Cutting bevel gears
Gear cutting and grinding processes

Just as a rack is the limit of a cylindrical wheel whose primitive cylinder has become a primitive plane, we'll call a flat wheel a conical wheel whose primitive cone has become a plane, i.e. whose half-angle at the apex has become 90. A flat wheel rotates around an axis that is normal to its primitive plane.

We'll start by looking at the generation of a bevel gear's teeth from a generating flat wheel. Figure 23 shows the primitive cone C₁ of a cut bevel gear, axis X₁, tangent along SI to the primitive plane P of the generating flat gear, rotating around axis X₀.