PASSENGER VEHICLE TIRE INSPECTION EQUIPMENT DEVELOPMENT. VOLUME I: SUMMARY REPORT

Nondestructive tire testing techniques have been developed and the resultant technology enhancement has been incorporated into a prototype machine capable of performing on-vehicle tests of passenger vehicle tires with respect to three parameters: carcass integrity, inflation pressure, and tread depth. Carcass integrity determinations are made by exciting the tire with a random forcing function (bandwidth 100-400 Hz) and measuring the sidewall response as the tire rotates between displacement transducers. The random noise concept is shown to be superior to using a sinusoidal forcing function at a particular frequency. A temperature and pressure compensating inflation pressure control device has been developed. The device consists of an instrumented chuck and a control system capable of calculating the equivalent tire pressure at 72F, comparing it to a preset value, and adjusting the tire pressure as necessary to the set cold pressure point. A passover tread depth device has been produced. The device is basically a feeler gage, with 400 probes over a 10-inch distance which extend to engage the tire as it passes over the head plate. The travel of the probe results in a change in capacitance, and a processing circuit calculates a tread profile for each tire. These elements were incorporated into a prototype inspection machine intended for use in an automated vehicle inspection facility.