| 摘要 |
PROBLEM TO BE SOLVED: To devise such a structure that extension of a post is performed at a lower end part, to make the connecting work easy and safe and to perform a lifting work of a small crane easily and quickly. SOLUTION: Post single bodies 14a of unit lengths are successively added and a crane is lifted. A small crane 10 is provided with a base 18 supporting a post 14 and a crane main body 16 connected with a top part of this post 14, a frame 20 which is installed on this base 18 so as to be freely ascendable/ decendable and locks and freely locks and releases a lower end part of the post 14 and a driving means 22 elevating and lowering this frame 20 with stroke amount of at least a length L of the post single body 14a or more. The frame 20 is raised by the driving means 22, the post single body 14a is inserted between the post 14 and the base 18 and the inserted post single body 14a is connected with a lower end part of the post 14.
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