| 摘要 |
The hydraulic control system of this invention uses a series of hydraulic valves for directing hydraulic fluid to energize and pressurize rapidly the various clutches of a hydraulically driven transmission, while protecting the input clutch of the pump. A restrictor check valve slows the rate at which the input clutch disengages the pump from the power takeoff, thereby ensuring that the variable displacement pump destrokes during backdriving before the input clutch disengages. A sequence valve is ordinarily used to ensure that the winch is deactivated by dumping pressure in the system and by destroking the pump when control pressure in the system drops below a predetermined level. The hydraulic controls include a single-lever, four-function control valve for selecting four modes of operation: brake-off, reverse, free-spool, and forward, and a range selector for selecting between high and low range. Three three-way valves are used to shuttle hydraulic fluid to the main drive clutches (i.e., the high- and low-speed clutches of the transmission) and the input clutch of the pump.
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