| 摘要 |
<p>PROBLEM TO BE SOLVED: To compactly constitute a telescopic boom. SOLUTION: An expansion cylinder 13 for extending and contracting an intermediate boom 4b to a base end boom is arranged in such a manner that the bottom side of a cylinder tube 13a is protruded toward the tip side of a top boom 4c. A slider 41 for preventing the frictional damage by the abutment of the cylinder tube on the top boom inner surface is provided on the side surface of the cylinder tube 13a. A boom head 51 is fixed to the tip of the top boom 4c, a vertical post 6 is pivotally connected to the boom head through a rocking shaft 52 in such a manner as to be rockable within the vertical plane, and a leveling cylinder 14 is arranged to connect the base end side of the boom head 51 to the lower end of the vertical post 6. As the leveling cylinder 14, a tube end trunnion type cylinder is used.</p> |
