	US 7,556,322 B2
	Graduated release/proportioning valve
Michael J. Veltri, Pittsburgh, Pa. (US); and Jeffrey D. Wurzer, Turtle Creek, Pa. (US)
Assigned to Wabtec Holding Corp., Wilmerding, Pa. (US)
Filed on Oct. 03, 2005, as Appl. No. 11/242,184.
Application 11/242184 is a continuation in part of application No. 11/028779, filed on Jan. 03, 2005, granted, now 6,971,723.
Claims priority of provisional application 60/539482, filed on Jan. 27, 2004.
Prior Publication US 2006/0028062 A1, Feb. 09, 2006
This patent is subject to a terminal disclaimer.
Int. Cl. B60T 8/22 (2006.01); B60T 8/18 (2006.01)

U.S. Cl. 303—22.7 [303/22.2; 303/22.6; 303/22.8; 303/118.1; 303/74]

9 Claims

1. A release graduating proportioning valve for a rail car brake system having a brake pipe, a brake cylinder, and a load sensor valve for detecting an empty/loaded car condition, said release graduating proportioning valve comprising:

a. a proportioning piston having a control volume communicating on a first side of said piston and a second volume communicating on a second side of said piston;

b. a valve body in which said proportioning piston is movably received, said valve body having a port to atmosphere;

c. said load sensor valve having an empty car setting in which said control volume is connected to atmosphere via said load sensor valve, and a loaded car setting in which said control volume is connected to said brake cylinder via said load sensor valve;

d. said proportioning piston movable between first and second positions, said control volume isolated from said port to atmosphere at said first position, and said control volume communicating with said port to atmosphere at said second position, wherein said control volume is connected to atmosphere responsive to movement of said proportioning piston;

e. said valve body having a bore;

f. said proportioning piston having a skirt portion slidably received in said bore;

g. a first air passage through said bore, said first air passage communicating with said control volume;

h. at least one seal carried by said skirt portion, said at least one seal positioned intermediate said skirt portion and said bore; and

i. wherein at said first position said at least one seal is positioned between said first air passage and said port to atmosphere such that said at least one seal isolates said control volume from atmosphere, and at said second position said control volume is connected to atmosphere via said first air passage.