Friction Analysis of Oil Control Rings during Running-In

This SAE Technical Paper will give a summary of the detailed results of crank-angle-resolved friction measurements which were carried out in motored and pressureless operation on a floating liner single cylinder test engine with a displacement of 0.5 liters. Friction forces that occur during running-in are introduced and discussed with regard to mixed friction and hydrodynamic friction for different oil control rings. Three different ring pre-loads are examined using constant geometries. In a second test series, the outer contour and coating is varied while the pre-load stays constant.