| 摘要 |
PROBLEM TO BE SOLVED: To provide a jib projection device, with which work in height is avoided, and can facilitate execution while achieving simplification of work.SOLUTION: A tension rod 21 is comprised of a first rod 41 and a second rod 43. A jib projection device includes a rotation regulation member 51 for regulating predetermined rotation or more of the first rod 41 to a boom 2 front end side, and a rotation regulation means 52 for regulating rotation of the first rod whose rotation to the boom front end side is regulated by the rotation regulating member, to a counter boom front end side. The rotation regulating means has a sheave support member 10 attached to the boom front end rotatively around a spindle 62, and a rotation regulating part 65 provided to the sheave support member, and the sheave support member is positioned at a normal work position, and rotates to move to a retraction position above the work position when a hanging hook 61 is wound up which is hung via a rope 60 from an auxiliary sheave 9 until making contact with a part of the sheave support member, and rotation of the first rod to the counter boom front end side is regulated by the rotation regulation part. |
