| 摘要 |
PROBLEM TO BE SOLVED: To improve the efficiency and the safety in the oscillating operation of an auxiliary jib by dispensing with the operation by an operator coming out from a crane cab. SOLUTION: This auxiliary jib housing device is composed of a pair of left and right jib connecting means 50 interposed between a tip part of a point boom 31 and a basic end part of an auxiliary jib 40 in a projecting posture, and capable of mounting and demounting the auxiliary jib to the tip part of the point boom, and folding the auxiliary jib along a side face of a basic end boom 32 in a state that one side is released and the other side is used as a spindle, an auxiliary jib supporting means being engaged by miniaturizing the point boom to the basic boom in a state that the auxiliary jib is folded, and supporting the auxiliary jib oscillatably on the supporting parts 61, 62 in the direction of the housing posture where the tip part of the auxiliary jib is close to the basic end boom, in a condition that the jib connecting means are released, and an auxiliary jib oscillating means 70 composed of a hydraulic cylinder 71 mounted between the basic end boom and the auxiliary jib supported by the auxiliary jib supporting means.
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