Importance

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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. The bulldozer's hydraulic system is connected in series to the pipelayer's hydraulic system to permit operation of the pipelayer boom and load winches at the same speed for improved load control without stalling the heavier loaded winch drum. Also provided is a quick load release arrangement for allowing a load to free-fall to the ground in the event of an unstable condition in lifting the load.

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First Claim