The surface hardness in Brinell (HB) is used to determine the hardness ratio factor ZW. The hardness ratio factor ZW considers different hardness values of the pinion and wheel. When the pinion is substantially harder than the wheel, the work hardening effect increases the gear pitting capacity.
- If the wheel has a significantly lower surface hardness than the pinion, the calculation for the ring gear assumes an increasing surface hardness during operation. This increases the pitting load capacity and is taken into account in the hardness ratio factor ZW. This effect only occurs with hardened and tempered ring gears.
- If the pinion and wheel are hardened and tempered, the ratio of the surface hardness in Brinell (HB) and the transmission ratio are taken into account when calculating the hardness ratio factor ZW.
- If a hardened and tempered wheel is paired with a surface-hardened pinion, the surface hardness of the wheel in Brinell (HB) and the flank roughness of the pinion are taken into account when calculating the hardness ratio factor ZW.
- If the flank hardness of the pinion and wheel is approximately the same, the hardness ratio factor ZW has a value of 1.0.
- In the case of different surface hardnesses, if the flank hardness of the pinion and wheel is not entered, the hardness values are converted from the Vickers hardness (see "Material").