Power Transmission Efficiencies and Friction Coefficients at Teeth of Novikov-Wildhaber and Involute Gears

Abstract

New equations have been derived to calculate the power transmission efficiencies, at the meshing teeth, of two kinds of representative cylindrical gears, Novikov-Wildhaber and involute gears. The efficiencies could be calculated from the equations and the friction coefficients obtained by simple experiments with test rollers. In order to show clearly the difference in the power transmission efficiencies of the two kinds of gears, the authors designed and made two interesting gear pairs with a small number of pinion teeth (Z1 = 3) and with a high gear ratio (Z2 /Z1 = 9) by applying new techniques developed by them. The effects of gear speed, tooth load, type of lubricant, etc. upon the power transmission efficiencies were clarified using two interesting techniques to measure the efficiency. The experimental results indicated that the efficiency of the Novikov-Wildhaber gears was appreciably higher at high speeds, while it was lower than the involute gears at the start of rotation and also at low speeds.