Abstract
A new test method for evaluating gear fatigue life of 4- stroke motorcycle engine oil is proposed. A newly developed rolling 4-ball type apparatus demonstrated good discrimination of anti-fatigue performance of known motorcycle engine oils with relatively shorter test duration, smaller sample size and reasonably good precision in comparison with the conventional fatigue tests available in the industry. The effects of operating parameters on test accuracy and repeatability have been studied. The parameters studied are oil temperature, contact pressure, speed and the test specimen batch.