Abstract: In order to ensure that a certain degree of transmission accuracy, the remains deformation of gear teeth must be restricted within a certain range. In other words, the allowable remains deformation depends on the accuracy of the transmission and the conditions under which the gear is working. Based on a large number of test results, the relationship between remains deformation and static bending strength limit σ_Films was obtained as follows: σ_Films=σ₁(δ/m)^K. Where σ₁-the gear bending stress at the moment when 1 um remains deformation is produced for unit module. K - a coefficient which is dependent on the material and its heat treatment method, σ₁ and K for spheroidal cast iron gears are shoun in this paper.