In the expansion and contraction feature which expands and contracts

摘要

PROBLEM TO BE SOLVED: To provide an arm telescopic structure of a work machine with a simple structure at low cost.;SOLUTION: This arm telescopic structure comprises a first arm 4a rotatably connected to the end of a boom 3 and a second arm 4b pinned to the upper side of the first arm through parallel links 9a, 9b, swingable in the longitudinal direction, and placed on the upper end surface of the first arm 4a when longitudinally retracted relative to the first arm 4a. Connection parts 4e, 4f detachably connected to the mounting part formed at the end of the first arm 4a during the extension and retraction are formed on the lower part of the second arm 4b at least two positions. A hook 10 locked to positioning pins 4g, 4h for extension and retraction provided separately from each other at least longitudinal two positions during the extension and retraction is installed in the rear of the second arm 2.;COPYRIGHT: (C)2008,JPO&INPIT