| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a mobile tower crane capable of being utilized for the house construction work and facilitating the carrying-out work from a construction site. SOLUTION: An expandable mast 15 is journalled to a mobile travel body 1 erectably and rockably around a horizontal spindle 19 between a vertically erected attitude P1 and a prostrated attitude P2. A swivel base 24 is supported on the lift upper end section of the mast 15, and the base end section of a crane boom 25 is vertically erectably journalled to an overhang end section 24a expanded on one side from the mast center of the swivel base 24 in this mobile tower crane. The crane boom 25 is made expandable and prostratable to a downward attitude, rather than a horizontal attitude, against the mast 15 kept in the vertically erected attitude P1. The radius of gyration of the tip of the crane boom 25 kept in a shrunk state and the downward prostrated attitude is reduced when the mast 15 is prostrated around the horizontal spindle 19.</p> |
