| 摘要 |
PROBLEM TO BE SOLVED: To materialize smooth start by preventing sudden start and start delay of a hydraulic actuator while employing a load sensing control system. SOLUTION: A control valve 23 provided with both of a meter in and a meter out opening 23a, 23b is provided between a variable capacity hydraulic pump 21 and a hydraulic actuator 22. A control valve 23 is operated by remote control pressure from a remote control valve 24 to change opening area of the meter in and the meter out. Unload valve 26 is provided between a pump line 25 and a tank T and load sensing control changing pump flow rate and opening area of the unload valve 26 to keep load sensing differential pressure which is difference of upstream pressure and downstream pressure of the meter in opening constant is executed. Supposing this structure, a structure provided with an unload control valve 33 in parallel with the unload valve 26, and controlling opening area of the unload control valve 33 according to remote control pressure is employed. COPYRIGHT: (C)2008,JPO&INPIT
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