GB796342A - Improvements relating to vacuum brake cylinders - Google Patents

Abstract

796,342. Brake cylinders. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., and SIMMONS, A. W. May 9, 1956 [May 24, 1955], No. 14938/55. Class 103 (1). In order to prevent the diaphragm of a vacuum brake cylinder from being distorted sideways during its upward movement in the brake - applying direction, causing wear in the guide bush when atmospheric air is admitted into the vacuum brake pipe, thus raising the pressure in the lower chamber communicating therewith which acts on the underside of the diaphragm and causes the piston member to rise, the vacuum brake cylinder is provided with a piston-rod passing freely, without lateral restraint, through an aperture in the lower portion of the cylinder; the leakage of air through the aperture being prevented by a flexible sleeve or gaiter clamped at its ends around the aperture and piston-rod respectively. In the embodiment shown in Fig. 1, the increased pressure of air in lower chamber 24 during a brake application acts uniformly around the diaphragm 6 and keeps the piston member 11 substantially central within the cylinder and permits, at the same time, limited lateral movement of the piston-rod 18 in aperture 22 in bush 14 to allow for any uneven flexing of the diaphragm 6 as it rolls up and down in the inner surface of the cylinder guide 2. Flexible sleeve or gaiter 17 seals the aperture 22 of the bush 14 without restricting movement of the piston-rod 18. Fig. 2 illustrates alternative means for limiting the lateral movement of piston 11 during release of the brakes; wherein the piston-rod 18a is hollow and is open at its upper end into which extends a guide-rod 27 depending axially from the cylindrical cover 1 to which it is rigidly secured. Specification 760,544 is referred to.