Abstract: A crawler has a track tensioning system. The crawler includes a crawler frame having a bottom; at least one drive tumbler supported on the frame; a track made of a plurality of connected track shoes and is wrapped around the drive tumbler so that a plurality of the shoes are in contact with the drive tumbler. The track tensioning system, mounted to the frame, includes a roller engaging the inside surface of the track; and a roller positioning structure attached to the frame that can raise the roller relative to the bottom of the frame to thereby increase the tension of the track.

Abstract: A combination of a drive tumbler and a track includes a track made of a plurality of connected track shoes and a plurality of driven surfaces. The track is wrapped around the drive tumbler so that a plurality of the shoes are in contact with the drive tumbler. The drive tumbler has a plurality of drive surfaces and a circumferential rim surface that includes a plurality of shoe contact surfaces that each contact the inside surface of one of the track shoes that are in contact with the tumbler. The shoe contact surface has a shape such that a line normal to the tangent of the shoe contact surface does not pass through the axis of rotation of the drive tumbler, thereby allowing the shoe contact surfaces on the rim of the drive tumbler to transmit a tractive force to the track. A preferred drive tumbler comprises a center hub and a plurality of individual tooth members connected to the center hub by welds.

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; a mast mounted at its first end on the rotating bed; a backhitch connected between the mast and a rear portion of the rotating bed; a moveable counterweight unit; at least one hydraulic cylinder; and at least one arm pivotally connected at a first end to the rotating bed and at a second end to the hydraulic cylinder. The arm and hydraulic cylinder are connected between the rotating bed and the counterweight unit such that extension and retraction of the hydraulic cylinder changes the position of the counterweight unit compared to the rotating bed.

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 is never supported by the ground during crane pick, move and set operations other than indirectly by the ground engaging members on the carbody. The linear actuation device can include at least one rack and pinion assembly or hydraulic cylinder.

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; a mast mounted at its first end on the rotating bed; a backhitch connected between the mast and a rear portion of the rotating bed; a moveable counterweight unit; at least one hydraulic cylinder; and at least one arm pivotally connected at a first end to the rotating bed and at a second end to the hydraulic cylinder. The arm and hydraulic cylinder are connected between the rotating bed and the counterweight unit such that extension and retraction of the hydraulic cylinder changes the position of the counterweight unit compared to the rotating bed.

Abstract: An improved method and system for a liftcrane in which a load is lifted through the combined action of first and second hoist drums. The method and system use a first rope wound on one hoist drum and a second rope wound on the second hoist drum. The ends of the ropes opposite the hoist drums are linked together to transmit tension between them. The load is coupled to the ropes. If the take up speed of one of the ropes exceeds the take up speed of the other, the linked ends of the ropes will shift. This condition is detected and the operation of at least one of the first and second hoist drums is modified to bring the take up rates into balance. This system is advantageously used with a hoist block sheave arrangement. This system can also be used with a single rope in which each of the ends of the single rope are wound on a separate one of the hoist drums and the load is coupled to the middle of the rope.

Abstract: A crawler that includes a first crawler assembly and a second crawler assembly attached to the first crawler so that the first crawler assembly is aligned with the direction of travel of the second crawler assembly.

Abstract: A crawler that includes a first crawler assembly and a second crawler assembly attached to the first crawler assembly so that the first crawler assembly is aligned with the direction of travel of the second crawler assembly.

Abstract: A crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works includes a hydraulic boom hoist cylinder and a hydraulic circuit for controlling the hydraulic boom hoist cylinder. The hydraulic cylinder is pivotally connected to a mast on the upper works and pendently connected to the boom. The boom hoist cylinder preferably comprises two double-acting hydraulic cylinders. The hydraulic circuit includes a closed loop pump and a hydraulic controller connecting the closed loop pump and the double-acting cylinders such that fluid from the pump can be directed either to extend or retract the cylinders, with the hydraulic fluid exiting the cylinders being directed to return to the pump.

Abstract: A crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works includes a hydraulic boom hoist cylinder and a hydraulic circuit for controlling the hydraulic boom hoist cylinder. The hydraulic cylinder is pivotally connected to a mast on the upper works and pendently connected to the boom. The boom hoist cylinder preferably comprises two double-acting hydraulic cylinders. The hydraulic circuit includes a closed loop pump and a hydraulic controller connecting the closed loop pump and the double-acting cylinders such that fluid from the pump can be directed either to extend or retract the cylinders, with the hydraulic fluid exiting the cylinders being directed to return to the pump.

Abstract: A drum drive assembly for cranes which use a load hoist line reeled onto a load hoist line drum to lift loads allows the load hoist line drum to be disconnected from the drum drive motor to permit the load hoist line drum to rotate independent of the drum drive motor. The drum drive assembly comprises one or more motors for rotating the load hoist line drum to either pay out or reel in the load hoist line; a brake for slowing, stopping or preventing the rotation of the load hoist line drum; and a jaw clutch which may be disengaged to permit the load hoist line drum to rotate independently of the motor.

Abstract: A crane having an upper works rotatably mounted on a lower works and a boom pivotally mounted on the upper works, wherein the crane further comprises an apparatus and method for lifting, positioning, and assembling a counter weight to the upper works. The apparatus and method includes pivotally connecting a counter weight pivot frame between the counter weight and the upper works and lifting the counter weight into position with the hydraulic boom hoist cylinder. The crane further comprises a boom parking device.

Abstract: A crane having an upper works rotatably mounted on a lower works, a boom pivotally mounted on the upper works, and a hydraulic boom hoist cylinder to control the angle of the boom. The crane further comprises a mast and a hydraulic cylinder pivotally connected to the upper works. The connection of the mast to the upper works is at a location separate from, and at an elevation below, the elevation of the connection of the hydraulic cylinder to the upper works. The hydraulic cylinder is pivotally connected to the mast and pendently connected to the boom.

Abstract: A swing lock mechanism for machines having an upper works rotatably mounted on a lower works by a swing bearing is connected to the drive shaft of a swing bearing drive assembly and comprises a swing lock plate, an annular pin support, and a plurality of locking pins. The swing lock plate is affixed to the drive shaft and has at least one hole disposed about the axis of the drive shaft. The annular pin support is fixed against rotation relative to the drive shaft is disposed about the axis of the drive shaft. The locking pins are supported by the annular pin support and are also disposed about the axis of the drive shaft. The locking pins are arranged in such a manner so as at least one pin may engage a hole in the swing lock plate irrespective of the angular orientation of the swing lock plate relative to the annular pin support.

Abstract: An improved method and system for a liftcrane in which a load is lifted through the combined action of first and second hoist drums. The method and system use a first rope wound on one hoist drum and a second rope wound on the second hoist drum. The ends of the ropes opposite the hoist drums are linked together to transmit tension between them. The load is coupled to the ropes. If the take up speed of one of the ropes exceeds the take up speed of the other, the linked ends of the ropes will shift. This condition is detected and the operation of at least one of the first and second hoist drums is modified to bring the take up rates into balance. This system is advantageously used with a hoist block sheave arrangement. This system can also be used with a single rope in which each of the ends of the single rope are wound on a separate one of the hoist drums and the load is coupled to the middle of the rope.

Abstract: A ring for supporting a lift crane includes at least two ring segments each having two ends, the ends of the ring segments comprising at least one horizontal plate and at least one vertical plate. The horizontal plates and the vertical plates of adjacent ends of the ring segments are disconnectably secured to one another to form the ring support. In a preferred embodiment, the horizontal plates are connected by a vertical pin and the vertical plates are connected by a horizontal pin.

Abstract: A longitudinally divisible crane boom segment includes at least a first and a second section that are easily nested together for transport. The sections each include at least one chord member, at least one bracket attached to the section, and a plurality of partial lacing elements. Each partial lacing element has a first end permanently attached to the at least one chord member and a second end. The second end of at least one of the plurality of partial lacing elements of the first section is connectable to a bracket attached to the second section to hold the sections in a nested fashion.

Abstract: A longitudinally divisible crane boom segment includes a plurality of sections that are easily transportable. The sections each include at least one chord member, and a plurality of partial lacing elements. Each partial lacing element has a first end permanently attached to the at least one chord member and a second end connectable to one or more corresponding ends of plurality of partial lacing elements attached to a chord member of another section. Preferably the partial lacing elements are connected by dovetail connectors.

Abstract: A system for aligning a crane upper works with a crane lower works for redecking the upper works with the lower works comprises at least one roller operatively connected to at least one of the upper works and the lower works, and at least one surface operatively connected to at least one of the upper works and the lower works. The at least one roller is engagable with the at least one surface such that the roller moves along the surface under the influence of gravity for aligning the upper works with the lower works. A method for aligning a crane upper works with a crane lower works for redecking the upper works with the lower works is also provided.

Abstract: A quick-connect system is disclosed for sectional boom members for cranes and the like. The sectional boom members comprise chords for carrying compressive loads, each chord terminating in an end configured to abut against an end of a chord of an adjacent sectional boom member. The quick-connect system comprises at least one easily alignable connector secured to the ends of at least one of the chords, the connector comprising a compressive load bearing surface intersected by the intersection of the vertical and horizontal neutral axes of the chord to which the connector is attached.