Wildhaber–Novikov circular arc gears: some properties of relevance to their design

This paper follows an earlier one by Dyson et al. (Proc. R. Soc. Lond. A 403, 313 (1986)) in which a rigorous basic theory of the geometry and kinematics of Wildhaber–Novikov circular arc gears was developed. It was then applied to a pair of helicopter rotor final drive gears, operating in the conditions for which they were designed. The present paper extends this treatment by considering the effect of some variations on the same basic design, and of operating in conditions different from those for which the gears were designed. Aspects considered include the sensitivity of the pressure angle to changes in centres distance, the compromise between this sensitivity and reduction in contact stress, the relation between pressure angle and centres distance over the entire range theoretically possible, the avoidance of interference, the extent of the contact area in terms of position on the teeth, backlash and internal gears.