GB854079A - Power gear-shifting mechanism - Google Patents

Abstract

854,079. Change-speed control. CLARK EQUIPMENT CO. Dec. 19, 1958 [Dec. 24, 1957 (3)], No. 41178/58. Class 80 (2). [Also in Group XXIX] Speed-changing in a vehicle transmission gear is effected by a fluid-pressure servomotor under the control of a manually-actuated valve member which is slidable in and has a lostmotion connection with a valve seat 'sleeve that is connected to move with the servomotor, means being provided for urging the valve member to a neutral or central position relative to the sleeve. In one embodiment, the valve member and sleeve 35, 34 respectively, Fig. 4, has a pin and slot lost-motion connection 68 and springs 56, 57 for centralizing the valve member relative to the sleeve. The servomotor consists of a piston 37 in a cylinder 38 and connected to a rod 64 which has a connection 67 with the sleeve 34. When the valve member is centralized relative to the sleeve pressure, fluid admitted at 75 has access to both ends of the cylinder 38, but when the valve member is displaced one end of the cylinder is disconnected from the pressure fluid supply and vented such that the piston 37 moves in a direction to cause the sleeve 34 to follow-up the movement of the valve member. The piston 37 continues to move so as long as an operator applies to the gear lever, connected to the valve member at 73, a force sufficient to overcome the springs 56, 57. Should this force cease to be applied the valve member will be centralized relative to the sleeve and the piston 37 brought to rest. The gear lever 10, Fig. 3, is connected to the valve member by a shaft 12 having at one end a lever 16 connected to the valve member and at the other end a bracket 22 with a yoke portion 23 engaging the gear lever. The gear lever has a pivotal mounting 19 at the end of a sleeve 13 which is connected by a lever 17 to the piston-rod 64. Pivotal movement of the gear lever about the pivot 19 selects one of a plurality of gear shifter rails 6, 7, 8, and subsequent movement of the gear lever about the axis of the shaft 12 causes operation of the piston 37 to rotate the sleeve 13 and cause the selected shifter rail to be operated. In a modification the servopiston 84, Fig. 7, is mounted on the valve seat sleeve 37 in which the valve member is centralized by springs 92, 93 bearing against the pin 90 of the lost-motion connection. Gear-shift fork members 25, 26, 27 are mounted on sliding rails 14, 15, 16 and are so arranged that selection of any one of them can be effected by angular movement of an arm 35 fixed to the sleeve 37. Such angular movement is brought about by a sleeve 38 having a pin and slot connection 45 with the sleeve 37 and a linkage connection 57 with a manually-operable hollow shaft. Mounted for rotation within this hollow shaft is a further shaft, also manually actuated, having a con- 'nection with pins 73 on a block 70 by which the valve member is actuated to cause axial movement of the piston 84 and sleeve 37. The sleeve 38 has a projection (not shown) which engages a spring-urged plunger whereby an operator experiences an increased resistance to engagement of first and reverse gears.