| 摘要 |
The invention provides a pump and motor assembly (10) connected to a reservoir (24). The pump can be used for the purpose of supplying fluid to a double acting hydraulic cylinder the ends of which are connected to two connection ports (1, 2) provided on the pump housing (11). The pumping mechanism includes one single acting piston (5) that reciprocates and rotates simultaneously on the piston axis with the reciprocating piston motion imported by a single row ball bearing (13) mounted on the piston (5) and inclined at an angle to the piston axis and having a single point on the outer race of the single row ball bearing (13) restrained. The pump includes two one way check valves (25, 26 and 27, 28) in passages between the reservoir and the connection ports that allow fluid to be drawn into the pumping chamber when the attached cylinder is expanding. A bleed valve, constructed using two balls (30, 31), allows fluid displaced by the rod of a double acting cylinder to be returned through a third passage to the reservoir when the attached cylinder is retracting.</SD OAB>
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