Thickness modification coefficient (theoretical)

The theoretical thickness modification coefficient, x_smn, determines the relative change of pinion and crown gear tooth thickness to each other. It is relative to the mean normal module m_mn. The theoretical thickness modification coefficient is used to compensate for the tooth root load capacity on the wheel and pinion.

Together with the basic crown gear addendum factor k_hap, basic crown gear dedendum factor k_hfp, and profile shift coefficient x_hm1, it describes the tooth profile according to data type I in ISO 23509 (according to European standards). These dimensionless factors are relative to the mean normal module m_mn.

Relations between type I data (European Standards) and type II data (AGMA)

$x_{sm}=\frac{k_t}{2}$