Study of Half Toroidal Continuously Variable Transmission (1st Report, Analysis of the Contact Force by Means of Loading Cam)

In traction drives, the contact force is one of the most important factors used to obtain traction force. A loading cam and preload springs are used in the Half Toroidal CVT (Continuously Variable Transmission) for automobiles. Their use is very practical and it is considered that enough contact force is obtained on the traction contact point. Actually, on the cam surface, there is a friction loss which makes the contact force lower. In this report, the analysis of the cam force is examined and measured actual cam forces under various conditions are shown. The friction loss on the cam surface causes skew of the cam rollers. The friction coefficient is about 0.016~0.019. The cam force is decreased by almost 20%.