GB626330A - An improved air pressure system for controlling brakes and other apparatus on rail vehicles - Google Patents

Abstract

626,330. Fluid-actuated valves. CLAYTON DEWANDRE CO., Ltd., and RODWAY, J. Oct. 16, 1946, No. 30829. [Class 135] [Also in Groups XXXII and XXXIV] A self - lapping driver's valve in an automatic compressed-air brake system (see Group XXXIV) comprises inlet and release valves 48, 50 carried by a stem 49. In the release position of the handle 46, the trainpipe is in communication with the main reservoir through a connection 47, passage 76, valve 48, passages 52, annular chamber 53, passage 54, Fig. 7, valve 56 and passage 59, the valve 50 being seated to close a passage 61 in the rod 65 of a piston 62 passing ports 66 open to atmosphere. The piston 62 is normally held in the position shown by a piston 63 acted on by main reservoir pressure and having a rod 64 whose end abuts the end of rod 65, springs 69, 70 being interposed between the piston 62 and a third piston 71 abutting a shoulder 72 on the rod 64, which is formed with rack teeth engaged by a pinion 68 on the shaft 67 of the handle 46. Rotation of the latter to apply the brakes moves the piston 63 and rod 64 to the left so that trainpipe pressure acting on the piston 62 compresses the springs 69, 70 sufficiently to allow the valve 48 to close and to unseat the valve 50. The trainpipe pressure then drops until the valve 50 is reseated by the springs, the reduction in trainpipe pressure thus corresponding to the amount of movement of the handle 46. As the effort to move the handle depends on the difference between the forces acting on pistons 62, 63, i.e. a function of main reservoir pressure minus trainpipe pressure, this effort increases progressively and the driver is enabled to " feel " the application of the brakes.