BOOM BACK STOP FOR MOBILE CRANE

摘要

PROBLEM TO BE SOLVED: To make a mobile crane structure capable of selecting boom angles which a back stop operates at from plural settings in rearrangement from a crane boom to a tower crane or a reverse arrangement thereof. SOLUTION: In a back stop having an inner pipe slidably inserted in an outer pipe and a coil spring inserted between an end of the outer pipe and a base part of the inner pipe, a spacer of a U shaped section which can swing between a periphery of the inner pipe and a housing position on an outer plate side part through a swing out mechanism is provided between the outer pipe and the coil spring to make boom angles which the back stop operates at selectable from plural settings.