Patent GB-260250-A (GB)
Title: Improvements in air pressure brakes
IPC: B60T15/54
Filed: 1926-10-15
Abstract: 260,250. Rihosek, J., Leuchter, R. L., and Hardy Maschinenfabrik und Giesserei Akt.-Ges., Geb. Oct. 21, 1925, [Convention date]. Fluid-pressure. - In graduated-release valve mechanism for use in connection with the triple valves of single-chamber compressed-air brakes, the release vale is actuated by a piston subject to the opposing pressures in the train-pipe and auxiliary reservoir whereby, upon raising the train-pipe pressure after an application of the brakes, the release valve is opened until this pressure and the auxiliary reservoir pressure have equalized; the release valve piston is exposed to train-pipe pressure only during the release of the brakes. The main control or triple valve piston 31 in the release position shown connects the train-pipe 30 with the auxiliary reservoir 39 through the feed groove 32 and the slide valve 34 actuated by this piston connects the passage 38 leading from the brake cylinder to the release valve 1 by the passage 15, the piston chamber of a valve 21 and a valve chamber 22. The release valve comprises a piston 7 permanently open to the auxiliary reservoir 39 and, when the valve 21 is open, to the train-pipe by passages 14, 2. The left-hand side of the piston 19 of the valve 21 is connected to atmosphere by a leak port 17, or it may be by a port 47 controlled by the slide valve 34 or by a spring-pressed valve 25 so that @ the cylinder is exhausted to a sufficient degree the valve 21 is held in the closed position shown by the train-pipe pressure. The piston 7 actuates a valve 10 controlling a port 3 leading to atmosphere. When the train-pipe pressure is reduced to effect an application of the brake, the slide valve passage 35 registers with the passage 38 to supply air from the auxiliary reservoir to the brake cylinder. If subsequently the tram-pipe pressure is raised to a certain extent, the slide valve 34 returns to the release position shown and the brake cylinder pressure acting on the piston 19 moves this piston to the right and opens the valve 21, thus exposing the piston 7 of the release valve to the train-pipe pressure wherebv the valve. 10 is opened and the brake cylinders commences to exhaust. Air from the train-pipe then feeds to the auxiliary reservoir by a port 6 in the release valve chamber as well as by the groove 32 of the main valve and as soon as equalization of the pressures is reached the piston 7 returns to close the valve 10. The brake cylinder can thus be exhausted in stages by effecting successive increases in the train pipe pressure. When the brake cylinder pressure has fallen to a predetermined value, the valve 21 closes and final exhaust thereof takes place, either through the port 17 or 47 if such is provided or trough a valve 25 which opens under spring action. Bv the provision of the port 17 a continuous slow reduction of the brake cylinder pressure mav be effected if desired. The valve 25 prevents pressure from building up in the brake cylinder under running conditions by leakage in the main control valve. This valve and a valve 29 may be operated by hand to release rapidly the brakes on a detached vehicle. In modified constructions, the connection of the train-pipe with the release valve chamber 1 is controlled by additional passage in the main slide valve 34 or by a separate slide valve connected to the piston 31, instead of bv the valve 21.