Influence of Lubricant Breakdown on Frictional Performance

The influence of lubricant breakdown and additives on the frictional performance of wet automatic transmission clutch linings was studied with a low velocity friction apparatus. Base oil degradation products were shown to reduce static friction. Type A fluids were degraded in the friction machine to evaluate initial effects and in a bench oxidizing apparatus to evaluate extensive degradation effects. These methods rated the fluids in the same order and showed they varied widely in sludge formation, frictional and chemical stability. On frictional degradation, the friction level of two fluids increased with paper-based linings and decreased with sintered copper powder linings. The copper linings accelerated lubricant degradation and caused a different type of degradation.