The interactions between organic Friction Modifiers (FMs) and other additives in a CVT fluid (CVTF) are investigated aimed at optimizing friction management of metal pushing Vbelt CVTs. Three types of FMs (oleic acid, oleyl alcohol and glycerol mono-oleate (GMO)) were formulated in Poly--olefin (PAO) and a fully-formulated CVTF, and the friction performance was evaluated in a reciprocating test apparatus (TE77). For estimating their effect at the major frictional components in the CVTs, a steel belt-pulley and a torque converter clutch, the tribotests were carried out with both steel/steel and paper/steel sliding configurations. Then, the post-test materials were assessed by surface analysis techniques to observe the chemical nature of any reacted layers at the surface. 2The results indicate that the friction on the steel surface was significantly influenced by a combination of the FMs and the CVTF additives as well as the functional group of the FMs.Although oleic acid and GMO typically present more friction reduction than oleyl alcohol in most of the conditions, oleic acid did not decrease friction at the steel/steel contact with the presence of the other additives in the CVTF formulation; the friction reduction effect was poisoned by the presence of other additives. Surface analysis of the post-test specimens implied that it was interactions with the calcium detergent that inactivated the FM effect of oleic acid.

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This study proposes a novel approach for controlling frictional performances at paper clutch systems by a combination of organic friction modifiers (OFMs). The OFMs are commonly used for modifying the frictional properties at the paper clutch. Although the effect of the OFMs tends to be dependent on temperature due to their working mechanism based on the surface adsorption, the frictional properties are preferable to be stable in all the operating temperature for the consistent and precise clutch control. Aiming to modify the temperature dependence of the OFM effect, an OFM with an Advanced Concept (FMAC) was newly developed, and the impact on the clutch frictional performance was investigated using Low Velocity Friction Apparatus (LVFA). Only with the conventional OFM, the friction values experienced excessive reduction at 80 or 120°C, while an optimal property was achieved at 40°C. In the presence of the FMAC, it was possible to inhibit the conventional OFM selectively at the high temperature conditions preventing the friction reduction, leading to the ideal frictional property in all the temperature conditions. The surface analysis revealed that the FMACs were capable of adsorbing on the substrate more intensively at high temperature, which should be the reason of the temperature dependent competitive effect of the FMACs.