| 摘要 |
A lift crane includes a carbody; moveable ground engaging members mounted on the carbody allowing the crane to move over the ground; a rotating bed rotatably connected to the carbody about an axis of rotation; a boom pivotally mounted about a boom hinge point on the front portion of the rotating bed and including a hoist line for handling a load; a counterweight support beam coupled to the rotating bed; and a moveable counterweight unit comprising a counterweight tray suspended beneath the counterweight support beam wherein the counterweight tray is operable to move toward and away from the boom during a pick, move, and set operation by moving relative to the counterweight support beam. The crane has at least two set-up configurations: in a first set-up configuration the crane comprises a live mast, and in a second set-up configuration the crane comprises a lattice mast. The crane is configured such that the counterweight unit is never supported by the ground other than indirectly by the moveable ground engaging members on the carbody throughout a pick, move, and set operation. |
