Influence of Surface Roughness on the Tribological Behavior of Gear Oils in Steel–Steel Contacts: Part II—Mixed Friction Properties

Abstract

Hypoid gears are known to be commonly used in rear-wheel-drive automobiles and they typically operate under high sliding and high contact pressure conditions. Providing efficient lubrication and necessary surface finish to such gear contacts is important in order to achieve a significant gain in energy and torque efficiencies. This requires knowledge of the behavior of gear oils under different operating conditions, especially their abilities to work under high contact pressure and sliding conditions. In light of this and in view of optimizing friction in transmission systems, this article explores the influence of surface roughness on friction in a mixed lubrication regime. In addition to friction–speed measurements and Stribeck curves described in a companion article (Vengudusamy, et al. (1)), this article explores the friction response of tribofilm-generated surfaces with base oil and highlights the significance of such experiments.

KEY WORDS:

• Gear Oils
• Surface Roughness
• Mixed Friction
• SRV

ACKNOWLEDGEMENTS

The authors are thankful to Michael Schweitzer for conducting SRV experiments and Philipp Eidenberger and Fjorda Xhiku of AC2T research GmbH, Austria, for carrying out the surface roughness measurements.