Why modify the addendum?
Addendum modification serves two main purposes.
· Addendum modification will help avoid tip interference between the gear and the pinion.
· The gear tooth is really just a short cantilevered beam. For the gear set to have a balanced strength, the teeth of the pinion need to be stronger than that of the gear. Gears made of weaker materials like plastic; this may be critical to the life and the performance of the gear set. See the PGT Tooth Form for more information.
As the addendum length changes, so does the tooth width at the pitch circle. This change in thickness is equal to twice the addendum change multiplied by the tangent of the pressure angle.
Note: All width dimensions are arc lengths.