You need help with a detailed gear design for your application? Our portfolio includes the development, design, calculation and testing of gears, gearboxes and transmission components. Contact us for a free consultation and a non-binding offer.

Theoretical background. The topic of Noise-Vibration-Harshness (NVH) is particularly important in the course of the electrification of the drivetrain. Noise excitation from gears results from fluctuations in the mesh stiffness as pinion and wheel rotate. The decisive parameter for smoothing the contact stiffness is the total contact ratio ε_γ, which results from the sum of transverse- and axial contact ratios: ε_γ = ε_α + ε_β. The transverse contact ratio describes the average number of teeth actively engaged in the transverse section. The axial contact ratio describes the average number of teeth which are additionally in contact due to the helix angle β. Often, one aims at integer values for ε_α and ε_β, because then, the theoretical sum of the lengths of all contact lines along the active flanks remains constant over time. As a rule of thumb, for total contact ratios ε_γ > 2.5 the influence of further increasing the contact ratio is only small. The helix angle β is calculated from the desired axial contact ratio and the gear width b. For a given axial contact ratio ε_β the helix angle decreases with increasing gear width.