PROJECTOR EXCURSION COMPENSATION IN WHEEL ALIGNMENT SYSTEMS

摘要

Abstract of the DisclosureAn improved method and apparatus for aligningthe front wheels of a motor vehicle utilizing a beam pro-jector and detector assembly on each wheel and anelectronic computing means for determining the toe anglesof the wheels in response to measured toe signals gener-ated by the detectors. The computing means first sub-tracts one of the toe signals from the other, multipliesthe difference by a selected correction factor to producea correction signal, and then adds the correction signalto the larger of the measured toe signals and subtractsthe correction signal from the smaller one to providethe true individual toe angles of the wheels. Thesignal, derived by the computing means are applied todisplay devices which read out the correct values of theright and left toe angles. Although the correction factoris dependent on the dimensions of the frame of thevehicle, the steering suspension, and the mounting of theprojector and detector assembly, it has been found thata correction factor of approximately 0.28 is indicatedfor a great portion of the United States automobile andsmall truck population, whereby a single alignment systemincorporating the improvement herein disclosed may beused to provide accurate front-end alignment with onlyone adjustment of each wheel. The improved system isparticularly useful when aligning vehicles having grossmalalignment. Also, since the system utilizes noreference to the rear wheels of the vehicle, it providesexpeditious alignment of vehicles having rear wheelswhich are not aligned with the front wheels, e.g., as inthe case of a truck tractor or motor home with dualwheels on the rear axle.-1a-