A Vehicle Test Procedure for Determining Adhesion Utilization Properties

A vehicle test procedure for determining the adhesion utilization properties of braking systems has been developed. The procedure requires minima instrumentation and equipment. It was applied to 19 passenger cars over a range of conditions and the effects of factors such as load, center of gravity height, speed, parasitic drag, engine braking, drive configuration (front or rear), brake conditioning, and tire properties on adhesion utilization were determined. The vehicles were also subjected to a series of stopping tests on six different surfaces to evaluate the degree of correlation between predictions from the adhesion utilization curves and actual performance. Frictional properties of the tires from 11 of the vehicles were measured on the surfaces to aid in this correlation study.