| 摘要 |
<P>PROBLEM TO BE SOLVED: To secure responsiveness when a large hydraulic cylinder is operated, and to supply oil in the capacity based on a load pressure of the hydraulic cylinder. <P>SOLUTION: The hydraulic drive device includes a directional control valve 30, a pilot operation valve 40 that outputs a pilot pressure based on an operation amount of an operation lever 41, and a pump capacity control valve 52 operated in accordance with a differential pressure between a load pressure of a hydraulic cylinder 10 and a discharge pressure of a hydraulic pump 20. A throttle 44 is installed in a pilot hydraulic passage 42 that outputs the pilot pressure to the directional control valve 30 from the pilot operation valve 40. The pressure between the pilot operation valve 40 and the throttle 44 acts on the pump capacity control valve 52 in the same direction as the load pressure of the hydraulic cylinder 10, and the pressure between the throttle 44 and the directional control valve 30 acts on the pump capacity control valve 52 in the same direction as the discharge pressure of the hydraulic pump 20. <P>COPYRIGHT: (C)2012,JPO&INPIT |
