1. Power Transmission Case Study
Lecture Slides
Chapter 18
Power Transmission Case Study
The McGraw-Hill Companies © 2012

2. Chapter Outline
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3. Power Transmission Case Study Specifications
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4. Power Transmission Case Study Specifications
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5. Power Transmission Case Study Specifications
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6. A Compound Reverted Gear Train
Fig. 18–1
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7. Design Sequence for Power Transmission
Power and torque requirements
Gear specification
Shaft layout
Force analysis
Shaft material selection
Shaft design for stress (fatigue and static)
Shaft design for deflection
Bearing selection
Key and retaining ring selection
Final analysis
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8. Power and Torque Requirements
In ideal case, neglecting losses, power in equals power out
Power is product of torque and speed
Gear ratio, or train value,
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9. Case Study Part 2: Speed, Torque, and Gear Ratios
Fig. 18–1
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10. Case Study Part 2: Speed, Torque, and Gear Ratios
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11. Case Study Part 2: Speed, Torque, and Gear Ratios
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12. Case Study Part 2: Speed, Torque, and Gear Ratios
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13. Gearbox Size
Fig. 18–1
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14. Case Study Part 3: Gear Specification
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15. Case Study Part 3: Gear Specification
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16. Case Study Part 3: Gear Specification
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17. Case Study Part 3: Gear Specification
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18. Case Study Part 3: Gear Specification
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19. Case Study Part 3: Gear Specification
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20. Case Study Part 3: Gear Specification
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21. Case Study Part 3: Gear Specification
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22. Case Study Part 3: Gear Specification
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23. Case Study Part 3: Gear Specification
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24. Case Study Part 3: Gear Specification
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25. See Sec. 7–3 for discussion of issues involved in shaft layout
The following case study focuses on how decisions relate to the overall process
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26. Case Study Part 4: Shaft Layout
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27. Case Study Part 4: Shaft Layout
Fig. 18–2
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28. See Secs. 13–14 through 13–17 for discussion of force analysis
The first of Ex. 7–2 covers the force analysis for the intermediate shaft of the case study. It is included in Case Study Part 5.
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29. Shaft Material Selection
Sec. 7–2 provides details for decisions regarding material selection.
For the case study, select an inexpensive 1020 CD steel as a starting point.
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30. Shaft Design for Stress
See Sec. 7–4 for details regarding shaft design for stress.
Ex. 7–2 demonstrates the process for the case study, and is presented as Case Study Part 5.
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31. Case Study Part 5: Design for Stress
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32. Case Study Part 5: Design for Stress
Fig. 7-10
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33. Case Study Part 5: Design for Stress
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34. Case Study Part 5: Design for Stress
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35. Case Study Part 5: Design for Stress
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36. Case Study Part 5: Design for Stress
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37. Case Study Part 5: Design for Stress
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38. Case Study Part 5: Design for Stress
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39. Case Study Part 5: Design for Stress
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40. Case Study Part 5: Design for Stress
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41. Case Study Part 5: Design for Stress
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42. Case Study Part 5: Design for Stress
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43. Case Study Part 5: Design for Stress
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44. Case Study Part 5: Design for Stress
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45. Shaft Design for Deflection
Sec. 7–5 provides a detailed discussion of deflection considerations for shafts.
Ex. 7–3 demonstrated the process for the case study, and is presented as Case Study Part 6.
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46. Case Study Part 6: Deflection Check
Fig. 7-10
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47. Case Study Part 6: Deflection Check
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48. Case Study Part 6: Deflection Check
Fig. 7-11
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49. Case Study Part 6: Deflection Check
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50. Case Study Part 6: Deflection Check
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51. See Ch. 11 for details on bearing selection.
Case Study Part 7 demonstrated the bearing selection process for the case study.
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52. Case Study Part 7: Bearing Selection
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53. Case Study Part 7: Bearing Selection
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54. Case Study Part 7: Bearing Selection
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55. Key and Retaining Ring Selection
Sec. 7–7 discusses the sizing and selection of keys.
Case Study Part 8 demonstrates this for the case study.
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56. Case Study Part 8: Key Design
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57. Case Study Part 8: Key Design
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58. Retaining Ring Specifications
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59. The final shaft machine drawing is shown in Fig. 18–3.
Final Analysis
See Sec. 7–8 for details on determining appropriate tolerances for desired fits between the shaft and the gears and bearings.
The final shaft machine drawing is shown in Fig. 18–3.
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60. Final Shaft Machine Drawing
Fig. 18–3
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