The Effect of Friction Modifiers on the Low-Speed Friction Characteristics of Automatic Transmission Fluids Observed with Scanning Force Microscopy 981099
The effect of friction modifiers on the low-speed frictional properties of automatic transmission fluids (ATFs) was investigated by scanning force microscopy (SFM). A clutch lining material was covered by a droplet of test ATF, and a steel tip was scanned over the sample. The scanning speeds were varied from 0.13 to 8.56 mm /sec, and the frictional force was deduced from the torsion of the SFM cantilever. A reduction in dynamic friction due to the addition of the friction modifier was clearly observed over the entire speed range. This indicates that the boundary lubrication mechanism is dominant under this condition, and therefore surface-active friction modifiers can effectively improve the frictional characteristics. The friction reduction was more pronounced at lower sliding speeds. Thus addition of friction modifiers produced a more positive slope in the μ-ν (friction vs. sliding speed) plots, and would contribute to make wet clutch systems less susceptible to shudder vibrations. The effect of thermal aging of ATFs in the μ-ν characteristics has been also discussed.
Citation: Slough, C., Ohtani, H., Everson, M., and Melotik, D., "The Effect of Friction Modifiers on the Low-Speed Friction Characteristics of Automatic Transmission Fluids Observed with Scanning Force Microscopy," SAE Technical Paper 981099, 1998, https://doi.org/10.4271/981099. Download Citation
Carlton G. Slough, Hiroko Ohtani, Mark P. Everson, Donald J. Melotik
Ford Motor Company
International Congress & Exposition
1998 Transmission and Driveline Systems Symposium: New Developments and Advanced Concepts in Systems and Components-SP-1324, SAE 1998 Transactions - Journal of Fuels and Lubricants-V107-4