| 摘要 |
PROBLEM TO BE SOLVED: To easily execute the maintenance work of an expansion cylinder by expansibly and contractively providing an inner cylinder within an outer cylinder in an expansion boom, pivotally supporting each end part of an inner cylinder expanding expansion cylinder within the outer cylinder and the inner cylinder, forming an opening part on the outer cylinder, and arranging a connecting member in the opening part. SOLUTION: An expansion boom comprises an inner cylinder 15 expansibly and contractively provided within an outer cylinder 14 and an expansion cylinder 16 for expanding and contracting the inner cylinder 15, which is arranged within the outer cylinder 14 and the inner cylinder 15. The base part of the expansion cylinder 16 is pivotally supported in the inner cylinder 15, and the tip of a rod is pivotally supported in a piton fitted to a boss part. An opening part 20 is formed on the lower surface of the outer cylinder 14 in the boom device housing position adjacent to the rod tip, and a connecting member 21 is arranged in the opening part 20 in the state where it is protruded downward from the outer cylinder 14, and fixed to the rod tip of the expansion cylinder 16 by a bolt 22 from the lower surface.
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