| 摘要 |
PROBLEM TO BE SOLVED: To provide a derricking gear for a folding boom capable of reducing power of a motor for derricking the folding boom. SOLUTION: This device is provided with a crane main body comprising an upper tower, a base attaching boom mounted to the crane main body near the base of the upper tower so as to freely derrick, and a tip boom mounted to the tip of the base attaching boom so as to freely derrick. The device is also provided with a hoisting rope R3 and a supporting rope R2, and the hoisting rope R3 is connected to a winch 3 placed on an upper surface of the crane main body 1, and the supporting rope R2 is wound between a first supporting sheave 25 journaled at a tip part on an upper side of the base attaching boom 5 and a second supporting sheave 26 journaled on both the tip boom and a base end part upper surface, fixed to a suitable place of the base attaching boom 5 at one end, and fixed to the upper tower 2 at the other end. The supporting rope R2 supports the tip boom 6 with always retaining tension during derricking operation from when the base attaching boom 5 being in a horizontal attitude to just before completing standing up.
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