Minimizing gear friction with water-containing gear fluids

Abstract

Lubricants have a large influence on gear friction and therefore on gearbox losses and heat balance. Synthetic oils can exhibit significantly lower gear friction than mineral oils. Recent basic research on water-containing gear fluids has demonstrated superlubricity in highly-loaded elastohydrodynamically lubricated (EHL) contacts. Following up these results, the potential of water-containing gear fluids to improve the efficiency and heat balance of gearboxes was investigated. Experimental results from an efficiency gear test rig demonstrate significant lower load-dependent gear losses compared to mineral and polyalphaolefine oils. The mean coefficient of friction for a wide range of operating conditions is clearly smaller than 0.01, which is referred to as superlubricity.