| 摘要 |
1489954 Hydrostatic transmission control CLARK EQUIPMENT CO 28 Aug 1975 [10 June 1975] 35583/75 Heading F2W In a hydrostatic transmission for a fork-lift truck having a variable-displacement swashplate pump 24 supplying motors 26, the pump displacement is varied in dependence on engine 18 speed by means of a spring-centred servo 100 which receives pressures on opposite sides of a piston 104 through conduits 120 and 118 which are connected respectively to the upstream and downstream sides of a fixed orifice 92 in a conduit 80 fed by a charge pump 22 whose output is proportional to engine speed, a direction control valve 124 being provided in the conduits 120 and 118 downstream of an adjustable restriction 134 between the conduits, for regulating the pressure differential and a regulator valve 128 closed by operation of a service brake pedal 53. The valve 128 (Fig. 3, not shown) regulates the higher pressure suplied to the servo 100 in response to the movement of the brake pedal 53 and so provides inching, with full depression of pedal 53 interconnecting the two sides of servo 100 to return the pump 24 to neutral. The adjustable restriction 104 provides accurate adjustment of the operation of the transmission, irrespective of manufacturing tolerances. Service brakes 50 are operated by brake pedal 53 through a valve arrangement 50. One motor may be provided instead of the two motors 26 shown. The motors 26 are in a casing 27 drained through a heat exchanger 66 with a by-pass relief valve 74, drained casing 25 and 138 being provided for the pumps 22, 24 and the valves 124, 128 respectively, with the relief valve 94 of pump 22 having its outlet into casing 25. |
