GB878445A - Improvements relating to driver's brake valves for railway vehicle fluid pressure braking apparatus - Google Patents

Abstract

878,445. Driver's brake valves. WESTING- HOUSE BRAKE & SIGNAL CO. Ltd. April 15, 1959 [April 15, 1958], No. 11913/58. Addition to 739,785. Class 103 (1). A driver's brake valve of the graduated release kind has one portion 11, 13, 17, 18 determining a control pressure in accordance with the position of the valve, and a second portion 12, 24, 26 to reproduce a pressure in the brake pipe 23 proportional to the control pressure (in passage 16), the pressures being restored for brake release or maintaining an existing reduce brake pressure from a main source (in passage 20), and has a valve 33 operable by the brake valve in the graduated release zone to close communication 31 between the control reservoir and the main source, and an arrangement 35-37 by which closure is freely effected. The control pressure acts through passage 21 on diaphragm 12 to connect brake pipe passage 23 to exhaust passage 25 via stem 26 or to the main reservoir passage 20 via valve 24 to equalize the control and brake pipe pressures for positions of lever 14 in the graduated release zone and the release and running positions, a valve 22 in brake pipe passage 23 being opened by cam 23. The control reservoir is charged from passage 20 through passages 31, 32 but in direct release apparatus the passage 32 is closed by plunger 35, 36 operated by lever 37 and a cam 34 opens valve 33 except in the graduated release zone of lever 14; hence when used in direct release apparatus the control reservoir pressure cannot be increased with lever 14 in this zone. The passage 32 is opened for graduated release apparatus. In emergency applications valve 29 is opened by cam 30 to vent brake pipe passage 23 directly to exhaust passage 25. The valve may be used in vacuum apparatus.