Effect of ATF temperature on the friction-wear characteristic of a wet multi-disc clutch during the running-in process

Purpose: This paper aims to explore the effect of automatic transmission fluid (ATF) temperature on the dynamic friction-wear properties of the friction component in a wet multi-disc clutch during the running-in process. Design/methodology/approach: The running-in evolution was explored in terms of global friction performance and instantaneous friction characteristics. The variation of friction torque of the initial 300 engagement cycles was obtained by wet-clutch tests. Finally, an optical microscope was used to detect the wear mechanism of friction surfaces. Findings: The ATF temperature showed a significant effect on the friction-wear performance in the clutch running-in process. The mean coefficient of friction decreased with the increase of the ATF temperature and decreased rapidly in the approximately initial 60 clutch engagements. The higher the ATF temperature was, the thinner the ATF film was, and more asperity summits were cut, thus leading to a smoother surface. Considering the slightly instantaneous friction fluctuation and the wear performance, a proper ATF temperature is necessary. Originality/value: The results provide theoretical guidance for selecting the optimal ATF temperature during the running-in process.