GB980948A - Improvements in railway vehicle brake control equipment - Google Patents

Abstract

980,948. Fluid-pressure brakes. WESTING- HOUSE BRAKE & SIGNAL CO. Ltd. May 23, 1962 [July 6, 1961], No. 24475/61. Heading F2F. In an electropneumatic/pneumatic compressed air braking system of the kind having a magnet valve which is normally maintained energized to cut out the pneumatic system so that braking is effected electropneumatically, but which on failure of the current supply connects a pilot valve associated with the driver's valve and also an accelerator bulb to a compensating reservoir so that a pneumatic braking action corresponding to the position of the driver's valve is initiated by means of a triple valve, the magnet valve is associated with first and second check valves such that when the magnet valve is energized the first check valve allows compressed air to pass from the pilot valve to the compensating valve but prevents reverse flow, the bulb being exhausted to atmosphere by the magnet valve, and when the magnet valve is de-energized to connect the bulb to the compensating reservoir the second check valve allows flow of air from the compensating reservoir to the pilot valve. As shown, in an electropneumatic/pneumatic braking system having a driver's valve which in any position selects both an electropneumatic and, by means of the pilot valve, a corresponding pneumatic braking operation, the pneumatic braking operation is normally prevented by magnet valve 11 the armature 21 of which carries a valve element 23 closing a valve opening 25 so long as current passes through the windings 20. At the same time a valve element 22 is clear of an exhaust opening 29 so that a bulb connected to passage 19 is exhausted. Valve element 23 prevents exhaust of fluid from the equalizing reservoir which is connected to passage 18, while air can pass via the first check valve 12 from the pilot valve, connected to passage 17, to the compensating reservoir to maintain the latter charged. When the magnet valve drops out, as shown, exhaust opening 29 is closed and passages 17, 18, 19 are interconnected, the second check valve 13 ensuring that air can flow from the compensating reservoir to the pilot valve, after initial reduction of pressure caused by the bulb, in addition to its being able to flow from the pilot valve to the compensating reservoir via the first check valve.