Abstract: An automatic wheel alignment system for aligning the wheels of an automotive vehicle includes head units adapted for coupling to the wheels of the automotive vehicle and a hand held module. The wheel units provide angle information related to the alignment of the wheels of the automotive vehicle. The hand held module is coupled to the wheel alignment units and provides information to an operator through a liquid crystal display. The hand held module includes a controller and memory means. A keypad input is provided for receiving an input from the operator. The liquid crystal display includes an liquid crystal display matrix for forming an image. A contrast control means is coupled to the liquid crystal display and provides a contrast signal to the liquid crystal display.

Abstract: An automatic wheel alignment system for aligning the wheels of an automotive vehicle includes head units adapted for coupling to the wheels of the automotive vehicle and a hand held module. The wheel units provide angle information related to the alignment of the wheels of the automotive vehicle. The hand held module is coupled to the wheel alignment units and provides information to an operator through a liquid crystal display. The hand held module includes a controller and memory means. A keypad input is provided for receiving an input from the operator. The liquid crystal display includes an liquid crystal display matrix for forming an image. A contrast control means is coupled to the liquid crystal display and provides a contrast signal to the liquid crystal display.

Abstract: In an automotive vehicle wheel alignment system, a rim clamp is attached onto the rim of a wheel and a head unit is connected to the rim clamp. The rim clamp includes a spindle having circumferential grooves. The head unit includes a spindle-receiving sleeve with a spring loaded plunger and a set screw adapted for being received by the grooves in the spindle. The set screw tightens the head unit on the spindle of the rim clamp. The spring loaded plunger and groove allow the head unit to rotate with respect to the wheel without loss of registration in the axial direction between the head unit and the wheel.

Abstract: A cross toe zero calibration system for use in an automotive vehicle wheel alignment system uses a calibration bar for receiving cross toe measuring head units. A first set of cross toe measurements are taken with the bar in a first position and a second set of cross toe measurements are taken with the bar in a second position. In the second position, the bar is rotated 180.degree. from the first position. The two sets of measurements are averaged to yield zone cross toe angle calibration factors. The combination of rotating the bar and averaging the two sets of measurements nulls out errors introduced into the calibration measurements due to deformities in the bar. The calibration bar is mounted on the main console of an automotive vehicle wheel alignment system. Switches are included which indicate the position of the bar.