VERTICAL MOTION COMPENSATED CRANE APPARATUS

摘要

"VERTICAL MOTION COMPENSATED CRANE APPARATUS" A relative motion compensation apparatus is provided in a crane having two platforms vertically movable with respect to each other and employing a boom supported on the first platform, a cable depending from the boom and supporting a hook and a winch to move the cable. The relative motion apparatus uses a fluid cylinder and piston assembly secured to the crane boom. Sensing means generate a signal responsive to the relative vertical movement of the two platforms. The signal is used to control the position of the piston in the cylinder to thereby vary the vertical separation between the hook and the boom.