| 摘要 |
PROBLEM TO BE SOLVED: To compensate for an arm operation when an actuator operation is added during the compound operation of rotation and arm pulling. SOLUTION: A rotation priority valve 15 serving as a flow control valve of hydraulic pilot type is provided on the meter-in side of an arm cylinder 7. During the combined operation of rotation and arm pulling, the rotation priority valve 15 is activated by rotation pilot pressure so that a meter-in flow rate of the arm cylinder 7 is restricted to prioritize rotating motion, On the premise of the above, a selector valve 20 is provided in a pilot line 16 of the rotation priority valve 15 and changed over so as to release a restriction effect of the rotation priority valve 15 when boom lowering movement is added to the combined operation of rotation and arm pulling so that a rotation priority function is canceled. COPYRIGHT: (C)2009,JPO&INPIT
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