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Base number of stress cycles
2.3.1. The gearing service life in hours is: t =4000…5000 hours 2.3.2. Let factor KHE that reduces variable load conditions to the constant load equivalence be: KHE=1 2.3.3. Determine the equivalent number of cycles for the pinion and the gear. where np and ng are rotational speeds of the pinion and the gear correspondingly. 2.3.4. Determine the durability factor for the pinion and gear if: NHE ≥ NHO then KHL=1, NHE < NHOthen
then
then 2.3.5. Determine the safety factor SH for the pinion and gear. - for homogeneous structure of the material (heat treatment is normalizing, martempering and full hardening) SH = 1.1; - for heterogeneous structure of the material (heat treatment is surface hardening, case hardening, nitriding) SH=1.2. 2.3.6. Determine the contact allowable stresses for the gear and for the pinion
In our case:
If Hp-Hg Otherwise, the design allowable contact stress is determined by the following formula:
Thus, for further calculations we assume as the design allowable contact stress 2.4. Determine the allowable bending stresses for the pinion and for the gear. 2.4.1. Determine the limits of the bending endurance for the pinion
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