GB1265239A - - Google Patents

Abstract

1,265,239. Release valves. ATELIERS DES CHARMILLES S.A. 6 Oct., 1970 [6 Oct., 1969], No. 47352/70. Headings F2F and F2V. A release valve assembly incorporated in railway vehicle pneumatic brake control apparatus and actuable to vent a control reservoir RC and thereby release the brakes, comprises a cylinder 1 holding a piston 2 and a diaphragm 3 which divides the cylinder bore into two chambers 21, 23, whereof chamber 21 is in communication with a main supply conduit CG of the apparatus via a pipe 9 and chamber 23 is in communication with atmosphere via a pipe 12, and a further pipe 11 from the control reservoir RC may be vented via pipe 12 according to the action of a control valve 15, 16 which comprises a spring-biased obturating member 15 and an annular valve seat 16 there also being provided a device in the form of spring element 20 or a permanent magnet which permits the piston 2 to be maintained in any one of several stable positions in operation of the release valve assembly. The operation of the illustrated valve assembly is such that with the main conduit CG and its branch pipe 9 under pressure, the piston 2 is held against an end wall 10 of the cylinder 1 by the action of the pressure and by a spring 18, and the valve 15, 16 is thereby held closed. When the conduit CG and pipe 9 are communicated to atmosphere, piston 2 moves away from the end wall 10 at most by a distance a, which distance a is equal to the distance between a flange 14 of the piston 2 and the obturating member 15 in the position of Fig. 1. The spring 17 of the control valve 15, 16 is as strong as or stronger than the spring 18 and with the pipe 9 at atmospheric pressure the valve assembly is held in a stable position until the pressure in pipe 9 is reduced whereupon the piston 2 moves up to abut the end wall 8 entraining with it the spring segment 20 and the control valve 15, 16 is opened to vent the reservoir RC to atmosphere (Fig. 2). When the pressure on piston 2 from the control reservoir RC drops, the piston 2 will move away from the end wall 8 through an axial distance b but the pipe 11 is maintained open. When the pipe 9 is repressurized, the piston 2 is moved against the end wall 10 and the valve 15, 16 is closed. The spring element 20 may be replaced by a permanent magnet either in the end wall 8 or in the corresponding face of the piston 2.