GB473987A - Improvements relating to fluid pressure braking apparatus - Google Patents

Abstract

473,987. Fluid-pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. April 24, 1936, No. 11741. Convention date, July 23, 1935. [Class 103 (i)] Fluid-pressure brakes in which brakes are released by temporarily supplying fluid at an abnormal pressure to the train pipe through the driver's valve, comprises a feed valve having a piston operating a valve which closes the main reservoir from the train pipe when pressure on both sides of the piston is equal and in which fluid is vented from one side of the piston to atmosphere to connect the'main reservoir to the train pipe by a valve device which also controls communication between the two sides of the piston. When the brakes are applied the pressure in the reservoir 6 connected to the train pipe 3 and thus the pressure in the pipes 42, 31, is released allowing pistons 35, 27 to rise and the space 8 above a piston 7 is vented through a passage 15, groove 30 and a port 29 to atmosphere. The piston 7 and the slide valve 12 rise, thus connecting the pipe 2 from the main reservoir to the pipe 14 leading to the driver's valve 1. When the driver's valve 1 is moved to charging position the train pipe 3 is connected to the pipe 14 and the train pipe is charged from the main reservoir pipe 2. The reservoir 6 is charged through a choke 41 so that it attains normal train pipe pressure, unless train pipe is at a pressure above this at which time the pressure in reservoir 6 forces down the piston 35 and then the piston 27 thereby closing the atmospheric port 29 and opening a valve 24 which connects both sides of the piston 7 allowing the spring 9 to depress it and disconnect pipes 2, 14. Thereafter train pipe pressure is maintained by the usual feed valve 17. In a modification, the piston 27 is a differential piston and is controlled by a direct connection to the brake cylinder instead of to a reservoir 6. Brake cylinder pressure raises the piston 27 thereby allowing the piston 7 to rise and connect the pipes 2, 14. When brake cylinder pressure has fallen to a low value, piston 27 falls and causes the piston 7 to fall and to close the connection between the pipes 2, 14. Specification 441,880 is referred to.