GB1214535A - Apparatus for checking wheel alignment - Google Patents

Abstract

1,214,535. Measuring vehicle wheel alignment electrically. J. C. FROST. April 1, 1969 [April 3, 1968], No. 16000/68. Heading G1N. Apparatus for measuring various angles representative of the alignment of the steerable wheels of a vehicle comprises on each wheel 12, Figs. 1, 2, a level sensing head 13 including clinometers 25, 26, 27, Figs. 3, 4, of which the resistances vary as the tilt angles, each of which is connected in a bridge circuit Figs.8, 9, 10 (not shown). Each wheel is supported on a turnable, 10, on a box, 36, which box includes a potentiometer (41), Figs. 5, 6 (not shown), the setting of which is controlled by movement of a radius arm 33 which in use, is engaged with an arm 28 pivoted on a pin 29 to the head 13 so that movement of the wheels by a steering wheel produces an indication of the angle of the wheel with respect to a straight ahead position i.e. toe-in, or the difference between the angular positions of two wheels may be taken to give the toe-out on turns. Each head is mounted on clamps 11 and may be adjusted so that the spindle 21 is coaxial with the wheel by means of a slide 19 and fitting 20. The clinometer 25 is mounted with its axis perpendicular to that of the vehicle and measures camber, that 27 is similarly disposed and measures caster, while that 26 is disposed parallel of the vehicle axis and is used to measure king-pin inclination. The arm 28 may be moved from an inoperative position shown dotted in Fig. 4 to its vertically downwardly extended position where it also makes a switch (32) to supply power to the bridge circuits and light an indicator lamp. The clinometers each contain a pool of mercury in a curved glass tube and may have two or three electrodes. It is stated that measurements of camber and caster may be effected using a single clinometer.