GB1164643A - Draw Gear Using a Hydraulic Spring - Google Patents

Abstract

1,164,643. Railway vehicle draw gear. ZENTRALE ENTWICKLUNG UND KONSTRUKTION ZEK HYDRAULIK VEB. 28 Sept., 1966, No. 43407/66. Heading B7T. During slow compression a draw gear yoke or cradle 1, Figs. 1 and 2, moves a follower 2 to the left and forces a plunger 14 into a liquid cylinder 5 abutted against fixed stops 4. An auxiliary plunger 12, containing a plunger 23, piston 24 and liquid under very high pressure,- is provided with a piston 13 having spring loaded valves 21 and valves 18 fixed to a spring loaded plate 19, so that as the plunger 14 moves into the cylinder 5 the chamber 28, due to differential piston areas, has a pressure generated in it which is higher than the pressure in chamber 29 so that the valves 21 remain closed and the valves 18 open, the plunger 12 being moved out of cylinder 5 and to the left. The plunger 23 also moves out with the plunger 12 and keeps contact with the cradle 1, the plunger 12 finally abutting a stop 32. As the compression takes place the spring characteristics vary, the slight difference in cross-section between plungers 12 and 14 producing an initial very flat rate of spring rise until the piston 13 comes to abut the stop 32 when the rate rises steeply. If, however, dynamic compression is effected then the spring rate rises steeply from the beginning. The piston 13 may also have a throttle gap similar to that of piston 15, or the opening of the valves 18 may be delayed by a heavier spring 20 to further vary the spring characteristic. In a further modification the plunger 12 may be made slightly conical. During traction, the plunger 14 is held stationary by the stop plate 2 and movement of the housing 5 under pull on the yoke 1 is resisted by the pressure in chamber 29. The plunger 23 is in contact with the yoke 1 and is moved with it but the plunger 12 is moved outwardly by the increasing pressure in chamber 29 until it abuts the yoke 1. When the pressure in 28 reaches a certain valve the valves 18 open so that when piston 13 abuts the stop 32 the pressure in 29 rises so that valves 18 close and valves 21 open. The main plunger 14 then acts upon the liquid in chambers 28, 29. The liquid spring in the piston 12 being at very high pressure compensates for the changes in volume or pressure produced by the influence of temperature in chambers 28, 29, 30, since the substantially constant force of the plunger 23, which is little effected by temperature, presses the plunger 12 inwardly with the same force to produce constant pressure in 28, 29 or 30.