Abstract
In this paper, we evaluated the difference in the grease of a small sized geared motor, which was kind and kinematic viscosity of base oil and cone penetration. The result shows that, the loss at no loading depends on the cone penetration and the kinematic viscosity of base oil. Load depending part, the friction loss of gear mesh not depends on the cone penetration and the kinematic viscosity of base oil. The mean friction coefficient of a tooth flank by grease lubrication proved the constant value that mineral base oil type was 0.09 to 0.11, and synthetic base oil type was 0.07 to 0.08.
