| 摘要 |
PROBLEM TO BE SOLVED: To improve workability. SOLUTION: Each grapple arm 2 consists of an opening/closing arm 5 vertically swingably supported on a base 1 and a telescopic arm 6 provided at a lower portion of the opening/closing arm 5. A first feeding/discharging path 11 and a second feeding/discharging path 12 communicated to an opening operation chamber 8a and a closing operation chamber 8b of an opening/closing cylinder 8, respectively, are selectively connected to a hydraulic pump 14 and an oil tank 15 by a solenoid directional control valve 13. The opening operation chamber 8a is communicated to an extending operation chamber 9a of an extending cylinder 9 through a first branch path 21 and the closing operation chamber 8b is communicated to a contraction operation chamber 9b through a second branch path 22. The first feeding/discharging path 11 is provided with a first counterbalance valve 31. The second branch path 22 is provided with a sequence valve 38 and a second counterbalance valve 32 in series and a check valve 39 in parallel with the sequence valve 38.
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