A comparison of the performances of full and half toroidal traction drives

The efficiency of two different typologies of the toroidal traction drive, the full-toroidal and the half-toroidal, is estimated in order to point out which of them offers the higher mechanical efficiency. A fully flooded isothermal contact model between the discs and rollers, based on the results of EHL theory, is used to evaluate the slip, the spin losses and the mechanical performances of the variators. It is shown that the half-toroidal traction drive offers higher efficiency and higher maximum transmissible torque.