Investigation on Elliptical Contact Starvation for High Slide-to-Roll Ratio: Application to Gears

Abstract

Starvation can occur in lubricated systems due to a lack of lubricant. Though the starvation conditions of rolling element bearings are fairly well known, fewer studies are devoted to gears. In this study, experiments are conducted to analyze starvation for contact conditions similar to those of gears; that is, for high slide-to-roll ratio. A new oil-off test procedure on a twin-disc machine is proposed. The oil-off phase is analyzed through the friction coefficient and the bulk temperatures of discs. It is highlighted that low viscosities of residual oil located on the track have a positive effect on starved conditions. Otherwise, large ellipticities worsen starvation by reducing replenishment in the contact vicinity. Finally, a new inverse method is proposed to estimate the central oil film thickness during oil-off phases. The results obtained are consistent with existing models. This method proves to be suitable for severe starvation because it takes into account the lubrication regimes and the lubricant–material interactions.