Patent GB-988399-A (GB)
Title: Distributor for automatic vacuum braking system
IPC: B60T13/46
Filed: 1962-05-11
Abstract: 988,399. Fluid-pressure brakes. COMPAGNIE DES FREINS ET SIGNAUX WESTINGHOUSE. May 11, 1962 [May 16, 1961], No. 18158/62. Heading F2F. A distributer for railway vacuum brakes comprises a main valve member having a diaphragm-piston subject on one side to the pressure prevailing in the lower chamber of the brake cylinder and on the other side, during a brake application, to the pressure in the brake pipe, and, during a brake release, to a pressure slightly lower than that on the first mentioned one side and caused by a brake release regulator spring, means corresponding to a brake relay valve, means for introducing acceleration, and means corresponding to a brake release regulator. To apply the brakes air is introduced into the brake pipe 1 which reduces the vacuum in a chamber 17. A piston 13 rises suddenly and the valves 30 and 44 open simultaneously to allow atmospheric air contained in the acceleration reservoir 8 to spread in the brake pipe 1 through the valve 44 and to permit atmospheric air to enter through ports 5 into the lower chambers of the brake cylinders CFT, CFC via open valve 30 and ports 2 and 3. As soon as the pressure in the lower chamber of the cylinder CFT, which prevails in a chamber 61 through pipes 27, and 64, reaches such a value that the force applied on the piston 58, the upper face of which is exposed to the pressure of the auxiliary reservoir R.A. through the pipe 4, exceeds the force of a spring 68 the piston 58 rises and closes a valve 66 on its seat 67. From then on the reservoir 8 slowly returns to atmospheric pressure through the choked port 77. The rise in pressure is also manifested in a chamber 18 through a pipe 26 and as soon as this rise equals the rise in the pressure of the brake pipe the piston 13 moves down to close the valve 30, thus limiting the braking rate to the value chosen. If the brake pipe leaks, a small drop in vacuum in chamber 17 upsetting the balance of piston 13 is balanced by the opening of a small central valve 33 which permits atmospheric air to enter the pipe 35, the brake cylinder and the chamber 18. On brake release the brake pipe is connected to an exhaust device and the reduction in pressure is manifested in chamber 17 through the pipe 19, the chamber 23, and the pipe 24. The piston 13 drops, opening the valve 22; consequently the vacuum spreads via the pipe 47 to the cylinders CFC, CFT. If the drop in pressure is too rapid in the chamber 17, the piston 13 drops compressing the spring 53 by means of the valve 22 which seats on a cup 52; the flow of air which comes via the pipe 47 is interrupted due to the valve 22 being on its seat 21. The air from the brake cylinders passes through the valve 22 into the chamber 20 then via pipe 19 into chamber 17 to increase the pressure therein. As soon as the pressure in chamber 17 is only slightly lower than that in chamber 18 the valve 22 rises and reopens the passage between the brake pipe and the chamber 17. Also during brake release the brake pipe pressure spreads through pipes 27, 64 into chamber 61. The rod 59 moves downwards and drops down the small valve 70 which causes the chambers 57 and 73 to be connected. The pressure on the valve 66 is limited to that of the spring 69 so the valve opens to prepare the acceleration device for a brake application.