Base number of stress cycles

stress cycles;

stress cycles.

2.3.1. The gearing service life in hours is:

t =4000…5000 hours

2.3.2. Let factor K_HE that reduces variable load conditions to the constant load equivalence be:

K_HE=1

2.3.3. Determine the equivalent number of cycles for the pinion and the gear.

where n^p and n^g are rotational speeds of the pinion and the gear correspondingly.

2.3.4. Determine the durability factor for the pinion and gear if:

N_HE ≥ N_HO then K_HL=1,

N_HE < N_HOthen .

, ,

then

; , ,

then

2.3.5. Determine the safety factor S_H for the pinion and gear.

- for homogeneous structure of the material (heat treatment is normalizing, martempering and full hardening) S_H = 1.1;

- for heterogeneous structure of the material (heat treatment is surface hardening, case hardening, nitriding) S_H=1.2.

2.3.6. Determine the contact allowable stresses for the gear and for the pinion

, .

In our case:

.

If H^p-H^g 70BHN, we assume that the design allowable contact stress is less value of above calculated stresses, where H^p and H^g are hardness of the pinion and gear materials correspondingly.

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 and for the gear . For this purpose we use table 2.1.