Lift Crane with Moveable Counterweight
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.
1 . A mobile lift crane, comprising:
a) a carbody;
b) moveable ground engaging members mounted on the carbody allowing the crane to move over the ground;
c) a rotating bed rotatably connected to the carbody about an axis of rotation;
d) 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;
e) a counterweight support beam coupled to the rotating bed; and
f) 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;
g) wherein the crane has at least two set-up configurations, wherein in a first set-up configuration the crane comprises a live mast, and, wherein in a second set-up configuration the crane comprises a lattice mast; and
h) wherein 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,
2 . The mobile lift crane of claim 1 wherein the counterweight support beam further comprises a pair of spaced-apart side members.
3 . The mobile lift crane of claim 1 wherein the moveable counterweight tray is attached to a trolley operable to move toward and away from the boom during a pick, move, and set operation by moving relative to the counterweight support beam.
4 . The mobile lift crane of claim 1 , further comprising a counterweight support frame; and wherein the counterweight support beam is coupled to the counterweight support frame and is operable to move relative to the counterweight support frame while moving toward and away from the boom during a pick, move, and set operation.
5 . The mobile lift crane of claim 1 wherein the counterweight support beam is removably secured to the rotating bed.
6 . The mobile lift crane of claim 4 wherein the moveable counterweight tray is attached to a trolley operable to move toward and away from the boom during a pick, move, and set operation by moving relative to the counterweight support beam.
7 . The mobile lift crane of claim I, further comprising a plurality of rollers to facilitate the movement of the moveable counterweight unit relative to the counterweight support beam.
8 . The mobile lift crane of claim 1 , further comprising:
a) a counterweight support frame; and
b) a telescoping cylinder operable to move the counterweight support beam relative to the counterweight support frame.
9 . The mobile lift crane of claim 2 wherein the counterweight support beam further comprises a first flange on one of the spaced-apart side members and a second flange on the opposite spaced-apart side member; and wherein the moveable counterweight unit moves toward and away from the boom during a pick, move, and set operation by traveling on the first flange and second flange.
10 . The mobile lift crane of claim 1 wherein the counterweight support beam comprises a telescoping beam.
11 . The mobile lift crane of claim 10 wherein the moveable counterweight tray is attached to a trolley operable to move toward and away from the boom during a pick, move, and set operation by moving relative to the counterweight support beam.
12 . The mobile lift crane of claim 2 , further comprising a counterweight support frame; and wherein the counterweight support beam is coupled to the counterweight support frame and is operable to move relative to the counterweight support frame while moving toward and away from the boom during a pick, move, and set operation.
13 . The mobile lift crane of claim 12 wherein the moveable counterweight tray is attached to a trolley operable to move toward and away from the boom during a pick, move, and set operation by moving relative to the counterweight support beam.
14 . The mobile lift crane of claim 12 , further comprising:
a) a counterweight support frame; and
b) a telescoping cylinder operable to move the counterweight support beam relative. to the counterweight support frame.
15 . The mobile lift crane of claim 12 , further comprising a plurality of rollers to facilitate the movement of the moveable counterweight unit relative. to the counterweight support beam.
16 . The mobile lift crane of claim 13 , further comprising:
a) a counterweight support frame; and
b) a telescoping cylinder operable to move the counterweight support beam relative to the counterweight support frame.
17 . The mobile lift crane of claim 16 wherein the counterweight support beam further comprises a first flange on one of the spaced-apart side members and a second flange on the opposite apart side member; and wherein the moveable counterweight unit moves toward and away from the boom during a pick, move, and set operation by traveling on the first flange and second flange.
18 . The mobile lift crane of claim 16 , further comprising a plurality of rollers to facilitate the movement of the moveable counterweight unit relative to the counterweight support beam.