GB820297A - Improvements in compressed fluid braking apparatus, particularly for railway vehicles - Google Patents

Abstract

820,297. Fluid pressure brakes. WESTING- HOUSE AIR BRAKE CO. July 9, 1957 [July 19, 1956], No. 21676/57. Class 103 (1). In a compressed fluid braking apparatus, the service valve device 7 automatically controls the application and release of brakes in dependence on the reduction or restoration of pressure in brake pipe 2 relative to pressure in a control reservoir 3 which is charged through communication 12, 32a, 33, 42, 46, 14, the service valve device 7 being such that in response to an initial reduction in brake pipe pressure insufficient to cause brake application, it interrupts the charging communication at one point (32a) and causes the supply of fluid to a valve 8 to move that valve to interrupt the charging communication at a second point (42), fluid so supplied being released on brake release at a rate which is so restricted that reopening of the charging communication coincides substantially with full brake release. The fluid is supplied to a chamber 32 of valve device 8 via passage 31 and chamber 32a from a chamber 34 normally connected to the control sylinder 3, on slight reduction in brake pipe pressure the valve 39 of valve device 8 moves down to cut the charging communication at 42 and connect the branch 14 of brake pipe 2 with a quick-release volume 54 via chamber 44, passage 53 and choke 60 to locally reduce brake pipe pressure to cause service valve 7 to move further to overcome spring 27 and connect the auxiliary reservoir 4 to the brake cylinder 5, via passage 49, valve 51, chamber 23 and passage 19, the bore 24 in valve stem 21 being closed by contact with valve 51. On brake release due to restoration of pressure in brake pipe 2, valve 21 moves down due to increase in pressure in chamber 13 to permit exhaust of fluid from brake cylinder 5 through passage 19, chamber 23, bore 24, chamber 25, passage 55 and choke 56, the fluid in chamber 32 of valve device 8 also exhausting through passage 31, chamber 30, passage 19 where it connects with the brake cylinder exhaust communication, so that the control reservoir charging communication is completely opened on complete brake release. The valve device 8 also controls the charging communication to the auxiliary reservoir.