Internal Gear

Internal Gear

Internal Gear
A gear with teeth on the inner cylindrical surface. The teeth can be either spur or helical. In an involute-form, internal gear teeth have a concave rather convex shape with a thicker base than an equivalent external gear. This not only gives it greater tooth strength but due to a lower sliding velocity along the tooth profile, also makes them quieter. With internal helical gears, the hand of helix must be the same in both mating gears, i.e. the external helical pinion and its mating helical internal gear must be either right-hand or left-hand.
Whereas: From Gear Data
Formula: