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CLASS 337,	ELECTRICITY: ELECTROTHERMALLY OR THERMALLY ACTUATEDSWITCHES
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SECTION I - CLASS DEFINITION

This class is restricted to the structure of electric current switching devices of general application for closing or opening electrical circuits which devices depend upon the heating effect of a current or of the ambient temperature of the surrounding medium for their operation.

This class also includes miscellaneous elements, or subcombinations of elements, restricted for use in and with the class type switches and which have not reached the status of separate classification elsewhere.

This class also includes implements or handling devices specifically adapted for use with the class type switches and not provided for elsewhere in a separate class.

Electrical systems or circuits which include electrothermally or thermally operated switches, comprising the subject matter of this class, are excluded from this class. These systems or circuits are classified in the various electrical or art classes depending upon the type of system or apparatus controlled.

SECTION II - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

SUBCLASSES

1	WITH DIVERSE ART-TYPE DEVICE:
	This subclass is indented under the class definition.  Subject matter wherein an electrothermal or thermally actuated switch is combined with another device having an added purpose or utility independent of the switch and in which the utility of the other art device is not destroyed by the removal of or deactivation of the switching device and which claimed combination does not include sufficient specific structure of the other art device as to be classified either with the other art device, per se, or elsewhere. (1) Note. See the appropriate other art class in the Manual of Classification for specific other art devices which may be combined with switching means.

2	WITH SEPARATE DISTINCT DIVERSE ART-TYPE SWITCHING DEVICE (E.G., FLUID- OR MECHANICAL-ACTUATED):
	This subclass is indented under the class definition.  Subject matter wherein the structure includes at least two independent separate and distinct switches, one or more of which is of the type classifiable in this class combined with at least one diverse art type switch classifiable in another art class. (1) Note. Example (1) Fuses connected or associated with automatic circuit breakers of the mechanical type. The fused means being adapted to open an electric circuit breaker means opens or closes the same circuit independently of the fuses under certain other conditions. SEE OR SEARCH THIS CLASS, SUBCLASS: 1, for specific art type electrothermal device combined with other art type. SEE OR SEARCH CLASS: 62,  Refrigeration,   subclass 4 , for refrigerator devices utilizing combined expansible fluid actuated switches with other art types. 74,  Machine Element or Mechanism,   subclasses 471+ for control lever and linkage systems controlling multiple elements and utilizing multiple switches. 123,  Internal-Combustion Engines,   subclass 198 for control devices utilizing combined electrothermal and magnetic switches. 200,  Electricity: Circuit Makers and Breakers,   subclass 3 for mechanical multiple circuit control devices with thermal current means. 219,  Electric Heating,   subclasses 482+ for power supply and voltage or current regulatory systems for electric heaters which may utilize plural diverse switches. 236,  Automatic Temperature and Humidity Regulation,   appropriate subclasses particularly subclasses 2+ for electric heaters of different art types combined with an operative in an incubator and subclasses 91+ for various thermostatic controls which may combine two or more types. 335,  Electricity: Magnetically Operated Switches, Magnets, and Electromagnets,   subclass 1 for magnetically actuated switches combined with electrothermal or thermally actuated switch, subclasses 141+ for magnetically actuated switches with additional electrothermal means.

3	Bimetallic device with other:
	This subclass is indented under subclass 2.  Subject matter wherein the art type switch comprises or utilizes at least one thermally responsive element consisting of a composite of two dissimilar metals which expand different amounts under the influence of heat and whereby associated circuit contacts are opened or closed as a result of the bending of the element. SEE OR SEARCH THIS CLASS, SUBCLASS: 13, for thermally actuated switches utilizing a bimetallic element combined with other diverse actuating means such as a magnet. 16, for shunt circuit completion devices with bimetallic elements. 35, for plural bimetallic actuating means in a single switch. 36, for electrothermal switches in general using bimetallic elements.

4	Fusible element device with other:
	This subclass is indented under subclass 2.  Subject matter wherein the art type switch comprises or utilizes a device capable of melting and thereby causing the interruption of an electric circuit when abnormally heated by the current in the electrical circuit. SEE OR SEARCH THIS CLASS, SUBCLASS: 142+, for electrothermal switches of the fusible type. 299, for thermally actuated fuses combined with diverse similar art type devices. 401+, for thermal switches utilizing fuses for the principal operating means. SEE OR SEARCH CLASS: 218,  High-Voltage Switches With Arc Preventing or Extinguishing Devices,   subclasses 22+ for mechanical magnetic blowout switches which may employ fusible elements. 335,  Electricity: Magnetically Operated Switches, Magnets, and Electromagnets,   subclass 142 for magnetically operated switches with fuses. 361,  Electricity: Electrical Systems and Devices,   appropriate subclasses for safety and protection devices which may utilize fuses combined with mechanical means.

5	Diverse art-type switching device responsive to the condition of fusible element:
	This subclass is indented under subclass 4.  Subject matter including structure whereby the operative condition of the other art switching device is directly controlled by the condition of the fusible element. (1) Note. Example: A spring controlled mechanical circuit closing device the operation of which takes place upon the rupture of a fusible device which normally completes the circuit. SEE OR SEARCH THIS CLASS, SUBCLASS: 143, for electrothermal switches having a fuse controlling mechanical contact control means. 402, for thermally actuated fuses controlling mechanical contact control means.

6	With automatic circuit-interrupting device:
	This subclass is indented under subclass 4.  Subject matter wherein the other art switching device comprises means whereby normally closed contacts are automatically opened upon the occurrence of an abnormal circuit condition. (1) Note. This subclass also includes patents where the fusible element device is claimed in detail and the other art type switch is specifically described as a circuit breaker, providing plural distinctive switches are in fact claimed and the combination is not classifiable in another art. SEE OR SEARCH CLASS: 361,  Electricity: Electrical Systems and Devices,   subclasses 103+ for automatic circuit breakers, and subclasses 161+ for thermal controls for relays.

7	Multiphase of multipole:
	This subclass is indented under subclass 6.  Subject matter wherein the other art switching device is further described as comprising a plurality of individual conductors which comprise the conductors of a polyphase or plural conductor transmission line. (1) Note. See the note to the definition of subclass 6 above. SEE OR SEARCH THIS CLASS, SUBCLASS: 45+, for bimetallic element operated electrothermal switches of the multipole or polyphase type with manual control. 146, for fusible element actuated electrothermal switches of the multipole or polyphase type.

8	Manually operable mechanical device:
	This subclass is indented under subclass 4.  Subject matter wherein the other art switch device is recited as comprising a manually operated circuit controller. SEE OR SEARCH THIS CLASS, SUBCLASS: 143+, for electrothermally actuated fuses combined with and controlling manual or other mechanical contact operating means. 402+, for thermally actuated fuses controlling manually operated contact control means.

9	Knife or blade switch:
	This subclass is indented under subclass 8.  Subject matter wherein the manually operable other art device is specifically recited as a knife or blade switch wherein the movable element, a hinged blade, enters or embraces the contact clips. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   subclasses 554+ for mechanical knife switches which may be protected by fuses.

10	Rotary or reciprocating mechanism:
	This subclass is indented under subclass 8.  Subject matter wherein the manually operated other art device is specifically recited as comprising rotary or reciprocating mechanical contact actuating structure. SEE OR SEARCH THIS CLASS, SUBCLASS: 64, for bimetallic element electrothermal switch with reciprocating spring actuated actuating device. 111, and 149, respectively, for reciprocating or rotary mechanical actuators for fusible element type electrothermal switches. 200+, and 410, respectively, for reciprocating or rotary mechanical actuators of thermal switches of the fusible, combustible or explosive material type. 238, for bimetallic element electrothermal switch with rotary or oscillatory motion spring actuated operator. 347+, and 348, respectively, for rotary or reciprocating mechanical actuators for bimetallic element thermally operated switches. 398+, and 401, respectively, for reciprocating or rotary mechanical actuators for expansible or vaporizable fluid actuated thermal switches. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   subclasses 465+ for mechanical switches with rotating contact control means which may be protected by fuses.

11	With multiple circuit connector device (e.g., multiple mechanical):
	This subclass is indented under subclass 4.  Subject matter wherein the other art device is specifically described as a device in which a plurality of contacts are arranged to control two or more independent electrical circuits. (1) Note. The subject matter in this subclass should not be confused with the other art type devices in subclass 7 above in which a plurality of conductors comprise a single circuit. SEE OR SEARCH THIS CLASS, SUBCLASS: 59+, for electrothermal bimetallic element switch with multiple contacts and mechanical actuator. 145, for electrothermal fuse means controlling multiple contact or plural circuit control means. 337+, for thermal bimetallic element switches of the multiple contact type and with mechanical actuator. 406, for thermally actuated fuses controlling multiple contacts or plural circuit control means. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   subclasses 1+ for mechanical multiple circuit control devices which may be protected by fuses. 361,  Electricity: Electrical Systems and Devices,   subclasses 1+ and 114+ for mechanical safety and protective devices which may control a multiplicity of circuits.

12	WITH DIVERSE ART-TYPE ACTUATOR FOR SINGLE SWITCH:
	This subclass is indented under the class definition.  Subject matter including at least one contact actuating means of the type classifiable in this class in combination with a diverse type actuating means of a type classifiable elsewhere in another art class and each one acting singly or conjointly to control the same single set of switch contacts. The two or more actuating means may be physically located in the same housing or casing and may have cooperative features as long as each one is operative independent of the other. Some examples of diverse type switch actuating means are the mechanical special application switches in Class 200. (1) Note. For similar subject matter including the combination of electromagnetic or magnetic control means combined with thermal-current responsive means, search will be in Class 335, Electricity: Magnetically Operated Switches, Magnets, and Electromagnets, subclasses 141+ and in the classes and subclasses referred to in the search notes under the subclass definition. SEE OR SEARCH THIS CLASS, SUBCLASS: 54, and 90, for electrothermally actuated bimetallic switches which operate with a snap action and have additional magnetic flux sources to act as holding or biasing means. 134, for longitudinally expansible element devices with magnetic biasing or holding means. 344, and 366, for thermally actuated bimetallic switch devices with magnetic holding or biasing means. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   appropriate subclass for special application switches which may also include electrothermal or thermal actuating means. 219,  Electric Heating,   subclass 491 for heating devices with combined regulating or control means. 335,  Electricity: Magnetically Operated Switches, Magnets, and Electromagnets,   subclasses 141+ for electromagnetically actuated switches which include additional electrothermal or thermal actuating means.

13	Bimetallic with other:
	This subclass is indented under subclass 12.  Subject matter wherein one of the claimed thermally responsive elements is specifically recited as being a bimetallic element. SEE OR SEARCH THIS CLASS, SUBCLASS: 3, above for a bimetallic element actuated switch combined with a diverse art type switch (e.g., fluid actuated).

14	ELECTROTHERMALLY ACTUATED SWITCHES:
	This subclass is indented under the class definition.  Devices relating to structure operative to open or close an electric circuit or circuits and the combination of those devices; the operating means whereby the opening or closing function is accomplished by a thermal device directly inserted in the circuit and traversed by the controlling current. The circuit generally is the circuit which is to be controlled. (1) Note. The electrothermal actuated switches of subclasses 14+ are distinguished from the thermally actuated switches in subclasses 298+ in that in the latter group the devices are principally responsive to heat from an external source, for instance the heat in a surrounding medium. SEE OR SEARCH THIS CLASS, SUBCLASS: 2+, for electrothermal switches combined with diverse art type switches. SEE OR SEARCH CLASS: 99,  Foods and Beverages: Apparatus,   subclasses 324+ for cooking apparatus with electrothermal control. 219,  Electric Heating,   subclasses 482+ for electrothermally controlled heating devices and subclasses 507+ for heating devices. 313,  Electric Lamp and Discharge Devices,   appropriate subclasses, especially subclasses 11+ for discharge devices with temperature modifying means. 314,  Electric Lamp and Discharge Devices: Consumable Electrodes,   subclasses 89+ for glow discharge devices with thermostatic operator means. 315,  Electric Lamp and Discharge Devices: Systems,   appropriate subclasses for discharge device systems with electrothermal control means combined with a discharge device load. 318,  Electricity: Motive Power Systems,   and subclasses 471+ for thermally controlled automatic starting and/or stopping systems. 320,  Electricity: Battery or Capacitor Charging or Discharging,   subclasses 166+ for charging or discharging a capacitor, per se. 322,  Electricity: Single Generator Systems,   subclasses 33+ for thermally responsive automatic control means for a single generator. 335,  Electricity: Magnetically Operated Switches, Magnets, and Electromagnets,   subclass 23 for circuit breakers with combined magnets and thermal latch or trip means and subclasses 141+ for electromagnetically actuated switches combined with electrothermal actuating means. 340,  Communications: Electrical,   subclasses 584+ for alarms and signal systems which are temperature controlled. 361,  Electricity: Electrical Systems and Devices,   subclasses 161+ for thermal controls for relays, subclasses 247+ for ignition systems with a spark gap igniter, and subclasses 627+ for distribution boards with fuse means. 388,  Electricity: Motor Control Systems,   art collections 934 for motor control systems responsive to a thermal condition.

15	Shunt or short circuit completion devices:
	This subclass is indented under subclass 14.  Subject matter including means whereby upon the failure of any selected portion of an electrical circuit or a device within the selected portion, an electrical conducting shunt circuit is automatically established around the device or the selected portion of the circuit. (1) Note. The devices found here are especially adapted for use in closing a shunt circuit around a translating device or a loop circuit when such translating device becomes inoperative or the loop circuit is broken. These devices are generally used in series lighting circuits so that in case a lamp breaks or burns out a shunt circuit is completed around the lamp in order to keep the main circuit closed. SEE OR SEARCH THIS CLASS, SUBCLASS: 125, for electrothermal switch with longitudinally expansible element type with electrical shunting means. 221, for electrothermal switch of the fusible element type with electrical shunt circuit means. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   for shunt circuit closing devices for multiple control (loop), subclass 51.5 for short circuit closing devices actuated by the separation of coupling members and subclass 51.11 for shunt circuit closing devices wherein the switch is in parallel with the coupling contacts. 315,  Electric Lamp and Discharge Devices: Systems,   subclasses 74+ and 119+ for electric lamp and electric space discharge device systems, provided with automatic shunt circuit closing means.

16	Bimetallic means:
	This subclass is indented under subclass 15.  Subject matter wherein the shunt circuit completing means comprises at least one bimetallic device, i.e., an element consisting of at least two solid strips or bars formed of materials having different coefficients of expansion. SEE OR SEARCH CLASS: 290,  Prime-Mover Dynamo Plants,   subclass 38 for electrical starting motors which may have bimetallic means shunting the starting resistance. 315,  Electric Lamp and Discharge Devices: Systems,   appropriate subclasses, especially subclasses 74 and 83 for load devices with electrical circuits and temperature modifying means utilizing bimetallic shunting means. 324,  Electricity: Measuring and Testing,   subclasses 105+ for electrical measuring devices with bimetallic shunting means. 335,  Electricity: Magnetically Operated Switches, Magnets, and Electromagnets,   subclass 12 for automatic circuit interrupting devices with shunting contacts and subclasses 35+ for plural means for operating automatic trip means one of which may be a shunt contact operated by bimetallic means. 338,  Electrical Resistors,   subclass 31 for resistors with mechanical variation means which is thermally responsive and subclass 215 for a resistance with a switch, i.e., shunt. 361,  Electricity: Electrical Systems and Devices,   subclasses 139+ for electric circuits for relays and electromagnets, especially subclasses 163+ for bimetallic elements shunting a resistance.

17	Fusible material combined with gap:
	This subclass is indented under subclass 15.  Subject matter relating to a device wherein during normal conditions of a circuit at least two contacts or electrodes are separated by an insulating gap which is bypassed by a fuse and upon the occurrence of abnormal conditions in the circuit causing failure of the fuse current is allowed to pass directly between the contacts or electrodes. The thermo responsive fusible means usually comprises latching or holding means releasable, when subject to overheating, to allow the main contacts to close. SEE OR SEARCH THIS CLASS, SUBCLASS: 31, for fusible structure combined with a spark gap or lighting arrester means. SEE OR SEARCH CLASS: 338,  Electrical Resistors,   subclass 215 for fusible elements shunting a resistance.

18	Gaseous space discharge gap (e.g., air gap):
	This subclass is indented under subclass 17.  Subject matter wherein the insulating gap is an air gap. SEE OR SEARCH CLASS: 361,  Electricity: Electrical Systems and Devices,   subclasses 115+ , especially subclasses 124+ for lightning arresters with fusible links.

19	Gap with thin film dielectric (e.g., voltage-responsive):
	This subclass is indented under subclass 15.  Subject matter including contacts or electrodes separated from one another by a film of dielectric material which is adapted to break down upon the impression thereof of an abnormal voltage thereby allowing the setting up of a conductive arc.

20	With significant housing or casing structure:
	This subclass is indented under subclass 15.  Subject matter relating to a device under the definition of subclass 15 with significant details of a housing or casing structure peculiarly adapted for the claimed device. SEE OR SEARCH THIS CLASS, SUBCLASS: 34, for electrothermal switches of the space discharge type with housing or casing. 112+, for electrothermal switches of the bimetallic type with housing or casing. 121, for electrothermal switches of the expansible fluid actuated type with housing or casing. 186+, for electrothermal switches of the fusible element actuated type with housing or casing. 327+, for thermally actuated switches of the expansible fluid type with housing or casing. 380+, for thermally actuated switches of the bimetallic type with housing or casing. 398, for thermally actuated switches of the longitudinally expansible solid element type with housing or casing. 414+, for thermally actuated switches of the fusible element type with housing or casing.

21	Conductive fluid devices:
	This subclass is indented under subclass 14.  Subject matter wherein the continuity of an electrical circuit is normally maintained through a conductive liquid. Upon the occurrence of an excessive current in the circuit the liquid is vaporized or otherwise dispersed or displaced whereupon the circuit is interrupted. In this subclass the conductive liquid comprises the electrothermal element which is directly in the circuit to be controlled which circuit is completely opened when the liquid is in its operated state. SEE OR SEARCH THIS CLASS, SUBCLASS: 80, for electrothermally responsive bimetallically actuated switches with mercury or other conductive liquid contact means. 331, for thermally responsive expansible or vaporizable fluid actuated switches with a conductive liquid comprising the contact material. SEE OR SEARCH CLASS: 200,  Electricity: Circuit Makers and Breakers,   appropriate subclasses, especially subclasses 61.47 , 81.6, and 182+ for mechanical switches with mercury or other liquid contacts. 219,  Electric Heating,   subclasses 510+ for automatically operated heating device current supply means with thermally responsive means. 315,  Electric Lamp and Discharge Devices: Systems,   appropriate subclasses, especially subclass 362 for a discharge device with a mercury switch in the circuit.

22	Fluorescent lamp-starting devices:
	This subclass is indented under subclass 14.  Subject matter relating to structure whereby the voltage or current applied to a fluorescent lamp device is controlled in such a manner as to establish a discharge through the lamp device. SEE OR SEARCH CLASS: 315,  Electric Lamp and Discharge Devices: Systems,   subclasses 94+ , especially subclass 100 for discharge devices with a thermostatic switch in the cathode heater supply circuit.

23	With significant heating means:
	This subclass is indented under subclass 22.  Subject matter including at least one metallic resistance or other heating means whereby a thermostatic contact actuating means is heated by the current passing through the resistor or other heating means. (1) Note. For other heating means employed in the devices of this class, see the subclasses listed under SEARCH THIS CLASS, SUBCLASS in subclasses 103+.

24	With shunt or short-circuiting means (for resistor):
	This subclass is indented under subclass 23.  Subject matter including significant structure whereby an electrical shunt circuit is established around the heating means or whereby the heater contacts may be short circuited. SEE OR SEARCH THIS CLASS, SUBCLASS: 15+, for electrothermal switches with electrical shunt or short circuit completion devices. 125, for electrothermal switches of the longitudinally expansible solid element type with electrical shunting means. 221, for electrothermal switches of the fusible element type with electrical shunting means.

25	Electric discharge means (e.g., electron-emissive):
	This subclass is indented under subclass 22.  Subject matter including at least two switch contacts designed to contact with each other to open and/or close an electrical circuit, one of the switch contacts being mounted so as to be moved by a thermostatic element, the contacts, their supports, or lead-in means being electron emissive so that an electric space discharge can be established between the electron emissive substance and the cooperating contact, when the switch contacts are in open circuit position, to heat the thermostatic element thereby actuating the movable contact or contacts. (1) Note. In some of the patents in this subclass the switch contacts are normally separated when no current is being supplied to the circuit which includes the switch contacts. The electric space discharge being established when the current is supplied to the circuit, the space discharge then heating the thermostatic element so that the switch contacts are moved to circuit closing position to establish a conductive path through the electrodes and thereby short circuiting the electric space discharge. This subclass also includes patents where the switch includes means other than the glow discharge, such as electric heating means, the glow discharge being used in conjunction with the other heating means to cause the switch contacts to be moved into open or closed circuit condition. (2) Note. The circuit makers and breakers in this subclass are often used with glow discharge lamps which require preheating of the filamentary electrodes before an electric space discharge can be established between such filamentary electrodes. (3) Note. The circuit makers and breakers in this subclass are somewhat analogous in structure to electric space discharge devices of the arc drawing type having two electrodes, at least one of which is electron emissive, which are normally in contact when the supply circuit is open and which are separated by any suitable means, such as thermostatic means, to establish the space discharge when potential is applied to the discharge device. For such discharge devices, Search Classes 313 and 314 in the appropriate subclasses.

26	With significant contact structure or composition:
	This subclass is indented under subclass 22.  Subject matter including specific details of contact arrangement, structure or composition of material. (1) Note. Contact structure or composition will also be found in the following subclasses of this class. SEE OR SEARCH THIS CLASS, SUBCLASS: 109, electrothermally actuated switches of the bimetallic type. 122, electrothermal switches of the expansible fluid type. 137, electrothermally actuated switches of the longitudinally expansible solid type. 251+, electrothermally actuated switches of the fusible element cartridge or tube type. 268+, electrothermally actuated switches of the fusible element plug type. 273+, thermally actuated switches of the bimetallic type. 329+, thermally actuated switches of the expansible fluid type. 399+, thermally actuated switches of the longitudinally expansible solid type. 413, thermally actuated switches of the fusible element type.

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