Abstract
In order to clarify influence of the lubricant composition on the transmission efficiency of the helical gear for vehicles driven at high speed and low load conditions, traction measurement of lubricants was conducted using a Four-roller tester. As a result of the measurement using three sets of rollers with which surface roughness differs, when the surface roughness was smaller, the difference in the traction coefficient between commercial ATF and traction oil KTF-1 was larger. On the other hand, the difference was smaller when the surface roughness was larger. The surface roughness of the test gear was almost same as that of the latter case, and there was a good correlation between the average traction coefficient obtained in the case of rougher test rollers and gear power losses which is mainly caused by meshing lose.
