| 摘要 |
PROBLEM TO BE SOLVED: To provide a working tool hang-down device such as a spring balancer capable of preventing a working tool from falling off by restricting rotation of a drum using a simple constitution even if an energizing spring is broken. SOLUTION: A drum stopper 18 moves to the admitting position to enable the drum 30 to rotate in the pull-out direction in case the energizing force of a spiral spring 50 is greater than that of a torsion spring 19e, for example when a wire rope 40 to hang down the working tool is pulled out of the drum 30. On the other hand, in the case the energizing force of the torsion spring 19e is greater than that of the spiral spring 50, for example when the spiral spring 50 is broken owing to metal fatigue etc., the drum stopper 18 moves to the restricting position to prevent the drum 30 from rotating in the pull-out direction, and to prevent the wire rope 40 to hang down the working tool from being pulled out of the drum 30. COPYRIGHT: (C)2010,JPO&INPIT
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