초록 ▼

A mobile lift crane includes a carbody, a rotating bed, a boom, a moveable counterweight unit, at least one linear actuation device and at least one arm pivotally connected at a first end to the rotating bed and at a second end to the linear actuation device. The arm and linear actuation device are

A mobile lift crane includes a carbody, a rotating bed, a boom, a moveable counterweight unit, at least one linear actuation device and at least one arm pivotally connected at a first end to the rotating bed and at a second end to the linear actuation device. The arm and linear actuation device are connected between the rotating bed and the counterweight unit such that extension and retraction of the linear actuation device changes the position of the counterweight unit. In one method of operation, the counterweight is never supported by the ground during crane pick, move and set operations other than indirectly by the ground engaging members on the carbody. One embodiment includes a counterweight movement structure having a rectangular rack with at least first and third pinion gears engaged with teeth on one side and second and fourth pinion gears engaged with teeth on the opposing side.

대표청구항 ▼

The invention claimed is: 1. A method of operating a mobile lift crane, the lift crane comprising a carbody having moveable ground engaging members; a rotating bed rotatably connected to the carbody such that the rotating bed can swing with respect to the ground engaging members; a boom pivotally mo

The invention claimed is: 1. A method of operating a mobile lift crane, the lift crane comprising a carbody having moveable ground engaging members; a rotating bed rotatably connected to the carbody such that the rotating bed can swing with respect to the ground engaging members; a boom pivotally mounted on a front portion of the rotating bed, with a hoist line extending therefrom; a mast mounted at its first end on the rotating bed; at least one linear actuation device; and a moveable counterweight unit; the method comprising:a) performing a pick, move and set operation with a load wherein the moveable counterweight unit is moved toward and away from the front portion of the rotating bed by extending and retracting the linear actuation device during the pick, move and set operation to help counterbalance the load, but wherein the counterweight unit is never supported by the ground other than indirectly by the moveable ground engaging members on the carbody throughout the pick, move and set operation, and wherein the counterweight is moved a greater distance than a stroke of the linear actuation device that causes the counterweight to move.