King Fahd University of Petroleum & Minerals

Department of Mechanical Engineering

Machine Design - II Laboratory - ME 308 - Term 991

Project 3

1. Calculate the Nominal Velocity Ratio (VR):
2. VR = np/average ng

3. Specify a reasonable Module (m):
4. m = 4                                                                                (mm)

5. Select the number of teeth on the pinion (Np):
6. Hint:

Minimum number of teeth to avoid interference for pinions having 20° pressure angles is 18

Select Np= 28

7. Calculate the Pinion Diameter (dp):
8. dp = Np ´ m                                                                         (mm)

9. Calculate the number of teeth on the gear (Ng):
10. Ng = Np ´ VR

Round-off the calculated value to a closest higher integer value

11. Calculate the Gear Diameter (dg):
12. dg = Ng ´ m                                                                         (mm)

13. Calculate & Check the final Output Speed (ng):
14. ng = np ´ (Np/Ng)                                                                  (rpm)

Check if this value falls within the specified output speed range, i.e. (270~280 rpm)

15. Calculate the Center Distance (C):
16. C = (Np+Ng)m/2                                                                   (mm)

17. Calculate the Pitch Line Velocity (n t):
18. n t = p dpnp/60000                                                                (m/sec.)

19. Calculate the Tangential Force (Wt):
20. Wt = P ´ 1000/n t                                                                (N)

21. Calculate the Face Width (F) of the gears:
22. F = (8~16)m                                                                         (mm)

23. Calculate Bending Stress on the pinion (s tp) and gear (s tg):
24.                                             (MPa)

25. Calculate the Contact Stress (s c) on the gear pair:
26.                                             (MPa)

27. Select Materials for the pinion and gear depending upon the hardness values for each stress

 Stress Brinell Hardness Selection Procedure Bending Stress on Pinion x }} Contact Stress on Gear Pair y Bending Stress on Gear z