Fundamental Research on the Gear Lubrication : 2nd Report, Lubrication Performance on Gear-Tooth Surface

Abstract

For the purpose of improving lubricating performance on the gear-tooth surface, the authors investigated the relationships of lubrication properties to the driving conditions and the lubricating methods with back-to-back type gear testing machine with which the frictional moment and the oil-film thickness between gear-teeth were measured. The lubricating characteristics have been classified by the values of the dimensionless parameter ηυ_r/P^^^-_n as follows : boundary lubrication ≤5×10^-6≤ semi-fluid lubrication ≤5×10^-4≤ fluid lubrication. Owing to the effects of the discontinuous contact, the dynamic load, the variation of frictional direction and the surface roughness on the gear-tooth surface, the frictional coefficient is larger and the oil-film thickness is smaller than those obtained respectively on the roller surface which was considered in the equivalent condition to the gear-tooth surface. The stirring resistance in the oil-bath lubrication is much influenced by the oil viscosity, the rotating speed, and the oil amount.