Vehicle wheel aligner for measuring front wheel toe with respect to the rear wheel axis of rotation

Claim 1

Apparatus for measuring the front wheel toe angles of a motor vehicle having pairs of front and rear wheels, said apparatus comprising alignment means adapted to be mounted upon one of said front wheels of the vehicle in a predetermined position with respect to the axis of rotation of said one front wheel, a mirror adapted to be mounted upon the rear wheel of said vehicle on the same side of the vehicle as said one front wheel, said mirror being mounted in a predetermined position with respect to the axis of rotation of said rear wheel, said alignment means including means for projecting a beam of light to said mirror, said alignment means further including means for receiving the reflected beam of light from said mirror and for calculating the toe angle of said one front wheel relative to said axis of rotation of said rear wheel in accordance with the position of the received light beam, means mounted upon one of the front wheels of the vehicle for projecting a beam across the front of the vehicle toward the other front wheel of said vehicle, means mounted upon said other front wheel of said vehicle for projecting a beam across the vehicle toward said one front wheel, means responsive to the positions of said projected beams for providing a signal proportional to the total toe angle between said two front wheels of the vehicle, means connected to said last named means for calculating the total toe angle between said two front wheels of the vehicle, and logic means connected to both of said calculating means for subtracting the toe angle of said one front wheel from the total toe angle and for providing an output reading of the toe angle of the other of said front wheels with respect to said axis of rotation of said rear wheel.