ABSTRACT
For illustrative purposes, several basic types of gears are considered in this chapter. Although the number of gear forms, shapes of gear teeth, and teeth profiles is large, only several basic types of gear design are commonly recognized. The discussion aims to provide the reader with an overview of the geometry of gear tooth flanks, a both qualitative and quantitative understanding of how complex the geometry of gear tooth flanks can be, and the types of problems that often arise when machining gear teeth. A spur involute gear is the simplest type of involute gear. A gear sector can be cut off from either an external or an internal spur helical gear. A straight-sided helical rack has a plane pitch surface and straight teeth that are oblique to the face surfaces. A herringbone involute gear and a double-helical involute gear can be both interpreted as gears composed of two helical gears facing in the opposite directions of the helix.
