Investigations on the power losses and thermal effects in gear transmissions

Abstract

It is generally accepted that the total power loss in gears can be decomposed into contributions of friction between the teeth, lubrication (churning and/or jet lubrication that could induce gas—oil trapping in inter-tooth spaces), and gear windage effects. For low- to medium-speed transmissions, tooth friction is recognized as the main source of dissipation for gears and can significantly influence the temperature equilibrium of a gearbox. In this article, a model to predict power losses due to tooth friction combined with a thermal network to describe the temperature distribution in a geared transmission are presented. The numerical results compare favourably with experimental measurements from a gear test rig.