GB917390A - Improvements relating to railway vehicle vacuum braking apparatus - Google Patents

Abstract

917,390. Vacuum brakes. GRESHAM & CRAVEN Ltd., and MARCH, G. C. Sept. 30, 1960 [Oct. 9, 1959], No. 34259/59. Class 103 (1). In railway vehicle vacuum-braking apparatus in which the degree of vacuum in a reservoir 13 is reproduced in a train pipe 11 by means of a relay valve 14, a driver's brake valve 12 has a range of adjustment in which it varies the flow capacity of a leak path from the reservoir whilst maintaining communication between the reservoir and an exhauster 15 whereby inflow and outflow from the reservoir are balanced at a degree of vacuum determined by the setting of the driver's valve 12. For this purpose a handle 34 of the driver's valve 12 turns a disc 36, Fig. 2, having a tapered port 37 or series of ports, thereby selectively venting the reservoir to an atmospheric chamber 40. An emergency position beyond the normal range registers larger ports 41, 38 for rapid venting of the train pipe, and a covered port 42 connects the reservoir to a train pipe through ports 38, 38a. Operation of the driver's valve 12 also operates a switch 35, energizing a valve 16 which cuts off communication between the train pipe and the exhauster 15. During brake operation, as the vacuum falls in reservoir 13, a diaphragm 23 of the relay valve 14 rises to admit atmosphere which decreases the vacuum in the train pipe through a port 28 in accordance with the selected reservoir vacuum.