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The purpose of this research work is to develop more accurate calculating method of the efficiency of a half toroidal CVT. Previous analysis does not consider the bulk deformation of the CVT components. However, the bulk deformation of the CVT components is not negligible to predict the efficiency of the unit. For example, the half-contact angle between the power roller and disks is changed due to the deformation of these components at the high contact load. Therefore, it is important to establish more accurate calculating method of efficiency considering the bulk deformation for the high performance CVT unit, that is compact, highly efficient, and provides high-torque capability. This paper describes the analytical method to calculate the efficiency of the CVT taking the deformation into consideration. Firstly, the analysis of the efficiency on the traction surface considering deformation of the trunnion is shown.

A computer program package named “BRAIN” has been developed to simulate the kinematics and the performance of rolling bearings under various running conditions. The calculation time necessary for running BRAIN software on a PC is very short. Various outputs can be obtained using BRAIN such as running torque, roller skew angle, roller slippage, and PV values. Several experiments have been conducted to confirm the validity of BRAIN. The running torque of a four point contact ball bearing and that of a tapered roller bearing were measured. In addition, the skew of the roller in a needle bearing was measured. These experimental results were compared with the calculation results. The experiments and the calculations showed good agreement.