Friction Between High Speed Gear Coupling Teeth

Under misalignment, the teeth of a coupling hub and sleeve slide over each other axially. This motion and the torque transmission generate friction forces. Although laboratory measurements indicated that the friction coefficients are very low, many a thrust bearing failure was blamed on coupling “lock-up”. This paper discusses the results obtained from an exhaustive test program in which the friction forces were measured as a function of many variables, including torque, axial velocity, misalignment and lubrication. Friction coefficients as large as .16 were computed when the coupling operated under adverse conditions. Lubrication proved to have the largest influence on the magnitude of the friction coefficients.