Compact hoisting device

Claim 1

A hoisting mechanism for projecting a load along a substantially linear travel path by means of a train of elongated hoist links sequentially pivoted to one another, comprising: a base; a primary link, pivotably attached to said base; a final link, operatively connected to said primary link; motion transmission means, to project and rotate said final link such that the angular travel of said final link substantially equals the absolute value of the angular travel of said primary link; a load support, pivotably mounted on said final link; positive attitude control means, independent of said motion transmission means, to maintain a constant spatial attitude of said load support, with respect to said base; said positive attitude control means including: a cross-shaft, coaxial with a hinge axis passing through the outboard end, remote from said base, of said primary link and the inboard end, remote from said load support, of said final link; journal means, allowing for the free rotation of said cross-shaft independent of the position of either hoist link; a load support shaft integral with said load support and parallel to said cross-shaft; a pivot shaft, irrotatably fixed in said base; a primary mechanical position control drive operatively interconnecting said pivot shaft with said cross-shaft, said primary mechanical position control drive incorporating parallel drive rods pinned to planarly aligned disks keyed, respectively, to said horizontal pivot shaft and to said cross shaft; a final mechanical position control drive, operatively interconnecting said cross-shaft with said load support shaft, and actuator means, for impelling said primary link into rotational movement about said pivot axis, thereby elevating said load support.