FRICTION COEFFICIENT OF SMALL-SIZED GEAR LUBRICATED WITH GREASE

抄録

We previously investigated the influence of grease characteristics upon the gear-mesh-friction loss of a small-sized gear reducer. Thus, the average friction coefficient between the gear teeth can be assumed constant. At low circumferential velocities, the thickener is likely to affect the grease lubrication of the gear mesh.
This study experimentally investigates in detail the average friction coefficient between the gear teeth of a small-sized gear pair lubricated with grease, examining a wider range of circumferential velocities than previously reported. The influence of grease temperature on the friction coefficient was evaluated in relation to the grease's consistency and the base oil's kinematic viscosity. The friction coefficient of the gear teeth was almost constant at a lower circumferential-velocity range, which is assumed to be the boundary lubrication condition. When the circumferential velocity increases, the friction coefficient depends on this velocity, the load, and the grease's viscosity. Thus, we considered that the fluid-lubricating state occurs because of the squeeze effect.