Auxiliary traction system

Claim 1

In combination with a vehicle having a chassis and one drive wheel mounted each side of said chassis on a transverse axis, an endless track unit comprising: a frame formed by substantially continuous upper and lower plates interconnected by web plates, and having telescoping sections biased to increased overall length of said frame to maintain tension on said tracks, and means normally securing said frame to said chassis; a pair of laterally spaced endless tracks each forming a loop surrounding said frame; track-locating means establishing turns in each said loop on horizontally spaced axes parallel to said drive wheel axis, said track-locating means including a pair of rollers rotatably mounted on said frame; a pair of first sprocket, said first sprockets being each normally secured to said drive wheel; a second sprocket, said second sprocket being secured to a respective roller, each of said first and second sprockets having pitch diameters proportioned to induce a track velocity corresponding to the peripheral velocity of said drive wheel; and drive chain means engaging said first and second sprockets.