Patent GB-907639-A (GB)
Title: Improvements relating to railway vehicle vacuum braking apparatus
Inventor: SIMMONS ARTHUR WILLIAM
IPC: B60T15/18
Filed: 1958-08-28
Abstract: 907,639. Fluid-pressure brakes. WESTING- HOUSE BRAKE & SIGNAL CO. Ltd. Aug. 28, 1959 [Aug. 28, 1958; Dec. 16, 1958], Nos. 27670/58 and 40515/58. Class 103 (1). A railway vehicle braking apparatus comprises a vacuum supply pipe 10 in the figure of Provisional Specification 27670/58, by which the upper chamber of brake cylinder 12 is maintained evacuated and a self-lapping valve 16 by which the lower brake cylinder chamber is connected to vacuum pipe 10 or to atmosphere, or in the lap position, is closed from both, the valve including a pressure-sensitive element 21 subject to the pressure differential in the two chambers tending to move the device to the lap position. The pipe 10 is connected to chamber 24 of device 16, the lower chamber being connected via pipe 23 to chamber 22. Element 21 co-operates with a valve 26 urged to close a port connecting chambers 22, 24 and having a head 26a co-operating with an atmospheric port 27. A spring 20 is compressed to operate valve 16, by a member 19 of actuator 17 controlled by remotelycontrolled electromagnetically-operated valves A, B, C which connect separate chambers of actuator 17 to atmosphere or to pipe 10; when all chambers are connected to atmosphere the device 16 is set for maximum braking and with vacuum in all chambers, member 19 is retracted to permit evacuation of the whole apparatus. Atmosphere admitted to one or more chambers of actuator 17, compresses spring 20 to open port 27 and admit atmosphere to the lower chamber for braking until the pressure in chamber 22 overcomes spring 20 to move valve device 16 to the lap position, the upper chamber remaining charged. For brake release, vacuum is re-admitted to actuator 17 allowing diaphragm 21 to move to open the connection between chambers 22, 24 to evacuate the lower chamber. Should the vacuum in pipe 10 drop below a predetermined amount compared with that in a reservoir 13, a valve 28 opens pipe 10 to atmosphere the actuator 17 being responsive to the complete destruction of vacuum in pipe 10 to initiate brake application. In the Figure of Provisional Specification 40515/58, a diaphragm 28 connected to diaphragm 21, is subject to pressure in a train pipe 31 acting in a chamber 29 ; a reduction in train pipe vacuum operates device 16 to admit the appropriate degree of atmosphere to the lower chamber via pipe 23. An emergency valve 33 has a diaphragm 36 separating chambers 37, 38 connected respectively to the upper chamber directly and via check valve 39 ; when upper chamber vacuum drops below a predetermined value diaphragm 36 moves against spring 40 to connect train pipe 31 to atmosphere via valve 35 and filter 34 for emergency braking. Chamber 38 can be vented via manual valve 42. A rapid acting valve 32 may be used to propogate emergency reduction in the train pipe pressure. A check valve 43 may be connected between pipes 15 and 31 so that the upper chamber can be evacuated from pipe 31. For working in mixed trains, the cock 44 is rotated through 90 degrees to connect pipe 31 to pipe 27 and chamber 29 to atmosphere, the valve 26a being opened to connect train pipe 31 direct to the lower chamber.