Temperature Distribution and Thermal Degradation of the Lubricant in EHL Line Contact Conjunctions

Temperatures of the lubricant in the inlet zone, the central contact zone, and the outlet zone of EHL line contact conjunctions were simultaneously calculated for a complete range of sliding conditions by using the new thermal circular non-Newtonian EHL model. The complete range of sliding conditions includes pure rolling, normal sliding, simple sliding, and opposite sliding. The result reveals the strong effect of sliding condition on the magnitude and distribution of the lubricant temperature. It also shows the diffusion time effect on the lubricant temperature, which builds up near the slower moving solid surface in the inlet zone. The effect of viscous normal stress on the temperature distribution was also investigated. Results indicate that the effect is not significant except for applications at very high entraining velocities. In addition, thermal degradation of the lubricant was studied. Results show that it may become a problem for applications at high speeds and high sliding conditions.