MULTI-STAGE TROLLEY FOR A CRANE AND A CRANE THEREWITH

摘要

A crane for loading and unloading a cargo includes multi-stage trolley. The multi-stage trolley for a crane includes a first trolley movable in a longitudinal direction along a boom of the crane; a second trolley movable in a lateral direction on the first trolley; a hoisting wire provided in the longitudinal direction along the boom; spreader connected to the hoisting wire through the first trolley and the second trolley and supported by the hoisting wire, the spreader being movable in a vertical direction according to a movement of the hoisting wire. The multi-stage trolley further includes a sheave block unit for changing a direction of the hoisting wire to maintain a vertical level of the spreader constant when the first trolley and/or the second trolley is moved.