4. Summary of Test Method
4.1 The tester is operated with one steel ball under load rotating against three steel balls held stationary in the form of a cradle. Test lubricant covers the lower three balls. The rotating speed is 1760 6 40 rpm. The machine and test lubricant are brought to 18 to 35°C (65 to 95°F) and then a series of tests of 10-s duration are made at increasing loads until welding occurs. Ten tests are made below the welding point. If ten loads have not been run when welding occurs and the scars at loads below seizure are within 5% of the compensation line (AB Fig.1) no further runs are necessary. The total can be brought to ten by assuming that loads below the last nonseizure load will produce wear scars equal to the "compensation scar diameter." Values of these "assumed" scars are given in Table 1. For clarification of "last nonseizure load" and "weld point" see Fig.1.
5. Significance and Use
5.1 This test method, used for specification purposes, differentiates between lubricating fluids having low, medium, and high level of extreme-pressure properties. The user of this method should determine to his own satisfaction whether results of this test procedure correlate with field performance or other bench test machines.
