Quite easy to miss a key point, but it actually doesn't matter. When I was updating the calculations per your comment, I realized that I had erroneously used the helical gear formula (Eq. 4.4) for the pinion radius of curvature instead of the spur gear formula (Eq. 4.6).
When I corrected the...
Example calculation attachedhttp://files.engineering.com/getfile.aspx?folder=e1f470b4-ee00-498a-8fbb-a497533a19a4&file=AGMA_Pitting_Geometry_Factor.pdf
I'm using AGMA 908-B89 and trying to calculate "I" for a pair of external spur gears. I can't seem to match the "I" calculation from Equation 4.1 with the values published in the tables in Paragraph 7.
For example, 20 deg pressure angle, 0 deg helix angle, equal addendum Np=21, Ng=135. I get...
