Four commercial greases with various thickeners and base oils were experimentally examined to compare their false brinelling wear resistance in a test rig simulating roller bearings during rail/sea transportation for the first time. Greases containing zinc dialkyl dithiophosphates (ZDDP) showed superior false brinelling reduction, evidenced by no visible wear mark in the raceways. The mechanism for false brinelling mitigation was shown to be from a ZDDP-induced tribofilm which decreases the friction and wear coefficient in the contact area. Surface chemical analysis showed that for grease lubricated fretting contacts, ZDDP-derived tribofilms can be generated in the presence of micro-sliding motions and energy dissipation at the contact interface at low frequency (i.e., 4-8 Hz), due to the mechanochemical reactions. For greases without ZDDP, false brinelling wear was reduced by 97% when using grease with a more abundant and less viscous oil, which bleeds readily from an open structured thickener. The results highlight the ability of ZDDP as an additive in grease to better protect roller bearings against false brinelling during rail/sea transportation.
Details
Title
Mitigation of False Brinelling in a Roller Bearing: A Case Study of Four Types of Greases
Creators
Chih-Ling Lin - The University of Queensland
Khosro Fallahnezhad - Flinders University
Osama Brinji - The University of Queensland
Paul A. Meehan - The University of Queensland
Publication Details
Tribology letters, Vol.70(1), pp.1-18
Publisher
Springer Nature
Number of pages
18
Grant note
The authors greatly appreciate the financial support from the Rail Manufacturing Cooperative Research Centre (funded jointly by participating rail organisations and the Australian Federal Government’s Business Cooperative Research Centres Program) through Project “Monitoring and Control of False Brinelling”.