Lubricants, Vol. 14, Pages 13: Efficient Characterization of Extreme Pressure Properties of Lubricants Using Advanced Four-Ball Test Methodology

Lubricants doi: 10.3390/lubricants14010013

Authors:
Krishnamurti Singh
Tushar Khosla
Mathias Woydt

The classic four-ball test was developed in the 1930s and has remained unchanged to this day. This versatile and widely used methodology would benefit from further development with modern tools and techniques. The classic four-ball test is traditionally performed with load steps, which makes it slow, and determining the exact last non-seizure load is quite challenging. To overcome this situation, a new methodology for testing the high-pressure properties (EP) of greases and oils is presented, using a continuous, constant-load ramp rate. The peak in the evolution of the coefficient of friction represents the occurrence of the last non-seizure sliding. The load at which the final non-seizure sliding occurs is defined as the last non-seizure load (LNSL). The obtained results are consistent with historical experience with “classic” four-ball EP tests, and the test procedure is fast and highly repeatable.

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Krishnamurti Singh www.mdpi.com