GB1500983A - Vehicle track and camber angle measuring apparatus - Google Patents

Abstract

1500983 Measuring wheel alignment electrically MATRA-WERKE GmbH 23 Jan 1975 [26 Jan 1974] 2903/75 Heading G1N(A) Apparatus for measuring the track and/or camber angle of wheels on a vehicle axle comprises a measuring device for each wheel which is arranged to measure the distance of a given part of the wheel from a datum plane when the part is in each of two specific diametrically opposed positions, means for determining the difference between the two measurements and means for comparing the said difference with that obtained for the other wheel on the axle to produce an output representing track and/or camber angle. The measuring device may comprise a telescopic arm 4, 59 which is rotated synchronously with the wheel either by a probe element 8 engaging the wheel, Fig. 9, or by a motor 79 under control of speed sensor 85, Fig. 10 the said distance measurement represented by a 1 , a 2 being stored when the arm is in a horizontal position for track angle determination and is in a vertical position for camber angle determination. Alternatively the rotating arm may be replaced by fixed vertical and horizontal arms each with a contractless measuring device 84, Fig. 13, at each end and only the extreme value, e.g. the minimum of a 1 and a 2 , measured by each device stored. In a further modification Fig. 14, (not shown) the two orthogonal arms are mounted on a universal joint and the plane of the arms is varied by a control circuit and indexing motor (110) until the output signals of devices 84 are equal. The disposition of the arms then representing the track and camber angles. The contactless measuring device may comprise oscillatory circuits the frequency of which is influenced capacitively or inductively. Preferably a coil is supplied with oscillatory pulses the damping of which is dependent on the said distance and the number of pulses whose amplitude exceeds a predetermined level are counted digitally to provide a measure of the distance. Alternatively the probe 8, Fig. 9, may be replaced by a roller displacing a potentiometer or armature of a coil.