Importance

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Abstract

A mobile lift crane includes 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 and a mast mounted at its first end on the rotating bed and having a second end; and at least one hydraulic cylinder pivotally connected at a first end to the rotating bed. The hydraulic cylinder is positioned and configured so as to be able to raise the second end of the mast from the mast being in a near horizontal position to a position where the mast is used during crane pick, move and set operations. In a preferred embodiment, at least one arm is pivotally connected at a first end to the rotating bed and at a second end to the hydraulic cylinder. The arm and cylinder are connected together such that extension and retraction of a piston within the hydraulic cylinder causes the second end of the arm to raise and lower. The arm and cylinder support at least one mast-engaging member positioned such that raising the second end of the arm causes the mast-engaging member to push against and raise the mast when the mast is in a set-up state. Thus the hydraulic cylinder is used to pivotally rotate the mast about its connection to the rotating bed, thereby raising the second end of the mast.

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First Claim