This study proposes a method to predict the efficiency of a worm gear with a plastic worm wheel. The theoretical efficiency is obtained from friction coefficient experiments and mathematical calculations. A tribometer is used to measure the friction c...
This study proposes a method to predict the efficiency of a worm gear with a plastic worm wheel. The theoretical efficiency is obtained from friction coefficient experiments and mathematical calculations. A tribometer is used to measure the friction coefficient of nylon6 on steel at various normal pressures. Gear geometry is employed to calculate the position of the contact point and the curvature at the contact point, and Hertz' Law is employed to calculate the contact area. In order to verify the efficiency prediction method, the efficiency of a worm gear which is used in an EPS system is theoretically calculated by the method, and then, the result is compared with the measured efficiency of the worm gear. With consideration of all factors, the theoretical efficiency was very accurate, showing the same efficiency trend with the increase of output torque and little difference among the values. Their maximum values were obtained at the same output torque. This efficiency prediction method can be applied to various types of gears with plastic materials.