Abstract
The wear behavior of two lubricant base stocks, a pentaerythrityl ester and a synthetic hydrocarbon, was investigated with the Four-Ball machine. Wear volumes of the stationary balls were evaluated from the wear scar diameter and by surface profilometry. Surface profilometry was also used to determine wear volumes for the rotating ball. The two methods for evaluating stationary ball wear were in good agreement. Significant differences were found between wear of the rotating ball and wear of the three stationary balls. These differences were related to the lubricant and to the test conditions.