Owing to the curved contact surfaces in a spherical roller thrust bearing, the rollers will undergo sliding. For an unskewed roller there will be two points along each contact where the sliding velocity is zero. At all other points along the contact, sliding is present. Under boundary lubricated conditions the sliding can give rise to mild wear. Experimental results show that this wear can cause a significant change in the surface profile outside the zero sliding points. The mild wear in the contact was simulated using Archard's wear law. An iterative wear model is described in which the normal load distribution, the tangential tractions and the sliding distances are repeatedly calculated to simulate the changes in surface geometry due to wear. Good qualitative agreement was achieved between the simulation results and the previously presented experimental results.

Simulation of Mild Wear in Boundary Lubricated Spherical Roller Thrust Bearings

Experimental investigation of the chemical degradation of lubricating grease from an energy point of view

The process of churning in a grease lubricated rolling bearing: Channeling and clearing

Abstract Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology. 

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A review of advances in tribology in 2020–2021

On the application of the mechanical aging Master Curve for lubricating greases to rolling bearings

Aged mineral-oil-based, lithium-hydroxystearate-thickened grease was collected from used axle spherical roller bearings, which were used for urban commuter trains. Three types of aged greas...

Microstructure Characterization of Degraded Grease in Axle Roller Bearings

Morphological and elemental analysis of wear debris naturally formed in grease lubricated railway axle bearings

This work presents an approach for modeling grease-lubricated bearing wear by coupling models for boundary-lubricated wear and bearing lubrication state. The lubrication model takes a mass balance approach, using previously developed models for pressure-driven side flow loss and centrifugally driven bleed supply mechanisms. These are combined with a contact model to determine the level of surface interaction and the impact that this interaction has on the lubricated wear and friction coefficients. The developed model was used in numerical simulation of the wear over time during operational conditions representative of 2 Mkm travel distance of a passenger train and the results were compared with experimental investigation of wear particles collected from field test lubricating grease. The results suggest nonlinear behavior with an increasing wear rate over time. Comparison between model results and wear volume estimated from collected wear particles is inconclusive and requires further investigation. A sensitivity analysis of the wear rate found that early in life the model is most sensitive to parameters that directly influence contact properties (load, boundary-lubricated friction coefficient, and wear coefficient). At later stages this shifts as parameters that affect the lubricant loss and supply mechanisms (temperature, base oil viscosity, lubricant fill) become equally or more important.

Chih-Ling Lin

Papers

Microstructure Characterization of Degraded Grease in Axle Roller Bearings

Morphological and elemental analysis of wear debris naturally formed in grease lubricated railway axle bearings

On the modelling of wear in grease lubricated spherical roller bearings