AGMA 13FTM03 PDF

Gear root is an important but often neglected element of the gear. The stress concentration point typically lies in the tooth to root transition area and it is this point that determines the life or the fatigue life of a gear in many applications. Specific standards are in place on design of the involute part of a gear tooth, the root area however is less standardized. New manufacturing methods enable the designer of gears greater latitude in the design of strong alternative root forms. The standards on design and specification for the root geometry are lax so these root forms fit into current standards.

This paper reviews the designs of various root forms for the gears. It compares the various root forms on basis of their strength, fatigue resistance and other parameters. This analysis will be based on compilation of various research previously conducted on gear root forms.

The paper also discusses current manufacturing methods to produce the roots, and recently introduced alternatives. It will compare the traditional methods with new methods of gear manufacturing it terms of types of roots produced and overall control over the root profile.