The radial distance between the pitch circle and the top land of a tooth is known as?

The radial distance between the pitch circle and the top land of a tooth is accurately identified as the addendum. In gear design, the addendum is the portion of a gear tooth that extends above the pitch circle and it plays a crucial role in defining the height of the tooth. Specifically, it is the distance from the pitch circle up to the top of the tooth, where the tooth meets the outer surface. This dimension is essential for ensuring proper meshing of gears, as it affects the tooth contact and the overall performance of the gear system.

The addendum must be carefully calculated to ensure that gears operate smoothly without interference while transmitting motion. While related terms may exist, such as 'land' which refers to the flat top surface of the tooth, or other terms that pertain to tooth profile, the specific measurement from the pitch circle up to the top of the tooth is best described by the term addendum in the context of gear design.