Citation

Bergman W. Transp. Res. Rec. 1977; 621: 8-18.

Copyright

(Copyright © 1977, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

This paper provides an analysis of skid resistance of tires and vehicles in several operating modes - braking, acceleration, cornering and their combination. It shows the limitations of skid number as a criterion of skid resistance. It describes the tire skid resistance characteristics as a relationship between the braking (driving, cornering) coefficient and wheel slip of slip angle, within the range of coefficient between its peak and slide values. It introduces the concept of peak and slide traction envelopes as boundaries of tire skid resistance characteristics and applies it for analysis of skid resistance characteristics of a tire in cornering with braking or driving torque application. It analyzes tire characteristics in braking-in-a-turn in a complete skid at slip angles up to 90 degrees. It shows that, within a slip angle range between 20 and 90 degrees, the lateral force measured on a free rolling tire decreases with an increase of slip angle; however the force measured on a locked wheel increases. At a 90 degree slip angle, the lateral force measured on a locked wheel reaches the value at the force on the free rolling wheel. It shows effects of proportioning valves and different types of anti-skid systems on braking performance in straight line driving and cornering. Relationships between understeer/oversteer and vehicle skid resistance are shown. Effects of power-to-weight ratio and fore and aft roll stiffness distribution on vehcile skid resistance in cornering with full throttle acceleration are shown.