Effects of operating conditions on the tribological behavior of a wet multi-disc clutch during the running-in process

The torque model of a wet multi-disc clutch is developed to study the effect of operating conditions on its tribological behavior during the running-in process, which is verified by SAE#2 full-scale tests. The surface roughness of friction components decreases with the removal of asperities peaks, which changes the contact torque rather than viscous torque. Thus, the friction torque and mean COF decrease rapidly in the initial 50 engagement cycles. Subsequently, the surface topography becomes stable progressively, and the friction behavior is mainly affected by operating conditions. The contact torque increases with applied pressure and oil temperature and decreases with rotational speed. Accordingly, the applied pressure has the largest effect on surface roughness, followed by rotational speed and oil temperature.