The Manitowoc Company, Inc.

Percy R Helm

James G Morrow, Sr

David J Pech

Front and rear pairs of crawler assemblies are provided for supporting concentric ring segments disposed forwardly under the boom and rearwardly under the counterweight so the crane can travel under load and swing through at least a partial horizontal arc. One and preferably both crawler assemblies are selectively and reversely powered to facilitate forward and reverse as well as turning movement during travel under loaded and unloaded conditions. The inner ring segment is at least partially surrounded by a rotatable cage structure which provides a connection point for a frame element extending to the forwardly disposed crawler assembly to permit independent steering of the rear crawler assembly.

Steerable concentric ring segment supported lift crane

A lift crane having a separated transporter-supported front ring segment and a transporter-supported rear works including a counterweight. The front ring segment is connected by a frame element to the rear works and supports a carrier which pivotally mounts a forwardly-inclined boom and a rearwardly-inclined mast. Movement of the carrier across the front ring segment is permitted by two equal-length links pivotally connected to opposite sides of the carrier and the respective opposite sides of a horizontal bracket mounted on the frame element. The center of rotation of the carrier as it traverses the front ring segment is substantially coincident with the imaginary vertex of a truncated isosceles triangle formed by the carrier and lines running axially along the links. When the carrier is centered on the front ring segment, the center of rotation is also substantially coincident with a vertical axis running through the rearward-most point of the mast. Since the rearwardmost point of the mast is substantially coincident with the center of rotation, this point of the mast remains substantially stationary during the movement of the carrier across the front ring segment. A fixed length pendant connecting the rearwardmost point of the mast to the rear works also remains substantially stationary and in a vertical plane during the movement of the carrier across the ring segment, thus minimizing the amount of side loads and torsional forces induced in the mast due to such carrier movement.

Imaginary pivot lift crane

Front and rear pairs of crawler assemblies are provided for supporting separated ring segments disposed forwardly under the boom and rearwardly under the counterweight so the crane can travel under load and swing through at least a partial horizontal arc with separate pivots for the boom and counterweight. One and preferably both crawler assemblies are selectively and reversely powered to facilitate forward and reverse as well as turning movement during travel under loaded and unloaded conditions.

Separated ring segment dual pivot lift crane

Front and rear pairs of crawler assemblies are provided for supporting concentric ring segments disposed forwardly under the boom and rearwardly under the counterweight so the crane can travel under load and swing through at least a partial horizontal arc. One and preferably both crawler assemblies are selectively and reversely powered to facilitate forward and reverse as well as turning movement during travel under loaded and unloaded conditions.

Concentric ring segment supported lift crane

A mobile crane with rotating bed, mast, gantry and gantry backhitch is arranged for disassembly and ease of transport without unreeving the boom hoist rigging by collapsing the backhitch, folding the gantry back onto the backhitch, pinning together the backhitch, gantry and boom hoist assembly -- which includes the boom hoist drum and motor, and releasing the gantry, backhitch and boom hoist assembly from the rotating bed. A bracket is fixed to the gantry to provide an anchoring point for the equalizer assembly normally secured to the boom.

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Manitowoc, WI, United States of America

Percy R Helm