| 摘要 |
A hydraulic drive apparatus for example for driving the header of a combine harvester includes a pump, at least one motor driven by the pump, a reservoir in which the hydraulic fluid is cooled and degasified and a hydraulic circuit connecting the elements. The pump is driven by a shaft of the combine which can be reversed for short periods of time for discharging blockages. The hydraulic circuit is arranged with check valves so that when operating in the normal forward condition it operates in open circuit arrangement including the reservoir. When operating in the reverse condition, the reservoir is bypassed and the fluid is directed in closed circuit condition from the pump through the motor and back to the pump. This allows the drive apparatus to accommodate the necessary reverse condition for short periods of time using a simple hydraulic circuitry rather than the conventional mechanical drive arrangements.
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