GB282352A - Improvements relating to feed valve devices for fluid pressure braking apparatus - Google Patents

Abstract

282,352. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Dean, W. E.). Dec. 18, 1926, [Convention date]. Fluid-pressure.-The feed valve by which the train-pipe of fluid pressure braking apparatus is charged is arranged to be controlled directly by the pressure in the train-pipe instead of, as is usual, by that in the supply pipe leading from this valve to the driver's valve. The feed-valve comprises a diaphragm 12 subject on the one side to the adjustable pressure of a spring 13 which determines the pressure to be established in the train-pipe and on the other side to the pressure in a chamber 15 which is perinanently and directly connected to the train-pipe 3. A slide valve 11 connected to a loosely fitting piston 9 controls communication between the main reservoir 4 and the train-pipe 3 by way of passage 27, chamber 10 of the valve 11, the pipe 20 and the driver's valve 6. Normally the pressure in the chamber 8 of the piston 9 is equalized with that in the chamber 10 and the valve 11 is closed as shown by a spring 28. When the driver's valve 6 is in the running position shown pipes 3, 20 are connected by a cavity 24 and if the pressure in the train-pipe is below that for which the spring 13 is set, the diaphragm unseats a valve 17 by a pin 23, thus venting the chamber 8 to the pipe 20 and the train-pipe and thereby causing the slide-valve 11 to open communication between the main reservoir 4 and the train-pipe until the normal pressure is reached therein when the valves 17, 11 re-close. By connecting the diaphragm chamber 15 directly to the train-pipe the intermittent opening and closing of the feed valve which occurs when this chamber is connected to the pipe 20 is avoided and thus a more rapid increase in train-pipe pressure is obtained. When the train-pipe pressure is reduced to apply the brakes, the valve 17 will be opened but as the feed valve passage 25 is lapped the valve 11 is not operated. When the valve 17 is open a valve 14 provided on the pin 23 is seated and thus prevents leakage of air to the train-pipe past the valve 17 and chamber 15, which might cause release of the brakes.