Patent GB-556603-A (GB)
Title: Improvements in or relating to apparatus for aligning parts of a vehicle such as a wheel
IPC: G01B11/275
Filed: 1941-08-08
Abstract: 556,603. Gauging alignment; optical apparatus. STEVENS, A. H. (Thompson Products Inc.). Aug. 8, 1941, No. 10125. [Class 106 (ii)] [Also in Group XX] Apparatus for ascertaining the relative adjustment of parts of a vehicle such as a wheel, includes a light projector for attachment to the wheel and to project a beam of light in a predetermined direction, and a graduated surface arranged in the path of said beam in a predetermined position relatively to the body of the vehicle so that the point of incidence of the beam indicate the relative adjustment. To check the alignment of vehicle wheels, front side and rear charts 1, 2, 3 are arranged as shown. Projectors 4 are detachably held on the parts to be adjusted, for instance, the front wheel 5 of a car 6. The graduations on the chart 1 are grouped for various readings to be taken by the shifting of the projectors 4 with the turning of the front wheels 5. Vertical graduations are measured from a norm line A, above and below which and about the vertical " O " line the graduations are symmetrically spaced. The vertical lines of the middle group B denote the inner limits of the steering angle of each front wheel. The horizontal lines of this group are used for reading the lowest points of the fall of the wheel caused by the king pin slant. The markings C are placed to be aligned with the straight forward position of the front wheels 5. The vertical lines of these are marked 2-8 corresponding to the 22 inch - 28 inch width of track of usual cars. The projectors 4 throw a well-defined mark such as a cross-hair mark 8. When the beams 9, 10 coincide with the vertical lines of markings C, the charts are centered with respect to the vehicle. The angle made by the vertical line of the crosshair with the vertical lines of C indicate the camber of the wheels. The marks C<SP>1</SP> of the rear chart agree with the marks C, thus the difference between forward and rear readings gives the degree of "toe-in". The marks @ indicate 20 degrees to 25 degrees of turn. The horizontal lines above the norm A in this group co-operate, with the mark 8 to measure the maximum rise of the front wheel 5 at or near the outer extreme steering angle caused by the king- pin slant. The slant at the inner angle is checked on. the middle group B. The side lines E serve to check caster adjustment, the projection 11 being on the norm A when the wheels are straight. The relative alignment of front and rear wheels may also be determined by a set of projectors 4 on the rear wheels directly forward to the chart 1. The rear chart may be secured also at the rear as at 3<SP>1</SP>. This chart may be automatically centered by a calliper arm arrangement on the chart board adapted to engage inner wheel surfaces. Projector.-Each comprises a tube 18, Figs. 7 and 8, with aligned light-directing unit 19 and magnetic clamping means 20. When used as wheels the clamping means 20 align the projectors 4 so that the units 19 overlie a diameter of the wheel. The tube 18, open at the ends, has snaced from and within it a tube 21, a corrugated tube 22 being placed between to act as a heat dissinator. The tube 21 is fitted with a socket 25 for an electric lamp 24 below which is a cooling fan 26. Short tubes 27 are placed at right angles to the tube 18 and have adjustable tubes 29 each containing spaced lenses between which are arranged the cross-hairs the vertical member of the cross-hairs being parallel to the axis of tube 18. Holes through tubes 18, 21, 22 align with the tubes 27 to permit passage of the beam and the tube 18 has a series of holes 23 for cooling purposes.