| 摘要 |
<p>PROBLEM TO BE SOLVED: To simplify a tension adjustment work for a wire rope and a position adjustment work for a boom and to improve workability. SOLUTION: An extension-side wire rope 13 wound around an extension-side sheave 11 into a U shape and a contraction-side wire rope 14 wound around a contraction-side sheave 12 into a U shape are tensed across the base end of the tip-side boom and a movable member 16 provided in a connecting member 29a so that the both wire ropes are set into a loop shape. A wire tension adjustment member 21 provided in one of the connecting member side end part 13a of the extension-side wire rope and the connecting member side end part 14a of the contraction-side wire rope is operated so that the tensions of the both wire ropes 13, 14 are simultaneously adjusted. When the tension adjustment is completed, the movable member 16 is moved by a position adjusting member 22 so that the both wire ropes 13, 14 are relatively moved while holding the tension adjustment state by the wire tension adjustment member 21 and the positions of the intermediate boom and the tip-side boom are thus adjusted separately from the tension adjustment without affected by the tensile forces of the both wire ropes 13, 14.</p> |
