WIRE EXPANSION AND CONTRACTION MECHANISM FOR SIMULTANEOUS EXPANSION AND CONTRACTION BOOM

摘要

PURPOSE: To reduce the size and the weight of an expandable boom by a method wherein a remarkably increased life is provided for a wire rope for expansion and contraction and besides an installation space for a pulley for expansion and contraction and a lock space for a wire end are reduced as much as possible. CONSTITUTION: Wire ropes 13 and 19 for expansion and contraction consist of two or more wire ropes juxtaposed with each other and a pulley groove for pulleys 14 and 20 for expansion and contraction is formed in width wide enough to allow return of the wire ropes for expansion and contraction in a juxtaposed state. The ends of the wire ropes 13 and 19 for expansion and contraction are collectively fixed to single rope end lock fitments 16 and 22 and locked to a boom 1 on the base end side or a boom 3 on the tip side.