Elastohydrodynamic lubrication design of internal gear transmission

Based on elastic hydrodynamic lubrication (EHL or EHD) theory, an EHL model of the internal meshing between ring gear and planet gear in Planetary Gear Transmission was established. The EHL oil film thicknesses and those distributions for two operation cases on meshing line were calculated: one case with the sun gear as the driving gear and another case with the ring gear as the driving gear. The worse Lubrication occurred near the root of the tooth of the planetary gear in the second case that has the lower speed. Through the many comparing calculations the lubrication oil film thickness can be significantly increased by the raise of oil viscosity and gear pressure angle. The increase of oil film thickness can improve the lubrication of gears and prevent wearing and reduce the production cost of gears, which have great practical value.