Mixed-elastohydrodynamic analysis of helical gears using load-sharing concept

Abstract

Helical gears are widely used in power transmission systems, and hence any improvement in their design and also the ability to predict their performance is of great importance. The key issues related to gears are their film thickness, which represents the lubricant ability to protect the surfaces from wear, and friction coefficient, which reflects the power loss. Since the pinion and gear mesh is usually under mixed-elastohydrodynamic lubrication, the effect of asperities should also be considered. The goal of this research is to present a model for predicting the performance of helical gears with consideration of surface roughness. Initially, the pinion and gear engagement analysis is performed considering non-uniform load distribution on gear’s tooth. In this model, each of the contact points on the gear flank is replaced with two cylinders, and lubrication analysis will be executed on these cylinders. The load-sharing concept has been employed to account for lubricant and surface roughness contribution in carrying the applied load. The predicted results are compared to other published data, and an acceptable agreement is seen. Acceptable accuracy, short execution time, and consideration of surface roughness are among the features of this model. It is shown that increasing the applied load results in an increase in the portion of the load that is carried by asperities as well as the friction coefficient.