Influence of temperature on the friction performance of gear oils in rolling-sliding and pure sliding contacts

The friction behaviour of five different gear oils in rolling-sliding and pure sliding contacts and how temperature influences their friction properties were investigated. It is found that increasing temperature decreases boundary friction with gear oils that contain friction modifiers while not for other gear oils, at all contact pressures investigated. In mixed lubrication region, temperature decreases friction at low contact pressures while increases friction at high contact pressures. The effect of slide-roll ratio on friction is significant in boundary lubrication region especially at higher temperature while less significant in mixed lubrication region at both low and high temperatures. The ranking of gear oils for friction in boundary and mixed lubrication regimes is similar both in rolling-sliding and pure sliding contacts, regardless of temperature. Copyright (c) 2013 John Wiley & Sons, Ltd.