Test method for determining the scuffing capacity of oils with reduced oil volume

Abstract

Previous studies by several researchers have shown that the aging of the transmission fluid in dual clutch transmissions has a major impact on the wear protection of the highly loaded tribological contacts. Depending on the transmission design, oil sump temperature, transmitted torque, rotational speed and oil volume, the scuffing ability decreases significantly. Since typically only limited quantities of oil from gearbox tests are available to evaluate oil condition with respect to wear protection properties, available analytical standards are currently limited to methods such as viscometry, TAN, elemental analysis, and IR. A test method is presented that can be used to determine the gear scuffing load capacity of transmission fluids with a reduced oil volume. For this purpose, a standard test rig is modified to reduce the test oil volume from 1.25 liters, as specified in the public standards, to 0.5 liters. The applicability of the reduced test oil volume is demonstrated and the remaining scuffing wear protection of several used oil samples from durability testing is presented. A comparison of the tribological results with the chemical oil analysis results shows the advantage of direct testing of the oil's service properties.