In a previous study, we analyzed the mechanical loss factors of a small-sized geared motor comprising an induction motor and a parallel gear reducer. The load dependent loss is mainly caused by gear mesh friction, which is related to grease characteristics.
This study investigates how the grease characteristics influence the friction loss of the gear mesh. The important grease characteristics are the cone penetration, kinematic viscosity, type of base oil, and type of thickener.
The loss of gear mesh friction was evaluated in terms of the average friction coefficient between the gear teeth and was found to be unrelated to the cone penetration and kinematic viscosity of the base oil. The average friction coefficient of grease combined with lithium soap/poly urea and mineral base oil was 0.09–0.11; when combined with aluminum complex soap and synthetic base oil, the friction coefficient reduced to 0.07–0.08.