Abstract: A combination bulldozer and pipelayer includes a front mounted blade, or scoop, and a side mounted pipelayer attachment. When operated as a bulldozer, a pair of endless track roller frames are free to oscillate up and down about a horizontal axis passing through the bulldozer's main frame for improved traction and grading characteristics, reduced stress on the tractor structure, and a more comfortable ride for the operator. When operated in the pipelayer mode, the track roller frames are locked in fixed position to the vehicle's main frame to provide a stable platform for lifting and transporting a heavy load such as sections of pipe. The side mounted pipelayer attachment includes a folding boom which can be stowed in a retracted position or extended to the use position by the operator using only the boom and load controls.

Abstract: A combination bulldozer and pipelayer includes a front mounted blade, or scoop, and a side mounted pipelayer attachment. When operated as a bulldozer, a pair of endless track roller frames are free to oscillate up and down about a horizontal axis passing through the bulldozer's main frame for improved traction and grading characteristics, reduced stress on the tractor structure, and a more comfortable ride for the operator. When operated in the pipelayer mode, the track roller frames are locked in fixed position to the vehicle's main frame to provide a stable platform for lifting and transporting a heavy load such as sections of pipe. The side mounted pipelayer attachment includes a folding boom which can be stowed in a retracted position or extended to the use position by the operator using only the boom and load controls.

Abstract: A tractor having a pair of endless, segmented, high drive tracks includes a side boom and a side-mounted counterweight. Boom angle is controlled by a boom winch with a load winch provided for lifting a load. Both winches are hydraulically driven and provide positive drive in raising and lowering. A boom automatic stop arrangement detects full-up boom position and actuates a release valve for dumping hydraulic pressure and preventing further retraction of the boom. The counterweight is pivotally coupled to the tractor by means of a support frame which provides for outward and upward as well as downward and inward displacement of the counterweight over an arc-like path to compensate for boom inclination and the weight of a load.