MOBILE LIFT CRANE WITH VARIABLE POSITION COUNTERWEIGHT

摘要

A mobile lift crane (610) includes a carbody (612) having moveable ground engaging members (614, 616); a rotating bed (620) rotatably connected to the carbody (612) such that the rotating bed (620) can swing with respect to the ground engaging members (614, 616); a boom (622) pivotally mounted on a front portion of the rotating bed (620); a mast (628) mounted at its first end on the rotating bed (620); a moveable counterweight unit (634); and at least one arm (636) pivotally connected at a first end to the rotating bed (620) and at a second end to a rack and pinion assembly (636). Extension and retraction of the rack and pinion assembly (636) changes the position of the counterweight unit (634) compared to the rotating bed (620).