Citation

Kullberg G. Highw. Res. Board bull. 1962; 348: 18-35.

Copyright

(Copyright © 1962, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

The coefficients of friction were experimentally determined for rubber tires on road surfaces in relation to slip when a wheel is braked. The method and equipment are described. The slip can be varied from 0 to 50 percent. When measuring with this method, no brake is used. The test wheel is connected to the driving wheels of a truck by means of transmission units. A variable transmission makes it possible to change continuously the gear ratio between the test wheel and the driving wheels. Thus it is possible to measure the coefficient of friction continuously on longer distances along the road. The differences between the coefficient of friction at incipient skid and at locked wheel is discussed. Experimental results are presented. This method is also used to measure the behavior of winter tires.