| 摘要 |
PROBLEM TO BE SOLVED: To reduce the work load in connecting work of a main jib and an auxiliary jib. SOLUTION: In a tower boom 21 (main jib) and a tower jib 22 (auxiliary jib), positioning holes 21d and 22d are provided in positions in the same distance from pin holes 21b and 22b, and an insertion hole 21e opened larger than the positioning hole 21d is provided in the tower boom 21 in such a manner of continuing to the positioning hole 21d. When connecting the tower jib 22 to the tower boom 21, the positioning hole 22d and the insertion hole 21e are positioned, and a positioning pin 24 is inserted to them, and then, the positioning pin 24 is moved to the positioning hole 21d continuing from the insertion hole 21e by lowering a base end part 22a of the tower jib 22, the tower jib 22 is turned in the state while having the positioning pin 24 as an axis, and the pin hole 21b of the tower boom 21 and the pin hole 22b of the tower jib 22 are positioned, and a connecting pin 23 is inserted into the pin holes 21b and 22b. COPYRIGHT: (C)2008,JPO&INPIT
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