Research Note: Average Friction Coefficients in Gears

Abstract

Variation in sliding velocity—both in magnitude and direction—during a meshing cycle, the load distribution among the pairs of teeth, and the accuracy with which teeth are cut are some of the factors that make the mathematical analysis of friction in gear teeth extremely difficult. Of these, sliding velocity, which is responsible for the formation of an oil film between the teeth, plays an important role, and any attempt to determine the friction coefficients must take account of changes in sliding velocity. In this note an expression has been developed, considering the variation in sliding velocity, for power loss in terms of the coefficient of friction and gear parameters. The experimental results are compared with those obtained by other methods.