4. Continuity of meshing

4.1 Straight teeth

• External gear

  Figure 18 allows us to follow the meshing of a pair of conjugate profiles P ₁ (driving) and P ₂ (driven). We know that the line of action passes through the point of tangency I of the two pitch circles and is inclined by the value of the pressure angle α.

  • Beginning of meshing: the driven profile is attacked by its vertex A (figure 18 a ).