| 摘要 |
PURPOSE:To contrive reduction of cost by providing a plurality of fixed displacement pumps and connecting the fixed displacement pumps with inlet lines, outlet lines and a suction line including first, second and third selector means, respectively. CONSTITUTION:A plurality of fixed displacement pumps 2, 3 are provided in main lines 4, 5 and connected with inlet lines 2a1-2a4, 3a1-3a4, outlet lines 2b1-2b4, 3b1-3b4 and a suction line 7, and directional control valves 2c1-2c4, 3c1-3c4 are provided in respective lines. Thus constructed, appropriate combination of the directional control valves 2c1-2c4, 3c1-3c4 enables control of flow rate and direction of fluid flowing in the main lines 4, 5, permitting rapid changeover of rotational speed and direction of an actuator. Furthermore, as cooled fluid can be introduced through the suction line 7, no cooling pump is required, permitting reduction of cost.
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