Lubricants

Influence of oil ageing on low speed wear in gears

Based on the results of the DGMK projects 377 and 377-01, the objective of this research project was to investigate the low speed wear characteristics of lubricants which were aged in the FVA research projects 171/1-Ill simulating practical gearbox operation.
None of the ten investigated lubricants showed worse wear behaviour in aged condition compared to new condition. For mineral oils wear behaviour was mostly improved with oil ageing. For synthetic oils the wear level was very low in both new and aged condition. The changes in viscosity, total acid number and additive content due to oil ageing do not correlate with the wear behaviour. Further investigations concerning the polarity and the wetting properties of the lubricants did not contribute to an explanation of the wear characteristics. Experiments showed that running-in the gears significantly reduced wear.