Multi-stage trolley for a crane and a crane therewith

A multi-stage trolley for a crane, comprising:

• a first trolley movable in a longitudinal direction along a boom of the crane;
• a second trolley movable in a lateral direction perpendicular to the longitudinal direction on the first trolley;
• a hoisting wire provided in the longitudinal direction along the boom;
• a 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;
• a wire driving drum for winding or unwinding the hoisting wire to adjust a vertical level of the spreader;
• and
• a sheave block unit for changing a direction of the hoisting wire to maintain the vertical level of the spreader constant without operating the wire driving drum when the first trolley and the second trolley are moved,
• wherein the sheave block unit includes direction changing sheave blocks provided at the first trolley, at least one of the direction changing sheave blocks changing a direction of the hoisting wire provided thereto in the longitudinal direction into the lateral direction, and
• wherein at least one of the direction changing sheave blocks changes the direction of the hoisting wire provided thereto in the longitudinal direction into the vertical direction and then into the lateral direction.

A multi-stage trolley for a crane, comprising:

• a first trolley movable in a longitudinal direction along a boom of the crane;
• a second trolley movable in a lateral direction perpendicular to the longitudinal direction on the first trolley;
• a hoisting wire provided in the longitudinal direction along the boom;
• a 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;
• a wire driving drum for winding or unwinding the hoisting wire to adjust a vertical level of the spreader;
• and
• a sheave block unit for changing a direction of the hoisting wire to maintain the vertical level of the spreader constant without operating the wire driving drum when the first trolley and the second trolley are moved,
• the sheave block unit includes direction reversing sheave blocks provided at the first trolley,
• at least one of the direction reversing sheave blocks changing a direction of the hoisting wire provided thereto in the lateral direction by 180 degree to connect the hoisting wire to the second trolley.