ABSTRACT
An involute gear pair is an extensively used type of parallel-axes gearing. The tooth flank of a gear in a perfect parallel-axes gearing is a kind of involute surface. The tooth flanks of helical gears with involute tooth profiles are shaped in the form of a screw involute surface. The three curves involved in the most fundamental part of gear design are as follows: path of contact; profile of the gear tooth; profile of the pinion tooth. A gear can be generated by specifying only four elements, namely: the reference cylinder; the basic rack profile; the helix angle; the basic rack's position in relation to the generating pitch line, that is, the addendum modification. In a spur gear, the nominal tooth surface can be regarded as swept out by a specified profile moved axially. In a helical gear, the tooth surface is swept out by a specified profile moved along a helical path.
