Abstract:A transient elastohydrodynamic lubrication (EHL) model of finite line contact was developed for helical gears with the unified Reynolds equation.This model was used to comprehensively show the transient effects and surface roughness on the lubricating performance.The results show that,the lubrication parameters of helical gear pair are changed dramatically during the single tooth meshing region due to the transient effect.The corresponding film thickness is lower as well as the friction coefficient is larger than that of other meshing region,and the mixed EHL may occur in this region.In the single tooth meshing region,the effective contact area of the transient state becomes smaller and the pressure peak is increased obviously.In the current case,the effect of surface roughness is insignificant for the full EHL state.Meanwhile,in the doublegearpair engaging area,the average film thickness with roughness is larger than that of the smooth solution,and the corresponding pressure and film thickness fluctuate around the smooth results.
