| 摘要 |
PURPOSE: To enable pump output constant control, cut off control, and the minimum flow amount control at the time of load neutral position. CONSTITUTION: A variable capacity piston pump 2 is connected to an actuator 30 through an operating valve 12 which bares a constant load in a neutral condition, and the returning point of discharging pressure is changed according whether the operating valve 12 is in a neutral position or not. When the operating valve 12 is the neutral position, minimum flow amount control is selected, power consumption in the variable capacity piston pump 2 is controlled. On the other hand, when the actuator 30 is operated by the operating valve 12 and the operating valve 12 is not in neutral condition, constant output control and cut off control are carried out while adapting to load condition which appears on discharging pressure of the variable capacity piston pump 2, so that the actuator 30 is driven ideally and safely. |
