GB1156325A - Improvements in or relating to the Measurement of Alignment Angles of the Wheels of a Road Vehicle - Google Patents

Abstract

1,156,325. Gauges for vehicle wheels. SPERRY RAND Ltd., Nov. 23, 1966 [Sept. 3, 1965], No. 37644/ 65. Heading G1X. Apparatus for measuring the alignment angles of a steerable vehicle wheel e.g. castor angle, comprises rollers 12 to support a vehicle wheel on the vehicle, a roller 30 contacting a point on the vertical diameter of the wheel to sense lateral displacement of the wheel when steered through an angle to one side of the straight ahead position; the roller 30 being mounted on an arm 31 for pivotal movement about a horizontal axis intersecting the lowermost point of the wheel so that it can be pivoted to contact another point of the wheel where the lateral displacement is the same as that previously noted when the wheel is steered through the same angle to the other side of the straight-ahead position, and means for measuring the angle through which the arm 31 pivots this being approximately twice the castor angle. The Figure shows apparatus for use with one of the front wheels of a vehicle. Similar apparatus is provided for use with the other wheel. The apparatus is mounted on a base 14 for movement by means of a handle 15 to bring a roller 17 into engagement with the inside of the wheel to locate the apparatus with respect to the vehicle. The support rollers 12 are carried by a cradle 13 mounted on a vertical shaft having a disc 18 with three V-notches in its edge engageable by a hydraulically actuated wedge 20. The rollers can thus move the wheel to define a "straight-ahead" position and two positions equiangularly displaced on either side thereof say by 5‹. The roller 30 is carried by a head 24 which is urged by a spring 25 towards the wheel. The head 24 can be retracted by a hydraulic cylinder 26. The arm 31 is pivoted at 32 and its movements are fed to an electrical measuring device. In use the roller 30 is set against the wheel 11, which is continuously rotated, in the "straight-ahead" position. The wheel is steered to one side and locked in position by the wedge 20, and the displacement of the roller 30 measured by the electrical device being stored in a memory device. The wheel is steered through the same angle to the other side of the straight-ahead position and the arm 31 is rotated about a shaft 39 by a motor 41 until the displacement of the roller 30 is the same as that stored in the memory device. The angle of rotation of the arm 31 is measured and halved to give the castor angle. The camber angle of the wheel 11 can also be measured using the roller 30 which is first set in a true vertical position and its displacement measured when contacting the wheel. The movement of the arm 31 about the pivot 32 gives the camber angle direct. Two rollers 22 (one shown) mounted on an arm 27 pivoted at 28 are also provided to measure toe-in. The rollers 22 contact the horizontal diameter of the wheel 11 when set in the straight-ahead position, and the angular position of the arm 27 with respect to its support is noted to give the toe-in angle.