Many studies on the wear of cylindrical rolling elements with the twodisk machin have been reported by several groups of workers in recent years. However, most of them are researches under the constant condition of specific sliding.
The present investigation was undertaken to determine the influence of the specific sliding or the tangential force upon the wear and the surface roughness of disks in "pure rolling contact" and "rolling-sliding contacts" in which the specific sliding vary continuously with the angle of rotation at every point on circumference. The results were obtained as follows :
(1) It was found that the surface roughness was dependent upon the amount of cycles, and its value increased with the passing of time. The relative specific sliding influenced fairly the surface roughness. That is, the form of the relationship curves between the relative specific sliding and the surface roughness was dependent on the absolute value of the relative specific sliding ; the roughness at a larger absolute value tended to increase compared with that at a smaller absolute value.
(2) In the case of pure rolling contact, the transition from the initial wear period to the constant wear period was clearly recognized, and the specific wear decreased after the initial wear period. On the contrary, in the case of rolling-sliding contacts, the constant wear period practicaly disappeared and the wear slope was considerably steeper. In view of the sliding effect, the rolling endurance limit was obviously reduced compared with that in the absence of sliding.
(3) The volume of wear was nearly similar at each relative specific sliding, but it was seen that the specific wear showed somewhat large values with the increasing of the absolute value of relative specific sliding. These tendencies resembled the results obtaind in the case of spur gears. However, the difference of the value of relative specific sliding had little influence over the wear under this experimental conditions (and when the direction of sliding was not taken into consideration with regard to the value of specific sliding).