During the past few years several electronically controllable automotive transmission systems, where wet clutches are used as intelligent differentials, have emerged in the market. In this type of application the anti-shudder properties of the lubricants are of vital importance. This paper investigates the influence of base fluids on the anti-shudder properties of transmission fluids for wet clutches in all-wheel-drive systems. The investigated all-wheel-drive system featuring a wet multi-plate clutch with a sintered brass-based friction material is described. The test equipment used to determine the frictional characteristics of the transmission fluid is described. Five different transmission fluids, with different bas dluied and the same additive package have been tested. The parameters studied include base fluid type and base fluid viscosity. It is shown that the choice of base fluid has no impact on torque capacity, but that the base fluid influences the temperature dependence of the dynamic friction and the anti-shudder properties. It is also shown that the major effect on the friction characteristics is caused by additive effects rather than base fluid effects. The low-viscosity base fluids show a higher temeprature depnedence of the daynamic friction compared to the high viscosity fluids. The low-viscosity fluids have better anti-shudder properties compared to the high-viscosity fluids, especially at lower temperatures. The friction characteristics are mainly additive dependent. The synthetic and mineral base fluids show similar behaviour whereas the semi-synthetic commercial fluid shows a better performance in some areas, implying that the additive package loses some of its effects when added to a different base fluid than originally intended.


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    Title :

    Wet clutch transmission fluid for AWD differentials: base fluid influence on friction characteristics


    Contributors:

    Published in:

    Tribo Test ; 12 , 1 ; 47-56


    Publication date :

    2006


    Size :

    10 Seiten, 7 Bilder, 5 Tabellen, 17 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




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