Mobile lift crane with variable position counterweight
AssigneeManitowoc Crane Companies, LLC
InventorsDavid J. Pech, Kenneth J. Porubcansky
Life of this patent
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Abstract
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 compared to the rotating bed. In one method of operation, the counterweight unit is never supported by the ground during crane pick, move and set operations other than indirectly by the ground engaging members on the carbody.
Claims24
A mobile lift crane comprising:
- a) a carbody having moveable ground engaging members;
- b) a rotating bed rotatably connected about an axis of rotation to the carbody such that the rotating bed can swing with respect to the ground engaging members;
- c) a boom pivotally mounted on a front portion of the rotating bed;
- d) a mast mounted at its first end on the rotating bed;
- e) a moveable counterweight unit;
- and
- f) a counterweight movement structure connected between the rotating bed and the counterweight unit such that the counterweight unit may be moved to and held at both a forward position and a rearward position;
- g) wherein the crane has a total amount of counterweight of at least 250 metric tonne and a maximum rated load moment of at least 6,250 tonne-meters, and the ratio of maximum rated load moment to total weight of the counterweight is at least 25 tonne-meters/tonne.
Dependencies are inferred from the claim text.