FZG test

Thermal/oxidative effects contribute to viscosity change in the FZG test [77]. Diesel injector and FZG shear data were shown to correlate reasonably well in spite of evidence, based on GPC data, that the former appeared to be a purely mechanical process while the latter had a significant thermal and/or oxidation component. This may well relate back to the observation that a diesel injector shear process can best be simulated by assuming two steps [58], whilst others found that the FZG shear data appeared to involve three steps [59]. There is also a clear chemical bias indicating that the PMA thermal/oxidative component is less than that of other VI improvers in the study [77]. 

Figure 8. Pressure and film thickness at a particular timestep in a micro EHL solution for gear tooth contact in an FZG test. Corresponding maximum Hertzian pressure = 1.4 GPa. Also shown are contours of z/GPa, the sub-surface maximum shear stress.

Hohn et al [1] performed several FZG tests with type C gears, using speeds going from 350 to... 

Niemann four-square gear oil test see FZG four-square gear oil test. 

Figure 3. Average friction coefficients (experimental and extrapolated from disk machine tests) for FZG type C gears [1].

Figure 11 shows the average friction coefficients calculated using the mixed film lubrication model and compares them with the experimental results, already shown in figure 3, for the FZG type C gears tested. 

Powrie, H.E.G., Fisher, C.E, Tasbaz, O.D. and Wood, R.J.K., Performance of an Electrostatic Oil Monitoring system during an FZG gear scuffing test. International Conference on Condition Monitoring, University of Wales Swansea, 12-15 April 1999. 

Powrie, H E G Wood, R J K. Harvey, T J, Morris, S, Re-analysis of electrostatic wear-site sensor data from FZG gear scuffing tests. International Conference on Condition Monitoring, 25th-27th June 2001 also Condition Monitor, ISSN 0268/8050, Sept 2001 6-12... 

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