| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a backtop structure of a crane can eliminate removing work of a spacer, and prevent the breakage of a boom or a jib due to forgetting of removing. Ž<P>SOLUTION: In the backstop structure, a base end of the jib is rotatably coupled to a distal end of the boom 2, and a base end of a jib strut 5 supporting the jib is rotatably mounted. A contracting backstop 6 composed of an inner member 6a regulating a tilting angle of the jib strut and an outer member 6b is provided over the jib strut and the boom. A spacer 11 for adjusting the maximum contracting length of the backstop is provided. The spacer is supported so as to rotate about a supporting shaft on the outer member side of the backtop, positioned at a regular position getting close to the inner member of the backtop when the boom and the jib carries out work in a standing state, by its weight, and rotated to a retracting position separating from the regular position when the boom and the jib ground in an assembling state. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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