Improvement of Torque Capacity of Metal V-Belt Type CVT Fluids

The influences of the transmittable torque capacity were evaluated using commercial CVT unit. We found that the contact surface between the belt and pulley lie in boundary lubrication. The maximum torque capacity difference among all tested fluids reached up to 40%. In order to analyze the friction characteristics of contact parts of CVT, a block on disk type friction test was created. As a result, the torque capacity in actual CVT correlated with the friction coefficient of the friction test. In addition, the effects of oil additives on the torque capacity were investigated. The combination of detergent (overbased calcium sulfonate) and phosphorus additive was the most effective for increasing friction coefficient. The formation of calcium carbonate, iron phosphate, and calcium phosphate on the friction surface possibly has a great impact on the increment torque capacity.