Traction device for motor vehicle

Claim 1

An anti-skid mechanism for a motor vehicle having a sprung frame, rear drive wheels mounted on unsprung rear axles, and a housing for said rear axles, said anti-skid mechanism comprising: a. a pair of auxiliary wheels equipped with anti-skid tire means; b. support means for said auxiliary wheels connected to the frame of said vehicle; c. said support means including elevator means connected to said auxiliary wheels for lowering said auxiliary wheel-tires into contact with the surface of the ground behind the rear drive wheels and for raising said auxiliary wheels into storage position; d. said elevator means including a pair of vertical screw stems, one on each side of said vehicle, an elevator bar driven by each screw stem, an elevator carriage supported from each screw-driven elevator bar, an auxiliary axle carried by each elevator carriage on which said auxiliary wheel is freely rotatable, and a plurality of vertical spring-loaded rods extending between said elevator bar and said elevator carriage for supporting said elevator carriage from said screw-driven elevator bar; e. means coupled between said elevator means and said rear-axle housing for applying an upward jacking force to the rear-axle housing when said auxiliary wheel tires are lowered into ground-contact position; f. said means coupled between said elevator means and said rearaxle housing including a lever bar on each side of said vehicle, means connecting the rearward end of the lever bar to the screw-driven elevator bar, flexible link means connecting an intermediate point on said lever bar to a fixed point on said frame, and means on the rear-axle housing adapted to be engaged by the rising forward end of the lever bar as the rearward end is lowered by the elevator bar; g. means coupled between the tires of said rear drive wheels and said auxiliary wheels when in lowered position for driving and braking said auxiliary wheels; h. said means coupled between the tires of the rear-drive wheels and auxiliary wheels including: h-1. an idler wheel freely rotatable above and between said rear drive wheel and said auxiliary wheel; h-2. a spring-loaded piston and cylinder assembly; h-3. means connecting one end of the piston and cylinder assembly to the idler wheel; and h-4. means connecting the other end of the piston and cylinder assembly to the elevator carriage for pulling down said idler wheels when said carriage is lowered.