| 摘要 |
PROBLEM TO BE SOLVED: To establish compatibility between the protection of a working arm of a working machine from an overload and the prevention of a decrease in working efficiency. SOLUTION: Only when an on-off switch 601 is turned on and a control lever 34 for driving a cylinder 20 is operated over a dead band in an object gripping direction, an electromagnetic selector valve 35 makes oil passages 41a and 42a communicate with oil passages 41b and 42b. A control valve 38 makes the oil passage 41b or 42b with higher pressure connected to an accumulator 39 via an oil passage 45, and makes the oil passage with lower pressure connected to an oil passage 46. Thus, pressure oil in either of oil chambers 14a and 14b, which ascends depending on an external force acting on a gripping claw 19, is absorbed/accumulated and discharged in accordance with the pressure by the accumulator 39. COPYRIGHT: (C)2008,JPO&INPIT
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