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Torque loss reduction at differential gear unit is important to improve the fuel economy of automobiles. One effective way is to decrease the viscosity of lubricants as it results in less churning loss. However, this option creates a higher potential for thin oil films, which could damage the mechanical parts. At tapered roller bearings, in particular, wear at the large end face of rollers and its counterpart, known as bearing bottom wear is one of major failure modes. To understand the wear mechanism, wear at the rolling contact surface of rollers and its counterpart, known as bearing side wear, was also observed to confirm the wear impact on the tapered roller bearings. Because gear oils are also required to avoid seizure under extreme pressure, the combination of a phosphorus anti-wear agent and a sulfurous extreme pressure agent are formulated.

We develop a new metal-belt continuously variable transmission fluid (CVTF) named FE to improve fuel economy and help reduce CO2 emissions. FE is a low-viscosity fluid that reduces friction loss at low temperatures. Low-viscosity fluids generally reduce hardware durability, resulting in reduced metal fatigue life. Therefore, FE is designed for maintaining oil film thickness throughout the life of a vehicle by optimizing the base oil and viscosity modifier. FE also exhibits long-term anti-shudder performance that enables frequent use of controlled-slip torque converter clutches for improving fuel economy, represented by the flex start system, without decreasing torque capacity between the belt and pulley. The key point in the formulation of design is the selection of a suitable friction modifier. A friction modifier is an additive that improves friction properties.