Lubricant Additive Effects Upon Bearing Metal Fatigue. I. Rolling Contact Adaptation for Four Ball EP Tester

摘要

A rolling contact adaptation of the Four Ball Extreme Pressure Tester was devised and evaluated for its utility in determining the effects of additives in oils on the fatigue life of 52100 steel balls. Six compounds, similar in molecular size to common additives but selected for different configurations and functional groups, were combined with low viscosity (80 SUS at 100F.) paraffinic and naphthenic oils in five percent concentrations. Their effects upon fatigue, compared with that of the oils alone, were determined. Molybdenum disulfide was also evaluated in the same manner. Based on fewer tests than statistically desirable, the '10% life' taken from Weibull distribution plots of the results indicate that different additives and lubricant bases have varying effects upon the fatigue life of bearings. It appears that reasonably fast, economical and reliable ball bearing fatigue life results can be expected with this relatively inexpensive rolling contact adaptation of the widely used Four Ball EP Tester. (Author)