The strength of plastic gear greatly varies with temperature; that is the strength increases as the temperature decreases. Therefore, the lifetime of a plastic gear can be increased by decreasing the meshing-teeth temperature. Hence, grease is mainly used to decrease the amount of frictional heat generated by plastic gears. In this study, we investigated the effect of grease properties on the load-carrying characteristics of crossed helical gears. Specifically, we investigated greases with different additive contents. As a result, there were confirmed that increasing the amount of MCA added decreases the temperature rise on the tooth surface and increases power transmission efficiency. However, the effects were not so clear, and M(0) without additive showed the same or better performance than the grease with additive. The reason for this has not yet been clarified. Therefore, further detailed investigation will be required in the future, such as by changing the operating conditions and measuring the changing in tooth profile.
MATSUYAMA et al. (Wed,) studied this question.