| 摘要 |
PROBLEM TO BE SOLVED: To provide a device provided with major and auxiliary sheave sets in which the auxiliary sheave set can be contained. SOLUTION: A plurally-disposed boom nose part includes a support structure 12 disposed at one end part of a boom 10. The support structure 12 supports a first sheave set 16 at least, and the first sheave set 16 includes at least one sheave. A pivot arm 18 is provided with a first end part connected to the support structure 12 to be pivotally rotated. A second end part of the pivot arm 18 supports a second sheave set 24 including at least one sheave. The pivot arm 18 is provided with first/second action/containing positions. The pivot arm 18 is extended into the boom 10 at the containing position. At the first action position, the pivot arm 18 is perpendicularly extended to the boom 10. At the second action position, the pivot arm 18 is extended to be apart from the boom 10, the first sheave set 16 supports a first load bearing part 28, and the second sheave set 24 supports a second load bearing part.
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