GB596031A - Improvements relating to fluid pressure braking apparatus of the vacuum type - Google Patents

Abstract

596,031. Fluid - pressure - operated brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., and BRACKENBURY, A. G. July 16, 1945, No. 18121. [Class 103 (i)] In order to accelerate the propagation of the pressure increase in the brake control pipe of vacuum brakes for railway and like vehicles, of the kind in which the vacuum normally existing in the brake pipe is reduced to apply the brakes, a limited amount of air under pressure is supplied to the brake pipe when an application is made. The driver's valve 1 is shown in the application position. In the running position, a reservoir 10 is connected to a supply pipe 9 through a port 32 in the valve member 3 and pipe 11. In the application position the brake pipe 6 is cut off from the vacuum source and connected by ports 8. 7 to atmosphere and the reservoir 10 is cut off from pipe 9 and is connected by the valve cavity 12 and pipe 13 to the chamber 14 of a control valve device then through an aperture 25 in a partition 26 to a chamber 16 thence to the nozzle 18 of a venturi injector device 19. The compressed air from the reservoir 10 is then supplied to the brake pipe 6 while also increasing the flow of atmospheric air into the pipe through the ports 7, 8. The aperture 25 is initially substantially restricted as shown by the conical part 27 of an obturator rod 24 which is connected to a diaphragm 22 urged to the lefthand by a spring 23. Air under pressure flows through a restricted passage 21 from the chamber 16 to a chamber 20 and moves the diaphragm and the rod 24 gradually to the right so as progressively to increase the effective area of the aperture 25, as the pressure in the reservoir 10 falls. The rate of flow of the compressed air from the reservoir is thus maintained substantially constant. To prevent the pressure in brake cylinders that are near the driver's valve or other point at which the application is made from rising too rapidly, the branch pipe 28 leading to the cylinder may be connected to the brake pipe 6 by oppositely arranged ejector nozzles 30, 31 so that air flowing along the pipe 6 at high speed tends to withdraw air from the branch pipe.