| 摘要 |
PURPOSE:To regulate power of a pump easily, make characteristic of a pump discharge amount in relation to outside pressure linear, and improve approximation accuracy at the time of power change control. CONSTITUTION:A pump discharging amount is increased/decreased according to pump discharge pressure by controlling pressure led into a regulator cylinder 3 for regulating the slant rotational angle of a swash plate by a regulator valve 8. In a first proportional pressure reducing valve 21, there is a prescribed initial pressure, and also pump discharge pressure is reduced by a prescribed pressure reducing ratio. And in a second proportional pressure reducing valve 31, there is a prescribed initial pressure which is different from that of the pressure reducing valve 21, and also pump discharge pressure is reduced by a prescribed pressure reducing ratio which is different from that of the pressure reducing valve 21. Lower pressure out of pressures reduced by two pressure reducing valves 21, 31 is selected by a low pressure selecting valve 41, and the valve 8 is pushed-pressed by plungers 10A, 10B in response to pressure of the low pressure selecting valve 41 so as to push and return the valve 8 by a control spring 43 having a constant spring constant against the plungers 10A, 10B. |
