| 摘要 |
A standard model truck or trailer, having a rear load bearing axle with dual pneumatic tires mounted on wheels at both ends of the axle, is provided a further set of like rear wheels with dual pneumatic tires which are connected to the vehicle's main frame by depending carriers pivoted thereto. These rear wheels are rearwardly biased by a compression spring and may be selectively moved forwardly or rearwardly in an arc about their pivotable connection by a hydraulic piston and cylinder arrangement. An endless tread-type track is adapted to be mounted around the succeeding pairs of dual tires on either side. Each track has two or more parts dovetailed together at the ends, held by a spring steel rod inserted in openings therethrough, each opening being defined by a polygonal tube which receives the rod so it cannot rotate. The rod is held in the tube by a detent member. A broad slightly curved plate, rectangular in plan, pivoted from supports depending from the frame forward of at least the rearmost wheels, extends rearwardly centrally between the wheels to where a hydraulic cylinder and piston assembly connects it to the frame to lift the wheels simultaneously for installing the tracks. They are installed by decreasing the distance between the wheels through the hydraulic arrangement and, when in place, by releasing pressure in the connected hydraulic piston and cylinder assembly whereby the compression spring tensions the wheels against them.
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