661,795. Gauging alignment of vehicle wheels. FORD MOTOR CO., Ltd. May 6, 1949 [May 7, 1948], No. 12171/49. Class 106 (ii). A gauge for checking wheel alignment comprising a rotatable member for frictional engagement with the periphery of the wheel, and means for measuring the transverse thrust of the wheel upon the rotatable member when the wheel is rotating is characterized in that the rotatable member is a drum having a spherical peripheral surface supported for movement in a direction transversely of the plane of rotation of the wheel and arranged for oscillating movement about a longitudinal axis located substantially in the plane of rotation of the wheel. Testing alignment. To test the alignment of the front wheels of a car, they are run over a pit 13, Fig. 1, covered by side-plates 17 with openings 18 covered by slidable plates 24 pneumatically opened to allow the front wheels to sink down on to gauges 11, 12 mounted below on slabs 36, the front wheels running outside guide rails 27, the back wheels inside guide-rails 29 and down ramps into depressions to maintain the car horizontal while under test. When run off after test the cover-plates 24 are closed to prevent the back wheels passing over the gauges. The guide-rails may be transversely adjustable for different cars. Gauges. Each gauge comprises a housing made up of sections, ribbed and braced for strength, with an opening in the top section to admit a vehicle wheel and roller bearings 58, 59, Figs. 2, 3, in the end sections to support trunnions 56, 57 extending from the ends of a yoke 51. A counterweight comprising discs 63, adjustable in number and position on a depending arm, is carried by an extension of the rear trunnion and tends to keep the yoke in a horizontal position. A drum 67 with exterior surface 73 formed in the shape of a sphere is mounted in roller bearings 74, 76 carried by the yoke 51 and one end of its shaft 72 extends outwardly to carry a multiple groove pulley 81 connected by a multiple V-belt 84 to a pulley 83 driven by an electric motor 82 carried on a pivoted plate 86 whose position is adjustable to tighten the belt 84. When the gauges 11, 12 are installed in the pit, they are placed at the same level, the drum axes 72 are aligned, the axes of rotation of the two yokes are arranged parallel to one another and, to balance the drums 67, an arm 169 is attached to one yoke 51 and a weight 171 is adjusted thereon to give a certain displacement, the arm 169 is then transferred to the other yoke and its counterweight is adjusted to give the same displacement. Operation. In operation the drums 67 are constantly driven by the motors 82 at a represensative speed, one or two mechanics are stationed in the pit to adjust the tie-rods of the steering mechanism, the car is run into position, the driver holds the steering-wheel in its central position and additional weight may be added. The front wheels are vertically aligned with the centre planes of the drums and longitudinal axes of the yokes by rollers 93, 94 and 97 mounted in the housing and are frictionally driven by the rotating drums. If a wheel toes in or out a sideways thrust will be imparted to the appropriate drum or if there is inherent wheel wobble or shimmy the yoke will oscillate about its axis, the displacement or the amplitude of oscillation depending on the amount of toe-in or toe-out or of wobble or shimmy. Indicating. Movement is transmitted from the yoke 51 through the front trunnion 56, Fig. 4, and gear-wheels 107, 108 to an arm 113 formed with a cam face 114 of extent sufficient to cover four contacts 123 of four switches 122 on each of two switch-plates 116 in arcuate guideways 119, 120 so that one, two, three or four switches on either plate 116 will be operated depending on the degree of mis-alignment of the wheel. The angular movement of the yoke before the first switch is actuated may be adjusted by moving the plates 116 by screw means 127, a pointer 129 being provided for centering the arm 113 between the plates 116. Two panels 156, Fig. 8, each comprising four pairs of yellow lights 157 and four pairs of green lights 159 are provided, each being in a parallel circuit including a switch 122 supplied from the secondary of a transformer 168 whose primary and the electric motors 82 are fed from a power supply 162. The lights are provided in pairs to avoid errors due to the failure of a bulb, a light 166 is provided to indicate a circuit failure and a manually operated switch 169 for a horn 167 is provided for the mechanic to signal to the driver upon completion of a test. The degree and sense of toe-in or toe-out are indicated by the number and colour of the lights that are lighted, the mechanic in the pit then makes appropriate adjustments to the tie-rods until all lights are extinguished for both wheels. Wheel wobble or shimmy will cause the colours to alternate and the number will again indicate degree of mis-alignment. Cover-plate control. The sliding plates 24 for protecting the gauges from the rear wheels are actuated by two air cylinders 26 controlled by piston-type air valves 133, Fig. 6, actuated by opening solenoids 137 and closing solenoids 138 in parallel circuits including switches 141, 142 and 143, respectively, Figs. 7, 2, switches 141, 143 being normally open and switch 142 normally closed. As the left front wheel approaches its gauging position it closes contact 141 and the plates slide outwards to allow the front wheels to sink on to the drums 67; as the left front wheel leaves this position it closes switch 143 and the plates slide inwards to cover the gauges and before the rear left wheel reaches the switch 141 the front left wheel opens switch 143 to open the circuit of the opening solenoids until the rear wheel is clear of the switch 141.