STUDY ON THE SCORING RESISTANCE OF LUBRICATING OIL IN FOUR BALL TEST - 4. RELATION BETWEEN THE SCORING RESISTANCE AND THE MAXIMUM CONTACT SURFACE TEMPERATURE.

For two kinds of non-EP mineral oils, the effects of lubricating method, operating time and sliding velocity on initial seizure load were examined by step-load method using a Shell type Four Ball Machine, and the relation between the thermal strength of boundary lubricating film and the maximum contact surface temperature was clarified. The results obtained are summarized as follows: (1) There is only a negligible difference in maximum contact surface temperature (T//c(maximum))s, at scoring between the results in 5 seconds test and the results in 300 seconds test. (2) Without regard to lubricating method and operating time, (T//c(maximum))s, increases with an increase in sliding velocity, and in the sliding velocity range higher than 35 or 46 cm/s, (T//c(maximum))s, is nearly constant. (3) In 300 seconds test, a bulk temperature rise in steel balls has great effect on (T//c(maximum))//s.