GB950356A - Improvements in or relating to buffing and draw gear for railway vehicles - Google Patents

Abstract

950,356. Railway vehicle combined buffer and draw gear. K. G. EMPSON. April 27, 1962 [May 8, 1961], No. 16666/61. Heading B7T. [Also in Division F2] A draft and buffing gear comprises a closed hydraulic cylinder 52, Figs. 2, 3, arms 44, 46 extending forwardly and rearwardly of the cylinder, rubber/metal sandwich buff and draw springs 74, 76 and movable compression plates 48, 50 supporting piston rods 56, 58 and a central main piston. In operation, the arms 44, 46 abut against end stops 16, 18, Fig. 1 (not shown), and hold the unit immovable within the vehicle centre sill so that on buff or draw loads one of the springs is compressed and the piston moves within the cylinder 52, which cylinder may have an internal surface which tapers from its centre towards the ends. In a modification, Fig. 4, the piston is provided with poppet valves 124, 126 carried by a sleeve 134 slidable within a cylinder 132, and a ring-shaped flange 136 on the sleeve, of slightly less surface area than the area of the end of one of the valves, moves as a piston within a cylinder 138 connected by ducts 140, 142 to the main piston faces. As the main piston moves in the cylinder under buff or draw load, the pressurized hydraulic fluid in advance of the piston acts on the poppet valve and moves it towards a closed or throttling position. At the same time, however, the pressurized fluid is conducted to the rear of the flange 136 to provide a nearly counterbalancing force in opposition to the force tending to close the valve. The sleeve is normally maintained in a centralized position by means of springs 139. The buff spring 74, Figs. 7, 8, comprises spacer plates 100, and concentric spaced rings of rubber moulded through holes in a mounting plate 90. The spring may, however, be formed without spacer plates and with rubber on one side only of the plate 90. Figs. 5 and 6 (not shown) illustrate a similarly constructed but stiffer draw spring. Shear pins 146, Fig. 3, which break off when the gear is first operated, are provided to hold the unit in a pre-compressed condition for initial fitting into the yoke.