Geometry factors, I, for straight bevel gears. Pressure angle = 20 degrees, shaft angle = 90 degrees. (From AGMA Information Sheet 215.91).
 
Number of teeth in pinion
|  | Number of teeth in gear. | 
Geometry factors, I, for spiral bevel gears. Pressure angle = 20 degrees, spiral angle = 35 degrees, shaft angle = 90 degrees.
(From AGMA Information Sheet 215.91)
 
Number of teeth in pinion
|  | Number of teeth in gear. |