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Ch_17beltsandchains.pdf
- 1. Belt and ChainDrives (Flexible Drive Elements) Shigley’s Mechanical Engineering Design
- 2. Why Flexible Drives? Shigley’sMechanical Engineering Design + • Long Distances Between Shafts • Less Expensive • Adjustable Centers • Tolerates some mis alignment better than gears - • Not as compact as gears • Some speed limits • Power and torque limits
- 3. Common Belt Types Shigley’sMechanical Engineering Design Type Pulley 1. Flat Crowned pulley (conveyor belts) 2. Round (O-ring) Grooved pulley 3. V-belt Flanged pulleys 4. Timing (toothed) Cogged pulley (no stretch or slip) 5. Proprietary belt designs
- 4. Characteristics of SomeCommon Belt Types Shigley’s Mechanical Engineering Design Table 17–1
- 5. Flat Belt Drive Shigley’sMechanical Engineering Design Better for high speed applications, rather than power. Good for tight clearances Can allow slip, to prevent breakage
- 6. Flat Belts asConveyer Belts Shigley’s Mechanical Engineering Design Usually seamed/stitched Crowned Pulleys for Tracking
- 7. O-Ring Drive Shigley’s MechanicalEngineering Design Good for low cost. Good for driving multiple shafts
- 8. Reversing Belts Shigley’s MechanicalEngineering Design Fig.17–2 Typically O-Ring Drives
- 9. Timing Belts Shigley’s MechanicalEngineering Design Fig.17–15
- 10. Flat-belt with Out-of-planePulleys Shigley’s Mechanical Engineering Design Fig.17–3
- 11. Variable-Speed Belt Drives Shigley’sMechanical Engineering Design Fig.17–5
- 12. Flat-Belt Geometry –Open Belt Shigley’s Mechanical Engineering Design Fig.17–1a
- 13. Free Body ofInfinitesimal Element of Flat Belt Shigley’s Mechanical Engineering Design Fig.17–6
- 14. Free Body ofInfinitesimal Element of Flat Belt Shigley’s Mechanical Engineering Design Fig.17–6
- 15. Analysis of FlatBelt, The Belting Equation Shigley’s Mechanical Engineering Design The Belting Equation
- 16. Fc = HoopTension Due to Centrifugal Force Shigley’s Mechanical Engineering Design
- 17. Forces and Torqueson a Pulley Shigley’s Mechanical Engineering Design Fig.17–7
- 18. Initial Tension Shigley’s MechanicalEngineering Design
- 19. Flat Belt Tensions Shigley’sMechanical Engineering Design
- 20. Transmitted Horsepower Shigley’s MechanicalEngineering Design
- 21. Correction Factors forBelts, Based on Manufacturer Data Shigley’s Mechanical Engineering Design
- 22. Velocity Correction FactorCv for Leather Belts Shigley’s Mechanical Engineering Design Fig.17–9
- 23. Pulley Correction FactorCP for Flat Belts Shigley’s Mechanical Engineering Design
- 24. Steps for Flat-BeltAnalysis Shigley’s Mechanical Engineering Design
- 25. Belt-Tensioning Schemes Shigley’s MechanicalEngineering Design Fig.17–11
- 26. Standard V-Belt Sections Shigley’sMechanical Engineering Design Table 17–9
- 27. Inside Circumferences ofStandard V-Belts Shigley’s Mechanical Engineering Design Table 17–10
- 28. Length Conversion Dimensions Shigley’sMechanical Engineering Design
- 29. V-Belt Pitch Lengthand Center-to-Center Distance Shigley’s Mechanical Engineering Design
- 30. Horsepower Ratings ofStandard V-Belts Shigley’s Mechanical Engineering Design Table 17–12
- 31. Adjusted Power Shigley’s MechanicalEngineering Design
- 32. Angle of WrapCorrection Factor Shigley’s Mechanical Engineering Design Table 17–13
- 33. Belt-Length Correction Factor Shigley’sMechanical Engineering Design Table 17–14
- 34. Belting Equation forV-Belt (Gates Belting) Shigley’s Mechanical Engineering Design
- 35. Design Power forV-Belt Shigley’s Mechanical Engineering Design Number of belts:
- 36. V-Belt Tensions Shigley’s MechanicalEngineering Design
- 37. Belting Selection Shigley’s MechanicalEngineering Design Use Belting Manufacture Specific Data For examples Gates Belts (know mostly for V-belts) https://www.gates.com/us/en.html Available Resources from the Manufacturer • Products and Applications (by Industry) • Engineering Applications & Design Software • Calculators • Resources Library
- 38. Roller Chain Shigley’s MechanicalEngineering Design
- 39. Roller Chain Characteristics Shigley’sMechanical Engineering Design • Similar to Timing Belts, no slip • Long life • Fairly large power can be transmitted • Costs less than gears • Easy to adjust centers, tolerant of large variation • Input and Output sprocket usually rotate in same direction • Only need light to no chain preload tension when installing, but may require a tensioner/idler • Usually requires lubrication • Can use multiple strands for increased power • Usually made of steel • Stainless steel versions available for food industry
- 40. Roller Chain Shigley’s MechanicalEngineering Design Fig.17–16
- 41. ANSI Chain SizeNumber Shigley’s Mechanical Engineering Design XXX First number(s) pitch p in number of 1/8” ANSI 40 chain is 4 x1/8” =0.50” pitch 0=Standard 1=Light Duty ANSI 41 chain is 4 x1/8” =0.50” pitch But Light Duty
- 42. Dimensions of AmericanStandard Roller Chains Shigley’s Mechanical Engineering Design Table 17–19
- 43. Engagement of Chainand Sprocket Shigley’s Mechanical Engineering Design Fig.17–17
- 44. Roller Chain Drive Shigley’sMechanical Engineering Design D2, N2 D1, N1
- 45. Roller Chain DesignGuide Rules of Thumb Shigley’s Mechanical Engineering Design • Min Teeth per Sprocket ~ 12 to 25 • Max Teeth per Sprocket ~120 • Max Speed Reduction ~7:1 • Min Wrap Angle ~ 120˚
- 46. Chain Velocity Shigley’s MechanicalEngineering Design
- 47. Chordal Speed Variation(as chain not perfectly round) Shigley’s Mechanical Engineering Design Fig.17–18
- 48. Roller Chain RatedHorsepower Capacity Shigley’s Mechanical Engineering Design
- 49. Roller Chain RatedHorsepower Capacity Shigley’s Mechanical Engineering Design
- 50. Available Sprocket ToothCounts Shigley’s Mechanical Engineering Design
- 51. Example 17–5 Shigley’s MechanicalEngineering Design
- 52. Example 17–5 Shigley’s MechanicalEngineering Design
- 53. Example 17–5 Shigley’s MechanicalEngineering Design
- 54. Wire Rope Shigley’s MechanicalEngineering Design Fig.17–19
- 55. Berg cable timingbelts Shigley’s Mechanical Engineering Design
- 56. Stress in WireRope Shigley’s Mechanical Engineering Design
- 57. Wire-Rope Data Shigley’s MechanicalEngineering Design Table 17–24
- 58. Equivalent Bending Loadin a Pulley, diameter D Wire rope tension giving same tensile stress as sheave bending is called equivalent bending load Fb Clearly the smaller the sheave diameter the higher the added bending tension of the sheave on the cable Shigley’s Mechanical Engineering Design
- 59. Percent Strength Lossfor D/d Shigley’s Mechanical Engineering Design Fig.17–20 D is sheave (pulley) diameter d is the cable diameter
- 60. Minimum Factors ofSafety for Wire Rope Shigley’s Mechanical Engineering Design Table 17–25
- 61. Bearing Pressure ofWire Rope in Sheave Groove Shigley’s Mechanical Engineering Design
- 62. Maximum Allowable BearingPressures (in psi) Shigley’s Mechanical Engineering Design Table 17–26
- 63. Relation Between FatigueLife of Wire Rope and Sheave Pressure Shigley’s Mechanical Engineering Design Fig.17–21
- 64. Fatigue of WireRope Fig. 17–21does not preclude failure by fatigue or wear It does show long life if p/Su is less than 0.001. Substituting this ratio in Eq. (17–42), Dividing both sides of Eq. (17–42) by Su and solving for F, gives allowable fatigue tension, Factor of safety for fatigue is Shigley’s Mechanical Engineering Design
- 65. Factor of Safetyfor Static Loading The factor of safety for static loading is Shigley’s Mechanical Engineering Design
- 66. Typical Strength ofIndividual Wires Shigley’s Mechanical Engineering Design
- 67. Service-Life Curve Basedon Bending and Tensile Stresses Shigley’s Mechanical Engineering Design Fig.17–22
- 68. Some Wire-Rope Properties Shigley’sMechanical Engineering Design
- 69. Working Equations forMine-Hoist Problem Shigley’s Mechanical Engineering Design
- 70. Working Equations forMine-Hoist Problem Shigley’s Mechanical Engineering Design
- 71. Working Equations forMine-Hoist Problem Shigley’s Mechanical Engineering Design
- 72. Example 17–6 Shigley’s MechanicalEngineering Design Fig.17–23
- 73. Example 17–6 Shigley’s MechanicalEngineering Design
- 74. Example 17–6 Shigley’s MechanicalEngineering Design
- 75. Example 17–6 Shigley’s MechanicalEngineering Design
- 76. Flexible Shaft Configurations Shigley’sMechanical Engineering Design Fig.17–24b
- 77. Flexible Shaft ConstructionDetails Shigley’s Mechanical Engineering Design Fig.17–24a