GB903262A - Improvements relating to driver's brake valves for compressed fluid braking apparatus - Google Patents

Abstract

903,262. Fluid-pressure brakes. WESTING- HOUSE BREMSEN-G.m.b.H. Dec. 23, 1959 [Dec. 23, 1958], No. 43669/59. Class 103 (1). A driver's brake valve device in a compressed fluid braking apparatus, comprises a relay valve portion 2 maintaining brake pipe pressure at a value corresponding to a control pressure derived from a main reservoir by a self-lapping pilot valve portion 1, the lapping force being that of the brake pipe pressure (in chamber 51) acting in opposition to a spring 20, and a loading device 18 which augments the force of spring 20 to a degree proportional to the pressure of fluid applied to the loading device 18, to enable the brake pipe pressure to be increased temporarily above the normal valve for rapid brake release. The stem 3 of driver's lever 9 controls, through cams 7, 8 an equalizing valve 10 and a high pressure charging valve 11 respectively, and carries a closure member 4 for co-operation with a tube 16 carried by a diaphragm 15. The brakes are applied by raising member 4 from tube 16 to vent control chamber 39 via chamber 50, tube 16 and chamber 21, brake pipe pressure in chamber 44 raising diaphragm 29 and tube 31 to connect atmospheric chamber 46 to brake pipe 42 via valve 31, 35. To release the brakes, valve 11 is opened to connect the main reservoir to chamber 19 via passages &c. 37, 36, 38, 6, 14, 13 and 23 and to valve 48 via passage 47 to open a large communication between pipe 37 and chamber 36. Pressure in chamber 19 raises piston 18 and tube 16 to move member 4 from stem 3 to admit main reservoir pressure from chamber 6 to chamber 39 via chambers &c. 6, 5, 50. 40, the diaphragm 39 moving tube 30 to connect brake pipe 42 to chamber 36. Meanwhile, pressure is built up in a timing reservoir 25 through choke 26; when lever 9 is returned to a running position to close valve 11, the fluid in reservoir 25 and chamber 19 gradually vent to atmospheric chamber 21 via port 28, piston 18 retracts downwards to gradually vent chamber 39 via passages &c. 40, 50, 16, 21 and slowly restore the brake pipe to the normal fully-charged value when chamber 19 is fully vented; the gradual restoration to normal brake pipe pressure prevents brake application. The spring 20 can be adjusted by a screw 22 acting on partition 27. Should the control reservoirs in a train have a higher reference pressure than the locomotive can supply, then valve 10 is opened to supply fluid to reservoir 25 via choke 24 and then via choke 26 to slowly raise the pressure in chamber 19 and in brake pipe 42. When the brake pipe pressure reaches a value such that the locomotive brake pipe pressure equalizes with the higher pressure in the control reservoirs, the valve 10 is closed and chamber 19 is vented and pipe 42 returns to its normal pressure.