| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem on a conventional live mast pull-out mechanism that it is difficult to compatibly use a single-stage hydraulic cylinder and downsize the mechanism and the capability of the hydraulic cylinder is not sufficiently developed. SOLUTION: A foot 21a of a guide link 21 is supported by a turning frame 12 located behind a foot 1a of a live mast 1. During pull-out of the live mast 1, the radius of an arc which the end of the guide link 21 for restricting the movement of the end of the hydraulic cylinder 20 draws around the foot 1a of the live mast 1 is, therefore, smaller than that in the conventional live mast pull-out mechanism which has a live mast and a guide link supported coaxially. Thus, the elongation required for the hydraulic cylinder 20 is smaller than conventional one. The hydraulic cylinder 20 should have almost constant thrust for a period after starting the pull-out of the live mast 1 but before finishing the pull-out thereof. COPYRIGHT: (C)2004,JPO
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