Samenvatting
The adaptation of the Penn State Road Friction Tester which was originally designed for measuring skid resistance with a full-scale tire, to the measurements of tire-pavement friction under slip is described. The method employed consist in gradually retarding the test wheel by an adjustable brake actuating system and measuring the forces in both horizontal arms of the test wheel parallelogram suspension. By electric addition of these forces and measuring vehicle speed and test wheel velocity the complete friction vs. slip relationship of an individual test cycle is obtained. Typical results are presented.