Designing parametric gear in Catia

Gears can fundamentally be classified according to the profile of the teeth. The profile of the teeth may be involute, cycloidal, trochoidal or even a combination of these profiles. 

Involute profile in red

The involute profile is basically a path traced by a point on a straight line which rolls without slipping on the circle. The circle is called the base circle of the involute. 

Epicycloid in red

The epicycloid is the path that's traced by a point on the circle as it rotates outside a circle, while hypocycloid is the path traced by a point on the circle as it rotates on the inside of another circle.