is interposed between the burned gases and the working piston or equivalent element, whereby power is communicated to the main driving-shaft of the engine, the said liquid preventing the burned gases within the combustion-chamber and working cylinder from coming into direct contact with the working piston or equivalent element.

21	CONVERTIBLE CYCLE:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and a working piston-reciprocating therein, but irrespective of other structural features, in which means are provided whereby the mode of operation of the engine may be determined and the engine caused to operate upon either a two-stroke or a four-stroke cycle.

22	INTERNAL COMBUSTION AND AIR:
	This subclass is indented under the class definition.  Engines including in their structure elements normally found only in hot-air engines and other elements normally found only in internal-combustion engines and having steps in their cycle of operation peculiar to both such types of engines. This subclass includes engines including elements selected from both the above-mentioned types and convertible either at will or automatically, as by a suitable governing device, so as to operate either as hot-air or as internal-combustion engines, and engines operating upon a predetermined cycle, including working strokes, upon which the piston is impelled alternately by gases heated within the working cylinder by combustion, as in internal-combustion engines, and by gases heated within the working cylinder by contact with the inner surface of said working cylinder and the clearance-space. SEE OR SEARCH THIS CLASS, SUBCLASS: 61, and 68.

23	SOLID FUEL:
	This subclass is indented under the class definition.  Internal-combustion engines in which a solid nonexplosive fuel or combustible is introduced into and burned within the working cylinder of an internal-combustion engine or into a combustion-chamber in permanently open communication therewith and the energy of the resulting gases converted into work by permitting them to expand and act upon a piston moving in the said cylinder. The solid fuel may be introduced into the working cylinder upon each successive cycle of operation of the engine and in quantities sufficient only to supply the energy required for the successive working strokes of the engine, or it may be introduced at comparatively long intervals of time and in quantities sufficient to furnish energy for several working strokes, in which case air only is supplied upon the successive cycles of operation to consume portions of the charge of fuel already within the engine. SEE OR SEARCH THIS CLASS, SUBCLASS: 24, and 445+, for feeding mechanism available generally for the purpose of supplying solid fuel to engines of the type occurring in this subclass. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 39.461 , for combustion motors other than internal-combustion engines operable on solid nonexplosive fuel.

24	GUNPOWDER:
	This subclass is indented under the class definition.  Internal-combustion engines in which a charge of gun powder or other explosive substances is supplied to and exploded within the cylinder of the engine or combustion-chamber in communication therewith and the energy of the resulting gases converted into work by permitting them to act upon a moving part of the engine. This subclass is intended to include all engines using an explosive substance as above, irrespective of other structural features, cycle, or mode of operation. SEE OR SEARCH THIS CLASS, SUBCLASS: 23, and 445+, for feeding mechanism available, generally for the purpose of supplying the explosive substance to engines of the type occurring in this subclass. SEE OR SEARCH CLASS: 60,  Power Plants,   subclasses 632+ , for one shot explosion actuated expansible chamber type motors, and subclass 39.47 for combustion products generators combined with motors, other than internal-combustion engines, which operate on solid fuel containing an oxidizer.

25	WATER AND HYDROCARBON:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and a working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which the combustible mixture supplied to and burned within the working cylinder contains a quantity of aqueous vapor or in which water in any form is supplied to the working cylinder after a charge has been ignited therein. The water may be supplied to the air and hydrocarbon before the charge is ignited in which case the combustible charge is made up of air, hydrocarbon, and aqueous vapor, or a combustible mixture of air and hydrocarbon may be ignited in the working cylinder, the water being supplied to the expanding gases therein during the working stroke. In cases where water in the form of steam is supplied to the combustible mixture, as above, the steam is frequently generated by means of heat ordinarily lost in the operation of the engine, as by the heat of the exhaust-gases, or the cooling-jacket may be utilized as a steam-generator to supply water to the combustible charge. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.22, for similar devices designed primarily to reduce the pressure of the cooling system and thus reduce the boiling point of the liquid coolant. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 39.54 where combustion products are used as a motive fluid having addition of steam or water within a prime mover, subclass 712 for an engine operated selectively or simultaneously by internal combustion of fuel and by expansion of motive fluid or subclass 775 for a process of introducing water or steam.

26	ADDITIONAL AIR SUPPLY:
	This subclass is indented under the class definition.  Internal-combustion engines in which a combustible mixture is ignited in the working cylinder at the beginning of the working stroke, as in the ordinary operation of internal-combustion engine, after which and at some time before the end of the working stroke an additional quantity of compressed air or equivalent non-combustible gas is supplied to the working cylinder and mingles with the burned gases therein, the piston being impelled through the remaining portion of its working stroke by the combined action of the burned gases and the air supplied thereto.

27	BURNING BY HIGHLY COMPRESSED AIR:
	This subclass is indented under the class definition.  Internal-combustion engines in which air or equivalent noncombustible gas is supplied to the working cylinder and compressed therein by a distinct compression-stroke of the working piston to such a degree that the temperature of the gas rises to such a point that a combustible supplied thereto will be ignited by the highly-compressed noncombustible gas upon coming into contact therewith, after which and after the beginning of the working stroke a combustible upon being supplied to the body of the compressed noncombustible gas ignited as it comes into contact therewith and burns at constant pressure or perhaps constant temperature. The cycle upon which the engines occurring in this subclass operate, is sometimes designated by text-writers as the "Diesel" cycle. (1) Note. For engines in which gas is burned at constant pressure, see this class, subclasses 61 and 68. SEE OR SEARCH THIS CLASS, SUBCLASS: 495+, for with Fuel Pump. SEE OR SEARCH CLASS: 239,  Fluid Sprinkling, Spraying, and Diffusing,   appropriate subclasses, especially subclasses 86 , 87, 88+, 95, 96, and 533.2+ for nozzles disclosed for injecting fuel into combustion chambers of internal combustion engines.

	Oil-Engines:
	The "oil-engine" subclasses contain internal-combustion engines, having a cylinder and a working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, which are designed to be operated by a liquid hydrocarbon and in which the means concerned with the supply and vaporization of the oil so closely associated with the elements constituting the engine that a true combination would appear to exist between the two sets of elements. A given mechanism including an engine and means for supplying oil thereto to be burned therein is not classified as an oil-engine merely because it is designed to use oil as a source of power if the means whereby the oil or vapor is supplied to the engine is capable of separation therefrom and of use with other engines without affecting the operation of either the engine or the oil-supplying devices. A given structure will be classified in these subclasses only in cases where mechanical separation of the elements concerned with the supply or vaporization of the oil from the elements constituting the engine is impossible without defeating the operation of the device as a whole in the manner contemplated by the inventor, and a simple pipe or equivalent connection through which the exhaust-gases from the engine are conducted to the oil-supplying or vaporizing device to heat the same is not considered as bringing the two sets of elements into such intimate association as to make the whole mechanism a single device and as such classifiable as an oil-engine. From these considerations it therefore ordinarily follows that patents disclosing both an engine and a device for supplying it with oil or vapor therefrom and which do not come within the terms of the above definition, and are therefore not classifiable in oil-engine subclasses, are classified and cross-referenced according to the separate groups of elements entering into and forming the complete device, the oil-supplying or vaporizing device ordinarily going into appropriate subclasses of Charge-forming devices and the engine into appropriate subclasses in this class, according to its form, mode or operation, of other distinguishing features.

37	MULTIPLE EXPLOSION:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which two or more separate and distinct charges of combustible mixture are burned and act in succession upon the working piston during each working stroke thereof, each charge after the first upon ignition entering the cylinder and mingling with and tending to increase the pressure of the burned gases already therein.

38	ATMOSPHERIC:
	This subclass is indented under the class definition.  Internal-combustion engines of the reciprocating type wherein the working piston is permanently connected with the main driving-shaft of the engine in which a combustible mixture is burned within the working cylinder thereof and the resulting gases cooled and condensed, thereby producing a more or less perfect vacuum within the said working cylinder, whereupon atmospheric pressure acts upon the said working piston to move it through a working stroke. The pressure of the atmosphere may be the only force acting upon the working piston, or the engine may be so designed that the combustible gases upon being ignited generate pressure which also acts upon the said working piston.

39	NONCOMPRESSION:
	This subclass is indented under the class definition.  Internal-combustion engines of the reciprocating type, but irrespective of other structural features, in which the combustible mixture is ignited in the working cylinder at or substantially at atmospheric pressure. The combustible mixture ordinarily begins to enter the working cylinder at the beginning of the working stroke in which case it is ignited at atmospheric pressure, as above, after a definite portion of the working stroke has been performed and the whole charge supplied, the engine thus working upon a two-stroke cycle without compression. The charge may, however, be drawn into the working cylinder by a distinct charging stroke, such stroke being followed by a stroke corresponding with the compression-stroke in four cycle engines during which the exhaust-valve is held open and the charge then ignited under atmospheric pressure at the beginning of the third or working stroke, in which case the engine works upon a four-stroke cycle without compression. (1) Note. Engines in this subclass working on the two stroke cycle without compression, as above, differ from the majority of the engines occurring in subclass 68, and engines working upon a similar cycle occurring in subclass 61, only in the degree of pressure under which the charge exists before the ignition thereof. SEE OR SEARCH THIS CLASS, SUBCLASS: 38,

41	REVERSIBLE:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and a working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which means are provided for causing the engine to run in either direction at the will of the operator and subordinate mechanism for accomplishing the same result, but not disclosed in connection with all the elements necessary to form a complete and operative engine. (1) Note. In this connection it should be observed that engines working upon a two-stroke cycle are frequently capable of operating in either direction without addition to or change in the elements necessary to the operation thereof, and this especially true of the engines in subclasses 71, 73 and 74.

41.01	COOLING:
	This subclass is indented under the class definition.  Such miscellaneous devices for cooling the working cylinder, piston, piston-rod, or other element of an internal-combustion engine as do not come within the terms of the definition of some one of the following subclasses of internal-combustion engines, cooling, and accessary devices designed for and used with cooling systems for internal-combustion engines and not classified in some appropriate cooling subclass. (1) Note. The expressions "primary coolant" and "secondary coolant", found in the definitions of the indented subclasses, refer, respectively to a fluid employed to cool an engine surface by direct contact therewith and to a fluid employed to cool such contacting fluid. For example, the liquid which flows through a radiator for an internal-combustion engine is the primary coolant, whereas the air passing through the radiator to cool the liquid coolant is a secondary coolant. (2) Note. Class 165 will receive the combination of an internal-combustion engine and radiator when the internal-combustion engine is included by name only. (3) Note. For structures including shutters for controlling the air flow, which devices do not include significant internal-combustion engine structure, search Classes 49, 180, 236, and 454. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 39.83 for cooling of parts of an engine of the internal combustion type; subclasses 597+ for a fluid motor driven by the waste heat of an internal combustion engine; subclasses 320+ for an internal combustion engine having a cooled exhaust or in which the exhaust is used as a heat source and subclass 714 for plural motors with a common cooling means. 165,  Heat Exchange,   subclasses 41+ for a heat exchanger installed on a vehicle, and subclasses 51+ for a heat exchanger installed on an engine. 180,  Motor Vehicles,   subclasses 68.4 and 68.6 for motor vehicle combinations including radiator mountings; and subclasses 68.1+ for hoods and such combinations including shutters. See (3) Note. 236,  Automatic Temperature and Humidity Regulation,   subclasses 34+ for automatic radiator cooling. See (3) Note. 237,  Heating Systems,   subclasses 70+ , for heating system radiators, per se. 244,  Aeronautics,   subclass 53 , for aircraft engine cowling or enclosure devices; see (3) Note to subclass 53 in Class 244 for the line; and subclass 57, for radiators combined with aircraft structure. 417,  Pumps,   subclass 372 , for an interrelated or common cooling means for a pump and drive motor therefor. 418,  Rotary Expansible Chamber Devices,   subclasses 83+ , for such devices provided with heat exchange means. 454,  Ventilation,   subclasses 3+ for ventilating cowls and subclasses 284+ for registers. See (3) Note.

41.02	Automatic coolant flow control:
	This subclass is indented under subclass 41.01.  Devices with means to sense some condition, which means causes operation of a control device for stopping, varying, or starting the flow of either the primary or secondary coolant. (1) Note. Control of replenishment from a reserve supply, which may be condensate, is included. (2) Note. The inclusion of significant engine structure or specific engine operation is the characteristic which distinguishes this type of device from those found in Class 236. SEE OR SEARCH CLASS: 126,  Stoves and Furnaces,   subclass 351.1 for a fluid fuel burner other than a top-accessible liquid heating vessel and a condition responsive feature. 137,  Fluid Handling,   subclasses 457 and 468 for valves controlled by change in the line temperature. 236,  Automatic Temperature and Humidity Regulation,   subclasses 34+ , for automatic coolant flow control. See (2) Note.

41.03	Float control:
	This subclass is indented under subclass 41.02.  Cooling systems wherein the control of the coolant flow is directly or indirectly controlled by a device which floats on the surface of the coolant. SEE OR SEARCH CLASS: 236,  Automatic Temperature and Humidity Regulation,   subclass 52 , for float control combined with thermal sensing means.

41.04	Shutters, air valves, dampers or adjustable cowls:
	This subclass is indented under subclass 41.02.  Cooling systems wherein the primary or secondary coolant is air or gas and the device for stopping, varying, or starting the flow of the air or gas is a shutter, valve, damper, adjustable cowl, etc. SEE OR SEARCH CLASS: 49,  Movable or Removable Closures,   appropriate subclasses, particularly subclasses 74.1+ for louvers interconnected for concurrent movement. 160,  Flexible or Portable Closure, Partition, or Panel,   appropriate subclass, for curtains, shades or screens, for radiator protectors. 236,  Automatic Temperature and Humidity Regulation,   subclass 35.2 , for automatic shutter control. 454,  Ventilation,   subclasses 3+ for ventilating cowls and subclasses 284+ for registers.

41.05	Temperature and engine operation responsive:
	This subclass is indented under subclass 41.04.  Devices in which the shutters are controlled by a temperature responsive device and also include an engine responsive device, e.g., an intake or exhaust manifold pressure responsive device or an oil pressure responsive device. (1) Note. The engine responsive device usually acts to automatically close the shutters upon stopping the engine and cooperates with the thermostat to control the shutters in response to engine temperature while the engine is in operation.

41.06	Servomotor-operated type:
	This subclass is indented under subclass 41.04.  Devices wherein an operator of the servo-motor (fluid, electric, etc.) type is interposed between the condition sensing means and the shutter, valve, damper, adjustable cowl, etc. SEE OR SEARCH CLASS: 236,  Automatic Temperature and Humidity Regulation,   subclass 35.3 , for heat responsive control of shutters including a servo-motor within the control linkage.

41.07	Interrelated shutter and throttle control:
	This subclass is indented under subclass 41.04.  Devices in which the control of the engine carburetor throttle valve also controls a shutter or shutters. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.13, for nonautomatic interrelated throttle and coolant flow control.

41.08	Valves for fluid coolant:
	This subclass is indented under subclass 41.02.  Cooling systems wherein the primary or secondary coolant is a fluid and the device for stopping, varying or starting the flow of liquid is a valve.

41.09	Coolant source bypass:
	This subclass is indented under subclass 41.08.  Cooling systems wherein the responsive valve interrupts the flow of fluid coolant from the engine block to a coolant source as in the case of a primary coolant, or from a radiator or heat exchanger to a coolant source in case of a secondary coolant, and directs the coolant to a bypass omitting the coolant source. (1) Note. The coolant source may be either an exchanger or an external supply, as an intake from the sea. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.25, for systems in which a liquid coolant bypasses a vapor condenser. 41.29, for bypasses for pump, radiator, etc., not automatically controlled. SEE OR SEARCH CLASS: 236,  Automatic Temperature and Humidity Regulation,   subclass 34.5 , for radiator bypass valves controlled by heat responsive means. 440,  Marine Propulsion,   subclass 88 , for combinations involving boat modification. Inclusion of hull by name only is not sufficient to place a patent in Class 440.

41.1	Radiator or condenser source:
	This subclass is indented under subclass 41.09.  Cooling systems wherein the coolant source is a radiator or condenser.

41.11	Air impeller:
	This subclass is indented under subclass 41.02.  Devices wherein the primary or secondary coolant is air and the device for stopping, varying or starting the flow of air is an impeller or fan which is controlled by an automatic device. SEE OR SEARCH CLASS: 236,  Automatic Temperature and Humidity Regulation,   subclasses 35+ , for automatic air impellers which are used to cool radiators. 416,  Fluid Reaction Surfaces (i.e., Impellers),   subclasses 31+ for an impeller, per se, controlled by an automatic device.

41.12	Temperature-responsive:
	This subclass is indented under subclass 41.11.  Devices in which the automatic control device is actuated in response to temperature.

41.13	Interrelated coolant flow and throttle control:
	This subclass is indented under subclass 41.01.  Cooling systems for controlling the flow of primary or secondary coolant flow conjointly with the engine throttle. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.07, for automatic shutter and throttle control.

41.14	System drained and/or heat-storing:
	This subclass is indented under subclass 41.01.  Cooling systems including (1) devices or arrangements for draining the entire cooling system or any part thereof, usually to prevent freezing, or (2) devices for storing heat to be returned to the system when the engine is stopped to prevent freezing. (1) Note. The draining devices usually include a heat insulated tank into which the coolant is drained and stored. (2) Note. Mere internal passages in a cooling system which are not closed in normal operation of the system are not considered draining devices, even though indented to allow complete emptying of the block or other port. (3) Note. Heat storing devices must include something in addition to mere bulk of coolant or stopping of circulation. SEE OR SEARCH CLASS: 137,  Fluid Handling,   subclasses 59+ for drain valves operated in response to a sensing of freeze conditions; subclass 107 for drains responsive to flow stoppage; and subclasses 301+ for hydrants combined with means to prevent freezing. 417,  Pumps,   subclass 434 , for means for draining a pump or pump portion.

41.15	Indicators and safety devices:
	This subclass is indented under subclass 41.01.  Cooling systems having means for indicating the condition or amount of coolant in the cooling system or any part thereof and devices responsive to the condition or amount of cooling fluid for preventing injury to the engine being cooled. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.5, for tank, radiator, or jacket constructions which permit rupture of easily replaced parts in case of excessive pressure or which have compressible means or air pockets or resilient walls to prevent damage to the system.

41.16	Coolant sealed in cylinder valve or piston:
	This subclass is indented under subclass 41.01.  Cylinders, pistons, or valves with chambers containing a confined coolant therein which may be either a liquid, solid or gas. (1) Note. If there is also an external flow circuit, there is no communication between the two. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclass 176 for a piston provided with an enclosed insulating space therein.

41.17	Coolant released into cylinder or valve passages:
	This subclass is indented under subclass 41.01.  Cooling systems in which the coolant, after cooling the engine or engine parts, discharges into the engine cylinder combustion space or valve passages or is merely exposed to the interior of said cylinder or valve passages. SEE OR SEARCH THIS CLASS, SUBCLASS: 25, for water injected into the cylinder during the working stroke, which water may be derived from the cooling system. 543, for admission of heated air to the cylinder. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 310 for a motor-exhaust combination in which the exhaust system includes liquid contact structure and subclasses 317+ for a system in which external fluid is mingled with exhaust gas.

41.18	Convertible:
	This subclass is indented under subclass 41.01.  Cooling systems which are capable of operating in more than one way or of changing from the use of one coolant to another, as air, vapor, liquid, and having means for changing the system to adapt it to the coolant or mode of operation selected, or having means for substituting tanks for radiators or making other equivalent changes. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.2, for vapor systems which are converted to liquid systems or vice versa merely by adding more liquid or according to the heat developed, without change or adjustment of the physical structure.

41.19	Refrigerating cycle:
	This subclass is indented under subclass 41.01.  Cooling systems including a vaporized liquid other than water which is liquefied and then allowed to expand into gas, thus removing heat directly from the engine parts or from the engine coolant. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.2, for aqueous vapor systems, especially subclass 41.25, for systems in which all the circulating coolant is vaporized. SEE OR SEARCH CLASS: 62,  Refrigeration,   for refrigerating systems, per se.

41.2	With vapor generation and/or condensing:
	This subclass is indented under subclass 41.01.  Cooling systems in which (1) vaporization is intended to occur, as evidenced by the creation of vapor in the jacket, the provision of vapor space therein or by a circulating system requiring vapor for its operation; (2) a closed system is provided which is claimed to be operated at pressures other than atmospheric; (3) there is manipulation to change the normal boiling point of the coolant in a part of the system as by providing a vacuum or pressurizing; or (4) a condenser is interposed in the system other than and/or in addition to the normal passage of the liquid coolant through a heat exchanging radiator, as (a) the radiator is vented through a condenser, or into the circulating fluid, (b) the radiator is modified to mix or recirculate vapors, or (c) the outlet from the water jacket enters the radiator at the bottom. (1) Note. Vapor type operation may occur only in the starting and warming up period of motor operation. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.19, for refrigerating type coolers which involve vaporizing a nonaqueous primary coolant.

41.21	Coolant circulation with condensing:
	This subclass is indented under subclass 41.2.  Cooling systems in which there is condensation of vapor in parts of the system external to the block or cylinder jacket and ultimate or immediate return of the condensate to the system. (1) Note. Condensation of vapor may be induced by passing the vapor through a heat exchanger, either with or without accompanying liquid, or by introducing it into a body of liquid either in a tank or in the circulating system. (2) Note. Circulation involves return of at least a portion of the condensate to the block or cylinder jacket, either directly or after a period of storage. The path is usually circuitous, but may be a surge in and out through the same line. (3) Note. Condensation of vapor in a heat exchanger opening widely and directly into the block water cavity or cylinder jacket is considered circulation, but a mere tank at the top of the water space or jacket is not so considered. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.51, 41.53, 41.54, and 41.55, for reserve supply tanks and for radiators combined with cooling systems.

41.22	Intake or carburetor connection:
	This subclass is indented under subclass 41.21.  Cooling systems in which a connection to the combustion intake or carburetor reduces pressure in the system or a portion of it, usually to promote circulation or reduce the boiling point of the coolant. SEE OR SEARCH THIS CLASS, SUBCLASS: 25, for systems in which vapor from the cooling system is drawn into the combustion chamber to effect combustion. 41.17, for systems in which coolant escapes directly into the combustion chamber or valve passages or is exposed thereto.

41.23	Entrained in secondary circuit:
	This subclass is indented under subclass 41.21.  Cooling systems in which the vapor emitted from the block or jacket or a portion of it, or the condensate resulting therefrom, is added to or separated into a fluid circuit which does not include the block or jacket, i.e., a secondary cooling circuit. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.55, for cooling a primary liquid coolant by a secondary liquid coolant.

41.24	From top of jacket to bottom of radiator:
	This subclass is indented under subclass 41.21.  Cooling systems in which vapor and/or water flows from the top of the block or cylinder jacket to the bottom of the radiator. (1) Note. This usually results in the water returning to the block or cylinder without circulating through the heat exchanger, which is an upflow condenser.

41.25	Water bypasses condenser:
	This subclass is indented under subclass 41.21.  Cooling systems in which vapor and water flow from the block or cylinder jacket through the same or adjacent outlets and the water is separated from the vapor and returned to the block or cylinder without passing through the condenser for the vapor. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.24, for similar systems in which the vapor and water flow from the top of the block or jacket to the bottom of the radiator.

41.26	Vapor only circulated:
	This subclass is indented under subclass 41.21.  Cooling systems in which only vapor is emitted from the block or cylinder jacket. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.19, for similar systems in which the vapor is nonaqueous.

41.27	Overflow vent to condenser:
	This subclass is indented under subclass 41.21.  Cooling systems provided with an overflow vent from the radiator-condenser which leads to a means for condensing vapors escaping from the system through the overflow. (1) Note. The overflow tube may lead to a heat exchanger, a tank or reservoir or to a part of the system in which liquid is circulating. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.54, for cooling system vents.

41.28	Multiple cylinders with equalized cooling:
	This subclass is indented under subclass 41.01.  Cooling systems having (1) conduits for furnishing each of a plurality of cylinders with an individual supply of coolant the distribution system branching either externally or internally of the jacket, or (2) passages within the jacket having capacities varying from cylinder to cylinder to produce equal cooling effects on all cylinders. (1) Note. Circulation through the head or body of the cylinder block or jacket with apertures individual to each cylinder for transfer of fluid between the head and body is not included under (1) above, but is included under (2) if the apertures vary in size. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.72+, for multiple cylinders having coolant circulating jackets or block passages where individual head chambers are supplied from the body or lower chambers through passages of uniform size. See (1) Note.

41.29	Parallel flow:
	This subclass is indented under subclass 41.01.  Cooling systems in which a liquid coolant is circulated through plural paths which have at least some portion in common and which are diverse in character. (1) Note. Typical examples of art are (1) bypass circuits, whether for pump, radiator or jacket; (2) primary and secondary liquid coolant circuits having a common portion in which the fluids mingle; and (3) separate circuits connecting either the pump or radiator to both the top and bottom of the block or jacket. (2) Note. Mere circulation from one part of a cylinder block or jacket to another is not included, even though the connection is external. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.09+, for automatically controlled bypass for coolant. 41.2+, especially subclass 41.25, for plural path coolant circulators where vapor forming or condensing or structure especially adapted thereto is claimed. 41.28, for plural circuits to plural cylinders which are either interior manifolds or externally divergent or which vary the flow to different cylinders. 41.72+, for plural circuits which are developed internally of cylinder blocks or jackets and are mere duplicates.

41.3	Mixed air and liquid:
	This subclass is indented under subclass 41.01.  Cooling systems wherein air is admitted to coolant water for cooling the water and/or for circulating the water around the cooling system. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.2+, for vapor systems. 41.44, and 41.45, for other circulating systems involving a gas other than air, such as exhaust gases. 41.48, for positively circulated gaseous secondary coolant.

41.31	With cooling of additional parts or materials:
	This subclass is indented under subclass 41.01.  Cooling systems with means for cooling such additional elements as spark plugs, exhaust manifolds, plural manifolds for both intake and exhaust, bearings, guides, transmissions, etc., or means for cooling substances such as exhaust gases, etc., together with the cooling of (1) the cylinder, (2) piston or (3) valves, or any combination thereof. (1) Note. Where the claims include exhaust manifold cooling with no detailed engine cooling, the patent belongs in Class 60, Power Plants, subclass 321, unless the exhaust gases are diverted to the engine, in which case the patent belongs in this subclass. SEE OR SEARCH THIS CLASS, SUBCLASS: 434+, and especially subclasses 543+, for inlet manifold cooling or heating.

41.32	With spark plug heat exchange:
	This subclass is indented under subclass 41.31.  Cooling systems in which the additional part that is cooled is a spark plug. SEE OR SEARCH THIS CLASS, SUBCLASS: 169, for spark plug cooling, per se.

41.33	With lubricant heat exchange:
	This subclass is indented under subclass 41.31.  Cooling systems in which the additional substance cooled is a lubricant. (1) Note. The passage of air through the crankcase is considered cooling lubricant in crankcase. (2) Note. Devices wherein the air is circulated through the crankcase by the pumping action of the piston are also included. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.86, for crankcase ventilation, per se. 196, for lubricant cooling, per se, where the lubricating system includes significant internal combustion engine structure.

41.34	Internal cooling of moving parts; e.g., hollow valves, pistons, and movable cylinder:
	This subclass is indented under subclass 41.01.  Cooling means in which various movable elements of the engine have their inside surfaces, which are not exposed to combustion, cooperating surfaces, or direct atmosphere, cooled. (1) Note. Movable elements in this subclass and in indented subclasses comprise pistons, cylinders, valves, etc. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.16, for pistons and valves having a coolant sealed therein. 41.56+, for air cooled pistons which do not have a definite fluid receiving compartment. 41.76+, for valve seats and valve stem guide cooling by fluid circulating in a jacket. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclass 173 for a piston having an enclosed insulating space therein; subclass 186 for a piston having a ported chamber therein for circulating a heat exchange fluid; subclass 239 for a piston provided with heat radiating rib means.

41.35	Piston:
	This subclass is indented under subclass 41.34.  Cooling means wherein the element cooled is a piston. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclass 173 for a piston having an enclosed insulating space therein; subclass 186 for a piston having a ported chamber therein for circulating heat exchange fluid; subclass 239 for a piston provided with heat radiating rib means.

41.36	Telescoping piston and stationary conduits:
	This subclass is indented under subclass 41.35.  Cooling means in which the piston has attached thereto a conduit, or the piston is shaped to include a conduit, which conduit slides in or on a stationary or fixed conduit for delivering coolant to or from said piston interior.

41.37	Hollow piston rod:
	This subclass is indented under subclass 41.35.  Cooling means wherein the piston rod is hollow or has passages therein for conducting coolant to and/or from the piston. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclasses 109+ for a piston having a hollow piston rod.

41.38	Wrist pin type; e.g., nonrigidly connected:
	This subclass is indented under subclass 41.37.  Cooling means wherein the hollow piston rod is pivotally or otherwise nonrigidly connected with the piston to permit said rod to swing.

41.39	Side wall opening:
	This subclass is indented under subclass 41.35.  Cooling means wherein the piston has openings in its side wall or cylindrical surface which usually communicate with openings in the cylinder for the passage of a coolant to or from the interior or side of the piston. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.78, for cylinder jackets adapted to be traversed by sidewall type cylinder valves.

41.4	Rotary valves:
	This subclass is indented under subclass 41.34.  Cooling means wherein the movable element cooled is a rotary valve.

41.41	Poppet-type valves:
	This subclass is indented under subclass 41.34.  Cooling means wherein the movable element cooled is a poppet type valve.

41.42	Liquid coolants other than water and water treatment:
	This subclass is indented under subclass 41.01.  Cooling systems employing liquid coolants other than water or water which has been treated to prevent freezing, corroding, etc. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.16, for nonaqueous coolants sealed in cylinder valves or pistons. 41.19, for nonaqueous coolants which are vaporized and condensed in a refrigerating cycle. 142.5, for systems in which water is heated by external energy. SEE OR SEARCH CLASS: 252,  Compositions,   subclasses 71+ , for heat exchange compositions having low freezing point or high boiling point, and 387+, for anti-corrosion agents.

41.43	Movably mounted tank or radiator:
	This subclass is indented under subclass 41.01.  Cooling systems employing at least one tank or radiator which is capable of linear or angular motion. SEE OR SEARCH CLASS: 165,  Heat Exchange,   subclasses 86+ for a movably mounted heat exchanger not limited to use on an internal combustion engine. 244,  Aeronautics,   subclass 57 for radiators which may be movably mounted on aircraft.

41.44	With liquid coolant circulating means:
	This subclass is indented under subclass 41.01.  Cooling systems having positively acting means for circulating a liquid coolant within the engine block, through the block to the head, or through the block and head to a radiator.

41.45	Jet pumps:
	This subclass is indented under subclass 41.44.  Cooling systems wherein the circulating means comprise a jet or aspirating device. (1) Note. The jet may be liquid or gas operated. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.2+, particularly 41.23, for vapor type cooling systems having a jet type condenser.

41.46	Common drive for pump and fan:
	This subclass is indented under subclass 41.44.  Cooling systems where the device for circulating the liquid is a pump which is operated in conjunction with an air cooling fan. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.49, for air cooling fans for liquid heat exchangers.

41.47	Engine shaft driven:
	This subclass is indented under subclass 41.44.  Cooling systems wherein the liquid coolant circulating means is driven from the engine shaft. (1) Note. The pump may be mounted on the engine shaft or may be on a separate shaft connected by some transmission to the engine drive shaft.

41.48	Devices for cooling liquid by air flow:
	This subclass is indented under subclass 41.01.  Cooling systems including devices which guide, force, or direct air over surfaces which enclose a liquid coolant or which separate the air and liquid coolant.

41.49	Fan type:
	This subclass is indented under subclass 41.48.  Cooling systems wherein the device which forces the air is of the fan type. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.46, for air cooling fans operated in conjunction with a liquid pump. 41.48, for driving impellers as means for forcing the air. 41.65+, for fans which cause air to flow over air cooled engines.

41.5	Yielding or resilient walls:
	This subclass is indented under subclass 41.01.  Cooling systems having a normally rigid body, as a tank, radiator or jacket wall, constructed of yieldable material or provided with a replaceable portion weaker than the normal wall, or having a compressible or yieldable body within a tank, radiator or jacket, to prevent breakage of permanent rigid parts, particularly when the coolant freezes.

41.51	Plural radiators and/or tanks in series:
	This subclass is indented under subclass 41.01.  Cooling systems in which two or more heat dissipators and/or tanks are included in a single circulating system so that the coolant passes through them successively.

41.52	Engine or cylinder-mounted heat dissipators:
	This subclass is indented under subclass 41.01.  Cooling systems including a radiator or heat exchange for liquid coolants mounted on or integral with the engine or engine cylinder. (1) Note. See (2) Note under subclass 41.01.

41.53	Hopper type:
	This subclass is indented under subclass 41.52.  Cooling systems wherein the heat exchanger or radiator is in the form of a tank shaped like a hopper and forming an extension of the block or cylinder jacket. The hopper or tank is coextensive with the cylinder exchange portion of the system or opens widely into it, and there is no other means for dissipating heat.

41.54	With vent:
	This subclass is indented under subclass 41.01.  Cooling systems having means for venting air or vapor to the atmosphere. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.27, for overflow type vents delivering fluid into a tank or condenser.

41.55	Combined:
	This subclass is indented under subclass 41.01.  Cooling systems including matter other than heat exchange jackets or casings for the combustion chambers, valves, pistons or their immediate associated parts or the heat exchange elements of the same as fins or air passages. (1) Note. Included are miscellaneous heat dissipators for liquid coolants including those involving a secondary liquid coolant, automatic devices not concerned with coolant, flow, combinations with external power and/or heat using devices, i.e., auxiliary power plants, filters, etc. SEE OR SEARCH THIS CLASS, SUBCLASS: 2, for internal combustion engines in which the heat energy imparted to the cooling medium is utilized for generating steam for general purposes. 41.02+, for automatic coolant flow control. 41.13, for interrelated coolant flow and throttle control. 41.15, for combined indicator and safety devices. 41.31, for cooling of parts in addition to cooling of cylinders, valves and pistons. 41.44+, for combined flow causing means. SEE OR SEARCH CLASS: 126,  Stoves and Furnaces,   subclasses 204+ , for devices in which the heat energy imparted to the cooling medium is utilized for warming purposes.

41.56	Air-cooled:
	This subclass is indented under subclass 41.01.  Cooling means wherein the primary coolant is air or other gaseous fluid. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.19, for nonaqueous vapor coolant. 41.2+, for aqueous vapor coolants.

41.57	With liquid cooling:
	This subclass is indented under subclass 41.56.  Cooling means wherein a part of the engine is cooled by a liquid, i.e., there is a primary liquid coolant as well as a primary air coolant. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.3, for mixed air and water coolant.

41.58	Flow-regulating means:
	This subclass is indented under subclass 41.56.  Cooling means comprising means forming an air duct or passage for conducting cooling air to or against the engine including devices for controlling the flow of air through the duct or passages. (1) Note. These devices for the most part include shutters mounted in or on cowling. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.04+, for automatic control of shutters. 41.7, for cowlings surrounding the engine cylinders. SEE OR SEARCH CLASS: 49,  Movable or Removable Closures,   appropriate subclasses, particularly subclasses 74.1+ for louvers interconnected for concurrent movement. 180,  Motor Vehicles,   subclass 69.2 , for hoods having adjustable shutters combined therewith. 236,  Automatic Temperature and Humidity Regulation,   subclass 35.2 , for automatic shutter control. 454,  Ventilation,   subclasses 3+ for ventilating cowls and subclasses 284+ for registers.

41.59	Adjustable discharge:
	This subclass is indented under subclass 41.58.  Subject matter wherein the flow of air through the duct of passage is controlled by adjustable means at the discharge end of the duct or passage.

41.6	Steam dividing vanes, baffles, conduits, or the like for multiple cylinders:
	This subclass is indented under subclass 41.56.  Devices for cooling a multiple cylinder engine which include vanes, baffles, conduits or the like, for dividing the flow of air into separate streams and directing said streams to different cylinders or portions of the cylinders of the engine.

41.61	Individual deflecting cylinder baffles:
	This subclass is indented under subclass 41.6.  Subject matter wherein the stream dividing means comprise deflecting baffles positioned adjacent to or attached to the cylinders of the engine for directing air to or about each cylinder.

41.62	Air duct with discharge ports or conduits:
	This subclass is indented under subclass 41.6.  Subject matter in which the stream dividing means comprises an air duct or passage having discharge ports or conduits for directing the air flow to or against different parts of the engine.

41.63	With impelling means:
	This subclass is indented under subclass 41.56.  Subject matter which includes devices for impelling cooling air over the engine. (1) Note. The impelling means includes fans, pumps, or like devices but excludes cowlings, ducts, or the like which merely direct the flow of air over the engine due to the movement of the vehicle. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.48, for means to force or direct air over a surface of a liquid coolant.

41.64	Jet type:
	This subclass is indented under subclass 41.63.  Cooling means wherein the air impelling device is a jet pump or the like. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.45, for jet pumps for impelling liquid coolants.

41.65	Fan type:
	This subclass is indented under subclass 41.63.  Subject matter in which the air impelling device is a fan. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.49, for fans used to cause air to flow over radiators and/or water cooled engines.

41.66	Suction:
	This subclass is indented under subclass 41.65.  Devices in which the air impeller is a suction fan for withdrawing air from the engine housing.

41.67	Jacketed cylinder:
	This subclass is indented under subclass 41.56.  Devices comprising a jacket, casing or conduit supported by or enclosing an individual cylinder for directing the flow of air thereover. (1) Note. Various shaped baffles which cause the air flow to be deflected over the cylinder heads are included in this subclass. (2) Note. Devices in which the heat dissipating fins cooperate with the jacket or casing to form channels to conduct the cooling air over the cylinder are in this subclass. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.62, for conduits surrounding the cylinders. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclass 144 for a cylinder for an expansible chamber device encompassed by a heat exchange modifying space or jacket.

41.68	Spiral passages:
	This subclass is indented under subclass 41.67.  Devices in which baffle means or cylinder fins are formed to impart a spiral flow to the air within the jacket, casing or conduit as it passes over the cylinder.

41.69	Finned cylinder and/or head:
	This subclass is indented under subclass 41.56.  Subject matter which includes cylinders and/or cylinder heads constructed with various shaped fins to increase the cooling area of the cylinder walls. SEE OR SEARCH CLASS: 165,  Heat Exchange,   subclass 51 for heat exchange means installed on an engine; subclasses 181+ for a tubular structure with discrete heat transfer means; and subclass 185 for a heat transmitter, per se.

41.7	Engine encasing air duct; e.g., cowling:
	This subclass is indented under subclass 41.56.  Devices which comprise air ducts or passages which surround the engine to conduct or direct a stream of cooling air to or against the engine. (1) Note. These devices are usually cowling and may include structure for supporting the air duct or cowling on the engine. SEE OR SEARCH CLASS: 180,  Motor Vehicles,   subclasses 68.1+ for similar structure combined with significant vehicle features. 244,  Aeronautics,   subclass 53 , for like structures. See (3) Note under definition of Class 244, subclass 53.

41.71	Plural materials:
	This subclass is indented under subclass 41.01.  Cylinder, piston or jacket construction in which a plurality of materials, usually of different thermal capacity, are combined in a single element. (1) Note. A liner or cover permanently attached is considered a combined single element.

41.72	With jacketed head and/or cylinder:
	This subclass is indented under subclass 41.01.  Structures comprising an engine part which is immediately connected with the combustion process, as a cylinder wall or head or valve seat jacketed, channeled or constructed to form a passage for a confined coolant. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.34+, for coolant introduction into moving parts. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 83+ , for such devices provided with heat exchange means.

41.73	Jet or spray within jacket:
	This subclass is indented under subclass 41.72.  Structures in which all or a portion of the coolant is confined in a channel within or adjacent jacket or coolant housing to a point immediately adjacent the part to be cooled, where it is released into the larger space with sufficient force to form a current, jet or spray directed toward said port.

41.74	Multiple cylinder:
	This subclass is indented under subclass 41.72.  Structures including a plurality of cylinders within the same jacket or cooled by the same system. SEE OR SEARCH THIS CLASS, SUBCLASS: 52+, for multiple cylinder engines.

41.75	Reentrant head:
	This subclass is indented under subclass 41.72.  Subject matter in which the cooling head is formed with an internal concave portion with which the jacket is coextensive. (1) Note. This concave portion usually constitutes the combustion space.

41.76	With cooled valve seats or guides:
	This subclass is indented under subclass 41.72.  Structures in which the cooling chamber is especially adapted to cool the valve areas, i.e., passages, seats and valve stem guides. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.16, for valves and cylinder ports having coolant sealed therein. 41.34, for means for cooling the moving parts of this area internally. 41.4, for internal cooling of valves combined with external cooling of valve seats or guides. 41.85, for cooling of valve seats or guides, per se.

41.77	Poppet-type valves:
	This subclass is indented under subclass 41.76.  Cooling means in which the valve seats or guides support a poppet-type valve. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.41, for internal cooling of poppet type valves.

41.78	Cylinder side wall valves:
	This subclass is indented under subclass 41.76.  Cooling means in which the valve passages, etc., are located in the side walls of the cylinders.

41.79	With passages, baffles, etc.:
	This subclass is indented under subclass 41.72.  Cooling structures in which the jacket or cylinder walls are constructed with channels or in such a way as to form channels, or baffles, fins, ribs or grooves are provided inside the coolant chamber, either to guide the coolant in particular paths or directions, or to increase the area of the wall exposed to the coolant. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.67+, for air cooled cylinders having cooling passages or baffles.

41.8	Spiral passages:
	This subclass is indented under subclass 41.79.  Structures in which the path formed for the coolant is spiral, or forms an ascending or descending path extending around the cylinder. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.68, for air cooled cylinders having spiral passages or conduits.

41.81	Cylinder jacket supported solely by cylinder:
	This subclass is indented under subclass 41.72.  Structures in which a member forming the external wall or walls of a coolant containing chamber are secured to the cylinder or cylinder block proper, so that they are carried thereby and have no other support or mounting means.

41.82	With head-cooling arrangements:
	This subclass is indented under subclass 41.72.  Structures involving the cylinder head cooling means. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.76+, for similar constructions involving coolant chambers for valve seats or stem guides.

41.83	Cylinder detachable:
	This subclass is indented under subclass 41.72.  Structures in which the cylinder or cylinder liner is detachably supported within the assembly in such a way as to form one wall of the coolant chamber.

41.84	Flanged cylinder or liner:
	This subclass is indented under subclass 41.83.  Structures in which the cylinder or liner has a flange by which it is engaged with or supported in the assembly.

41.85	Valve seats or guides:
	This subclass is indented under subclass 41.01.  Structures in which the cooling means is especially adapted to cool the valve areas, i.e., passages, seats or valve stem guides. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.76+, for cooling of valve areas combined with cooling of the cylinder or cylinder head.

41.86	CRANKCASE VENTILATION:
	This subclass is indented under the class definition.  Engines wherein air is forced through the crankcase by some manner other than the mere pumping effect of the engine pistons for ventilating or removing fumes from the crankcase. (1) Note. Air may be forced through the crankcase by the forward motion of the vehicle or by the fan due to the formation of a venture or aspirating nozzle on the crankcase. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.31+, for crankcase cooling or oil cooling by confined coolants and for crankcase ventilation combined with cylinder, piston or valve cooling. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclasses 78+ for a means to purify a fluid to or from a portion of an expansible chamber device, subclass 80 for a force exerting means to move fluid from a nonworking chamber of an expansible chamber device, and subclass 82 for a means to control the flow of fluid from a nonworking chamber of an expansible chamber device.

42	OSCILLATING CYLINDER:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which the working cylinder partakes of an oscillatory motion about a fixed axis as the piston reciprocates therein. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 176 and 210+ for expansible chamber motors of the oscillating cylinder type. 92,  Expansible Chamber Devices,   subclasses 118+ for an expansible chamber device having an oscillating cylinder.

43	ROTATING CYLINDER:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which the working cylinder partakes of a continuous rotary motion about a fixed axis as the working piston reciprocates therein and engines including a plurality of working cylinders each coming within the terms of this definition, the engine in question not coming within the terms of the definition of the subclass following this. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 176 , 197 and 472+, for expansible chamber motors of the rotating cylinder type. 92,  Expansible Chamber Devices,   subclasses 54+ for an expansible chamber device having a rotating cylinder.

44	Radial:
	This subclass is indented under subclass 43.  Internal-combustion engines differing from those occurring in the preceding subclass in that axial lines of the rotating cylinders lie in a plane perpendicular to the crank-shaft of the engine and are also radial thereto, the cylinders or cylinder when one only is disclosed being immovable relatively to the member by which they are carried and with which they rotate. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 491+ , for expansible chamber type motors having three or more radial rotating cylinders. 92,  Expansible Chamber Devices,   subclasses 58+ for an expansible chamber device provided with a plurality of radially disposed rotating cylinders.

45	ROTARY RECIPROCATING PISTON:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and a working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which the working piston rotates or oscillates upon its longitudinal axis and that of the working cylinder as it reciprocates therein and in so doing opens and closes in proper order the various ports necessary to supply combustible mixture to and to permit the exhaust of the burned gases from the engine, the periphery of the piston or an extension thereof forming a closure for the supply and exhaust ports when they are required to be closed.

46	FREE PISTON:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and one or more reciprocating pistons therein, one at least of which pistons is movable freely and independently of the main shaft of the engine on the stroke of such piston immediately following the ignition of the charge, during which stroke the energy of the burned gases is stored and thereafter transferred to the main shaft of the engine. Ordinarily the freely-movable piston is the only piston employed in engines in this subclass. The energy is ordinarily stored by forcing the piston against the pressure of the atmosphere; and the stored energy is ordinarily transferred to the main shaft by securing the piston thereto by means of a suitable clutch provided with suitable converting mechanism upon its return stroke. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 595 for an internal combustion type free piston device supplying motive fluid to a motor and subclass 596 for an internal combustion type of free piston device with a pressure fluid type starting structure.

47	VALVED PISTON:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, the said working piston being provided with a passage leading into the working cylinder and controlled by a valve depending upon the engine for its operation, said valve being concerned either with the supply of the successive combustible charges to the working cylinder or with the exhaust of the burned gases therefrom. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 222+ for cyclically operable, expansible chamber motors having a valved piston.

48	ADJUSTABLE COMBUSTION CHAMBER:
	This subclass is indented under the class definition.  Internal-combustion engines having a cylinder and a working piston reciprocating therein, but irrespective of other structural features, cycle, or mode of operation, in which means are provided whereby the volume of the clearance-space or combustion-chamber may be varied or adjusted either manually or automatically as by a suitable governing device, to thereby insure a proper degree of compression of the combustible charge before ignition thereof. SEE OR SEARCH THIS CLASS, SUBCLASS: 311+, for internal-combustion engines in which the volume of the clearance-space is varied in unison with the exhaust-stroke, such action being a definite step in each cycle of operation of the engine.

50	RECIPROCATING CYLINDER:
	This subclass is indented under the class definition.  Internal-combustion engines comprising a cylinder and a piston therein, the cylinder being capable or reciprocatory movement in a straight line relatively to the piston and the piston being either immovable or adapted for simultaneous movement in a direction opposite to the movement of the said movable cylinder whereby the gases resulting from the combustion of a combustible mixture within the cylinder as they expand act upon the movable cylinder and transmit power therethrough to the main driving-shaft of the engine or act upon the movable cylinder and the piston, when it also is movable, to transmit power through both said elements. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclasses 117+ for an expansible chamber device having a moving cylinder.

51	MULTIPLE PISTON, COMMON NONRESTRICTIVE COMBUSTION CHAMBER:
	This subclass is indented under the class definition.  Internal-combustion engines comprising two working pistons moving simultaneously in the opposite directions in a single cylindrical structure composed of two working cylinders arranged tandem with a combustion-chamber between and in permanently open communication with both said cylinders or two working pistons moving in like manner in two similarly-arranged cylinders whose axial lines when extended are parallel and adjacent and which communicate with a single combustion chamber, as above, whereby the gases resulting from the combustion of a combustible mixture within the combustion-chamber as they expand act with equal pressure upon both pistons and transmit substantially equal amounts of power through each piston to the main driving shaft of the engine, and internal-combustion engines comprising two or more such units as are above defined. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 170+ and 508+ for multi-piston or cylinder type expansible chamber motors. 92,  Expansible Chamber Devices,   subclasses 61+ for an expansible chamber device having relatively movable working members.

52.1	MULTIPLE CYLINDER:
	This subclass is indented under the class definition.  Internal-combustion engine having two or more separate and distinct cylinders and a single piston reciprocating in each cylinder to transmit force to a load. (1) Note. The following terms are defined as used in this subclass and indented subclasses. (2) Note. A "stroke" consists of a movement of the piston away from the cylinder head or a movement toward the cylinder head. (3) Note. An internal-combustion engine may be defined by the number of strokes between ignition, the most common types are as follows: (a) A "four-stroke" engine is one which operates as follows, starting with the piston near "top-dead-center": (1) The piston moves away from the head, for the "power" stroke, as the ignited fuel expands as gases, to go to "bottom-dead-center". (2) The piston moves toward the head for the "exhaust" stroke in which the combustion gases are expelled. (3) The piston again moves away from the head for the "intake" stroke in which air is drawn into the cylinder. (4) The piston moves toward the head for the "compression" stroke, at the conclusion of which ignition will occur and the cycles start over. Note that a "four-stroke" engine makes two complete revolutions for each power stroke. (b) A "two-stroke" engine is one which operates as follows, starting with the piston near "top-dead-center": (1) The piston moves away from the head for the power stroke, with exhaust beginning at the bottom of the stroke. (2) The piston moves toward the head as exhaust completes, with the charge simultaneously being transferred to the cylinder, the latter part of the stroke serving to compress the charge, at the conclusion of this stroke ignition will occur and the cycles start over. Note that a "two-stroke" engine makes one complete revolution for each power stroke. SEE OR SEARCH CLASS: 91,  Motors: Expansible Chamber Type,   subclasses 170+ and 508+ for a multi-piston or cylinder type, noninternal combustion, expansible chamber motor. 92,  Expansible Chamber Devices,   subclasses 146+ for plural unitarily mounted cylinders or a frame therefor for an expansible chamber device (that is not an engine).
	GLOSSARY
	CHARGE:
	a quantity of "working fluid" intended to be ignited for a working stroke of the "piston".
	COMBUSTION CHAMBER:
	that volume of a "cylinder" enclosed by the "head" and the "piston" when the piston is closest to the head.
	CONNECTING ROD:
	The most common link for transmitting power from a "piston" to a "crankshaft".
	CRANKSHAFT:
	The most common type of "output shaft", which is journaled to turn about a fixed axis and including an offset portion for receiving energy from the piston.
	CYLINDER:
	a member having an internally facing surface of a shape generated by a straight line rotating a fixed distance about an axis.
	HEAD:
	the portion of a cylinder which closes off one end thereof.

52.2	Simultaneous compression, distinct pistons, restricted communication to a single combustion chamber:
	This subclass is indented under subclass 52.1.  Multiple cylinder engine including at least two cylinders each of which is connected to a single combustion chamber by a passage which is constricted to limit free flow of gasses between at least one of the cylinders and the combustion chamber and including means to coordinate movement of the pistons so as to compress the charge in the single combustion chamber. (1) Note. One piston of the "at least two" cylinders may move somewhat in advance of the other. There may be provision to prevent a fresh combustible mixture separate from the residual products of combustion from the previous charge, as by leading the supply-conduit into one working cylinder, while the exhaust-conduit leads from another. SEE OR SEARCH THIS CLASS, SUBCLASS: 51, for an engine including multiple pistons that utilize a single combustion chamber without restriction of flow of combustion gases there between. The engine of that subclass may include two oppositely moving pistons in a single cylinder.

52.3	Four-stroke cycle:
	This subclass is indented under subclass 52.2.  Multiple cylinder engine wherein the pistons in the working cylinders operate on a four-stroke cycle.

52.4	Multiple crankshafts:
	This subclass is indented under subclass 52.3.  Multiple cylinder engine including two output shafts, the first having at least one crank thereon which is drivingly connected to a first piston so as to convert the reciprocating motion of the piston into rotary motion of the first output shaft, and the second output shaft having at least one crank thereon which is drivingly connected to a second piston so as to convert the reciprocating motion of that piston into rotary motion of the second output shaft.

52.5	Two-stroke cycle:
	This subclass is indented under subclass 52.2.  Multiple cylinder engine wherein the pistons in the working cylinders operate on a two-stroke cycle.

52.6	Multiple crankshafts:
	This subclass is indented under subclass 52.5.  Multiple cylinder engine including two output shafts, the first having at least one crank thereon which is drivingly connected to a first piston so as to convert the reciprocating motion of the piston into rotary motion of the first output shaft, and the second output shaft having at least one crank thereon which is drivingly connected to a second piston so as to convert the reciprocating motion of that piston into rotary motion of the second output shaft.

53.1	Cylinder offset from crankshaft axis:
	This subclass is indented under subclass 52.1.  Multiple cylinder engine including a crankshaft that turns about an axis extending generally perpendicularly to a plane passing through the axis of at least one cylinder the piston of which is drivingly connected thereto, wherein the cylinder axis, if extended, would not intersect the crankshaft axis.

53.2	Multiple crankshafts:
	This subclass is indented under subclass 53.1.  Multiple cylinder engine including two output shafts, the first having at least one crank thereon which is drivingly connected to a first piston so as to convert the reciprocating motion of the piston into rotary motion of the first output shaft, and the second output shaft having at least one crank thereon which is drivingly connected to a second piston so as to convert the reciprocating motion of that piston into rotary motion of the second output shaft.

53.3	Cylinders opposite:
	This subclass is indented under subclass 53.1.  Multiple cylinder engine wherein the axes of a first and a second cylinder are spaced from each other by 180° about the crankshaft.

53.4	Two-stroke cycle:
	This subclass is indented under subclass 53.3.  Multiple cylinder engine wherein the pistons in the working cylinders operate on a two-stroke cycle.

53.5	Crankshaft between parallel cylinders:
	This subclass is indented under subclass 53.1.  Multiple cylinder engine wherein the axes of two cylinders are parallel and the axis of the crankshaft extends between the parallel axes.

53.6	Cylinders having opposing heads:
	This subclass is indented under subclass 52.1.  Multiple cylinder engine wherein a first and a second cylinder having axes collinear and have the combustion chamber ends of the cylinders facing one another along their axes.

54.1	Cylinders radiating:
	This subclass is indented under subclass 52.1.  Multiple cylinder engine including a rotary output shaft that turns about an axis intersected by and extending generally perpendicular to the axes of the first and second cylinders, the pistons of which are drivingly connected to the output shaft, wherein the cylinder axes are not parallel to each other. (1) Note. The axes of the first and second cylinders may intersect the rotational axis of the crankshaft at the same or at different points along the axis of the crankshaft. (2) Note. When viewed as a cross-section normal to the crankshaft axis, the first and second cylinder axes intersect at the point defining the crankshaft axis. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclass 148 for a plurality of radially disposed cylinders for an expansible chamber device that is not an internal combustion engine.

54.2	Star:
	This subclass is indented under subclass 54.1.  Multiple cylinder engine wherein at least three cylinders are equally spaced about the centrally disposed rotary output shaft.

54.3	Cam on rotary output shaft:
	This subclass is indented under subclass 54.2.  Multiple cylinder engine wherein the rotary output shaft includes a disk or a drum with an irregularly shaped surface which is engaged by a follower linkage drivingly connected to the pistons to convert the reciprocating motion of the pistons into rotary motion of the output shaft.

54.4	"V" type:
	This subclass is indented under subclass 54.1.  Multiple cylinder engine wherein first and second radially extending banks of cylinders are spaced apart by an angle of less than 180°.

54.5	Odd number of cylinders:
	This subclass is indented under subclass 54.4.  Multiple cylinder engine wherein the total number of cylinders is not evenly divisible by two.

54.6	Six cylinder:
	This subclass is indented under subclass 54.4.  Multiple cylinder engine including six or more cylinders.

54.7	Eight cylinder:
	This subclass is indented under subclass 54.6.  Multiple cylinder including eight or more cylinders.

54.8	More than eight cylinder:
	This subclass is indented under subclass 54.7.  Multiple cylinder engine wherein the total number of cylinders is an even number greater than eight.

55.1	Semi-radial:
	This subclass is indented under subclass 54.1.  Multiple cylinder engine including at least three cylinders radially disposed and unequally spaced about the centrally disposed, rotary output shaft.

55.2	Cylinders opposite:
	This subclass is indented under subclass 54.1.  Multiple cylinder engine wherein the first and second cylinder axes are spaced from each other 180° about the crankshaft axis.

55.3	Cam on rotary output shaft:
	This subclass is indented under subclass 55.2.  Multiple cylinder engine wherein the rotary output shaft includes a disk or a drum with an irregularly shaped surface which is engaged by a follower linkage drivingly connected to the pistons to convert the reciprocating motion of the pistons into rotary motion of the output shaft.

55.4	Four-stroke cycle:
	This subclass is indented under subclass 55.2.  Multiple cylinder engine wherein the pistons in the cylinders operate on a four-stroke cycle.

55.5	Cylinders opposite and aligned:
	This subclass is indented under subclass 55.4.  Multiple cylinder engine wherein the axes of a first and a second cylinder are spaced from each other by 180° about the crankshaft and wherein the first and second cylinder axes are collinear.

55.6	Two-stroke cycle:
	This subclass is indented under subclass 55.2.  Multiple cylinder engine wherein the pistons in the working cylinders operate on a two-stroke cycle.

55.7	Cylinders opposite and aligned:
	This subclass is indented under subclass 55.6.  Multiple cylinder engine wherein the axes of a first and a second cylinder are spaced from each other by 180° about the crankshaft and wherein the first and second cylinder axes are collinear.

56.1	Having rotary output shaft parallel to cylinders:
	This subclass is indented under subclass 52.1.  Multiple cylinder engine including an elongated rotary output shaft intended to turn about its axis, in which the cylinder axes are parallel with the rotary output shaft axis. (1) Note. In the engine of this subclass, the cylinder axes are usually at equal radial distances from the axis of the main shaft and are arranged around said shaft at equal angular intervals.

56.2	Cam on rotary output shaft:
	This subclass is indented under subclass 56.1.  Multiple cylinder engine wherein the rotary output shaft includes a disk or a drum with an irregularly shaped surface which is engaged by a follower linkage drivingly connected to the pistons to convert the reciprocating motion of the pistons into rotary motion of the output shaft.

56.3	Swash plate type:
	This subclass is indented under subclass 56.2.  Multiple cylinder engine wherein the cam comprises: (a) a disk-shaped plate rigidly connected on an incline to the output shaft, the pistons engage the periphery of the disk-shaped plate with a follower linkage thereby converting reciprocating motion of the pistons to rotary motion of the output shaft; or (b) a disk-shaped plate journaled to an incline to the output shaft such that the plate wobbles without rotating about the output shaft, the pistons are linked to the periphery of the disk-shaped plate by swivel joints so that the reciprocating movement of the pistons produces a wobbling motion of the disk-shaped plate turning the inclined crank producing rotation motion of the output shaft.

56.4	Single bank of cylinders:
	This subclass is indented under subclass 56.3.  Multiple cylinder engine wherein the cylinders are oriented in the same direction and are configured in one group equally spaced from and encircling the output shaft.

56.5	Motion converting means between two banks of cylinders:
	This subclass is indented under subclass 56.3.  Multiple cylinder engine wherein the cylinders are separated into two groups, one on either side of the swash plate, each group is oriented in one direction and encircles the output shaft at equal spacing.

56.6	Multiple swash plate drive:
	This subclass is indented under subclass 56.3.  Multiple cylinder engine wherein the rotary output shaft includes at least two disk-shaped plates inclined to the axis of the output shaft and at least one piston is linked to the periphery of each of the disk-shaped plates such that the reciprocating motion of the pistons is converted into rotary motion of the output shaft.

56.7	Single bank of cylinders:
	This subclass is indented under subclass 56.2.  Multiple cylinder engine wherein the cylinders are oriented in the same direction and are configured in one group equally spaced from and encircling the output shaft.

56.8	Motion converting means between two banks of cylinders:
	This subclass is indented under subclass 56.2.  Multiple cylinder engine wherein the cylinders are separated into two groups, one on either side of the swash plate, each group is oriented in one direction and encircles the output shaft at equal spacing.

56.9	Multiple cam drives:
	This subclass is indented under subclass 56.2.  Multiple cylinder engine wherein the rotary output shaft includes at least two contoured disks or drums and at least one piston linked by a follower arrangement to the contoured surface of the cam, so that reciprocating motion of the pistons is converted into rotary motion of the output shaft.

57.1	Shaft rotates through piston:
	This subclass is indented under subclass 56.1.  Multiple cylinder engine wherein the rotary output shaft extends through and is rotatable in a longitudinal bore in the piston.

58.1	Cylinders in-line:
	This subclass is indented under subclass 52.1.  Multiple cylinder engine including a crankshaft that turns about an axis in the same plane with the axis of first and second cylinders, the pistons of which are drivingly connected to the crankshaft.

58.2	Locked pistons:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine wherein the pistons of the first and second cylinders are immovably secured to each other. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclasses 150 and 151+ for coaxially disposed cylinders for an expansible chamber device.

58.3	Two-stroke cycle:
	This subclass is indented under subclass 58.2.  Multiple cylinder engine wherein the pistons in the working cylinders operate on a two-stroke cycle.

58.4	Lengthwise charging:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine including means for charging the working cylinders, whereby the charging travels generally along the length of the working cylinders.

58.5	Step piston:
	This subclass is indented under subclass 58.4.  Multiple cylinder engine including at least one piston configured with at least two different cross sections along the piston"s length, the configured piston is received in a cylinder with at least two different diameter bores.

58.6	Step piston:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine including at least one piston configured with at least two different cross sections along the piston"s length, the configured piston is received in a cylinder with at least two different diameter bores.

58.7	Cylinder supercharged by pressure pulse of released exhaust gases:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine wherein prior to opening of a first cylinder"s exhaust port, the high pressure exhaust gases of the first cylinder are released to push additional charge into a second cylinder which has already inlet charged at atmospheric pressure.

58.8	Exhaust to next cylinder ready to fire:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine wherein exhaust from a first cylinder is released into a second cylinder to combust the residual fuel in the exhaust.

58.9	Oscillating or reciprocating, nonpoppet valve:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine including a valve mechanism which moves to-and-fro excluding poppet valves. (1) Note. A poppet valve consists of a valve member including a rodlike portion (i.e., stem) connected to the center of a disk-shaped portion, said valve member is resiliently biased into sealing engagement with the rim of a hole (i.e., the seat)

59.1	Rotary valve:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine including a rotating valve mechanism.

59.2	Tapered:
	This subclass is indented under subclass 59.1.  Multiple cylinder engine wherein the outer surface of revolution of the rotary valve includes at least one conical segment, the conical segment is received in a conical bore thereby sealing the conical portion of the rotary valve.

59.3	Sleeve valve:
	This subclass is indented under subclass 59.1.  Multiple cylinder engine wherein the rotary valve consists of a hollow, thin walled surface of revolution lining or in surrounding relationship to at least a portion of a working cylinder.

59.4	Disc valve:
	This subclass is indented under subclass 59.1.  Multiple cylinder engine wherein the rotary valve has one or more thin, circular member(s) with at least one flat surface perpendicular to the axis of rotation.

59.5	Plural carburetors:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine including at least two devices for mixing air and fuel external to the combustion chamber.

59.6	Multiple crankshafts:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine including at least two output shafts, each including one or more cranks, wherein the pistons are at the working cylinder and are drivingly connected to the cranks, thereby converting the reciprocating motion of the pistons into rotary motion of the output shaft.

59.7	Two-stroke cycle:
	This subclass is indented under subclass 58.1.  Multiple cylinder engine wherein the pistons in the working cylinders operate on a two-stroke cycle.

60.1	Locked annular piston:
	This subclass is indented under subclass 52.1.  Multiple cylinder engine including a first piston of circular cross section and including a second piston that is hollow and concentric about the first piston, wherein the two pistons are secured to each other so that they move together.

61	Two-cycle:
	This subclass is indented under the unnumbered subclass, DOUBLE-ACTING.  Internal-combustion engines working on a two-stroke cycle and in which successive burned charges act upon opposite sides of a single piston reciprocating in a single cylinder, whereby the working piston is impelled alternately in each direction. Includes two-cycle engines operating upon recompression and also two-cycle engines operating upon pump-compression cycles, both of which terms are more fully explained hereinafter. The working cylinder in the engines in this subclass is of simple cylindrical form, and the supply-pump for the combustible mixture is wholly separate and distinct from the working cylinder and is not considered in this definition.

62	Combined pump and motor cylinder:
	This subclass is indented under subclass 61.  Internal-combustion engines working on a two stroke cycle and in which successive combustible charges after ignition thereof act so as to impel the working piston alternately in each direction, the elements of the engine and of the pump for supplying the combustible mixture thereto being all contained within a single cylinder structure and so intimately associated as to make mechanical separation of the two sets of elements impossible without defeating the operation of the engine as a whole. SEE OR SEARCH THIS CLASS, SUBCLASS: 66, for combined pump and motor cylinder.

63	Four-cycle:
	This subclass is indented under the unnumbered subclass, DOUBLE-ACTING.  Internal-combustion engines working on the four-stroke cycle, hereinafter defined, in which successive burned charges act alternately upon opposite sides of a single reciprocating piston moving in a single cylinder.

64	SIX-CYCLE:
	This subclass is indented under the class definition.  Internal-combustion engines of the reciprocating type working upon a modified four-stroke cycle with recompression in the working cylinder, as defined in the definition of ... , below, and in which air unmixed with combustible is drawn into and expelled from the working cylinder one or more times upon distinct suction and expelling strokes of the working piston after the end of the exhaust-stroke and before the beginning of the suction-stroke of the normal four-stroke cycle, whereby a more complete removal of the burned gases, from the working cylinder and combustion-chamber is secured.

65	TWO-CYCLE:
	This subclass is indented under the class definition.  Internal-combustion engines having a single single-acting working cylinder and a single working piston reciprocating therein and having suitable means for supplying a combustible mixture thereto, such engines working on the two-stroke cycle and not coming within the definitions of the following subclasses of two-cycle engines. Internal-combustion engines are said to work upon the two-stroke cycle when a combustible mixture under pressure materially greater than atmospheric pressure is burned and the resulting products of combustion allowed to expand within the working cylinder upon every second stroke of the working piston of the engine. The means for supplying the combustible mixture to the engine ordinarily includes a pump operated by and in unison therewith, which pump and engine are generally inseparable without destroying the identity of the device as a whole. In the engines occurring in two-cycle subclasses a combustible mixture is supplied to the working cylinder and burned therein under pressure upon each second stroke of the working piston, and such mixture after having been supplied to the working cylinder at a pressure not necessarily greater than is sufficient to insure its flow there into may be recompressed therein by the working piston or by the working and pump pistons acting together before ignition and the beginning of the working stroke, which is the more ordinary mode of operation, or the mixture may be supplied to the working cylinder after the beginning of the working stroke and at the maximum pressure under which it exists before ignition, in which case it is not recompressed in the working cylinder before ignition, but is ignited either at constant pressure as it enters or at constant volume after the whole charge has been supplied. Two-cycle engines coming within the latter of the above cases are classified as two-cycle pump-compression engines. The combustible mixture is ordinarily supplied to the working cylinder by a pump, and in the first of the above cases, while the charge may be compressed to a considerable degree by the supply-pump, such charge enters the working cylinder only against the pressure of the atmosphere and after having entered must exist therein at or substantially at atmospheric pressure, and the initial compression of the charge upon which the efficiency of an internal-combustion engine so largely depends is produced wholly by recompression of the charge in the working cylinder while in the second case such initial pressure is produced wholly by the supply-pump which compresses the charge directly to the maximum pressure at which it exists before ignition. SEE OR SEARCH THIS CLASS, SUBCLASS: 61, for double-acting two-cycle engines having a separate and distinct supply pump. 62, for double-acting two-cycle engines in which the engine and supply pump elements are contained within a single cylinder structure.

66	Combined pump and motor cylinder:
	This subclass is indented under subclass 65.  Two-cycle internal-combustion engines in which separate and distinct working and pumping pistons operate in a single cylinder a portion of which together with the working piston, forms a motor, while another portion of such cylinder, together with the pumping-piston forms a pump for supplying a fresh charge to the working cylinder. The supply-pump is operated by and in unison with the engine, and as the supply-pump and motor elements of the engine are all contained in a single cylinder the two sets of elements are necessarily inseparable without wholly defeating the operation of the engine in the manner contemplated. SEE OR SEARCH THIS CLASS, SUBCLASS: 62, for combined pump and motor cylinder.

67	Divided pump discharge:
	This subclass is indented under subclass 65.  Two-cycle internal-combustion engines in which the air pumped by a single supply-pump operated by and in unison with the engine is separated or divided into two separate and distinct streams, one of which passes to the working cylinder unchanged, while the other receives a supply of hydrocarbon on its way to the working cylinder. The stream to which no hydrocarbon is supplied ordinarily acts to more or less thoroughly expel the burned gases from the working cylinder prior to the formation of a new charge therein, and the two streams frequently reunite as they enter the working cylinder or shortly before entry thereinto.

68	Pump compression:
	This subclass is indented under subclass 65.  Two-cycle internal-combustion engines in which the combustible mixture, or both the constituents thereof, is supplied to the working cylinder under pressure materially greater than atmospheric pressure, such supply beginning at the beginning of the working stroke and continuing for a determinate portion thereof, the combustible mixture being ignited either at constant pressure as it enters the cylinder or at constant volume after the whole charge has been supplied thereto, in either case without recompression in the working cylinder. The combustible mixture or the constituents thereof may be supplied directly to the working cylinder without preliminary storage or may be supplied to suitable reservoirs interposed between the compressing means and the working cylinder and within which a considerable volume of combustible mixture, or its constituents, is stored. Engines in this subclass in which ignition takes place after the whole charge has been supplied to the working cylinder differ from those in ... which work upon a two-stroke cycle, only in the degree of compression to which the charge is subjected before ignition, and as some of the engines in the subclass above mentioned are provided with a supply-pump for forcing air through a charge-forming device to the cylinder of the engine the combustible mixture thus produced is necessarily supplied to such engines under some pressure. However, where the structure and operation of the device as a whole clearly indicate that the pressure under which the charge is supplied is so slight as to be sufficient only to insure its flow into the working cylinder the engine is classified in subclass 39. In engines working on the two-cycle pump-compression cycle the whole charge properly mixed to form a combustible mixture may be compressed by a single pump or the air and combustible may be compressed by separate pumps to be mixed on their way to the working cylinder or after such constituents have entered thereinto. SEE OR SEARCH THIS CLASS, SUBCLASS: 61, for double-acting engines working on the two-stroke pump-compression cycle. 495+, and 590+, for oil-engines operating upon a cycle similar to that defined by this definition.

69	Separate air and gas pumps:
	This subclass is indented under subclass 65.  Two-cycle recompression internal-combustion engines in which air and combustible in the gaseous form are supplied to the working cylinder or combustion-chamber by separate and distinct pumps, each operated by and in unison with the engine, one at least of the constituents being recompressed within the working cylinder before the ignition of the combustible mixture. The air is ordinarily supplied to the working cylinder of the engine before the gas, and such air is frequently designed to more or less completely scavenge the working cylinder. In such cases a part of the air thus supplied remains in the cylinder to form with the gas subsequently supplied thereto the next following charge. The air and gas may, however, enter the working cylinder simultaneously. The air and gas are ordinarily intermixed within the working cylinder before the completion of the compression stroke, so that the complete charge is recompressed in the working cylinder before the ignition thereof and the beginning of the working stroke; but this subclass also includes engines in which one only of the constituents of the charge is recompressed in the working cylinder, in which case the other is supplied thereto under pressure during the working stroke. SEE OR SEARCH THIS CLASS, SUBCLASS: 61, and 68, for other internal-combustion engines having separate pumps for air and gas. 590+, for oil-engines having one pump for supplying air to the working cylinder thereof and another for supplying oil and air, the oil being frequently atomized by the air, but not vaporized prior to its entry into the working cylinder.

70	Pump and cylinder adjacent:
	This subclass is indented under subclass 65.  Two-cycle recompression internal-combustion engines in which the working cylinder and the pump for supplying a combustible mixture thereto are located adjacent each other, axial lines through the pump and motor cylinders being parallel and perpendicular to the axis of the main shaft of the engine and both lying in a plane passing through the axis of the main shaft. In engines in this subclass the supply-pump is inseparable from the engine and may draw both air and hydrocarbon into the cylinder thereof upon the suction-stroke, so that the pump operated upon the whole charge to be supplied to the working cylinder, or the supply-pump may draw in and discharge air only, in which case the combustible constituent of the charge is supplied to the air during its passage to the working cylinder. SEE OR SEARCH THIS CLASS, SUBCLASS: 68, for pump compression.

71	Pump and cylinder coaxial:
	This subclass is indented under subclass 65.  Two-cycle recompression internal-combustion engines in which the axes of the working and pump cylinders form a single straight line which, if extended, would intersect the main shaft of the engine at right angles, the cylinders abutting and the working piston being prolonged and extended into the pump-cylinder and enlarged therein to form the pumping-piston, thereby forming an annular pumping-chamber which surrounds the extension of the working piston. From the above it follows that the working and pump pistons form a single rigid structure. In engines in this subclass compression of the charge prior to the ignition thereof is effected by the joint action of the pump and motor pistons. The arrangement above defined may be reversed, in which case the cylinder above described as the working cylinder becomes the cylinder of the supply-pump and the annular pumping-chamber becomes the working chamber. (1) Note. The supply-pump is inseparable from the engine and ordinarily operated upon the whole charge, as in engines in subclass 70.

72	Pump and cylinder inclined:
	This subclass is indented under subclass 65.  Two-cycle recompression internal-combustion engines in which the working piston and the pump for supplying a combustible mixture thereto are arranged at an angle to each other, axial lines through the pump and motor cylinders being perpendicular to the main shaft of the engine and lying in planes inclined to each other, which pass through the said main shaft. The axes of the pump and working cylinder also ordinarily lie in a single plane perpendicular to the main shaft of the engine. (1) Note. The supply-pump is inseparable from the engine and ordinarily operated upon the whole charge, as in engines in subclass 70.

73	Crankcase:
	This subclass is indented under the unnumbered subclass, Rear compression.  Two-cycle recompression internal-combustion engines having a cylinder closed at one end and an air-tight casing inclosing the connecting-rod and crank and forming a closed crank-case in open communication with the other end of the cylinder and a piston reciprocating in the said cylinder, such piston performing at the same time the functions of both a working piston and a piston for the pump which supplies a fresh charge to the engine, one end of the cylinder and the corresponding end of the piston constituting the working cylinder and piston, while the other or rear end of the piston and the corresponding end of the cylinder, together with a closed crank-case form a pump for introducing a new charge into the working end of the cylinder. In engines in this subclass the supply or exhaust ports, or both, are generally formed in the cylinder-wall and are then controlled by the piston as it reciprocates, the piston forming a closure for such ports when it is required that they be kept closed.

74	Cylinder:
	This subclass is indented under the unnumbered subclass, Rear compression.  Two-cycle recompression internal-combustion engines having a cylinder closed at both ends and a piston reciprocating therein, such piston performing at the same time the functions of both a working piston and a piston for the pump which supplies a fresh charge to the engine, one end of the cylinder and the corresponding end of the piston constituting the working cylinder and piston, while the other or rear end of the piston and the corresponding end of the cylinder form a pump for introducing a new charge into the working end of the cylinder. In engines in this subclass the supply or exhaust ports, or both, are generally formed in the cylinder-wall and are then controlled by the piston as it reciprocates, the piston forming a closure for such ports when it is required that they be kept closed.

76	Scavenging:
	This subclass is indented under subclass 311.  Four-cycle internal combustion engines in which a volume of air unmixed with combustible is caused to pass through the working cylinder of the engine or the combustion-chamber thereof at any time between the end of the working stroke and the beginning of the next following charging stroke, whereby to secure a more complete removal of the burned gases of the previous charge from the cylinder and combustion-chamber, so that the successive charges will be unmixed with residual burned gases from a previous charge. The scavenging action may take place before or after or be simultaneous with the regular exhaust stroke of the engine. In the engines in this subclass a complete charge comprising all the ingredients necessary to form a combustible mixture enters the cylinder upon distinct charging stroke, the air supplied for the purpose of scavenging, not being necessary to form or complete the following charge. (1) Note. Engines frequently described as scavenging engines and in which a volume of air is caused to pass through the working cylinder and combustion-chamber for the same purpose as in this subclass, but in which a portion of such air is necessary to complete the following charge, are classified in this class, subclass 69. In subclass 76, the engine begins its suction-stroke with air in the clearance space only, while in engines in subclass 69, the engine begins it compression-stroke with a considerable volume of air in the cylinder thereof, to which a combustible is supplied to complete the charge. SEE OR SEARCH THIS CLASS, SUBCLASS: 64, and 69, for six-cycle two-cycle Separate Air and Gas Pumps.

77	Single revolution:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines in which a four-stroke cycle is carried out during a single revolution of the main shaft of the engine. For the purposes of this definition of continuous movement of the working piston in one direction is considered as two strokes and the sequence of the strokes is varied from that present in engines working on the ordinary four-stroke cycle, the working stroke being followed by the charging stroke as the piston moves in one direction and the exhaust and compression strokes taking place in the order named as the piston moves in the reverse direction. (1) Note. For engines working on this cycle, but having two or more working cylinders, see this class, subclass 53. (2) Note. For other engines in which the four strokes comprising a single cycle occur during a single revolution of the main shaft of the engine, see this class, subclass 78.

78	Variable clearance:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines provided with means whereby the clearance-space is varied in unison with the movement of the working piston, being as far as practicable eliminated at the end of the exhaust-stroke and greatest at the end of the compression-stroke, whereby to secure a more complete removal of the residual burned gases from the cylinder and combustion-chamber of the engine. The clearance-space is ordinarily varied by causing the strokes of the working piston to vary in length, and the four strokes required for a complete cycle are frequently performed during a single revolution of the main shaft of the engine. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclass 84 for an expansible chamber device having a resilient means interposed between the working member and a relatively movable power transmission element.

79	Single poppet valve:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines in which the combustible charge enters the working cylinder and after ignition and expansion the burned gases are exhausted therefrom through a single passage controlled by a single positively-operated poppet or equivalent valve, said common passage being provided with means for directing the flow of the combustible charge from a supply-conduit to the common conduit and for directing the flow of the exhaust-gases from such common conduit into the exhaust-conduit leading from the engine. The directing means ordinarily comprise a valve or valves operated either positively or by the suction and pressure alternately existing in the common conduit, and such means are protected from the pressure of the gases within the cylinder by the single valve.

80	Rotating valve:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines provided with a rotating valve for directly controlling the supply of combustible mixture to the working cylinder or the exhaust of burned gases therefrom and means operated by the engine for rotating the said valve to secure the continuous and automatic operation of the engine. The rotating valve in the engines in this subclass ordinarily control both the supply to and the exhaust from the engine and frequently also a passage used in connection with a flame or incandescent igniting device, and the valve is so designed with reference to the particular engine with which it is used or with reference to other elements of the engine as to be incapable of convenient separation therefrom or of use with other engines. (1) Note. For rotating valves capable of general use with internal-combustion engines, the structure of the engine or of elements thereof other than the valve not being involved, see this class, subclass 190. SEE OR SEARCH THIS CLASS, SUBCLASS: 144, and 151, for flame and combined Sparker and Valve.

81	Oscillating valve:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines provided with an oscillating valve for directly controlling the supply of combustible mixture to the working cylinder or the exhaust of burned gases therefrom and means operated by the engine for oscillating the said valve to secure the continuous and automatic operation of the engine. The oscillating valve ordinarily controls both the supply to and the exhaust from the engine and frequently also a passage used in connection with a flame or incandescent igniting device, and the valve is so designed with reference to the particular engine with which it is used or with reference to other elements of the engine as to be incapable of convenient separation therefrom or of use with other engines. (1) Note. For oscillating valves capable of general use with internal-combustion engines, the structure of the engine or of elements thereof other than the valve not being involved, see this class, subclass 190. SEE OR SEARCH THIS CLASS, SUBCLASS: 144, for flame.

82	Rotating side shaft:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having a rotating shaft driven from the crank-shaft thereof and extending parallel to the axis of the working cylinder and ordinarily along the side of the engine, said shaft being provided with means, generally in the form of cams, for operating in the proper order one or more of the valves, the igniting device or other element necessary for the continuous automatic operation of the engine, and mechanism including a rotating shaft located as above set forth and designed to operate the valves or other elements of the engine, but not shown in connection with all the elements necessary to form a complete and operative engine. SEE OR SEARCH THIS CLASS, SUBCLASS: 57, for cylinders tandem.

83	Rotating transverse shaft:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having a rotating shaft driven from the crank-shaft thereof and extending transverse to the axis of the working cylinder and clear across the engine, said shaft being provided with means, generally in the form of cams, for operating in the proper order one or more of the valves, the igniting device, or other element necessary for the continuous automatic operation of the engine, and mechanism including a rotating shaft located as above set forth and designed to operate the valves or other elements of the engine, but not shown in connection with all the elements necessary to form a complete and operative engine. SEE OR SEARCH THIS CLASS, SUBCLASS: 84, for engines coming within the terms of this definition, except that the transverse shaft does not extend clear across the engine, the axis of such shaft lying in a plane passing through the axis of the working cylinder.

84	Adjacent supply and exhaust valves:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having the supply and exhaust valves thereof located adjacent and in a single valve-chamber, the axes of such valves being parallel with the axial line of the working cylinder and both valves being positively operated, and reciprocating rods extending longitudinally of the engine and operated by and in unison therewith for operating such valves in the proper order to secure the continuous automatic operation of the engine, and similar arrangements of valves and operating means therefor but not shown in connection with all the elements necessary to form a complete and operative engine.

85	Aligned supply and exhaust valves:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having the supply and exhaust valves thereof arranged in alinement and in a single valve-chamber, the common axis of such valves being parallel with the axial line of the working cylinder, and a reciprocating rod or rods extending longitudinally of the engine and operated by and in unison therewith for operating one or both such valves in the proper order to secure the continuous automatic operation of the engine, and similar arrangements of valves and operating means therefor, but not shown in connection with all the elements necessary to form a complete and operative engine.

86	Opposite supply and exhaust valves:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having the supply and exhaust valves thereof located in separate valve-chambers upon opposite sides of the working cylinder, the axes of such valves being parallel with the axial line of the working cylinder and lying in a plane passing therethrough and through the axis of the crank-shaft, and a reciprocating rod or rods extending longitudinally of the engine and operated by and in unison therewith for operating one or both of such valves in the proper order to secure the continuous automatic operation of the engine, and similar arrangements of valves and operating means therefor, but not shown in connection with all the elements necessary to form a complete and operative engine.

87	Longitudinal valve and lever:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having the supply or exhaust valve thereof, or both, located in the cylinder head and disposed longitudinally to the working cylinder, the movement of such valve or valves being along a line parallel with the axial line of the working cylinder, a lever disposed transverse to the working cylinder and a reciprocating operating member operated by and in unison with the engine for operating such valve or valves in the proper order to secure continuous operation thereof, and similar arrangements of valves and operating means therefor, but not shown in connection with all the elements necessary to form a complete and operative engine.

88	Transverse valve and lever:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having the supply or exhaust valve thereof, or both, disposed transverse to the working cylinder, the axis of such valve or valves lying in a plane perpendicular to the axial line of the working cylinder, and a lever extending longitudinally of the engine and operated by and in unison therewith for operating the valve or valves aforesaid in the proper order to secure the continuous automatic operation thereof, and similar arrangements of valves and operating means therefor, but not shown in connection with all the elements necessary to form a complete and operative engine.

89	Transverse valve and bell crank:
	This subclass is indented under subclass 311.  Four-cycle internal-combustion engines having the supply or exhaust valve thereof, or both, disposed transverse to the working cylinder, the axis of such valve or valves lying in a plane perpendicular to the axial line of the working cylinder, and a bell-crank lever operated by and in unison with the engine for operating such valve or valves in the proper order to secure the continuous automatic operation thereof, and similar arrangements of valves and operating means therefor, but not shown in connection with all the elements necessary to form a complete and operative engine.

90.1	POPPET VALVE OPERATING MECHANISM:
	This subclass is indented under the class definition.  Subject matter relating to mechanism intermediate the crank-shaft and the poppet-type intake or exhaust valve of an internal combustion engine for operating at least one such valve. (1) Note. If the mechanism operates a reciprocating valve of a type other than a poppet valve, a body of art of such mechanism--as well as the valve that it operates--has evolved in subclass 188. (2) Note. The majority of the valve operating devices of this subclass are disclosed in connection with four-stroke-cycle engines; however, the devices occurring herein are not dependent upon the mode of operation of the engine, and are ordinarily capable of operating a poppet-type valve of an engine functioning upon a cycle of some other number of strokes. Valve operating mechanism especially designed for use with an engine of a particular form or mode of operation will be found in the subclasses pertaining to that engine. SEE OR SEARCH THIS CLASS, SUBCLASS: 41, for valve operating mechanism rendering the engine reversible. 64, for valve operating mechanism peculiar to a six-cycle engine. 65+, for valve operating mechanism peculiar to a two-cycle engine. 152, for valve operating mechanism combined with sparker operating mechanism. 179+, (particularly subclass 182), for valve operating mechanism related to facilitating engine starting. 188, for valve operating mechanism peculiar to reciprocating valves not of the poppet-type; see (1) Note above. 311+, (particularly subclasses 79 through 89), for valve operating mechanism peculiar to a four-cycle engine. 319+, for valve operating mechanism peculiar to the regulation of engine speed. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   appropriate subclasses for the actuation of valves of more general utility.

90.11	Electrical system:
	This subclass is indented under subclass 90.1.  Device wherein electrical energy provides the source of power for at least one direction of movement of the valve.

90.12	Hydraulic system:
	This subclass is indented under subclass 90.1.  Device wherein a liquid under pressure provides an essential link in the valve operating mechanism for at least one direction of movement of the valve. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 12+ , for a valve of more general utility which is opened or closed by fluid pressure.

90.13	With manifold and distributor:
	This subclass is indented under subclass 90.12.  Device wherein the liquid under pressure is cyclically delivered through a manifold by an engine-driven distributor.

90.14	Pneumatic system:
	This subclass is indented under subclass 90.1.  Device wherein positive or negative pressure of a gas provides the source of power for at least one direction of movement of the valve. SEE OR SEARCH THIS CLASS, SUBCLASS: 90.32, for a pneumatically-controlled interruption in the drive train of a valve that is not pneumatically actuated. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclasses 12+ , for a valve of more general utility which is opened or closed by fluid pressure.

90.15	With means for varying timing:
	This subclass is indented under subclass 90.1.  Device wherein means provided to vary the time, extent of duration of valve opening relative to the operating cycle of the engine. (1) Note. In the art herein the timing is varied to maximize engine efficiency, whereas in that of subclasses 319+ it is varied for the purpose of speed regulation or braking. SEE OR SEARCH CLASS: 464,  Rotary Shafts, Gudgeons, Housings, and Flexible Couplings for Rotary Shafts,   subclasses 1+ for a speed responsive device for adjusting the relative rotational position of coupled members.

90.16	Cam-to-valve relationship:
	This subclass is indented under subclass 90.15.  Device wherein the means is located between a cam and the valve actuated thereby and serves to modify the operational relationship of the one to the other.

90.17	Camshaft or cam characteristics:
	This subclass is indented under subclass 90.15.  Device wherein the means varies the structure or the axial disposition of a camshaft or its cam.

90.18	Axially shiftable camshaft:
	This subclass is indented under subclass 90.17.  Device wherein the means provides for displacing the camshaft in the direction of its longitudinal axis, thereby bringing a different cam contour into play.

90.19	With temperature compensation:
	This subclass is indented under subclass 90.1.  Device wherein means is provided to compensate for structural deformation in an element of the operating mechanism occurring as a result of a change in the ambient temperature of the element.

90.2	With compound movement of cam follower:
	This subclass is indented under subclass 90.1.  Device wherein means in the form of a groove, or its equivalent, in the outer surface of a revolving drum is provided to displace the cam follower both axially and radially of the camshaft. (1) Note. The groove is usually in the form of two, intersecting loops, of different effective elevations, and the effect of the axial displacement of the follower from one loop to the other is to impart a valve-actuating movement to it upon every other revolution of the camshaft. (2) Note. In a device of this nature, the crankshaft frequently serves as the camshaft.

90.21	Follower displaced axially of camshaft:
	This subclass is indented under subclass 90.1.  Device wherein means is provided, usually in the form of lobes perpendicular to the principal surface of a rotating disc, to displace a cam follower in a direction parallel to the longitudinal axis of the camshaft.

90.22	Plural valve trains, single actuator:
	This subclass is indented under subclass 90.1.  Device wherein one actuating element (cam) operates one or more other elements (followers, rods, rockers, etc.), in the valve trains of two or more valves of a cylinder. SEE OR SEARCH THIS CLASS, SUBCLASS: 90.4, for plural valves operated by a single train having a forked or branched rocker.

90.23	Intake and exhaust:
	This subclass is indented under subclass 90.22.  Device wherein the two or more valves control the intake and the exhaust passages of the cylinder.

90.24	Valve driven closed:
	This subclass is indented under subclass 90.1.  Device wherein means is provided to mechanically drive the valve in its closing (i.e., seating) direction of travel. (1) Note. While correctly identified as Desmodromic actuation, this aspect of valve operation frequently is termed "positive closing" (as contrasted with "spring return").

90.25	By valve-opening rocker:
	This subclass is indented under subclass 90.24.  Device wherein the driving means is the rocker that opens the valve.

90.26	By cam-actuated unitary follower:
	This subclass is indented under subclass 90.24.  Device wherein the driving means is a follower that is joined to the cam in such fashion as to partake of the total range of movement of the cam. (1) Note. By virtue of their marked similarity, eccentric-actuated unitary followers are included herein.

90.27	Overhead camshaft:
	This subclass is indented under subclass 90.1.  Device wherein the shaft carrying the actuating element (cam) of the operating mechanism is located in proximity to, and generally somewhat above, the valve-containing head of an engine cylinder. SEE OR SEARCH THIS CLASS, SUBCLASS: 193, for structural features of an engine cylinder.

90.28	With nonvalving movement (e.g., about valve stem):
	This subclass is indented under subclass 90.1.  Device wherein means is provided for movement of the valve in addition to that of opening and closing. (1) Note. Ordinarily this movement is in the form of rotation of the valve about the principal axis of its stem for such purposes as random seating surface engagement, seat cleaning, etc. SEE OR SEARCH CLASS: 137,  Fluid Handling,   subclasses 330+ , for nonvalving motion in a valve of more general utility. 251,  Valves and Valve Actuation,   subclass 56 , for a pressure actuated valve of more general utility having plural motions of the valve, and subclasses 215+, for a mechanical movement actuated valve of more general utility having plural motions of the valve.

90.29	Oscillating movement converted internally:
	This subclass is indented under subclass 90.28.  Device wherein means is provided within the operating mechanism to convert the oscillation imparted to the valve by the compression and decompression of its return spring into unidirectional movement (i.e., rotation). SEE OR SEARCH THIS CLASS, SUBCLASS: 90.28+, for devices generally similar to those of this subclass but involving (e.g., by attachment thereto) an element external to the operating mechanism.

90.3	Positive rotation provided by internal means:
	This subclass is indented under subclass 90.28.  Device wherein means is provided within the operating mechanism to rotate the valve. (1) Note. A device of this subclass is often referred to as a positive rotator, and usually comprises a self-contained, insertable unit.

90.31	Camshaft drive means:
	This subclass is indented under subclass 90.1.  Device wherein means is provided to drive a member (normally a rotating shaft) carrying the actuating element (cam) of the operation mechanism. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   appropriate subclasses for a specific power transfer means.

90.32	With alternate interruption of drive train:
	This subclass is indented under subclass 90.1.  Device wherein means is provided in an element (e.g., push rod, tappet, etc.), between the cam and the valve rendering that element ineffective--and interrupting the valve actuation--during alternate revolutions of the crankshaft. SEE OR SEARCH THIS CLASS, SUBCLASS: 90.31, for a cam that is driven in such fashion as to produce alternate interruption of actuation.

90.33	Lubrication:
	This subclass is indented under subclass 90.1.  Device wherein means is provided for supplying, or controlling a supply of, lubricant to one or more elements of the operating mechanism. SEE OR SEARCH THIS CLASS, SUBCLASS: 196, for lubricating means in general for internal combustion engines. SEE OR SEARCH CLASS: 184,  Lubrication,   subclass 6 , for lubricating systems for machines, particularly the bearing parts thereof, where no special combination exists between the system and the machine. 251,  Valves and Valve Actuation,   subclass 355 , for lubricating a valve of more general utility.

90.34	Camshaft:
	This subclass is indented under subclass 90.33.  Device wherein a lubricant supply means directs lubricant under pressure to the camshaft and its cams.

90.35	Tappet as conduit:
	This subclass is indented under subclass 90.33.  Device wherein a lubricant supply means directs lubricant under pressure through a tappet to another element of the operating mechanism.

90.36	Rocker fulcrum as conduit:
	This subclass is indented under subclass 90.33.  Device wherein a lubricant supply means directs lubricant under pressure through a rocker fulcrum (sometimes a tubular rocker support shaft) to another element of the operating mechanism.

90.37	Seals and shields:
	This subclass is indented under subclass 90.33.  Device wherein a lubricant control means is provided to restrict, confine or direct a supply of lubricant for the operating mechanism. (1) Note. Included herein are valve stem seals or shields which are movable with the operating mechanism. SEE OR SEARCH THIS CLASS, SUBCLASS: 188.6, for a valve stem seal or shield fixed to the engine (e.g., fixed to the valve stem guide, etc.). SEE OR SEARCH CLASS: 277,  Seal for a Joint or Juncture,   for a generic sealing means or process, subclasses 500+ for a dynamic, circumferential contact seal for other than a piston, especially subclass 502 for a valve stem seal for an internal combustion engine.

90.38	Housings:
	This subclass is indented under subclass 90.33.  Device wherein means is provided to enclose a portion of the operating mechanism which is subject to unrestrained lubricant flow. (1) Note. Ordinarily the means is detachable, and frequently is serves as an access opening cover.

90.39	Rocker:
	This subclass is indented under subclass 90.1.  Device comprising a pivoted element, usually directly engaging a valve stem, which transmits the motion developed in the operating mechanism to the valve. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclasses 519+ and 559, for linkage system elements in the form of a lever and a rocker arm, respectively.

90.4	Plural valves:
	This subclass is indented under subclass 90.39.  Device wherein the rocker element includes means to transmit motion to more than one valve.

90.41	Individually fulcrumed:
	This subclass is indented under subclass 90.39.  Device wherein the pivot means provided for the rocker element is separate form and independent of the pivot means provided for any like, pivoted element.

90.42	Rotation prevention:
	This subclass is indented under subclass 90.41.  Device wherein means is provided to restrict the pivotal movement of a rocker element to a plane defined by the pivot and by the stem of the valve which the rocker element engages.

90.43	Lash adjustment at fulcrum:
	This subclass is indented under subclass 90.41.  Device wherein means is provided in the region of the pivot to vary the relationship of the rocker element to other elements of the operating mechanism in order to create, modify or eliminate clearance (lash) in the mechanism. (1) Note. In most instances the lash adjusting means of a device of this subclass is of the self-operating kind; i.e., it functions on its own initiative in response to the presence of an incorrect amount of lash.

90.44	Cam engaged:
	This subclass is indented under subclass 90.39.  Device wherein the rocker element is in direct contact with the actuating element (cam) of the operating mechanism.

90.45	Lash adjustment:
	This subclass is indented under subclass 90.39.  Device wherein the rocker element is provided (other than at its pivot) with means to create, modify or eliminate clearance (lash) in the operating mechanism. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclass 522 , for a linkage system element in the form of an adjustable lever.

90.46	Hydraulic:
	This subclass is indented under subclass 90.45.  Device wherein the lash adjusting means is of the reciprocating hydraulic chamber type.

90.47	Yieldable engagement:
	This subclass is indented under subclass 90.39.  Device wherein means is provided to afford a degree of resilience to the transmitting of motion by the rocker element. (1) Note. In keeping any clearance or slack taken up (although not eliminated), the resilient means also serves to reduce the noise of operation.

90.48	Tappet:
	This subclass is indented under subclass 90.1.  Device comprising an element which is in direct contact with the actuating element (cam) and which transmits (ordinarily by reciprocatory movement) the motion of that element to other components of the operating mechanism. (1) Note. Occasionally a tappet is more descriptively referred to as a cam follower. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclass 569 for a mechanism element in the form of a cam follower.

90.49	Cushion and silencer:
	This subclass is indented under subclass 90.48.  Device wherein the tappet element includes a nonmetallic insert or yieldable clearance take-up means to soften and/or reduce the noise of its transmitting of motion.

90.5	Rotation prevention:
	This subclass is indented under subclass 90.48.  Device wherein means provided to restrict the movement of the tappet element to the reciprocatory one intended to be imparted to it by the actuating element (cam). (1) Note. This provision is most likely to be found where the tappet includes a roller for engagement by the cam.

90.51	Composition, surface treatment manufacture:
	This subclass is indented under subclass 90.48.  Device wherein the composition of material or the surface treatment or the process of manufacture, or more than one of them, of a tappet element is of primary concern. SEE OR SEARCH CLASS: 29,  Metal Working,   subclass 888.43 , for a process of making a tappet. 428,  Stock Material or Miscellaneous Articles,   subclasses 544+ for stock materials, e.g., of indefinite length, which are all metal or have adjacent metal components.

90.52	Lash adjustment:
	This subclass is indented under subclass 90.48.  Device wherein the tappet element is provided with means to create, modify or eliminate clearance (lash) in the operating mechanism.

90.53	Self-operating:
	This subclass is indented under subclass 90.52.  Device wherein the adjusting means of the tappet element functions on its own initiative in response to the presence of an incorrect amount of clearance (lash) in the operating mechanism.

90.54	Screw:
	This subclass is indented under subclass 90.53.  Device wherein the self-operating adjusting means is of the mechanical screw type.

90.55	Hydraulic:
	This subclass is indented under subclass 90.53.  Device wherein the self-operating adjusting means is of the reciprocating hydraulic chamber type. (1) Note. Requisite to a device of this nature is the presence, within the tappet element, of a reservoir, a pressure (or power) chamber, and a check valve to isolate the chamber from the reservoir.

90.56	Pressure flow upwardly into pressure chamber:
	This subclass is indented under subclass 90.55.  Device wherein the reciprocating hydraulic adjusting means has its pressure chamber located above (gravity-wise) its reservoir.

90.57	Vent or bleed means for pressure chamber:
	This subclass is indented under subclass 90.55.  Device wherein the reciprocating hydraulic adjusting means has a fluid vent from its pressure chamber. (1) Note. This characteristic is in contrast with the provision of such an outlet from the reservoir, which is relatively common. (2) Note. The presence of an anti-pump-up provision may be indicated where the medium vented is a liquid; the venting of a gas, on the other hand, indicates merely a provision to maintain the hydraulic fluid in a noncompressible (liquid) state.

90.58	Self-contained:
	This subclass is indented under subclass 90.55.  Device wherein the reciprocating hydraulic adjusting means is precharged with fluid and usually sealed; consequently, it does not require a continuous, external fluid supply (e.g., the lubricating system of an engine).

90.59	With provision for horizontal positioning:
	This subclass is indented under subclass 90.55.  Device wherein the reciprocating hydraulic adjusting means is modified in such fashion as to maintain the reservoir sufficiently charged that the check valve will be kept submerged while the means reciprocates in a generally horizontal plane.

90.6	Cam:
	This subclass is indented under subclass 90.1.  Device comprising a noncircular or eccentrically disposed surface formed on a rotating element, which constitutes the initial actuating means of the operating mechanism. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclass 567 , for a mechanism element in the form of a cam.

90.61	Rod:
	This subclass is indented under subclass 90.1.  Device comprising an elongated, reciprocating element located between a tappet and a rocker or valve and serving to transmit the motion of the tappet thereto. (1) Note. An element of the kind contemplated here may include means whereby its length can be changed manually in order to create, modify or eliminate clearance (lash) in the operating mechanism. In some types of mechanism (e.g., cam-engaged rocker), the element is not utilized. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclasses 579+ , for a mechanism element in the form of a rod.

90.62	Self-adjusting:
	This subclass is indented under subclass 90.61.  Device wherein the rod element includes a length-changing means which functions on its own initiative in response to the presence of an incorrect amount of clearance (lash) in the operating mechanism.

90.63	Hydraulic:
	This subclass is indented under subclass 90.62.  Device wherein the self-adjusting means of the rod element is of the reciprocating hydraulic chamber type.

90.64	Pull type:
	This subclass is indented under subclass 90.61.  Device wherein the rod element is subjected to tension while performing its operational function. (1) Note. This characteristic is in contrast with the arrangement found with most rod elements, which are of the "push" type and therefore function in compression. In a few instances the pull-type rod directly engages the valve, thereby eliminating the rocker element.

90.65	Spring:
	This subclass is indented under subclass 90.1.  Device comprising a resilient element which is utilized to bias a valve toward its normal (usually closed) position. SEE OR SEARCH CLASS: 251,  Valves and Valve Actuation,   subclass 337 , for a valve spring and for means for associating a spring with a valve where the valve is of more general utility. 267,  Spring Devices,   appropriate subclasses for a spring device of more general utility.

90.66	Attenuated:
	This subclass is indented under subclass 90.65.  Device wherein means is provided to dampen or otherwise regulate the rate at which the spring element imparts to the valve the potential energy that it received through the operation of the valve mechanism.

90.67	Seat and retainer:
	This subclass is indented under subclass 90.65.  Device wherein means is provided for receiving the fixed end portion of a spring element and/or for retaining the other end portion thereof in engagement with a valve or its operating mechanism. SEE OR SEARCH THIS CLASS, SUBCLASS: 90.28+, for a spring seat or a retainer comprising a portion of a device having to do with nonvalving motion of a valve.

142.5	WITH HEATING MEANS:
	This subclass is indented under the class definition.  Devices not provided for in any of the preceding subclasses or in other classes including (1) the combination of an internal-combustion engine with means for supplying external energy to heat the engine, or (2) the combination of an internal combustion engine and means supplying external energy to heat some part or adjunct of the engine such as a radiator, or (3) internal-combustion engines having means using heat from one part to heat another part by exchanging heat between the parts. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.01+, for internal combustion engine cooling systems and devices and see notes thereto. Such systems and devices including means to heat the radiator and/or other parts of the cooling system are classified in this subclass (142.5). 179, for starting devices there provided for combined with heating means where some starting feature other than heating is claimed. 196, for internal combustion engine lubricators there provided for combined with means for heating and/or cooling the lubricant or lubricator only, including such devices using the engine cooling fluid for lubricant or lubricator heating and/or cooling. 543+, for charge-forming devices there provided for combined with heating means. SEE OR SEARCH CLASS: 122,  Liquid Heaters and Vaporizers,   particularly subclass 23 and see notes thereto for field of search for fluid fuel heaters not in combination with an internal-combustion engine. 126,  Stoves and Furnaces,   subclass 19.5 for a combustion engine heated cooking stove, oven, or vessel; subclasses 93-97 for a heating stove that burns liquid fuel that may have a detachable hood that is placeable over an internal-combustion engine; and subclasses 271.1-271.3 for a surface heater that may use heat from the exhaust or cooling fluid of an engine. 165,  Heat Exchange,   subclasses 51+ for an engine installed heat exchanger that does not include significant internal-combustion engine structure. 184,  Lubrication,   subclasses 6 and 104.1+, for lubricators combined with heating means there provided for. 237,  Heating Systems,   subclasses 2 , 5, 12.3, and 12.4+ for vehicle heating systems using rejected heat of internal combustion engines. 290,  Prime-Mover Dynamo Plants,   particularly subclass 2 , for prime mover dynamo systems producing heat, and subclass 38, for prime mover dynamo systems having an electric motor for starting the prime mover. 392,  Electric Resistance Heating Devices,   subclasses 311+ for electric heaters for heating fluids not limited to an internal-combustion engine combination. 432,  Heating,   subclasses 227 through 232for a heat generator with an associated work support or heat delivery structure.

143	IGNITERS:
	This subclass is indented under the class definition.  Miscellaneous devices not coming within the terms of the definitions of the following subclasses of igniters for igniting the successive combustible charges supplied to and burned within an internal-combustion engine. SEE OR SEARCH THIS CLASS, SUBCLASS: 184, for devices for igniting the charge within the working cylinder at starting and designed for temporary use at such times. SEE OR SEARCH CLASS: 313,  Electric Lamp and Discharge Devices,   subclasses 118+ for spark plugs of the jump spark type. 361,  Electricity: Electrical Systems and Devices,   subclasses 247+ for electric igniters and igniter systems.

144	Flame:
	This subclass is indented under subclass 143.  Igniting devices for internal-combustion engines comprising a burner located without the working cylinder and means for igniting the combustible charge in the working cylinder from the flame of the burner either by causing the flame itself to come into direct contact with the combustible charge within the working cylinder or by causing the flame to ignite an auxiliary volume of combustible gas, which burning gas is then moved into direct contact with the combustible charge within the working cylinder. Also contains patents in which a flame-igniting device as above defined is disclosed and claimed in combination with the supply or exhaust valve of the engine or with a valve controlling both the supply and exhaust ports. Flame-igniting devices capable of use only with internal-combustion engines operating upon noncompression cycles are when disclosed or claimed in patents claiming also a complete noncompression engine, considered as a part of such an engine and are not cross-referenced into this subclass. SEE OR SEARCH THIS CLASS, SUBCLASS: 39, noncompression.

145	Incandescent:
	This subclass is indented under subclass 143.  Igniting devices for internal-combustion engines comprising an igniting member maintained at a temperature sufficient to ignite the combustible mixture when it comes into contact therewith and heating means for maintaining such igniting member at a high temperature, generally at incandescence, whereby the combustible charge will be ignited upon coming into contact with the igniting member. (1) Note. The igniting member may extend without the working cylinder or combustion-chamber of the engine, in which case it is generally maintained at a high temperature by means of an external heating-burner or the said igniting member may be located wholly within the working cylinder or combustion-chamber, in which case it is ordinarily maintained in a heated condition by the burning gases within the engine. The heating means for the igniting devices ordinarily forms no part of the igniting device itself; but such burners as are especially designed for and adapted to be used with an incandescent igniting device and are disclosed in connection with such a device are classified in this subclass. SEE OR SEARCH THIS CLASS, SUBCLASS: 250+, and indented subclasses, and 146, for other patents relating to devices located within the working cylinder or combustion-chamber of an internal combustion engine and designed to or which in fact would both vaporize oil supplied to the engine and ignite the resulting combustible mixture.

146	Valve controlled:
	This subclass is indented under subclass 145.  Incandescent igniting devices differing from those in the preceding subclass in that a valve operated by and in unison with the engine is provided for controlling the flow of the combustible charge to the igniting elements, whereby the time at which ignition of the charge takes place may be determined.

146.5	Sparkers:
	This subclass is indented under subclass 143.  Devices for igniting the successive combustible charges supplied to and burned within an internal-combustion engine, comprising electrodes extending into the space occupied by the charge to be ignited and electrical means for producing a spark or a series of sparks between the said electrodes, whereby the charge is ignited and subordinate and auxiliary devices designed and especially adapted for use with igniting devices of the type set forth above and incapable of use in the manner contemplated in other relations. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   subclass 19.01 , and indented subclasses, for intermittent circuit-closers which include distributors for internal-combustion engine ignition. 315,  Electric Lamp and Discharge Devices: Systems,   appropriate subclasses, for electrical, systems for supplying electric energy to electric space discharge devices of the arc or spark type. Merely claiming the spark or arc system as an ignition system will not exclude the system from class 315, provided that the claims are not otherwise limited by claimed subject matter to use with an internal-combustion engine. Such systems which include a periodic switch driven by the engine for timing the spark with reference to the engine cycle are in this subclass (146.5) or the indented subclasses of this class (123). Merely calling the discharge device a "spark plug" will not exclude the patent from Class 315. Note especially subclass 209 and indented subclasses of class 315, which provide for systems having a periodic switch in the supply circuit of the discharge device, and subclass 211, where the system includes a plurality of discharge devices and a distributor switch for distributing the energy to the discharge devices in sequence.

147	Low tension:
	This subclass is indented under subclass 146.5.  Miscellaneous sparking devices for internal-combustion engines in which a current of electricity of low electromotive force is employed, thus necessitating the use therewith of electrodes normally out of contact with each other and which must be brought into contact and separated to produce a spark, as in the following make-and-break subclasses of electrical igniting devices, and subordinate and auxiliary devices designed for use with and to form a part of such an igniting device and incapable of use in the manner contemplated, in other relations, the device in question in either case not coming within the terms of the definition of some one of the following sparker subclasses. SEE OR SEARCH CLASS: 361,  Electricity: Electrical Systems and Devices,   subclasses 247+ for electric igniting devices.

149	Dynamos:
	This subclass is indented under subclass 146.5.  Mechanism whereby a dynamo-electric machine is operated by an engine and is adapted to furnish a current of electricity for the purpose of igniting the successive, combustible charges supplied thereto and patents disclosing and claiming a dynamo in combination with igniting mechanism, which, considered by itself, would be classifiable in some one of the following igniter subclasses, the connection between the two being other than by means of mere conducting-wires, and patents disclosing and claiming dynamo-electric machines having features of construction or peculiarities in mode of operation particularly adapting them for use with internal-combustion engines for the purposes of igniting the successive combustible charges supplied thereto and rendering their use in other relations or with other devices impossible, or at least unlikely. Dynamo coming within the last of the above cases are generally so intimately associated with or built into the elements constituting the engine with which they are used as to be incapable of separation therefrom and of operation or existence as separate mechanism. (1) Note. Dynamo-electric machines complete in themselves having no element in common with an internal-combustion engine and capable when put in operation of furnishing a current of electricity available for any purpose to which the current produced by the said dynamo is suitable are classified in suitable subclasses of Class 310, Electrical Generator or Motor Structure, according to the type of device in question, and neither a positive statement in the specification to the effect that the device in question is intended to be used to furnish current for the igniting device of an internal-combustion engine nor the fact that a claim positively includes an internal-combustion engine or its igniting device in general terms will be sufficient to cause a patent for such a dynamo to be classified as an igniting device for internal combustion engines. (2) Note. Mechanism interposed between an internal combustion engine and a dynamo driven thereby and designed to furnish current for the igniting device of such engine, the purposes of said mechanism being to maintain a constant speed of the dynamo irrespective of variations in speed of the engine, are not classified in this subclass. For such devices see Class 188, Brakes, subclasses 180+; Class 192, Clutches and Power-Stop Control, subclasses 103, 104 and 105 and Class 310, Electrical Generator or Motor Structure, subclasses 75+. SEE OR SEARCH THIS CLASS, SUBCLASS: 147, and 594+, for low tension and high tension ignition systems. SEE OR SEARCH CLASS: 290,  Prime-Mover Dynamo Plants,   for pertinent subclass(es) as determined by schedule review.

150	Combined adjusting and exhaust regulating:
	This subclass is indented under subclass 146.5.  Manually operated means used in connections with sparking devices for determining the time in the cycle of operation of the engine at which the charge will be ignited, in combination with means for acting upon the exhaust-valve of the engine to regulate the said valve, said last-mentioned means ordinarily operating either to cause the exhaust-valve to be opened upon the compression-stroke of the engine to thereby facilitate the starting thereof or to maintain the exhaust-valve in a partially or wholly open position thereby acting as a manually controlled speed-regulator.

151	Combined sparker and valve:
	This subclass is indented under subclass 146.5.  Devices comprising a valve for controlling the supply of combustible mixture to the working cylinder or combustion-chamber of an internal-combustion engine or the exhaust of burned gases therefrom, or both the supply and exhaust, together with a sparking device one or both the electrodes of which is carried by and moves with the said valve.

152	Combined valve and sparker operating:
	This subclass is indented under subclass 146.5.  Valve-operating mechanism and sparker-operating mechanism in combination and either with or without speed-controlling mechanism. In such of the devices occurring in this subclass as include speed-controlling mechanism the speed-regulator is frequently of the charge-omitting type, and the combined valve and sparker operating mechanism then takes the form of means operating to interrupt the operation of the igniting device of the engine while the supply of combustible charges thereto is suspended. The valve acted upon may be the supply, exhaust, fuel, or other valve upon which the operation of the engine depends, and the sparking device is always of the make-and-break type, hereinafter defined. (1) Note. This subclass does not include devices in which the only connection between the valve-operating mechanism and the igniting device is that the valve-operating mechanism controls a circuit-closing device, whereby a circuit included in the sparking device is controlled. Such devices are classified in subclass 146.5, in this class.

153	Make and break:
	This subclass is indented under subclass 146.5.  Sparking devices comprising relatively fixed and movable electrodes normally out of contact with each other and mechanically-operated means adapted to move the movable electrode into contact with the fixed electrode shortly before and to separate the electrodes when the combustible charge is to be ignited, whereby an electric circuit in which the electrodes are included is alternately made and broken and a spark produced, and subordinate and auxiliary devices designed and especially adapted for use with sparking devices of the type above set forth and incapable of use in the manner contemplated in other relations, the device in question in either case not coming within the definition of some one of the following make-and-break subclasses. The make-and-break subclasses include sparking devices in which the time during which the electrodes are in contact with each other is much greater than the time during which they are separated, the normal condition of electrodes which must be brought into contact and then separated to produce a spark being considered as out of contact with each other.

154	Electromagnetic:
	This subclass is indented under subclass 153.  Sparking devices differing from those defined in the preceding definition in that the operating means for the movable electrode includes an electromagnet. SEE OR SEARCH CLASS: 361,  Electricity: Electrical Systems and Devices,   subclasses 247+ for electric ignitors and ignitor systems.

155	Pneumatic:
	This subclass is indented under subclass 153.  Sparking devices differing from those defined in the second preceding definition in that the means whereby the movable electrode is actuated and is dependent for its operation upon a gas under pressure.

156	Reciprocating electrode:
	This subclass is indented under subclass 153.  Make-and-break sparking devices in which the movable electrode partakes of a reciprocating motion of translation, the relatively fixed electrode being either rigid or yieldable.

157	Rocking-electrode hammer action:
	This subclass is indented under subclass 153.  Make-and-break sparking devices in which the movable electrode is carried by a rock-shaft and the electrodes separated by a reverse movement of the movable electrode, the relatively fixed electrode being rigid and unyielding the operating means to the movable electrode including a hammer element adapted to separate the electrodes by delivering a blow to the movable electrode, whereby a more sudden separation of the electrodes is secured and a more effective spark produced. (1) Note. For other sparking devices in which the means for separating the electrodes include an element designed to deliver a blow to the movable electrode, but which do not have the structural features enumerated in this definition, see the preceding subclass.

158	Rocking and rigid electrodes:
	This subclass is indented under subclass 153.  Make-and-break sparking devices in which the movable electrode is carried by a rock-shaft and the electrodes separated by a reverse movement of the movable electrode, the relatively fixed electrode being rigid and unyielding.

159	Rocking and yielding electrodes:
	This subclass is indented under subclass 153.  Make-and-break sparking devices in which the movable electrode is carried by a rock-shaft and the electrodes separated by a reverse movement of the movable electrode, the relatively fixed electrode being yieldable, so as to move slightly after contact of the electrodes and during the slight further movement of the movable electrode.

160	Oscillating electrodes:
	This subclass is indented under subclass 153.  Make-and-break sparking devices in which the movable electrode is carried by the rock-shaft and the electrodes separated by a farther movement of the movable electrode in the same direction.

161	Rotary electrodes:
	This subclass is indented under subclass 153.  Make-and-break sparking devices in which the movable electrode is carried by the rotating shaft driven continuously or intermittently in one direction.

162	Piston-operated:
	This subclass is indented under subclass 153.  Sparking devices comprising an electric circuit including relatively fixed and movable electrodes, the movable electrode being adapted to make and break the circuit, as in the preceding make-and-break subclasses, and the operation thereof depending immediately upon the piston of the engine with which the device is used. In the devices in this subclass the movable electrode is either carried by the working piston or is located in the clearance space of the engine, and said electrode when not carried by the piston is generally operated directly by the piston or by a projection thereon as it comes into contact with the movable electrode near the end of the compression-stroke.

163	Stationary-electrode structure:
	This subclass is indented under subclass 153.  The form of construction of the stationary electrode designed for use with and to form a part of a sparking device including relatively fixed and movable electrodes, as in the preceding make-and-break subclasses, such stationary electrodes being ordinarily capable of use with and as forming a part of any sparking device which includes fixed and movable electrodes. (1) Note. It is intended that patents classifiable in other make-and-break subclasses, but which disclose specific stationary-electrode structure shall appear in this subclass as cross-references. Inasmuch, however, as all make-and-break sparking devices necessarily include a stationary electrode, a search involving stationary-electrode structures may sometimes extend to all make-and-break subclasses.

164	Adjusting mechanism:
	This subclass is indented under subclass 153.  Inventions relating to manually-operated means used in connection with make-and-break sparking devices for determining the time in the cycle of operation of the engine at which the electrodes shall be separated and the combustible charge ignited. Includes manually-operated devices for temporarily delaying the ignition of the combustible charge when the engine is to be started for the purpose of preventing a reversal of rotation of the engine at such times. (1) Note. Patents disclosing devices designed for use with and to form a part of a high-tension electric igniting system for internal-combustion engines and including an electric circuit having suitable means therein for making and breaking such circuit and also means for adjusting the circuit making and breaking mechanism to vary the time at which the ignition of the charge takes place do not appear in this subclass as cross-references. For such devices see this class, subclass 146.5, and indented subclasses, and Class 200, Electricity: Circuit Makers and Breakers, subclasses 19.05, 19.11, 19.19, and 19.21+. (2) Note. For devices for regulating the speed of an internal-combustion engine by automatically varying the time at which the charge therein is ignited, see this class, subclasses 406+. (3) Note. For devices for determining the time at which the ignition of the charge shall take place in combination with means designed to act upon and regulate the exhaust-valve of the engine, generally for the purpose of facilitating the starting thereof, see subclass 150 in this class. (4) Note. Patents classifiable in other make-and-break subclasses but which discloses specific spark adjusting or timing mechanism, appear in this subclass as cross-references. Inasmuch, however, as make-and-break sparking devices ordinarily include means for varying the adjustment thereof, so that the charge will be ignited at the proper time, a search involving an adjusting or timing mechanism may extend to all make-and-break subclasses.

169	Plugs:
	This subclass is indented under subclass 146.5.  Combinations of a jump spark ignitor with internal combustion engine structure or an internal engine and spark plug accessory which is especially designed for use with an internal combustion engine. (1) Note. This subclass relates, for example, to the combination of a spark plug and a cylinder head; the combination of a plug and cylinder space in which the interior of the skirt has a special claimed relationship to the cylinder volume; the combination of a spark plug with an adaptor of the screw coupling type (which, for example, permits a small plug to be inserted in a large hole or which acts to extend the shell skirt to provide a chamber for the spark), etc. Also included are accessories designed to fit onto the engine and also provided with means to hold the spark plug which are not of general utility. SEE OR SEARCH CLASS: 313,  Electric Lamp and Discharge Devices,   provides for the structure of spark plugs, per se. See especially subclasses 11.5 and 118+ and the subclasses mentioned in the Notes thereto for the subclasses to be searched for spark plugs. Note also the classes listed under "SEARCH CLASS" in Class 313, subclass 118 for other classes which provide for parts of spark plugs and accessories used with spark plugs. 315,  Electric Lamp and Discharge Devices: Systems,   subclass 32 and indented subclasses, for electric space discharge devices of the spark plug type and other electric space discharge devices which have combined therewith an electric circuit element, such as a resistance inductance, or condenser, the discharge device and the circuit element being structurally united so as to form a unitary device.

179.1	STARTING DEVICE:
	This subclass is indented under the class definition.  Apparatus, for starting an internal combustion engine from a condition of rest or for facilitating the starting of such an engine (i.e., starter) or accessory device designed to facilitate the starting of such an engine and incapable of use in the manner contemplated in other relations. SEE OR SEARCH THIS CLASS, SUBCLASS: 142.5, for internal combustion engine combined with heating means where no starting features are claimed. SEE OR SEARCH CLASS: 60,  Power Plants,   subclasses 632+ , for one shot explosion actuated expansible chamber-type motor. 91,  Motors: Expansible Chamber Type,   subclass 53 for expansible motor of the engine rotating or starting type. 290,  Prime-Mover Dynamo Plants,   subclasses 10+ , 22+, 30, 31+, 36+, 38, 46, 47, and 48 for an electric starting motor and for an electric generator used as a starting motor.

179.11	Manual pump device or squeeze bulb:
	This subclass is indented under subclass 179.9.  Apparatus wherein the primer is a hand-operated fluid transfer means.

179.12	Condition responsive:
	This subclass is indented under subclass 179.9.  Apparatus wherein the primer operates in response to a sensed parameter.

179.13	Temperature:
	This subclass is indented under subclass 179.12.  Apparatus wherein the sensed parameter to which the primer responds is temperature.

179.14	Condition responsive:
	This subclass is indented under subclass 179.7.  Apparatus wherein the means for supplying a mixture operates in response to a sensed parameter.

179.15	Temperature:
	This subclass is indented under subclass 179.14.  Apparatus wherein the sensed parameter to which the means for supplying a mixture responds is temperature.

179.16	With fuel or intake air control:
	This subclass is indented under subclass 179.1.  Apparatus wherein the starter regulates hydrocarbon delivery or incoming air.

179.17	Fuel injection pump:
	This subclass is indented under subclass 179.16.  Apparatus wherein the hydrocarbon regulating means is a fluid transfer means which delivers hydrocarbon directly into a cylinder of the engine.

179.18	Intake air control:
	This subclass is indented under subclass 179.16.  Apparatus wherein a means regulates the flow of incoming air.

179.19	Includes auxiliary internal combustion engine:
	This subclass is indented under subclass 179.1.  Apparatus wherein the starter is an additional or another engine.

179.2	Remote control:
	This subclass is indented under subclass 179.1.  Apparatus having a means separated from the engine which directs the operation of the starter (e.g., radioed instruction).

179.21	With charge or cylinder heating:
	This subclass is indented under subclass 179.1.  Apparatus wherein an accessory device increases the temperature of the hydrocarbon in a combustion chamber or cylinder which makes up a combustion chamber.

179.22	Inertia type:
	This subclass is indented under subclass 179.1.  Apparatus wherein the energy for the starter is obtained from a moving mass (e.g., flywheel).

179.24	Either power or manual starting device:
	This subclass is indented under subclass 179.1.  Apparatus having a starter which can be manipulated by hand or by an application of energy.

179.25	Having specific mounting or drive connection for electric starter motor:
	This subclass is indented under subclass 179.1.  Apparatus having detail to an electric motor support or to its linkage between the starter and the internal combustion engine.

179.26	For nonoperator supporting wheeled platform:
	This subclass is indented under subclass 179.25.  Apparatus wherein the internal combustion engine and starter are mounted on a distinct wheeled platform such as a mower which is not intended to support a human.

179.27	For airplane:
	This subclass is indented under subclass 179.1.  Apparatus wherein the starter is especially adapted for use with an aircraft (e.g., toy airplane).

179.28	With electric generating means:
	This subclass is indented under subclass 179.1.  Apparatus wherein the starter is equipped with a producer of electricity.

179.29	Auxiliary magneto:
	This subclass is indented under subclass 179.1.  Apparatus wherein the electric producer generates alternating current with small magnets.

179.3	Condition responsive control of starting device:
	This subclass is indented under subclass 179.1.  Apparatus having means to regulate operation of the starter in response to a sensed parameter.

179.31	Having fluid-driven starting motor:
	This subclass is indented under subclass 179.1.  Apparatus wherein the starter includes a motor which is powered by pneumatic or hydraulic means.

179.4	Including automatic engine stop:
	This subclass is indented under subclass 179.3.  Apparatus wherein the regulation of the engine is a ceasing operation for the engine.

179.5	Control of spark ignition during starting:
	This subclass is indented under subclass 179.1.  Apparatus wherein a means is provided to regulate intermittent firing of the igniter when the engine is starting.

179.6	Control of glow plug during starting:
	This subclass is indented under subclass 179.1.  Apparatus wherein a means is provided to regulate a small heating element used to start ignition, when the engine is starting.

179.7	Auxiliary fuel supply device:
	This subclass is indented under subclass 179.1.  Apparatus wherein the accessory device comprises means for supplying a combustible mixture of air and hydrocarbon directly to the working cylinder of the engine, together with means for igniting the mixture within the working cylinder after the mixture is supplied to the cylinder, and the accessory devices being separate and distinct from the elements constituting the engine and not involved in its normal operation. (1) Note. The accessory device for this and the indented subclasses include means for supplying an easily vaporized fluid to the engine when it is to be started, whereby the initial combustible charge is more easily formed, the engine being afterwords operated by a less volatile fluid, the means not coming within the terms of subclass 127 definition. The means for igniting the combustible mixture is frequently the regular igniting device of the engine or such device with suitable auxiliary appliances to adapt it to use in a starting device of the type occurring in the subclass. The essential features in the devices is that a combustible mixture is supplied directly to the interior of the working cylinder and ignited to start the engine by power generated within itself. Such mixture may be supplied at substantially atmospheric pressure or at a comparatively high pressure, and it may or may not be compressed in the working cylinder by a movement of the working piston before ignition. (2) Note. Inventions limited to a mechanism for igniting a combustible mixture as above where the engine is to be started are classified in this class, subclass 184.1, notwithstanding the fact that the starting devices occurring in this subclass are necessarily provided with some type of igniting device or the fact that the igniting device in question may be designed for use with a starting device of the type occurring in this subclass. (3) Note. For internal combustion engines which are self-starting because of the cycle upon which they operate, a combustible mixture being supplied to the working cylinder under pressure, see this class, subclass 68.

179.8	Starting fluid:
	This subclass is indented under subclass 179.7.  Apparatus having a separate distinct liquid or gas, such as alcohol or acetylene, used to initiate ignition.

179.9	Priming means:
	This subclass is indented under subclass 179.7.  Apparatus having means to prepare the engine for ignition by adding an initial amount of priming fuel to a carburetor or cylinder.

182.1	Compression relieving type:
	This subclass is indented under subclass 179.1.  Apparatus wherein the accessory device comprises means for permitting a portion of the combustible charge in the working cylinder to escape during a part of the compression stroke of the engine, whereby the volume of the combustible charge compressed and ignited upon the initial strokes of the engine is reduced and the external work necessary to start the engine is lessened. SEE OR SEARCH THIS CLASS, SUBCLASS: 150, for combined adjusting and exhaust regulating.

183.1	Gunpowder type:
	This subclass is indented under subclass 179.1.  Apparatus wherein the accessory device utilizes a charge of gunpowder or other explosive substance which is exploded and the resulting gases act upon the working piston of the engine. SEE OR SEARCH CLASS: 60,  Power Plants,   subclasses 632+ for one shot explosion activated expansible chamber-type motors.

184.1	With auxiliary igniters:
	This subclass is indented under subclass 179.1.  Apparatus wherein the engine is started by introducing and burning a combustible mixture within the working cylinder, and the starting means includes either (1) a supplemental igniting device separate and distinct from the regular igniting device of the engine and designed for temporary use at starting or (2) a device independent of the engine for actuating the regular igniting device. (1) Note. The combustible mixture may be supplied to the working cylinder by separate and distinct means as in subclasses 179.7+, or it may reach the cylinder by way of the regular supply passage and inlet valve of the engine in their ordinary manner. (2) Note. This subclass does not include a device for delaying the ignition of the combustible mixture to facilitate the starting of the engine, but which device is not in itself capable of igniting the charge. For such device, if manually operated, see subclass 164, and if automatically operated, see subclasses 406+ in this class. (3) Note. For electrical igniting devices provided with interchangeable sources of electricity, one for use at starting and the other in the normal operation of the engine, see this, class subclasses 147 and 594+. SEE OR SEARCH THIS CLASS, SUBCLASS: 179.7+, for combustible mixture supplying means.

184.21	INTAKE MANIFOLD:
	This subclass is indented under the class definition.  Internal-combustion engine component including at least one passage in fluid communication with an inlet port of the engine through which working fluid (i.e., air, air and fuel mixture, etc.) is distributed to the engine. (1) Note. A manifold that conveys intake gases to an engine and also conveys exhaust gases away from an engine is included herein. Preheating of intake gases may be done by the exhaust gases in such a manifold. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 323 for an exhaust manifold, per se, or in combination with a power plant.

184.22	Passage to crankcase:
	This subclass is indented under subclass 184.21.  Intake manifold wherein the chamber enclosing the crankshaft is connected to the intake manifold to draw working fluid therethrough.

184.23	For use with carburetor upstream of manifold:
	This subclass is indented under subclass 184.22.  Intake manifold which communicates between the engine and a device for mixing air with fuel working fluid.

184.24	Manifold having plenum:
	This subclass is indented under subclass 184.22.  Intake manifold including a chamber in which the working fluid is contained at a pressure different from the pressure surrounding the chamber.

184.25	Plural plenums:
	This subclass is indented under subclass 184.24.  Intake manifold including more than one chamber in which the working fluid is contained.

184.26	Interconnection between plenums:
	This subclass is indented under subclass 184.25.  Intake manifold wherein the plenums communicate with one another so that working fluid may pass between the plenums.

184.27	Multiple passage leading to inlet of one cylinder head:
	This subclass is indented under subclass 184.22.  Intake manifold including more than one passage communicating with inlet ports at the end of a single cylinder in the closed end of a single cylinder so that working fluid is distributed therethrough.

184.28	For engine having radiating cylinders:
	This subclass is indented under subclass 184.21.  Intake manifold adapted to be used on an engine which includes a rotary output shaft that turns about an axis intersected by and extending perpendicular to the axes of first and second cylinders, the pistons of these cylinders are drivingly connected to the rotary output shaft, wherein the cylinder axes are separated at an angle with respect to one another.

184.29	Star-type engine:
	This subclass is indented under subclass 184.28.  Intake manifold wherein the engine includes at least three cylinders which are equally spaced about the centrally disposed rotary output shaft.

184.31	For V-type engine:
	This subclass is indented under subclass 184.28.  Intake manifold wherein the engine has first and second cylinders with axes spaced apart by an angle less than 180°.

184.32	For use with carburetor upstream of manifold:
	This subclass is indented under subclass 184.31.  Intake manifold which communicates between the engine and a device for mixing air with fuel working fluid.

184.33	Inlet manifold heated by outlet manifold:
	This subclass is indented under subclass 184.32.  Intake manifold wherein the engine also includes at least one exhaust passage intermingling with or in thermal communication with at least a portion of the intake manifold.

184.34	Manifold having plenum:
	This subclass is indented under subclass 184.31.  Intake manifold including a chamber in which the working fluid is contained at a pressure different from the pressure surrounding the chamber.

184.35	Plural plenums:
	This subclass is indented under subclass 184.31.  Intake manifold including more than one chamber in which the working fluid is contained.

184.36	Interconnection between plenums:
	This subclass is indented under subclass 184.35.  Intake manifold wherein the plenums communicate with one another so that working fluid may pass between the plenums.

184.37	Multiple passage leading to inlet of one cylinder:
	This subclass is indented under subclass 184.31.  Intake manifold including more than one passage communicating with inlet ports at the end of a single cylinder in the closed end of a single cylinder so that working fluid is distributed therethrough.

184.38	For in-line engine:
	This subclass is indented under subclass 184.21.  Intake manifold wherein the engine has first and second cylinders with axes coplanar with the axis of the rotary output axis.

184.39	For use with carburetor upstream of manifold:
	This subclass is indented under subclass 184.38.  Intake manifold which communicates between the engine and a device for mixing air with fuel working fluid.

184.41	Intake manifold heated by outlet manifold:
	This subclass is indented under subclass 184.39.  Intake manifold wherein the engine also includes at least one exhaust passage intermingling with or in thermal communication with at least a portion of the intake manifold.

184.42	Manifold having plenum:
	This subclass is indented under subclass 184.38.  Intake manifold including a chamber in which the working fluid is contained at a pressure different from the pressure surrounding the chamber.

184.43	Plural plenums:
	This subclass is indented under subclass 184.42.  Intake manifold including more than one chamber in which the working fluid is contained.

184.44	Interconnection between plenums:
	This subclass is indented under subclass 184.43.  Intake manifold wherein the plenums communicate with one another so that working fluid may pass between the plenums.

184.45	Multiple passage leading to inlet of one cylinder:
	This subclass is indented under subclass 184.38.  Intake manifold including more than one passage communicating with inlet ports at the end of a single cylinder in the closed end of a single cylinder so that working fluid is distributed therethrough.

184.46	For use with carburetor upstream of manifold:
	This subclass is indented under subclass 184.21.  Intake manifold which communicates between the engine and a device for mixing air with fuel working fluid.

184.47	Manifold having plenum:
	This subclass is indented under subclass 184.21.  Intake manifold including a chamber in which the working fluid is contained at a pressure different from the pressure surrounding the chamber.

184.48	Plural plenums:
	This subclass is indented under subclass 184.47.  Intake manifold including more than one chamber in which the working fluid is contained.

184.49	Interconnection between plenums:
	This subclass is indented under subclass 184.48.  Intake manifold wherein the plenums communicate with one another so that working fluid may pass between the plenums.

184.51	Adjustable plenum:
	This subclass is indented under subclass 184.47.  Intake manifold wherein the volume of the plenum chamber is variably controlled.

184.52	Multiple passage leading to inlet of one cylinder:
	This subclass is indented under subclass 184.21.  Intake manifold including more than one passage communicating with inlet ports at the end of a single cylinder in the closed end of a single cylinder so that working fluid is distributed therethrough.

184.53	Manifold tuning, balancing, or pressure regulating means:
	This subclass is indented under subclass 184.21.  Intake manifold including means to: (a) select the resonant frequency of the chamber for desired flow of the working fluid; (b) optimally vary the passage to one cylinder with respect to another; (c) control the pressure of the working fluid therein.

184.54	With back flow prevention valve:
	This subclass is indented under subclass 184.53.  Intake manifold including a one-way valve for restricting the flow of working material to one direction.

184.55	Adjustable length passage:
	This subclass is indented under subclass 184.53.  Intake manifold including a means for changing the length of the work fluids path to the engine.

184.56	Adjustable cross section passage:
	This subclass is indented under subclass 184.53.  Intake manifold including a means for reversibly blocking a portion of the flow path of the working fluid.

184.57	Resonator chamber:
	This subclass is indented under subclass 184.53.  Intake manifold including an enclosed portion that is tuned to convert the pressure pulses of the pistons sucking in air into resonating waves which facilitates more efficient charging of the cylinders.

184.58	Return loop to inlet:
	This subclass is indented under subclass 184.53.  Intake manifold including a recirculation passage which allows a portion of the working fluid to bypass the engine cylinder and return to the inlet of the manifold.

184.59	Interconnection between passages:
	This subclass is indented under subclass 184.53.  Intake manifold wherein the inlet passages communicate with one another allowing working fluid to pass there between.

184.61	Manifold material or composition:
	This subclass is indented under subclass 184.21.  Intake manifold wherein the material or composition of the manifold is specifically claimed.

185.1	Mechanical:
	This subclass is indented under subclass 179.1.  Apparatus wherein the starter includes mechanical means forming a connection between the mainshaft of the engine and starting force input operating member. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclass 6 , and indented subclasses for engine starters, per se.

185.11	Includes worm gear in linkage:
	This subclass is indented under subclass 185.1.  Apparatus wherein the mechanical means connecting the operating member to the main shaft includes a threaded shaft and a wheel with teeth that mesh into the threads.

185.12	Including crank-type handle:
	This subclass is indented under subclass 185.1.  Apparatus wherein the operating member for the mechanical means consists of a hand operated lever or arm attached at a right angle to the engine or a linking shaft which it revolves.

185.13	Means provided to prevent counter rotation of crank:
	This subclass is indented under subclass 185.12.  Apparatus having a means to preclude the lever or arm from revolving in a direction opposite its normal direction of operation.

185.14	Includes mechanical potential motor (e. g., spring motor):
	This subclass is indented under subclass 185.1.  Apparatus wherein the starter includes a motor which is powered by means which stores mechanical energy.

185.15	Operated by wheels of vehicle:
	This subclass is indented under subclass 185.14.  Apparatus wherein the energy input source for the energy storing means is a wheel of a vehicle.

185.2	Includes cable:
	This subclass is indented under subclass 185.1.  Apparatus wherein the operating member or mechanical means includes an elongated flaccid member (e.g., cord, chain, etc.) which the operator uses to revolve the main shaft of the engine.

185.3	Including recoil mechanism:
	This subclass is indented under subclass 185.2.  Apparatus which also includes a grooved wheel around which the elongated flaccid member is turned and a resilient coil which draws the cord tight.

185.4	Lever connected to the cable:
	This subclass is indented under subclass 185.3.  Apparatus having a rigid rod pivoted on a fixed fulcrum attached to the elongated flaccid member which assists the operator in revolving the mainshaft of the engine.

185.5	Includes lever or slide linkage:
	This subclass is indented under subclass 185.1.  Apparatus wherein the mechanical means includes a rigid rod pivoted on a fixed fulcrum or a rod that glides along a guide and is used to revolve the main shaft of the engine.

185.6	Lever or slide actuates a gear segment:
	This subclass is indented under subclass 185.5.  Apparatus wherein the rod moves a toothed machine element to revolve the mainshaft of the engine.

185.7	Manual type:
	This subclass is indented under subclass 179.27.  Apparatus wherein starting means is hand-operated.

185.8	Includes friction means in linkage:
	This subclass is indented under subclass 185.1.  Apparatus wherein the mechanical means connecting the operating member to the main shaft includes means which transmits power to the main shaft solely by rubbing contact between two or more of its components.

185.9	Includes coaxial cooperating threaded members in linkage:
	This subclass is indented under subclass 185.1.  Apparatus wherein the mechanical means connecting the operating member to the main shaft includes means which transmits power to the main shaft when two helical or spiral ridged members rotate relative to each other about the same axis.

188.1	VALVE:
	This subclass is indented under the class definition.  Apparatus relating to either (1) the intake, exhaust, or fuel valve of an internal-combustion engine having a stationary opening (i.e., seat) and moving closure (i.e., head) or (2), a component thereof (e.g., a valve-seat), or (3), an adjunct accessory (e.g., supply conduit for valve) solely for use with the supply, exhaust or fuel valve of an internal combustion engine. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.16, for valve having coolant sealed therein. 41.34, for internal cooling of moving valve parts. 41.76+, for valve seats and guide with cooling means. 144+, for supply or exhaust valves or a single valve controlling both the supply and exhaust ports of the engine, in combination with a flame igniting device. 434+, for valves used in connection with charge-forming devices. SEE OR SEARCH CLASS: 148,  Metal Treatment,   appropriate subclasses for valves claimed broadly by name only and defined significantly or broadly solely by their metal or alloy compositions and including a specific Class 148 treatment of the metal or alloy, or for products distinguished only by the internal structure or characteristics of the metals, metallic compositions or alloys comprising such structures. 251,  Valves and Valve Actuation,   particularly subclasses 251+ for cam actuated valves. 420,  Alloys or Metallic Compositions,   appropriate subclasses for valves claimed by name only and defined solely by their metal or alloy composition. 428,  Stock Material or Miscellaneous Articles,   subclasses 544+ for valve element or adjunct having only nominally claimed structure, that is, one insufficiently defined in its ultimate use form, comprised all of metal or having metal components.

188.11	Wear feature:
	This subclass is indented under subclass 188.1.  Apparatus wherein a feature or means is provided to compensate for changes or deterioration of a valve component or accessory caused by prolonged use.

188.12	For spring:
	This subclass is indented under subclass 188.11.  Apparatus wherein the component or accessory compensated is a resilient element.

188.13	Including attaching means:
	This subclass is indented under subclass 188.12.  Apparatus having means to hold spring in place.

188.14	Valve head cooperates with manifold:
	This subclass is indented under subclass 188.1.  Apparatus wherein the valve head has a specific form to engage an aperture of the manifold.

188.15	Shepherd type:
	This subclass is indented under subclass 188.4.  Apparatus having two valve heads one on top of the other with concentric valve stems.

188.16	Pivoted:
	This subclass is indented under subclass 188.2.  Apparatus wherein there is a hinge member between the stem and the valve head.

188.17	Having actuation springs concentric with valve stem:
	This subclass is indented under subclass 188.1.  Apparatus wherein a valve return spring encircles the valve stem and is centered around the same axis.

188.2	Poppet:
	This subclass is indented under subclass 188.4.  Apparatus wherein the valve head has a flat disk shape on the end of a vertically set stem.

188.3	Material or structure:
	This subclass is indented under subclass 188.2.  Apparatus having specific substance, or arrangement (e.g., ceramic) of the valve.

188.4	Reciprocating valve:
	This subclass is indented under subclass 188.1.  Apparatus wherein the valve head slides to and fro during an opening and closing operation.

188.5	Sleeve:
	This subclass is indented under subclass 188.4.  Apparatus wherein the valve head consists of a thin cylindrically shaped sheet having an inlet or outlet port.

188.6	Packing:
	This subclass is indented under subclass 188.1.  Apparatus having a sealing means located around a valve stem. SEE OR SEARCH THIS CLASS, SUBCLASS: 90.37, for a poppet valve mechanism"s lubrication system including a seal or shield that may include a valve stem seal or shield movable with the operating mechanism. SEE OR SEARCH CLASS: 277,  Seal for a Joint or Juncture,   for a generic sealing means or process, subclass 502 for a valve stem seal for an internal combustion engine.

188.7	Combustion improving accessory:
	This subclass is indented under subclass 188.1.  Apparatus having adjuncts for the valve (e.g., vanes) for enhancing the combustion process.

188.8	Valve seat relation:
	This subclass is indented under subclass 188.1.  Apparatus having specific characteristics of a stationary opening with which the valve head cooperates.

188.9	Guide, lubricant or coolant:
	This subclass is indented under subclass 188.1.  Apparatus either (1) having means to direct the motion of a valve stem or (2) having a substance to reduce friction or (3) has a substance to dissipate heat.

189	Detachable:
	This subclass is indented under subclass 188.1.  Conveniently disassembled valves and accessories thereof and ordinarily comprises means for attaching the supply or exhaust conduit to the engine in such a way as to be readily disconnected therefrom, thereby permitting the convenient inspection and generally the removal of the valve located at the end of the conduit in question. SEE OR SEARCH CLASS: 417,  Pumps,   subclass 454 , for expansible chamber type pumps having means to facilitate assembly or disassembly of a pump valve.

190.1	Rotary:
	This subclass is indented under subclass 188.1.  Apparatus having a valve that rotates, or revolves during opening and closing. SEE OR SEARCH THIS CLASS, SUBCLASS: 80, for rotating valve, specific to a 4 cycle engine.

190.11	In horizontal plane on the side of the cylinder:
	This subclass is indented under subclass 190.4.  Apparatus wherein the rotary valve lies in a plane perpendicular to the cylinder axis and is located at the side of the cylinder.

190.12	Sleeve:
	This subclass is indented under subclass 190.1.  Apparatus wherein the rotary valve comprises a thin cylindrical sheet which rotates on an axis which is the same axis as the central axis of the cylinder.

190.13	With lubrication means:
	This subclass is indented under subclass 190.12.  Apparatus having a means to reduce the friction of the valve.

190.14	Disc, cone, or sphere shaped:
	This subclass is indented under subclass 190.1.  Apparatus wherein the rotating valve body is in the form of either (1) a thin flat rotor; (2) a surface generated by a straight line passing through a fixed point and moving along the intersection with a fixed curve; or (3) a three-dimensional surface all points of which are equidistant from a fixed point.

190.15	Controls plural cylinders:
	This subclass is indented under subclass 190.14.  Apparatus wherein the valve controls the intake, exhaust or fuel to more than one cylinder.

190.16	Lubricant:
	This subclass is indented under subclass 190.1.  Apparatus having means to reduce the friction of the rotary valve.

190.17	Seal:
	This subclass is indented under subclass 190.1.  Apparatus having means to prevent leaking of fluids around the rotary valve.

190.2	Single function, (i.e., exhaust and intake by separate tube):
	This subclass is indented under subclass 190.1.  Apparatus wherein the rotary valve moves between individual distinct ducts.

190.3	For crankcase:
	This subclass is indented under subclass 190.1.  Apparatus wherein fuel and combustion products enter or leave the crankcase through a rotary valve.

190.4	Double function type:
	This subclass is indented under subclass 190.1.  Apparatus wherein a single rotary valve handles both intake and exhaust gases for cylinder.

190.5	For two or more cylinders:
	This subclass is indented under subclass 190.4.  Apparatus wherein a single multi-passage rotary valve handles both intake and exhaust gases for multiple cylinders.

190.6	Elongated rotary double-function valve:
	This subclass is indented under subclass 190.4.  Apparatus wherein a cross section of the rotary valve perpendicular to its rotational axis is significantly smaller than the dimension of the valve parallel to its rotational axis.

190.7	Tapered:
	This subclass is indented under subclass 190.6.  Apparatus wherein the cross section of the rotary valve becomes gradually narrower along the rotational axis.

190.8	In horizontal plane above cylinder:
	This subclass is indented under subclass 190.4.  Apparatus wherein the rotary valve lies in a plane which is perpendicular to the cylinder axis and located over the top of the cylinder.

190.9	Tapered:
	This subclass is indented under subclass 190.8.  Apparatus wherein the cross section of the rotary valve perpendicular to the rotational axis becomes gradually narrowed along the rotational axis.

192.1	VIBRATION COMPENSATING DEVICE:
	This subclass is indented under the class definition.  Apparatus having a stabilizing device adapted only for use with an internal combustion engine, which renders the force transmitted to the main driving shaft of the engine more uniform and minimizes or counteracts a shaking or oscillating motion caused by the reciprocation of engine parts. SEE OR SEARCH CLASS: 29,  Metal Working,   subclass 6.01 for crankshaft making. 73,  Measuring and Testing,   subclasses 66+ for testing instruments for determining imbalances including arrangements employing compensating countershafts. 74,  Machine Element or Mechanism,   subclass 36 for overcoming dead centers; subclass 573.1 for fluid balanced flywheels; subclass 574.1 for flywheel with electrical or magnetic damping; subclass 574.2 for damping using swinging masses, e.g., pendulum type for damping, etc.; subclass 574.3 damping by increasing frictional force; and subclass 574.4 damping by absorbing the vibration force (via rubber, elastomeric material, etc.). 92,  Expansible Chamber Devices,   subclass 7 for an expansible chamber device having an over center means to bias the working member in opposite directions over different portions of the stroke. 464,  Rotary Shafts, Gudgeons, Housings, and Flexible Couplings for Rotary Shafts,   subclass 180 for shafting having particular balancing or vibration dampening structure.

192.2	Balancing arrangement:
	This subclass is indented under subclass 192.1.  Apparatus wherein the stabilizing device comprises means to establish equilibrium using equal opposing forces.

193.1	PARTICULAR PISTON AND ENCLOSING CYLINDER CONSTRUCTION:
	This subclass is indented under the class definition.  Apparatus including a specific detail of either a piston (e.g., shape, material, construction) or a guiding chamber cooperating with and surrounding the piston, the piston or guiding chamber being adapted soley for use with an internal combustion engine or having a feature, construction, or peculiarity in mode of operation rendering its use in other relations or with other devices either impossible, or improbable. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.01+, for cylinder or piston cooling arrangement, especially subclass 41.16, for those having coolant sealed inside; subclass 41.34 for cooling of a piston and moving cylinder; and subclasses 41.67+ and 1.72+, for a jacketed or finned cylinder. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclasses 169.1+ for cylinder details for an expansible chamber device, subclasses 172+ for a piston for an expansible chamber device.

193.2	Cylinder detail:
	This subclass is indented under subclass 193.1.  Apparatus having a specific detail of the chamber in which a piston moves.

193.3	Having detail of connection to other cylinder structure:
	This subclass is indented under subclass 193.5.  Apparatus having specific means which is utilized in fastening the structures to the upper end of the chamber.

193.4	Having detail to guiding structure cooperating with cylinder:
	This subclass is indented under subclass 193.6.  Apparatus wherein the piston has a specific surface or formation cooperating with the chamber.

193.5	Cylinder head:
	This subclass is indented under subclass 193.1.  Apparatus having structure which is utilized in an assembly which fits on the upper end of the combustion chamber and which may have provision for valves, spark plugs, etc.

193.6	Piston:
	This subclass is indented under subclass 193.1.  Apparatus having a structure, shape, material or construction which is utilized in a piston (i.e., a solid cylinder or disk fitting snugly in a cylinder and reciprocating).

195	FRAME CONSTRUCTION:
	This subclass is indented under the class definition.  The form, construction, or other features of the casing, frame, or bed-plate which supports the various elements necessary to form a complete internal-combustion engine and maintains them in proper operative relation with one another and includes such constructions of the cylinder as relate to the means of attachments to the bed. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   subclasses 606+ . 92,  Expansible Chamber Devices,   subclasses 146+ for a plurality of unitarily mounted cylinders or frame therefor for an expansible chamber device, subclass 161 for a support or frame for an expansible chamber device, and subclass 261 for a crankcase, per se, for a crank associated with an expansible chamber device.

196	LUBRICATORS:
	This subclass is indented under the class definition.  Lubricating means for internal-combustion engines, the device in question being designed and adapted for use only with such an engine and being dependent for its action upon peculiarities of operation present only in internal-combustion engines. (1) Note. Lubricating means capable of use with engines generally, irrespective of the fluid by which they are operated, and capable of use with air, steam, internal-combustion, or other engines are classified in Class 184, Lubrication appropriate subclasses, notwithstanding they may be designed with reference to use with internal-combustion engines. SEE OR SEARCH CLASS: 92,  Expansible Chamber Devices,   subclasses 153+ for lubricating means for an expansible chamber device. 210,  Liquid Purification or Separation,   subclasses 153+ for liquid purification or separation means in a structural installation, especially subclasses 167.02- 167.09 for a closed circulating system for a lubrication system and subclass 171 for machinery wherein an internal-combustion engine may be broadly recited as the source of the material to be treated.

197.1	TRANSMISSION MECHANISM FROM PISTON:
	This subclass is indented under the class definition.  Apparatus having a mechanism intermediate the working piston and the main driving-shaft of the engine through which power is transmitted to the shaft. (1) Note. A patent proper for this and the indented subclasses may have ordinary parts of the engine mentioned broadly in the claims, provided no specific construction of such parts is involved. SEE OR SEARCH THIS CLASS, SUBCLASS: 46, and 78, for a transmission-mechanism involved in the cycle upon which the engine operates. SEE OR SEARCH CLASS: 74,  Machine Element or Mechanism,   appropriate subclasses according to the character of the device in question.

197.2	With particular piston:
	This subclass is indented under subclass 197.1.  Apparatus provided with specific details to the working piston.

197.3	Particular connecting rod:
	This subclass is indented under subclass 197.4.  Apparatus wherein the transmitting mechanism includes specific details to the reciprocating rod.

197.4	Crankshaft and connecting rod:
	This subclass is indented under subclass 197.1.  Apparatus wherein the transmitting mechanism includes a reciprocating rod linking rotating parts and one of the rotating parts is a shaft that has a handle or arm attached at right angles.

197.5	Including clutch:
	This subclass is indented under subclass 197.1.  Apparatus wherein the transmitting mechanism includes a device to engage or disengage it from a drive shaft.

198	ACCESSORIES:
	This subclass is indented under the class definition.  Miscellaneous accessory device designed for use with internal-combustion engines not otherwise provided for in this classification. (1) Note. For thermometers combined with internal-combustion engine structure wherein no more of said internal combustion engine is included than is necessary to locate the thermometer, see the Search Class notes below. (2) Note. Cleaning apparatus and processes are for the most part provided for elsewhere. See the Search Class notes below. SEE OR SEARCH CLASS: 15,  Brushing, Scrubbing, and General Cleaning,   for cleaning apparatus which involve at least one of the following means or operations: a gas blast or vacuum, brushing, beating, scraping, wiping, shotting, the use of a squeegee, with or without a detergent. 134,  Cleaning and Liquid Contact With Solids,   for processes of cleaning engines or parts thereof even though claimed in combination with steps of engine operation, when only such engine operation steps are claimed as are necessary for the cleaning operation claimed and also for apparatus for cleaning engines when a combination with the engine is not claimed. 148,  Metal Treatment,   for metal cleaning or pickling processes combined with other metal treating steps. 181,  Acoustics,   subclass 204 for acoustical machine type enclosures specifically adapted for internal-combustion engines. 252,  Compositions,   for detergent compositions and for cleaning processes limited to the mere use of a detergent even though the thing or surface cleaned be specified. 374,  Thermal Measuring and Testing,   subclass 144 , and indented subclasses, for thermometers combined with internal-combustion engine structure wherein no more of said internal combustion engine is included than is necessary to locate the thermometer,

200	ROTARY:
	This subclass is indented under the class definition.  Apparatus having a cylinder structure enclosing a piston structure wherein the piston structure cooperates with the cylinder structure and one or more other elements to constitute an enclosed space for burning the combustible material wherein the piston structure and cylinder are capable of relative rotary movement. (1) Note. A rotary expansible chamber device having only nominally claimed air or fuel supply, air or fuel modifying means or ignition means without recitation of any other combustion aspects such as stratification, charge forming, scavenging, compression, etc., is properly classified in Class 418. (2) Note. Included in these subclasses are engines wherein a gas is transferred or moved from one variable volume to another. Transfer of gas after being acted upon by one surface of said piston to a point where said gas acts upon another surface of said piston is considered to be a transfer to a different volume. (3) Note. The majority of the engines found within this and indented subclasses are of the type in which the cylinder structure is stationary and the piston structure rotates; however, also included are engines wherein the cylinder structure rotated and the piston structure remains stationary, such engines being treated as kinematically inverted. (4) Note. The term "rotor" herein is synonymous with "piston structure"; the term "enclosed space" is synonymous with "working chamber". The term "rotation" herein includes "plantation". The term "partition structure" and "vane" are synonymous and refer to the generally long, thin platelike elements capable of reciprocation and designed to form working chambers within the engine by the separation of one volume of the piston-cylinder volume from others. (5) Note. Further included in these subclasses, from Class 60 (old subclass 39.61) are rotary engines provided with a volume structure external to the enclosed space for burning and with means for intermittently communicating the enclosed space with the external volume structure such that the combustion may occur either within the enclosed space or the external volume structure. SEE OR SEARCH THIS CLASS, SUBCLASS: 43+, for internal-combustion engines comprising a cylinder or cylinders having a continuous rotary movement, and pistons having reciprocating movement relative to the cylinder. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   appropriate subclasses for devices with similar structure but without significant internal-combustion features. See Class Definition, section III, miscellaneous class notes of Class 418, and (1) Note above in this subclass for statements of the line between Class 123 and Class 418.

201	Reversible:
	This subclass is indented under subclass 200.  Apparatus provided with means to allow the burning material to act on the piston structure or elements to produce rotary motion in either direction. (1) Note. An example of reversing arrangements not included within this subclass is reverse gearing to reverse the direction of rotation of the output while the direction of rotation of the engine remains unchanged. See Class 74, Machine Element or Mechanism, subclass 810.2.

202	With means to control degree of compression:
	This subclass is indented under subclass 200.  Apparatus provided with distinct means to vary the level of pressure of the air or combustible material prior to combustion. (1) Note. The means of this subclass is distinct structure, such as a bypass valve, e.g., and excludes the cooperating elements which normally and inherently produce compression in a rotary engine. SEE OR SEARCH CLASS: 417,  Pumps,   subclass 283 for a rotary expansion chamber device having a condition responsive bypass or relief valve. 418,  Rotary Expansible Chamber Devices,   subclass 159 for a rotary expansible chamber device provided with means adjacent to the fluid inlet or outlet for controllably modifying the flow of fluid.

203	With combusted gas treatment or handling means:
	This subclass is indented under subclass 200.  Apparatus provided with means for treating or handling the burning combustible material within the volume where the burning occurs during the expansion or exhaust phase of operating cycle. (1) Note. The treatment or handling of the combusted material is in addition to the expansion occurring in the working chamber and includes air injection, scavenging, etc. SEE OR SEARCH CLASS: 60,  Power Plants,   subclasses 272+ for an engine in which combusted gases are treated or handled after exhausting from the working chamber.

204	With compression volume means in uninterrupted communication with expansion volume means:
	This subclass is indented under subclass 200.  Apparatus wherein the piston structure cooperates with one or more other elements or with another piston structure or with the cylinder structure such that an unobstructed passageway always exists between the volume in which the air or combustible material is compressed and the volume in which the combustible material is burned. (1) Note. This subclass includes engines operating on the Brayton (constant pressure) cycle. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 39.01 for nonpositive displacement engines operating on the same cycle.

205	With fuel injection means:
	This subclass is indented under subclass 200.  Apparatus provided with means for introducing liquid combustible material under pressure into an air supply to form a combustible mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 32+, for other types of internal-combustion engines provided with fuel injectors.

206	And pump or control means:
	This subclass is indented under subclass 205.  Apparatus further provided with distinct means to either increase the pressure of the fuel being injected or to modify the amount of the fuel being injected into the combustion space. SEE OR SEARCH THIS CLASS, SUBCLASS: 139+, for a fuel injection pump, per se. SEE OR SEARCH CLASS: 417,  Pumps,   appropriate subclasses for generic pump structure.

207	Into intake port:
	This subclass is indented under subclass 205.  Apparatus wherein the fuel injector is located so as to inject the fuel into the passageway leading to the working chamber of the engine.

208	Into intake chamber:
	This subclass is indented under subclass 205.  Apparatus wherein the fuel injector is located so as to inject the fuel directly into the working chamber during the air and fuel induction stroke of the operating cycle.

209	Into prechamber:
	This subclass is indented under subclass 205.  Apparatus wherein the fuel injector is mounted for feeding fuel into a cavity structure external to but communicating with the working chamber via a passageway.

210	With ignition means:
	This subclass is indented under subclass 200.  Apparatus provided with a source of heat energy for initiating the combustion reaction. SEE OR SEARCH THIS CLASS, SUBCLASS: 143+, for ignition structure, per se.

211	Plural:
	This subclass is indented under subclass 210.  Apparatus provided with a plurality of ignition means.

212	With plural compression volume means:
	This subclass is indented under subclass 200.  Apparatus provided with a plurality of means to pressurize and deliver air or combustible material to the enclosed space. (1) Note. The volume designated for compressing the air or combustible material inherent in the operating cycle of most rotary piston engines is included as one of the compression volume means for this subclass.

213	In series:
	This subclass is indented under subclass 212.  Apparatus wherein the plural compression volume means are arranged such that the pressurized air or combustible material is passed directly in line from one compression volume means to the next. SEE OR SEARCH THIS CLASS, SUBCLASS: 119+, for other types of internal-combustion engines provided with serially arranged superchargers.

214	With plural expansion volume means:
	This subclass is indented under subclass 200.  Apparatus provided with a plurality of space means capable of enlargement to receive the combusted material from the combustion space such that the reception of the combusted material causes the space means to enlarge. (1) Note. The volume designed for receiving the combusted material inherent in the operating cycle of most rotary piston engines is included as an expansion volume means for this subclass.

215	In series:
	This subclass is indented under subclass 214.  Apparatus wherein the plural expansion volume means are arranged such that the combusted material is passed directly in line from one expansion volume means to the next. SEE OR SEARCH CLASS: 60,  Power Plants,   subclass 623 for a rotary motor driven by waste heat or exhaust energy.

216	With charge treatment means:
	This subclass is indented under subclass 200.  Apparatus provided with means to modify or prepare the combustible material prior to or during its delivery to the combustion space. (1) Note. Charge treatment means includes, e.g., preparation means such as mixing means for the fuel and air, or for a plurality of substances to form a combustible mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 434+, for charge forming devices, per se.

217	Exhaust gas recirculation:
	This subclass is indented under subclass 216.  Apparatus wherein the treatment means consists of structure returning a portion of the combusted material to the air or fuel being delivered to the combustion space.

218	Rotor shape:
	This subclass is indented under subclass 216.  Apparatus wherein the treatment means consists of a cavity structure integral to the piston structure for creating turbulence so as to mix the air and fuel during the compression phase of the operating cycle in preparation for combustion.

219	Stratification:
	This subclass is indented under subclass 216.  Apparatus wherein the treatment means consists of structure for feeding air or air/fuel mixtures having different air/fuel ratios into the working chamber.

220	Preheating:
	This subclass is indented under subclass 216.  Apparatus wherein the treatment means consists of structure for raising the temperature of the air or combustible material prior to delivery to the combustion space. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclass 86 for a rotary expansible chamber device provided with heat exchange means wherein the heating of the working fluid is an ancillary function to the cooling of the rotary device.

221	With transfer means intermediate single compression volume means and single expansion volume means:
	This subclass is indented under subclass 200.  Apparatus having a singular space means to pressurize the combustible material and a singular space means capable of enlargement to receive the combusted material and with means, located therebetween, to deliver the pressurized combustible material to the receiving space means. (1) Note. Combustion of the gas mixture may occur in the transfer passage means, in the expansion volume means, or in both. (2) Note. This subclass and indented subclasses include engines having an unequal number of compression volumes and expansion volume, wherein each compression volume serves only a single expansion volume at any one time. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   and appropriate subclasses for similar rotary expansion chamber device.

222	Isolated charge in movable transfer element:
	This subclass is indented under subclass 221.  Apparatus provided with means to isolate and physically move a quantity of combustible material from a source to the space in which it may be burned, there being no volumetric change in the material as it is being moved.

223	Reciprocating or oscillating compression volume means:
	This subclass is indented under subclass 221.  Apparatus wherein the means to pressurize the combustible material has a member capable of moving alternately backward and forward thereby pressurizing the combustible material.

224	Radially spaced from expansion volume means:
	This subclass is indented under subclass 223.  Apparatus wherein the compression volume means is spaced from the combusted material receiving means on a line radiating from the center or approximate center of rotation of the combusted material receiving means.

225	Abutment acts as compression means:
	This subclass is indented under subclass 224.  Apparatus wherein the means to receive the combusted material is formed in part by a first portion of a partition structure mounted within the cylinder structure for oscillation or reciprocation relative thereto during rotation of the piston structure, wherein the first portion of the partition structure engages the periphery of the piston structure to form a seal therebetween, and further wherein a second portion of the partition structure acts as a means to compress the air or combustible material.

226	Compression means disposed in rotor:
	This subclass is indented under subclass 224.  Apparatus wherein the compression volume means is mounted on the rotary piston structure.

227	Vane acts as compression means:
	This subclass is indented under subclass 226.  Apparatus wherein the means to receive the combusted material is formed in part by a first portion of a partition structure mounted within the piston structure for oscillation or reciprocation relative thereto during rotation of the piston structure, wherein the first portion of the partition structure engages the inner periphery of the cylinder structure to form a seal therebetween, and further wherein a second portion of the partition structure acts as a means to compress the air or combustible material.

228	Compression volume means circumferentially disposed relative to expansion volume means:
	This subclass is indented under subclass 221.  Apparatus wherein the means to pressurize the combustible material is distally located from the means to receive the combusted material on a closed curvilinear boundary about the axis of rotation of the piston structure.

229	Transfer means in rotor:
	This subclass is indented under subclass 228.  Apparatus wherein at least a portion of the means to transfer the pressurized material is composed of the rotary piston structure.

230	Compression volume is also expansion volume:
	This subclass is indented under subclass 228.  Apparatus wherein the singular space means to pressurize the combustible material acts alternately as the singular space means to receive the combusted material, the combustible material being confined in the transfer means after compression and prior to expansion.

231	Vane:
	This subclass is indented under subclass 228.  Apparatus wherein the means to pressurize the combustible material and the means to receive the combusted material are formed in part by a partition structure mounted within the piston structure for oscillation or reciprocation relative thereto during the rotation of the piston structure wherein the partition structure engages the inner periphery of the cylinder structure to form a seal therebetween. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 259+ for vane-type rotary chamber devices.

232	Interengaging rotors:
	This subclass is indented under subclass 228.  Apparatus wherein the means to pressurize the combustible material and the means to receive the combusted material are separated by a seal produced by the engagement of a rotatable element structure with the periphery of the piston structure. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 191+ for gear-type rotary chamber devices.

233	Nonparallel axes:
	This subclass is indented under subclass 232.  Apparatus wherein the piston structure and the partition structure are mounted for rotation about lines of center that are at an angle relative to each other. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclass 195 for a gear-type rotary chamber device having nonparallel axes.

234	Compression volume means axially disposed relative to expansion volume means:
	This subclass is indented under subclass 221.  Apparatus wherein the means to pressurize the combustible material is spaced from the means to receive the combusted material on the line of center of rotation of the piston structure.

235	Transfer means in rotor:
	This subclass is indented under subclass 234.  Apparatus wherein at least a portion of the means to transfer the pressurized material is disposed within the rotary piston structure.

236	Vane:
	This subclass is indented under subclass 234.  Apparatus wherein the means to pressurize the combustible material and the means to receive the combusted material are formed in part by a partition structure mounted within the piston structure for oscillation or reciprocation relative thereto during the rotation of the piston structure, wherein the partition structure engages the inner periphery of the cylinder structure to form a seal therebetween. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 259+ for a vane-type rotary chamber device.

237	Abutment:
	This subclass is indented under subclass 234.  Apparatus wherein the means to receive the combusted material is formed in part by a first portion of a partition structure mounted within the cylinder structure for oscillation or reciprocation relative thereto during rotation of the piston structure, wherein the first portion of the partition structure engages the periphery of the piston structure to form a seal therebetween. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 243+ for abutment-type rotary chamber devices.

238	Interengaging rotors:
	This subclass is indented under subclass 234.  Apparatus wherein the means to receive the combusted material is formed in part by a seal produced by the engagement of a rotatable element structure with the periphery of the piston structure. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 191+ for gear-type rotary chamber devices.

239	Compression volume means radially disposed relative to expansion volume means:
	This subclass is indented under subclass 221.  Apparatus wherein the means to pressurize the combustible material is spaced from the means to receive the combusted material on a line radiating from the center or approximate center of the combusted material receiving means.

240	Concentric:
	This subclass is indented under subclass 239.  Apparatus wherein the means to pressurize the combustible material and the means to receive the combusted material both are essentially toroidally, and further wherein one of the means encircles the other, with a common center, such that the air or combustible material is transferred from one toroidal shaped means to the other.

241	With compression, combustion, and expansion in a single variable volume:
	This subclass is indented under subclass 200.  Apparatus wherein the pressurization of the combustible material, the ignition of the combustible material, and the expansion of the combusted material all occur within the same enclosed space.

242	Planetating rotor:
	This subclass is indented under subclass 241.  Apparatus wherein the geometric center of the piston structure rotates about an axis noncoincident with said center. (1) Note. The term "planetating" includes both the rotary motion of an object about an axis other than its own geometric axis with or without rotary motion about its own geometric axis. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 54+ for planetating working member rotary chamber devices.

243	Vane:
	This subclass is indented under subclass 241.  Apparatus wherein the enclosed space is formed at least in part by a partition structure mounted within the piston structure for oscillation or reciprocation relative thereto during the rotation of the piston structure, wherein the partition structure engages the inner periphery of the cylinder structure to form a seal therebetween. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 259+ for vane-type rotary chamber devices.

244	Abutment:
	This subclass is indented under subclass 241.  Apparatus wherein the enclosed space is formed at least in part by a partition structure mounted within the cylinder structure for oscillation or reciprocation relative thereto during rotation of the piston structure, wherein the partition structure engages the periphery of the piston structure to form a seal therebetween. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 243+ for abutment-type rotary chamber devices.

245	Alternately approaching and receding elements:
	This subclass is indented under subclass 241.  Apparatus wherein the enclosed space is formed by the simultaneous combined movement produced by the rotation of a plurality of elements or piston structures and the oscillation of two or more of the elements or piston structures. SEE OR SEARCH THIS CLASS, SUBCLASS: 43+, for an internal-combustion engine wherein the piston reciprocates relative to a toroidal cylinder. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 33+ for alternating piston-type rotary chamber devices.

246	Eccentric interengaging rotors:
	This subclass is indented under subclass 245.  Apparatus wherein the peripheries of the elements or piston structures cooperate to form a seal therebetween thereby forming the enclosed space. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 191+ for gear-type rotary chamber devices.

247	Only combustion and expansion of charge in engine:
	This subclass is indented under subclass 200.  Apparatus wherein the piston structure, the cylinder structure, or the other elements cooperate to form an enclosed space in which only burning of the combustible mixture and the enlargement of the combusted material occurs, the compressed combustible material being supplied from an undefined source. (1) Note. This subclass is limited to patents which do not claim the kinetic compressor or other source of the compressed air or fuel mixture. Patents claiming such a compressor or source have been classified in subclasses 221+.

248	Abutment:
	This subclass is indented under subclass 247.  Apparatus wherein the enclosed space is formed at least in part by a partition structure mounted within the cylinder structure for oscillation or reciprocation relative thereto during rotation of the piston structure, wherein the partition structure engages the periphery of the piston structure to form a seal therebetween. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 243+ for abutment-type rotary chamber devices.

249	Interengaging rotors:
	This subclass is indented under subclass 247.  Apparatus wherein the enclosed space is formed at least in part by a seal produced by the engagement of a rotatable element structure with the periphery of the piston structure. SEE OR SEARCH CLASS: 418,  Rotary Expansible Chamber Devices,   subclasses 191+ for gear-type rotary chamber devices.

250	ENGINE MEANS HAVING INTERNAL VAPORIZING IN PRECHAMBER WITH ALL COMBUSTION IN MAIN CHAMBER:
	This subclass is indented under the class definition.  Subject matter having a main combustion chamber in which all combustion takes place and an auxiliary chamber (prechamber) that is used only to vaporize liquid fuel or thoroughly mix a fuel-air mixture before it is burned in the main combustion chamber.

251	Whirling in prechamber:
	This subclass is indented under subclass 250.  Subject matter in which means is provided to effect swirling of the fuel or fuel-air mixture in the prechamber to more thoroughly vaporize or mix the fuel.

252	Vaporizing by a hot surface of prechamber:
	This subclass is indented under subclass 250.  Subject matter in which the fuel in the prechamber is vaporized by heat stored in a surface (e.g., wall) of the prechamber. (1) Note. The heat is usually obtained from combustion in the main chamber.

253	PRECOMBUSTION AND MAIN COMBUSTION CHAMBERS IN SERIES:
	This subclass is indented under the class definition.  Subject matter having at least two distinct physical volumes or chambers in which combustion occurs. The combustion is multi-stage and is initiated in a first chamber, known as a prechamber or auxiliary combustion chamber, and spreads into a final or "main" combustion chamber where combustion is complete and expansion occurs. (1) Note. The prechamber must be a volume that is physically provided for and distinct from the main combustion space and must have at least intermittent fluid communication with the main chamber. (2) Note. Multiple prechambers may be provided for, emptying serially into each other and then into the main chamber, or each emptying in parallel into the main chamber.

254	Chamber temperature control means:
	This subclass is indented under subclass 253.  Subject matter in which means is provided to adjust, maintain, heat, cool, or otherwise control the temperature of the main combustion chamber or prechamber. (1) Note. The means may include particular positioning or construction of a chamber.

255	Vaporizing in precombustion chamber:
	This subclass is indented under subclass 253.  Subject matter in which means is provided in the prechamber to aid in the vaporization of fuel droplets to promote complete and smooth burning. SEE OR SEARCH THIS CLASS, SUBCLASS: 254, for an engine in which the vaporization is aided by heating.

256	Plural precombustion chambers:
	This subclass is indented under subclass 253.  Subject matter in which more than one prechamber is provided. (1) Note. They may empty separately into the main chamber, serially into each other then into the main chamber, or both.

257	Two-cycle:
	This subclass is indented under subclass 253.  Subject matter in which the engine operates on the two-stroke cycle principle. (1) Note. An engine operating in the two-stroke cycle principle completes its operating cycle in one crankshaft revolution.

258	Having timed valves to precombustion and main combustion chambers:
	This subclass is indented under subclass 253.  Subject matter in which the main and prechamber each have at least one intake valve, with significance attributed to the relative valve timing.

259	Having volumetric relation between precombustion and main combustion chambers:
	This subclass is indented under subclass 253.  Subject matter in which a specific ration of the volumes of the main and prechamber is specified.

260	With ignition means particularly positioned relative to precombustion and main combustion chambers:
	This subclass is indented under subclass 253.  Subject matter in which significance is attributed to the location of the ignition means in relation to the pre and main chambers.

261	With injection means particularly positioned relative to precombustion and main combustion chambers:
	This subclass is indented under subclass 253.  Subject matter in which significance is attributed to the location of the injection means in relation to the pre and main chambers.

262	Having fluid whirling means:
	This subclass is indented under subclass 253.  Subject matter wherein means is provided to cause whirling of the fluid in the pre or main chamber or in the intake manifold adjacent a pre or main chamber. SEE OR SEARCH THIS CLASS, SUBCLASS: 280, for atomizer, deflector, or shield in prechamber. 290, for positioning of connecting passage to cause whirling.

263	Whirling in precombustion chamber only:
	This subclass is indented under subclass 262.  Subject matter wherein the means causes whirling of the fluid only in the prechamber.

264	Precombustion chamber is carried by a valve:
	This subclass is indented under subclass 253.  Subject matter in which the prechamber is attached to or formed as an integral part of an engine valve.

265	Precombustion and main chambers form an "L" head:
	This subclass is indented under subclass 253.  Subject matter in which the main and prechamber are so located relative to each other than their cross section is in the shape of an "L". SEE OR SEARCH THIS CLASS, SUBCLASS: 658, for "L" shaped combustion chamber, per se.

266	Precombustion chamber assembly inserted in spark plug hole:
	This subclass is indented under subclass 253.  Subject matter in which the prechamber is attached to the engine by insertion into the hole provided for the spark plug. (1) Note. This type of prechamber is usually used as a retrofit device on an engine not normally having a prechamber. The displaced spark plug is usually screwed into a hole provided for in the prechamber assembly. (2) Note. Prechamber usually screws in. SEE OR SEARCH THIS CLASS, SUBCLASS: 273, for other prechamber mounting means.

267	Separate fuel or combustible mixture added to precombustion chamber:
	This subclass is indented under subclass 266.  Subject matter in which fuel or air-fuel mixture is added to the prechamber in addition to the fuel or mixture obtained from the main chamber.

268	Valveless precombustion chamber:
	This subclass is indented under subclass 253.  Subject matter in which the prechamber contains no valving of any type.

269	Piston shape complements precombustion chamber discharge:
	This subclass is indented under subclass 253.  Subject matter in which an engine piston is shaped to conform to the shape or direction of the discharge from the prechamber outlet and allows free flow therefrom. (1) Note. The piston may also be further shaped to direct the flow from the prechamber to a particular part of the main combustion chamber.

270	Precombustion chamber liner or coating:
	This subclass is indented under subclass 253.  Subject matter in which a surface of the prechamber is provided with a coating or liner. SEE OR SEARCH THIS CLASS, SUBCLASS: 280, for deflector or shield.

271	With liner mounting means:
	This subclass is indented under subclass 270.  Subject matter in which means is disclosed to secure the coating or liner within the prechamber (glue, screw, friction fit, etc.).

272	Including combustion catalyst liner or coating means:
	This subclass is indented under subclass 270.  Subject matter in which the liner or coating contains a catalytic agent that aids or enhances the combustion in the prechamber. (1) Note. The catalyst may even initiate combustion in the prechamber.

273	Precombustion chamber mounting means:
	This subclass is indented under subclass 253.  Subject matter wherein some specific structure or method is disclosed for fastening or removing the prechamber body. SEE OR SEARCH THIS CLASS, SUBCLASS: 266, for a prechamber mounted in a spark plug hole.

274	Having combustible mixture forming means:
	This subclass is indented under subclass 253.  Subject matter wherein specific means is disclosed to provide an air-fuel mixture for the pre or main combustion chamber.

275	By fuel injection into precombustion or main combustion chamber:
	This subclass is indented under subclass 274.  Subject matter wherein fuel at a pressure greater than atmospheric is introduced into either the pre or main combustion chamber.

276	Fuel injected into precombustion chamber formed in piston:
	This subclass is indented under subclass 275.  Subject matter where fuel under pressure greater than atmospheric is introduced into a prechamber which is located in the engine piston.

277	By fuel injection into precombustion chamber with carbureted main chamber:
	This subclass is indented under subclass 275.  Subject matter wherein fuel is introduced under pressure greater than atmospheric into the prechamber and the main chamber is fed with an aspirated or carbureted mixture of air and fuel.

278	By fuel injection into main chamber with carbureted precombustion chamber:
	This subclass is indented under subclass 275.  Subject matter wherein the main chamber is charged with fuel at a pressure greater than atmospheric and where the prechamber is fed with an aspirated or carbureted mixture of air and fuel.

279	Piston carried precombustion chamber:
	This subclass is indented under subclass 253.  Subject matter wherein the prechamber is carried by and mounted on the engine piston. (1) Note. The prechamber may be fueled from the combustion chamber, or through the piston, and/or cylinder wall.

280	Atomizer, deflector, or shield in precombustion chamber:
	This subclass is indented under subclass 253.  Subject matter wherein the prechamber or prechamber throat contains an atomizer, deflector, or shield mounted in the path of the fuel or air-fuel mixture. SEE OR SEARCH THIS CLASS, SUBCLASS: 270+, for prechamber with a liner.

281	Precombustion chamber shape is a figure of revolution:
	This subclass is indented under subclass 253.  Subject matter wherein the three-dimensional shape of the precombustion chamber can be formed by rotating a single planar shape, formed from a combination of straight or curved lines, through 360° about an axis. (1) Note. Connecting throats are not considered as part of the figure of revolution. (2) Note. An example would be to rotate a semicircle about a straight line connecting its free ends (diameter) thus forming a sphere.

282	Figure of revolution is multishaped to form a precombustion chamber:
	This subclass is indented under subclass 281.  Subject matter wherein the three-dimensional shape of the prechamber can be formed by rotating a plurality of separated planar shapes through 360° about an axis. (1) Note. The resulting separate volumes generally have an interconnecting passage.

283	Cylindrical:
	This subclass is indented under subclass 281.  Subject matter wherein the resulting 3-D shape is a cylinder.

284	Spherical:
	This subclass is indented under subclass 281.  Subject matter wherein the resulting 3-D shape is a sphere.

285	Precombustion chamber having a specific shape:
	This subclass is indented under subclass 253.  Subject matter wherein the prechamber has a shape disclosed as critical to the engine operation. SEE OR SEARCH THIS CLASS, SUBCLASS: 281+, for a prechamber having a shape that can be formed by a figure of revolution.

286	Having specific connecting passage means between precombustion and main combustion chambers:
	This subclass is indented under subclass 253.  Subject matter wherein significance is attributed to the design of the passage between the pre and main combustion chambers. (1) Note. The design is usually disclosed as being critical to the combustion process.

287	With ignition means in connecting passage:
	This subclass is indented under subclass 286.  Subject matter wherein combustion initiating means is employed in the connecting passage.

288	Having fuel, a combustible mixture, or air added in the connecting passage:
	This subclass is indented under subclass 286.  Subject matter wherein either fuel, air, or a mixture of both is supplied in the connecting passage.

289	Fluid flow through passage controlled by working piston:
	This subclass is indented under subclass 286.  Subject matter wherein the flow or fluid in the connecting passage between the main and pre chamber is valved or otherwise controlled by some portion of or attachment to the engine working piston.

290	With whirling:
	This subclass is indented under subclass 289.  Subject matter wherein means is provided for swirling the fluid contained in the pre or main chamber, or the connecting passage.

291	Multiple connecting passages:
	This subclass is indented under subclass 289.  Subject matter wherein there are multiple connecting passages or divisions of a single passage between the pre and main chambers.

292	With valve means or variable orifice means in the passage:
	This subclass is indented under subclass 286.  Subject matter wherein the means is provided in the connection between the pre and main chambers to vary the flow path therebetween. SEE OR SEARCH THIS CLASS, SUBCLASS: 289+, for piston-controlled connected passage.

293	Having multiple passages:
	This subclass is indented under subclass 286.  Subject matter wherein there are multiple connecting passages or divisions of a single passage between the pre and main chambers.

294	COMBUSTION CHAMBER MEANS HAVING FUEL INJECTION ONLY:
	This subclass is indented under the class definition.  Subject matter in which all fuel, liquid or gaseous, and unmixed with air, is supplied under pressure to the interior of the combustion or working chamber. SEE OR SEARCH THIS CLASS, SUBCLASS: 495+, for a fuel pump available for supplying fuel to form the combustible charge in an engine of the type in this subclass. 531+, for engines having air-fuel mixture injected into combustion chamber. SEE OR SEARCH CLASS: 239,  Fluid Sprinkling, Spraying, and Diffusing,   subclasses 533.2+ for injection nozzle structure, per se. 417,  Pumps,   subclass 364 for a fuel pump available for supplying fuel to form the combustion charge in an engine of the type in this subclass.

295	Combustible mixture stratification means:
	This subclass is indented under subclass 294.  Subject matter in which means is provided to deliberately create a nonhomogeneous mixture charge within the combustion chamber.

296	Injector is an integral part of engine valve:
	This subclass is indented under subclass 294.  Subject matter in which the fuel injector is mounted on, carried by, or otherwise an integral part of an engine intake or exhaust valve.

297	Combination igniting means and injector:
	This subclass is indented under subclass 294.  Subject matter wherein an engine spark plug or external ignition device and an engine fuel injection nozzle or valve are at least in part combined in one structural unit.

298	Injection of fuel onto igniter, deflector, heater, or atomizer:
	This subclass is indented under subclass 294.  Subject matter wherein the injected fuel spray pattern or some part of the pattern in the combustion chamber impacts on a heater, igniter, deflector, or atomizer.

299	Using multiple injectors or injections:
	This subclass is indented under subclass 294.  Subject matter wherein, a plurality of injectors or a plurality of distinct spray patterns from the same injector are employed in each engine cylinder. (1) Note. This includes simultaneous or sequential injections.

300	Alternating multiple injectors (e.g., series injection):
	This subclass is indented under subclass 299.  Subject matter wherein multiple injectors make their injections, one following the other, with no overlap of their injection periods (e.g., series injection).

301	Injected fuel spraying into whirling fluid:
	This subclass is indented under subclass 294.  Subject matter wherein the injected fuel is sprayed into a whirling, swirling, or rotating fluid mass in the engine cylinder.

302	Air entering combustion chamber through plural inlets:
	This subclass is indented under subclass 294.  Subject matter wherein the combustion chamber has plural separate air or oxidant inlet ports.

303	Having inlet uncovered by working piston:
	This subclass is indented under subclass 302.  Subject matter wherein at least one of the inlet ports is valved by a part of the engine piston during some portion of its working stroke.

304	Injecting diverse fuels or different states of same fuel:
	This subclass is indented under subclass 294.  Subject matter wherein at least two different types of fuel or the same fuel in two or more different states (e.g., liquid and gas, are injected directly into a combustion chamber).

305	Having a particular relationship between injection and ignition characteristics (e.g., nozzle location, spray pattern, timing relative to igniter location, timing):
	This subclass is indented under subclass 294.  Subject matter in which significance is attributed to the relationship between the functional or structural characteristics of injection and ignition.

306	MEANS TO WHIRL FLUID BEFORE, UPON, OR AFTER ENTRY INTO COMBUSTION CHAMBER:
	This subclass is indented under the class definition.  Subject matter which employs a combustion chamber and some means either in the inlet or outlet of the combustion chamber or within the chamber itself to whirl the engine fluid so that some fluid whirling results in the combustion chamber itself. SEE OR SEARCH THIS CLASS, SUBCLASS: 262+, and 290, for fluid whirling means with a prechamber.

307	Structural projection on working piston causes whirling:
	This subclass is indented under subclass 306.  Subject matter wherein the engine working piston includes some form of projection which induces whirling of the engine fluid in the combustion chamber. (1) Note. This subclass does not include a piston projection which merely directs the fluid along some nonrotary path. Whirling is rotary motion and is generally about the cylinder axis.

308	Having multiple oxidant inlet means:
	This subclass is indented under subclass 306.  Subject matter wherein the combustion chamber has a plurality of separate air or oxidant inlet members.

309	Specific spark plug location:
	This subclass is indented under subclass 306.  Subject matter wherein significance is attributed to the specific location of the spark plug with respect to the whirling fluid.

310	COMBUSTION CHAMBER HAVING MULTIPLE SPARK GAPS:
	This subclass is indented under the class definition.  Subject matter which employs a plurality of spark plugs per engine combustion chamber or which employs a plurality of spark gaps per combustion chamber with the spark gaps extending beyond the diameter of spark plug hole. SEE OR SEARCH THIS CLASS, SUBCLASS: 169+, for multiple gap spark plug. SEE OR SEARCH CLASS: 313,  Electric Lamp and Discharge Devices,   subclasses 123+ for multiple gap spark plug.

311	FOUR-CYCLE:
	This subclass is indented under the class definition.  Subject matter having a single-acting working cylinder and a single working piston reciprocating therein and in which compression takes place in the working cylinder before ignition, said engine working upon a cycle comprising four distinct strokes, namely, an expansion stroke following ignition of the charge, followed by exhaust, intake, and compression strokes. (1) Note. This subclass and those indented hereunder are intended to include four-stroke cycle engines in which at least one of the cycles is varied or modified from the conventional four-stroke cycle engine. A nominally claimed four-stroke cycle is not sufficient for classification in this and indented subclasses, if there is significant disclosure for classification elsewhere in the class, unless there is a claim for a specific four-stroke engine. SEE OR SEARCH THIS CLASS, SUBCLASS: 559+, for a super-charged four-cycle engine.

312	Engine cylinder having a reciprocating sleeve valve:
	This subclass is indented under subclass 311.  Subject matter in which the four-stroke engine utilizes a reciprocating sleeve to valve the intake or exhaust port. The sleeve is reciprocated in timed relationship with the movement of the piston in the cylinder. (1) Note. The sleeve valve is usually cylindrical in shape.

313	Having a junk ring seal:
	This subclass is indented under subclass 312.  Subject matter in which a sealing ring is provided between the sleeve valve and cylinder head. (1) Note. The ring is referred to as a junk ring, and is usually located between the head and the inside surface of the sleeve valve. (2) Note. The junk ring is usually provided to prevent combustion residue from entering the space provided for sleeve valve and interfering with the operation of said valve.

314	Having sleeve valve lubrication means:
	This subclass is indented under subclass 312.  Subject matter including means to provide for lubrication of the sleeve valve.

315	Multiple exhaust:
	This subclass is indented under subclass 311.  Subject matter wherein said exhaust means comprises a plurality of exhaust apertures.

316	Having subcharger associated with the cylinder:
	This subclass is indented under subclass 311.  Subject matter wherein some part of the charge is bled from the cylinder upon compression, stored and then returned to the system upon a subsequent intake stroke.

317	Crankcase compression of air or combustible mixture to be subsequently pumped into the working cylinder:
	This subclass is indented under subclass 311.  Subject matter wherein the charge or any part of the charge is compressed at least partially in the chamber housing the engine crankshaft upon the downstroke of the engine working piston; the pressurized air or mixture is then pumped into the cylinder to insure complete filling.

318	Rear compression of air or combustible mixture to be subsequently pumped into the working cylinder:
	This subclass is indented under subclass 311.  Subject matter wherein the charge or some part of the charge is compressed by the engine working piston on its downstroke in a volume other than that of the engine crankcase. (1) Note. This volume is generally immediately adjacent the connecting rod side of the engine piston and is sealed at the passage of the connecting rod to the crankcase. The pressurized air or mixture is pumped into the cylinder to insure complete filling.

319	ENGINE SPEED REGULATOR:
	This subclass is indented under the class definition.  Subject matter in which the output shaft speed of an internal combustion engine is controlled (i.e., accelerate, decelerate, or maintain constant R.P.M.) by varying the power input thereto. (1) Note. The primary purpose of a speed regulator is to regulate the shaft speed of the engine and includes feedback or nonfeedback types. Since fuel injection pump governors almost always regulate the engine shaft speed by varying the amount of fuel injected, they have been included in the speed regulating subclasses. The primary purpose of the charge former is to form a combustible charge to be fed to the engine at any given operating condition. Charge former may utilize sensed engine parameters to adjust the quality of the mixture formed. The parameters may include engine speed, vacuum (load), air flow, etc. SEE OR SEARCH CLASS: 48,  Gas: Heating and Illuminating,   subclasses 144+ and 180.1+. 60,  Power Plants,   where combustion products are used as a motive fluid subclass 773 for processes of having power output control or subclasses 793-39.3 for a power plant combined with a regulation of power output feature. 73,  Measuring and Testing,   subclasses 488+ for a speed-responsive device to general application. 137,  Fluid Handling,   subclasses 47+ for speed-responsive valve control. 180,  Motor Vehicles,   subclasses 170+ for vehicle speed-responsive regulators. 188,  Brakes,   subclasses 266+ for internal resistance brakes of the fluid type in which no significant internal combustion engine is claimed. 477,  Interrelated Power Delivery Controls, Including Engine Control,   for interrelated controls between an engine and a transmission, clutch, or brake.

320	Responsive to deceleration mode (e.g., engine acting as a brake):
	This subclass is indented under subclass 319.  Subject matter wherein the speed regulator senses high manifold vacuum, closed throttle, and rpm above idle and responds to cause or attempt to cause a further reduction in engine rpm. (1) Note. In many instances, the speed regulator includes means to reduce pollutants in the exhaust gas causes by the deceleration condition.

321	Valve timing altering means (e.g., axially sliding cam shift):
	This subclass is indented under subclass 320.  Subject matter in which a device is provided to alter the instant at which opening or closing of an engine valve begins, to cause the engine to act as a brake.

322	Electrical means adapted to alter valve timing:
	This subclass is indented under subclass 321.  Subject matter having means to change the amount of time the intake or exhaust valve is open, each cycle wherein said means is electric.

323	Exhaust throttling or blocking:
	This subclass is indented under subclass 320.  Subject matter to throttle or block the exhaust as the engine acts as a brake. SEE OR SEARCH CLASS: 188,  Brakes,   subclass 273 for a brake on an internal combustion engine acting by restricting the exhaust from said engine.

324	Part of the air or combustible mixture to the engine cylinder omitted:
	This subclass is indented under subclass 320.  Subject matter that includes means to omit a portion of the engine input air or charge, further decelerating the motor or clean the exhaust of the already decelerating motor.

325	Deceleration responsive cutoff of fuel to engine (e.g., pollution control):
	This subclass is indented under subclass 320.  Subject matter including means to stop fuel flow of the engine to decal the engine or clean up the emissions of the already decelerating engine.

326	Rich resupply of fuel at end of deceleration:
	This subclass is indented under subclass 325.  Subject matter to deliver a squirt of fuel to the engine to facilitate a burst of power for an impending acceleration.

327	Auxiliary air fed to the engine:
	This subclass is indented under subclass 320.  Subject matter wherein means are provided to supply additional air to the engine cylinder in response to a deceleration condition.

328	Idle jet bypassed by a slight opening of the throttle:
	This subclass is indented under subclass 320.  Subject matter in which the speed regulator includes means to open the throttle butterfly slightly when the engine is in a deceleration condition to prevent an excessive amount of fuel from being drawn from the idle jet.

329	Having means to retard spark (e.g., ignition timing):
	This subclass is indented under subclass 320.  Subject matter in which the speed regulator includes means to retard the spark firing instant so that the plug fires closer to or after top dead center.

330	Engine speed reduction by overriching the combustible mixture (e.g., choking engine):
	This subclass is indented under subclass 319.  Subject matter to regulate the engine speed by adding more fuel to the mix or otherwise providing less air per part of mix, thus producing a choking effect on the engine, resulting in engine speed reduction.

331	By electric means:
	This subclass is indented under subclass 330.  Subject matter wherein said engine speed regulating means is electrical or is an electrically actuated mechiready decelerating engine.

332	Engine speed reduction by fuel cutoff:
	This subclass is indented under subclass 319.  Subject matter to regulate the engine speed by stopping the fuel supply to the engine.

333	By electric means:
	This subclass is indented under subclass 332.  Subject matter including means to stop fuel flow to the engine wherein said means is electric or is an electrically actuated mechanical or fluidic means.

334	Engine speed reduction by partial or complete omission of the ignition:
	This subclass is indented under subclass 319.  Subject matter in which a means to regulate engine speed is operative to prevent ignition in at least one engine cylinder.

335	By electric means:
	This subclass is indented under subclass 334.  Subject matter in which a means to prevent ignition is electrically operated.

336	Having plural throttle valve structure:
	This subclass is indented under subclass 319.  Subject matter having more than one butterfly valve in the engine intake (e.g., carburetor).

337	Specific throttle valve structure:
	This subclass is indented under subclass 319.  Subject matter wherein the carburetor or engine intake has a unique butterfly configuration that is significant to its operation as a speed regulating device.

338	Fuel injection pump bypass control:
	This subclass is indented under subclass 319.  Subject matter having a fuel injection pump bypass governor so that fuel is diverted from the pumping chamber during the pump intake stroke, or part of the fuel delivered past the pump outlet valve is diverted from delivery to the associated engine. (1) Note. The fuel diverted is usually conducted back to the supply tank or inlet of the pump.

339.1	Idle speed control:
	This subclass is indented under subclass 319.  Subject matter (a) wherein the output shaft has a varied minimum operating speed, and (b) comprising a manual input member and means for adjusting the minimum operating speed of the shaft while maintaining the manual input member (e.g., accelerator pedal, hand control) at a minimum position. (1) Note. An engine idle speed control responsive to a signal indicative of an engine operating condition or indicative of an external load applied to the engine (e.g., power steering pump, lights, electric generator) is provided for here. SEE OR SEARCH CLASS: 290,  Prime-Mover Dynamo Plants,   appropriate subclasses, especially subclasses 40+ for engine idle speed control responsive to a sensed parameter of an electric generator. 477,  Interrelated Power Delivery Controls, Including Engine Control,   appropriate subclasses, especially subclasses 34+ for an engine idle speed control responsive to a signal indicative of a transmission, clutch, or brake condition.

339.11	By regulating spark ignition timing:
	This subclass is indented under subclass 339.1.  Subject matter comprising a combustion chamber, a combustible mixture, a piston traveling in the chamber, a rotatable crankshaft, and means creating a short pulse or flow of electric current for causing the combustible mixture to burn in the combustion chamber wherein the minimum output shaft operating speed is adjusted by varying the point of piston travel or crankshaft rotation at which the short pulse or flow of electric current occurs. SEE OR SEARCH THIS CLASS, SUBCLASS: 406.19+, for an internal combustion engine spark ignition timing control adjusted in response to sensed engine shaft output speed.

339.12	And air-fuel ratio feedback controlled:
	This subclass is indented under subclass 339.1.  Subject matter comprising a combustion chamber having a space therein, a combustible mixture containing an oxidant and a fuel, and wherein the minimum output shaft operating speed is adjusted and the relative proportion of oxidant and fuel in the combustible mixture which is fed to the combustion space or chamber is varied according to a sensed parameter indicative of the proportion of oxidant in the mixture. (1) Note. The parameter sensed may be indicative of an amount of a component of the combustible mixture fed to the combustion chamber or an amount of a component of the exhaust gas. SEE OR SEARCH THIS CLASS, SUBCLASS: 344, for a device for controlling the engine speed by varying the air-fuel ratio. 680, for a charge-forming device which is responsive to engine exhaust gas condition and idling condition. 704, for a charge-forming device which is responsive to a sensed air-fuel ratio prior to combustion.

339.13	Manual adjustment:
	This subclass is indented under subclass 339.1.  Subject matter wherein the means for adjusting the minimum output shaft operating speed of the internal combustion engine is adjusted by hand or through use of a hand-manipulated tool. (1) Note. The manual adjustment may be combined with an electrically operated control device. SEE OR SEARCH CLASS: 261,  Gas and Liquid Contact Apparatus,   appropriate subclasses for carburetor adjustments, per se.

339.14	Electrically operated control means:
	This subclass is indented under subclass 339.1.  Subject matter wherein the means for adjusting the minimum output shaft operating speed of the internal combustion engine is powered by electrical energy. SEE OR SEARCH THIS CLASS, SUBCLASS: 350+, for electrical sensing or regulating of engine speed with the engine being part of a closed loop condition responsive feedback system. 395+, for an open loop condition responsive speed regulator for an engine.

339.15	With fail-safe, backup, or malfunction detecting means:
	This subclass is indented under subclass 339.14.  Subject matter and wherein the electrically powered adjusting means includes an electrical circuit having a circuit element and wherein the electrically powered adjusting means (a) upon sensing failure in the circuit element shifts operation (1) into a substitute circuit, or (2) to a substitute mechanism to accomplish the same function, or (b) senses functioning of the circuit or circuit element outside of acceptable parameters. SEE OR SEARCH THIS CLASS, SUBCLASS: 479, for a charge-forming device having an electrically actuated fuel injector and an actuator circuit including a fail-safe, backup, or failure indicator. 690, for an exhaust gas condition responsive charge-forming device including a fail-safe, backup or malfunction means. SEE OR SEARCH CLASS: 340,  Communications: Electrical,   appropriate subclasses for an electrical alarm or indicating system. 361,  Electricity: Electrical Systems and Devices,   appropriate subclasses for an electrical fail-safe or backup system without significant internal combustion engine structure. 701,  Data Processing: Vehicles, Navigation, and Relative Location,   subclasses 99+ for control means for an internal-combustion engine including specific computer or data processing details.

339.16	External load condition responsive:
	This subclass is indented under subclass 339.14.  Subject matter wherein the electrically powered adjusting means is adjusted or modified in response to a signal from a transducer responsive to a parameter indicative of the resistance to rotation of the output shaft of the engine by a device driven by the engine. SEE OR SEARCH CLASS: 180,  Motor Vehicles,   subclass 69.3 for a motor vehicle having means to increase the idle speed of an internal combustion engine to compensate for an accessory load.

339.17	Air conditioner operating mode responsive (i.e., compressor on-off):
	This subclass is indented under subclass 339.16.  Subject matter including (1) an apparatus (a) for lowering a temperature and humidity of an enclosed space, and (b) having a clutch compressor and (2) wherein the minimum engine output shaft operating speed is adjusted in response to a parameter indicative of the state of engagement (i.e., on or off) of the compressor clutch. SEE OR SEARCH THIS CLASS, SUBCLASS: 41.19, for an internal combustion engine cooled by a refrigeration cycle. SEE OR SEARCH CLASS: 62,  Refrigeration,   appropriate subclasses, especially subclasses 323.1+ for engine idle speed control in response to a specific air conditioner parameter (e.g., refrigerant pressure).

339.18	Accessory load (e.g., lights, heater blower motor, radiator fan motor, generator) on engine electrical system responsive:
	This subclass is indented under subclass 339.16.  Subject matter comprising an ancillary device that induces a resistance to rotation of the output shaft and wherein the electrically powered means for adjusting the minimum engine output shaft operating speed responds to a condition indicative of the resistance to rotation of the output shaft induced by the ancillary device. (1) Note. An internal combustion engine idle speed control electric generator combination in which the electric generator is merely a nominal load driven by the internal combustion engine is found here. SEE OR SEARCH CLASS: 290,  Prime-Mover Dynamo Plants,   subclasses 40+ for the combination of an internal combustion engine idle speed control and an electric generator in which is included (a) any detail of the generator, (b) any relationship between a generator part and an internal combustion engine, or (c) any control of the internal combustion engine in response to the electricity produced by the generator.

339.19	By engine speed error feedback:
	This subclass is indented under subclass 339.14.  Subject matter wherein the electrically powered adjusting means (a) measures an actual minimum engine output shaft operating speed, (b) compares the measured output shaft operating speed to a target minimum output shaft operating speed, and (c) adjusts the measured output shaft operating speed to achieve the target minimum output shaft operating speed. SEE OR SEARCH THIS CLASS, SUBCLASS: 352+, for electrical sensing or regulating of engine speed with the engine being part of a closed loop condition responsive feedback system and an error signal producing circuit. 395+, for an open loop condition responsive speed regulator system for an engine.

339.2	Dynamic state variable model:
	This subclass is indented under subclass 339.19.  Subject matter wherein the electrically powered adjusting means (a) has a preprogrammed memory of stored values from a previous test phase (e.g., bench test), (b) compares actual engine condition values to the stored values, and (c) anticipates adjustments necessary to control the minimum output shaft operating speed. SEE OR SEARCH THIS CLASS, SUBCLASS: 350+, for electrical sensing or regulating of engine speed with the engine being part of a closed loop condition responsive feedback system. 395+, for an open loop condition responsive speed regulator for an engine. 418+, for a spark ignition timing control responsive to engine output shaft operating speed. 480, for an electrically actuated fuel injector actuator circuit having a microprocessor. SEE OR SEARCH CLASS: 701,  Data Processing: Vehicles, Navigation, and Relative Location,   subclasses 101+ for control means for an internal-combustion engine including specific computer or data processing details.

339.21	And integral or derivative control:
	This subclass is indented under subclass 339.19.  Subject matter and wherein the electrically powered adjusting means (a) receives a signal indicative of an engine operating parameter, and (b) either (1) determines on a continuous basis the total value of the parameter being measured as a function of time or (2) determines a rate of change of the parameter being measured as a function of time, and (c) uses the result to vary the minimum engine shaft operating speed.

339.22	And temperature responsive:
	This subclass is indented under subclass 339.19.  Subject matter and wherein the electrically powered adjusting means additionally adjusts the minimum engine shaft operating speed in response to changes in temperature (e.g., temperature of an engine component, engine fluid, or the ambient environment). SEE OR SEARCH THIS CLASS, SUBCLASS: