GB318352A - Improvements in pneumatic brakes for railroad vehicles - Google Patents

Abstract

318,352. Bailey, H. July 23, 1928. Fluid-pressure.-The standard air pressure brake equipment for railway &c. vehicles is supplemented by a spring-actuated piston normally held in the " off " positon by a latch which is automatically released upon failure of the pressure in the usual auxiliary reservoir to permit application of the brakes by the spring, compression of which to release the brakes is effected by the pressure in the train-pipe. The equipment comprises the usual brake cylinder B, Fig. 5, supplied by the auxiliary reservoir C under the control of the triple valve M and the train-pipe L. In addition there is provided the supplementary cylinder E containing a piston 10 subject to the action of a spring 18 and having a rod 12 connected by a chain G to the brake lever D. The connections are such that either piston can apply the brakes independently of the other. The piston-rod 12 has a squared part 20 upon which presses a guide roller 21 carried by a pivoted member 29 adjusted by a screw 23. This squared part is notched as shown for .the engagement normally therewith of a latch member 32 carried by a lever 33 connected to a piston 39 in a chamber 38 connected by the pipe R to the auxiliary reservoir C. A valve device O controls the connection of the chamber E of the spring piston 10 with the train-pipe and atmosphere. The chamber 44 of the valve is connected to the auxiliary reservoir through the pipe P, a valve Q operated by a projection 28, Fig. 4, on the piston-rod 12 and the pipe V. When subsequent to an application of the brakes by the piston 10 the pressure in the auxiliary reservoir is restored to the predetermined value, this pressure acting on the valve piston 48 closes the connection of the chamber E with the atmosphere through the pipe T and port 59 and connects it to the train-pipe through the pipes N, U. The parts thus assume the position shown in Fig. 2, the latch 32 being held in the engaged position by the auxiliary reservoir pressure acting on the piston 39. Movement of the piston-rod 12 to its outer position closes the valve Q and the consequent leakage of the pressure air from the valve chamber 44 permits a spring in the casing 53 to move the piston 48 to the left, closing the valve 54 to cut off the chamber E from the train-pipe and connect it to atmosphere through the port 59. Thus if subsequently the pressure in the auxiliary reservoir falls below the predetermined value, the latch 32 is disengaged by the spring 40 and the brakes are applied by the spring 18, the movement of the piston 10 being controlled by a. dashpot comprising a small valved piston 16 secured to the piston-rod 12 and working in a fixed cylinder 15. The piston 10 may be returned on a detached vehicle to take the spring-pressure off the brakes by a winding gear 61, K and a. lever H.