| 摘要 |
PURPOSE:To reduce the power loss of a variable pump, by controlling a delivery quantity control part by the pressure of fluid, introduced through a switching means, and decreasing a delivery quantity of the variable pump to almost zero, in the standby condition of a return end or the like where almost no power is required in a reciprocating actuator. CONSTITUTION:A variable pump 1 additionally provides the first delivery quantity control part 8, controlling a delivery quantity in a range reaching an intermediate flow from a large flow, and the second delivery quantity control part 9 controlling a delivery quantity to a range it reaches almost zero. And when an actuator 7 is in forward stroke operation, a control circuit respectively connects first by a rise of the pressure in a main flow line 2 the first control part 8 with the main flow line 2 through the first pressure control valve 10 and next by the following rise of the pressure the second control part 9 with the main flow line 2 through the second pressure control valve 20. While when the actuator is in return stroke operation, the control circuit, switching a switching means 30 to connect a line 14 with 28 and enabling the main flow line 2 to be connected with the second control part 9, decreases a delivery quantity of the variable pump 1 to almost zero.
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