Abstract: Lubricants working under heavy load are usually subjected to high contact pressure which may change the feature of lubricants in some way. As a result, the friction pair may fail which sometimes leads to even more serious situation like the collapse of the whole system. However, lacking necessary equipment, researchers perform experiments under the condition that the contact pressure is less than 2 GPa. New equipment is devised and manufactured to obtain interferometer image of lubricants at high contact pressure. The film thickness of GL-5 gear oil is tested with the new machine and its lubrication characteristic is analyzed. The results show that GL-5 gear oil can form thick lubrication film at high contact pressure but low rolling speed; flat and smooth lubrication film is formed at high pressure which makes contribution to reducing peak value of stress in contact area; with the increase of contact pressure measured film thickness gradually deviates from the theoretical value and adjustment is needed to the coefficients of rolling speed and load in Hamrock-Dowson formula.

Key words: Gear oil, Heavy load, High contact pressure, Lubrication characteristic