A Brief Examination of Factors Affecting Tractive Friction Coefficients of Spheres Rolling on Flat Plates

The use of steel ball-bearing balls in a new variable speed friction drive has given impetus to the study of factors governing their tractive capacity. The coefficient of tractive friction, defined as the ratio of tractive force to normal force at a specified slip rate, was observed to depend on lubricant properties and ball diameter, but to be relatively independent of normal load and rolling velocity. Coefficients of 0.08 were found to be attainable using conventional lubricants. Contributed by the ASLE Technical Committee on Bearings and Bearing Lubrication Contact and presented at the Annual Meeting of the American Society of Lubrication Engineers held in Buffalo, New York, April 1959.