CONTAINER-LIFTING SPREADER WITH DRIVE FOR THE TELESCOPIC MOVEMENT OF SPREADER'S BEAMS PROTECTED AGAINST DAMAGE BY COLLISION

摘要

A container- lifting spreader is disclosed, comprising at least two beams (1, 2) which are movably supported in a housing (3) and provided a drive by which the beams can be driven in telescopic movements for adjusting the length of the spreader, the drive comprising an electric motor (5) and a pusher (7) acting on the beams, the pusher interconnecting the beams for simultaneous telescopic movements in mutually opposite directions in the longitudinal direction of the spreader, and a power transmission (6) operatively coupled between the motor (5) and the pusher (7), the power transmission comprising an input shaft (11) carrying an external gear ring (12) driven by the motor, and an output shaft (14) likewise carrying an external gear ring (13) that operates the pusher, the gear rings (12, 13) in mutual engagement forming an angle gear (11, 12, 13, 14) arranged with an irreversible mesh of teeth such that rotation of the input shaft causes rotation of the output shaft whereas the reverse is prohibited by the irreversible mesh of teeth. A cut-off coupling is arranged in the power transmission, between the angle gear (11, 12, 13, 14) and the pusher, the cut-off coupling arranged to release in result of an abnormal torsional moment being externally applied to the output shaft (14).