GB563615A - Improvements relating to locomotive brake equipment - Google Patents

Abstract

563,615. Fluid - pressure brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. Nov. 14, 1941, No. 14664. Convention date, Feb. 28, 1941. [Class 103 (i)] A driver's brake valve for automatic compressed air systems has release and running positions in both of which the brake pipe supply is effected by a feed valve but the supply passage in the running position is relatively restricted to ensure brake application in the event of breakage of the train-pipe. Further, the action of the feed - valve is rendered dependent upon the rate of flow so as to prevent overcharging of the train-pipes. The driver's valve comprises a chamber 18 to which is connected by the pipe 8 the control chamber 56 of the feed valve 3. The brake pipe equalizing discharge valve 11 and reservoir 10 are connected by passage 14 to the seat of the rotary valve member 21 and in the release and running positions by the cavity 25 and port 24 in the rotary valve to the chamber 18. The rotary valve has two right-angle passages 38, 39 which in the release position both register with an arc-shaped passage 32 in the valve seat and with a wide passage 36 in the casing but in the running position shown in Fig. 6 only the passage 39 which has a relatively small port 41 so registers. The passages 32, 36 are connected respectively to the brake pipe 1 and the supply pipe 7 from the feed valve 3. A small port 42 connects the passage 39 and the chamber 18. The feed valve comprises a piston 45 operating a slide-valve 48 in a chamber 47 which is connected to the main reservoir 44 and by a restricted passage 60 and an air-strainer 59 to the chamber 46 above the piston. A diaphragm 54 which is subject above to the pressure of the spring 55 which determines the normal brake pipe pressure and below to the pressure in chambers 56 and 18 is arranged to operate a valve 57 which controls communication between chambers 56, 46. With the driver's valve in the release position, Fig. 1, for charging, the chambers 56, 18 are connected to the brake pipe 1 through port 42 so that the valve 57 is opened by spring 55 reducing the pressure in chamber 46 so that the piston 45 and valve 48 are moved upwards by the main reservoir pressure acting against a spring 61 as shown in. which the valve ports 51 fully register with passages 52 and air from the reservoir flows freely by pipe 7 and passages 38, 39 to the brake pipe 1. The relation of the passage 42 to the passage 39 is such that a suction effect is created bv the flow from the pipe 7 to the brake pipe 1 which tends to delay the rise of pressure in the chambers 18, 56 to an extent dependent upon the rate of flow to the pipe 1: As the pressure in this pipe and in the chambers 18, 56 rises the valve 57 gradually closes causing the piston 45 to be gradually lowered by the spring 61 and gradual shutting off of the supply passages 52. The driver's valve is then moved to the running position in which supply to the brake pipe is restricted to the capacity of the port 41.