GB297753A - Improvements in or relating to air pressure brakes - Google Patents

Abstract

297,753. Knorr-Bremse Akt.-Ges., (Assignees of Drolshammer, I.). Sept. 26, 1927, [Convention date]. Fluid-pressure. - In valve mechanism for air pressure brakes of the kind in which the valve operating piston is controlled by the pressure in the train-pipe and also that in a chamber which is connected to the train-pipe in the full release position of the valve, the chamber is arranged to be connected with the auxiliary reservoir in the release position so as to prevent the chamber from being overcharged. A valve of the Drolshammer type described in Specification 264,197 is shown, the upper chamber of the piston 1 of which is permanently connected to the trainpipe and the lower chamber to a chamber A. In the full release position of the piston 1 the chamber A is connected to the upper valve chamber and thus to the train-pipe by a passage 37 which, however, is closed by the initial movement of the piston in applying the brake. To enable the train-pipe pressure to be temporarily raised above the normal to effect a rapid release of the brake without overcharging the valve chamber A. The auxiliary reservoir B is connected to this chamber by means of a passage 121 which is uncovered in the full release position of the piston 1 by a small piston 120 connected to the piston 1, thereby increasing the effective capacity of the lower piston chamber. The normal filling of the auxiliary reservoir is effected through a separate passage provided with a non-return valve as described in Specification 219,331. The passage 121 may be so arranged as to be opened when releasing the brake, before the pressure existing previously to the operation of the brakes is reached so that the valve piston moves to its lowest position and the brake is fully released with a pressure somewhat below the normal pressure. The opening 121 can also be so arranged that it may be closed before the passage 37 or a non-return 123 may be disposed in the connection of the reservoir B to the passage 121 so that the passage 37 may be as small as possible having regard to the sensitiveness of the valve.