Roller sliding in engine valve train: Effect of oil film thickness considering lubricant composition

Abstract In roller follower valve train, proper rolling of roller reduces the chances of fatigue failure and power losses. During engine operation, the roller does slip on the camshaft surface. The oil film thickness plays an important role on the roller sliding which necessitates experimental investigations. A modern gasoline engine valve train has been instrumented using advanced sensors for real time measurement of oil film thickness and roller slip, simultaneously. Rise in oil film thickness at cam/roller interface increased the tendency of roller slip. Drag due to shear of lubricant and rise in contact loading at very high camshaft speeds resulted in reduction of roller sliding. Presence of anti-wear agents and friction modifiers increased the tendency of roller sliding.