Gear tooth sliding friction appreciably increases the magnitude of tooth root bending stresses in both the driving and driven gears. Compared to situations devoid of friction, these stresses are decreased in the approach portion of the mesh but are increased in the recess portion. Even coefficients of friction as low as 0.06 can change the point of tooth-load application for maximum bending stress in the driven pear from the hiehest-point-of-sinple-tooth-contact to the && p& at the beginning of recess action.

An analytical approach is described in the case where the driven load is constant and the coefficient of sliding friction remains unchanged throughout the mesh's entire contact zone. Equations are derived and effects demonstrated.