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Technical Committee Lubricants

Evaluation of Gear Oils for Mobile and Stationary Drives under Risk of Continuous Wear

The focus of this research project is on low-speed wear in gear applications when lubricated with gear oils. Wear describes the continuous removal of material from the tooth flank surfaces in mesh and is largely dependent on the properties of the lubricant used. In detail, a test procedure for the wear evaluation of gear oils was examined with regard to its accuracy, and an associated calculation procedure was extended for a wider range of applications. The results are based on extensive and systematic investigations, both theoretical and experimental.

First, relevant influencing variables on the test method were identified and their effects on the test result quantified. Furthermore, the repeatability and reproducibility of the test method as well as the differentiability of the results were determined in a comparison test among seven laboratories and compared with the current state of the art. On this enlarged test basis, it was possible to derive extended definitions and specifications for the test procedure, which ensure a comparable performance of the test.

Furthermore, the transfer of the results of a standardized gear oil wear test to the procedure for calculating wear in the design of gear units of different types was investigated. In the known test procedures, pairings of case-hardened gears are used. In many cases, however, pairs of case-hardened and quenched and tempered (and thus significantly softer) gears are also installed in practice. The risk of wear and the intensity of wear differ considerably between these types of gearing. Specific investigations with this material pairing under systematic variation of relevant influencing variables have made it possible to derive regularities that allow wear calculations to be extended for these applications.

The IGF project (20679 N) of the research association DGMK Deutsche Wissenschaftliche Gesellschaft für nachhaltige Energieträger, Mobilität und Kohlenstoffkreisläufe e.V.. Große Elbstraße 131, 22767 Hamburg, Germany, was funded by the German Federal Ministry of Economics and Climate Protection through the German Federation of Industrial Research Associations (AiF) as part of the program for the promotion of joint industrial research (IGF) on the basis of a resolution of the German Bundestag.

Chair for Machine Elements
Research Center for Gears and Gear Systems (FZG)
Technical University Munich
Dipl.-Ing. Benedikt Siewerin
Dr.-Ing. Thomas Tobie
Prof. Dr.-Ing. Karsten Stahl
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