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Because of their smooth torque transmission, high efficiency, low noise, and high running accuracy, planetary roller type traction drive units are becoming a common, widely used a speed increaser that can achieve rotational speeds of ten thousand RPM, or a speed reducer that has very small angular velocity fluctuation. When it is utilized as a transmission, particularly grease lubrication, traction damage is caused by excessive torque load and lubricant deterioration. This paper examines traction damage caused by torque load, using a machine tool high rotational speed planetary roller type traction drive unit with grease lubrication, and the practicality of an oil film monitor using electrical resistance, and direct current power source for monitoring the oil film condition of traction surface.

Many types of variable speed accessory drive systems have been researched and developed, but none have been adopted in a production car1,2. There has been an increasing demand on the accessory drive system due to the adoption of new accessories in passenger cars. Along with the increasing demand on the system, nothing can be done which would decrease fuel economy. So, the efficiency of the system must be improved. This has caused renewed interest in variable speed accessory drives. A compact V-ribbed (serpentine) belt CVT system for accessory drive (called CVAD: Continuously Variable Accessory Drive System) has been developed3. By applying the CVAD for the accessory belt drive system, fuel savings, increased vehicle performance in acceleration, noise reduction, increased life of accessories and V-ribbed belts, and a reduction in the size of accessories are possible. The performance of a prototype variator, the principal component of the CVAD, has been evaluated.