| 摘要 |
<p>PURPOSE: To control the order of motions of respective cylinders by providing such an arrangement that a lock member at an end face of an intermediate cylinder is held by a ratchet mechanism at a release position during retraction of a telescopic boom, the retracted condition of the cylinder is integrally gripped.by a bolt at the end face of the cylinder in a clamping member on the outside of the end face, and the clamping member is held by a ratchet bolt. CONSTITUTION: An innermost cylinder 6 is moved toward a cylinder 5 which is inhibited from axially sliding, a bolt at an end face of the cylinder 6 reaches a position in a clamping member at an end face of the cylinder 5, and a lock member 8 of the cylinder 5 is released by a ratchet bolt 5 provided at the inner end face 23 of the cylinder 6. The cylinder 5 is suspended from a bolt of the cylinder 6 by the clamping member, and the cylinders 5, 6 are further moved rightward. The movement is repeated until the cylinders 5, 4 and as well all the cylinders are retracted. With this arrangement, the cylinders are successively retracted from the large diameter one of them. The order of retractions can be held precisely, and the cylinders can be surely locked, thereby it is possible to surely prevent abrupt retraction.</p> |
