Patent GB-205481-A (GB)
IPC: B60T15/04
Filed: 1923-10-01
Abstract: 205,481. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Farmer, C. C.). Oct. 16, 1922, [Convention date]. Fluid-pressure.-Valve mechanism for charging the brake pipe of fluid-pressure brakes is adapted to give a rapid supply for a predetermined interval after the driver's valve is moved to the charging or release position, further supply being by means of a feed-valve device set to maintain the normal running pressure. The rapid-supply valve mechanism comprises a piston valve 21 adapted to open the chamber 21<1>, connected in certain positions of the driver's valve 8 to the main reservoir 3, to the chamber 38 connected to the brake pipe 5. The valve 21 is controlled by valves 22, 23 for connecting the chamber 24 either to an exhaust port x or to the main reservoir by way of the passages 46, 47 and chamber 38. The valves 22, 23 are actuated by a piston 25 the chamber 32 of which is connected through pipes and passages 33, 34, 37, 29, 28 with a timing reservoir 6. The parts are shown in the running position. In service application and all positions of the driver's valve other than the running and release positions the timing reservoir 6 is connected by passage 29 and a cavity (not shown) in the driver's valve 8 with the exhaust port 31. The piston 25 therefore assumes the upper position in which the valve 22 is open and the chamber 24 of the valve 21 is thereby connected to the exhaust port x. Train-pipe pressure in the chamber 21<1> therefore holds open the valve 21 but the passage 39 being blanked by the driver's valve 8 there is no supply to the train-pipe. When the driver's valve is moved to release position, the passage 29 leading to the timing reservoir 6 and to the chamber 32 above the piston 25 is connected through a restricted passage in the driver's valve 8 to the chamber 7 which is open by passage 44 to the main reservoir 3. The passage 39 is also connected to the chamber 7 by a passage 50 so that air from the main reservoir is supplied rapidly through the open valve 21 by passages 40, 41 to the brake pipe 5. When the pressure in the timing reservoir and chamber 32 has risen sufficiently, the piston 25 is depressed to close the valve 22 and open the valve 23, the chamber 24 is thereupon connected to the main reservoir pressure by the passages 46, 47 and the valve 21 closes. Any further supply to the brake pipe is effected through the feed-valve mechanism which comprises a piston 12 connected to a slide valve 14 with ports 49 and subject normally on both faces to main reservoir pressure through passages 41, 46. The chamber 11 of the piston 12 can be vented to the brake, pipe 5 by a valve 15 actuated by a diaphragm 16 which is subject upon its upper and lower sides respectively to brake-pipe pressure and to main reservoir pressure reduced to the normal running pressure it is desired to maintain in the brake pipe by the valve 18 loaded by the spring 20. If the brake-pipe pressure is below the running pressure, the valve 15 is opened by the diaphragm 16 to vent the chamber 11 to the brake pipe whereupon the piston 12 moves the slide, valve 14 to the open position to supply the brake pipe from the chamber 13. Since the ports 49 of the valve 14 are wider than usual, the supply passage 50 in the driver's valve by which the chamber 13 and the brake pipe are supplied in the running position of the valve, is restricted so that the supply may not be sufficient to prevent an emergency application of the brakes effected otherwise than by the driver's valve. To cut the limited-charging feature out of operation, a cock 36 may be turned to connect the passage 34 from the chamber 32 to a passage 51 which in the release position of the driver's valve is connected to the exhaust port 31 to maintain the valve 21 open and in the running position is connected by passage 53 to the main reservoir pressure supply to keep this valve closed.