For cylindrical gear pairs a sizing button allows to select the mesh stiffness according to ISO 6336-1. Either cγα or cγβ can be selected. The factors CB and CR are assumed to be equal one for the calculation of mesh stiffness.
The 
-button behind the selection for the calculation program allows to pass a face load coefficient to the gear calculation program. The face load coefficient is calculated as:
If a value for fma is defined, it is used for the calculation of the maximum line load just based on the gear stiffness keeping constant tilting angles.
