| 摘要 |
PROBLEM TO BE SOLVED: To provide an unload valve for setting the discharge pressure of a variable pump in advance to improve the responsiveness of an actuator to an operation of an actual machine operation lever without adding a value such as an electromagnetic proportional pressure-reducing valve. SOLUTION: This hydraulic driving device 10 has an unload valve 14 to introduce pressure oil discharged from a variable pump 11 according to a differential pressure reducing valve 25 detecting differential pressure between the discharge pressure P of the variable pump 11 and the maximum load pressure of one actuator 17 to a tank 18. The unload valve 14 is configured to be actuated in a direction where the discharge pressure P of the variable pump 11 acting on a first pressure receiving part 21 is made to be communicative via a discharge line 13, and to actuate in a blocking direction by the maximum load pressure received by a second pressure receiving part 22. COPYRIGHT: (C)2009,JPO&INPIT
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