Patent ID: 6067735
Filing Date: 2000-05-30
Classification: E02F

Abstract:
A machine for lifting heavy loads, the machine comprisinga main housing,a load hoist mechanism mounted on said housing,a boom having upper and lower ends, said lower end being connected to said main housing and said upper end having thereon a sheave mounted for rotation about a generally horizontal axis, said boom having a longitudinal axis and having a first boom top rail and a second boom top rail spaced apart from said first boom rail, both rails extending along said longitudinal axis,structure supporting said boom relative to said main housing,means for lifting a load,a hoist rope extending between said load lifting means and said load hoist mechanism and over said sheave to permit vertical movement of said load lifting means,a hoist rope support sheave, andmeans for mounting said rope support sheave on the top of said boom partway between the lower and upper ends of said boom, said mounting means comprisinga first sheave support link pivotally connected to said first boom rail,a second sheave support link pivotally connected to said second boom rail, said first and second sheave support links extending from said boom in an upright support position and having upper ends,a cross pin extending between the upper ends of said sheave support links, said hoist rope support sheave being rotatably mounted on said cross pin, andmeans for maintaining said support links in their upright support position and for pivoting said support links between their upright supporting position and a lowered maintenance position.