Spur Involute Gears

Abstract

INTRODUCTION The involute gearing, first proposed by Euler, has found widespread application in the industry due to its many advantages: (i) the tools for generation of involute gears can be produced with high precision, (ii) it is easy to vary the tooth thickness and provide a nonstandard center distance just by changing tool settings for gear generation, (iii) nonstandard involute gears can be generated by using standardized tools applied for standard gears, and (iv) the change of gear center distance does not cause transmission errors. The invention of Novikov–Wildhaber gearing is very attractive in its theoretical aspect and has found application in some areas. However, this gearing is limited to application to helical gears and has not replaced the involute gearing. A new version of Novikov–Wildhaber gears based on the latest developments is presented in Chapter 17 of this book. Spur involute gears are in line contact at every instant, and therefore they are sensitive to the misalignment of gear axes. For this reason, it is necessary to localize their bearing contact, and this can be achieved by crowning the surface of one of the mating gears. It is preferable to crown the pinion tooth surface rather than the gear tooth surface because the number of pinion teeth is smaller than the number of gear teeth. The tooth profile of the spur gears is generated as an involute curve.