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Chapter 1

Chapter 12. Chapter 1. Drive Shaft Assembly Construction and Operation. Objectives. Explain the purpose of a drive shaft assembly. List the major parts of a typical drive shaft assembly. Explain the function and operation of a slip yoke.

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Chapter 1

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  1. Chapter 12 Chapter 1 Drive Shaft Assembly Construction and Operation

  2. Objectives • Explain the purpose of a drive shaft assembly. • List the major parts of a typical drive shaft assembly. • Explain the function and operation of a slip yoke. • Explain the function and operation of a universal joint.

  3. Objectives • Name and describe different types of universal joints. • Discuss Hotchkiss drive and torque-tube drive. • Describe the function of a center support bearing in a two-piece drive shaft. • Briefly explain the concept of drive shaft assembly angles.

  4. Drive Shaft Assembly • Drive shaft assembly (driveline) transfers power between transmission and rear axle assembly • Drive shaft assembly consists of: • Slip yoke • Front universal joint • Drive shaft • Rear universal joint

  5. Drive Shaft Assembly (Cont.) (General Motors)

  6. Drive Shaft Assembly (Cont.) • Slip yoke connects to transmission output shaft • Rear universal joint connects to differential through differential pinion yoke or flange • Balance weights reduce vibration

  7. Drive Shaft Assembly (Cont.) (Ford)

  8. Drive Shaft Assembly (Cont.) • Drive shafts come in many sizes • Length is measured from center of each yoke hole on drive shaft ends (General Motors)

  9. Drive Shaft Assembly (Cont.) • On late-model vehicles, front and rear axles move to keep chassis level • On rear-wheel drives, rear axle housing and both rear wheels move up and down in relation to chassis • Suspension system connects rear axle assembly to chassis

  10. Drive Shaft Assembly (Cont.) • Drive shaft angle and length must change to compensate for rear axle assembly movement • Flexible joints allow drive shaft assembly to flex or bend as rear axle assembly moves

  11. Drive Shaft Assembly Power Flow • Transmission to slip yoke • Slip yoke to front universal joint and into drive shaft • Drive shaft into rear universal joint • Rear universal joint into rear axle assembly

  12. Drive Shaft • Drive shaft, or propeller shaft, is central part of drive shaft assembly • Universal joints and other parts are attached to it • Drive shaft consists of steel tube with yokes welded or pressed on each end • Shaft is balanced when manufactured

  13. Slip yoke Used where drive shaft assembly enters rear of transmission Slides on transmission output shaft whenever rear axle assembly moves Slip Yoke (Ford)

  14. Steel tube with yoke at one end Yoke attaches to front universal joint Internal part of tube is splined May have damper (weight) to absorb vibration Slip Yoke (Cont.) (Ford)

  15. Universal Joints • Universal joints(U-joints) are swivel connections, or couplings, that allow drive shaft assembly to transmit power smoothly and constantly • Two basic types: • Cross-and-roller • Constant-velocity

  16. Cross-and-Roller U-Joints • Cross-and-roller U-joint • Used on most rear-wheel drives • Sometimes called Cardan U-joint or conventional U-joint

  17. Center cross (spider) Four cups containing needle bearings Cups are machined to fit into: Drive shaft yokes Slip yoke Differential pinion yoke Cup seals keep grease in cup and prevent entry of dirt and water Cross-and-Roller U-Joints (Cont.) (General Motors)

  18. Cross-and-Roller U-Joints (Cont.) (General Motors)

  19. Some U-joints can be greased Some U-joints are sealed at factory and cannot be greased unless disassembled Cross-and-Roller U-Joints (Cont.) (Chrysler)

  20. Cross-and-Roller U-Joints (Cont.) • Cups may be held in yokes in different ways (Dana)

  21. Some vehicles use injected plastic to hold cups in place Cross-and-Roller U-Joints (Cont.) (Dana)

  22. Cross-and-Roller U-Joints (Cont.) • Larger vehicles may use more complex U-joints (ArvinMeritor)

  23. Cross-and-Roller U-Joints (Cont.) • Conventional U-joint is almost always driving at an angle, causing drive shaft speed to rise and fall twice for every revolution • Range of speed fluctuation increases as joint angle increases

  24. Cross-and-Roller U-Joints (Cont.) • Fluctuation in drive shaft speed • Created at front U-joint • Canceled at differential pinion yoke by rear U-joint • When equal angles are formed by U-joint at transmission and drive shaft and U-joint at drive shaft and rear axle • Canceled if U-joints are aligned in phase

  25. CV Joints • Constant-velocity U-joints(CV joints) • Provide extremely smooth power transfer • Are more complicated than conventional U-joints • Are used by larger rear-wheel drive vehicles to further reduce vibration

  26. Double Cardan U-joint Vibration forces are cancelled within center yoke CV Joints (Cont.) (General Motors)

  27. CV Joints (Cont.) • Ball-and-trunnion U-joint • Not used on modern vehicles • Separate slip yoke not needed

  28. Rzeppa joint Ball bearings held by slotted cross assembly Ball bearings move up and down on cross as torque is transmitted through them Transmits power through changing angles CV Joints (Cont.) (Dana)

  29. CV Joints (Cont.) • Tripod joint • Resembles ball-and-trunnion U-joint, but uses three-pointed cross pin • Often used as inner bearing on front-wheel drives • Sometimes used on drive axles of rear-wheel drives with independent rear suspension

  30. Differential Pinion Yoke • Differential pinion yoke • Connects to drive pinion gear in rear axle assembly • Has internal splines that fit external splines on drive pinion gear shaft • Held to shaft by large locknut

  31. Differential pinion flange, or companion flange Two-piece yoke joined by mating flanges One flange holds rear U-joint, other connects to pinion gear Differential Pinion Yoke (Cont.) (Ford)

  32. Classes of Drive Shaft Assemblies • Hotchkiss drive • Used almost exclusively in late-model, rear-wheel vehicles • Torque-tube drive • Used on some makes of vehicles for many years, but now uncommon

  33. Hotchkiss Drive • Hotchkiss drive • Used with rear leaf springs • Salsbury drive • Used with coil springs (Fiat)

  34. Hotchkiss Drive (Cont.) • Variation of Hotchkiss drive: • Constant-velocity U-joint is used • Slip yoke is at rear of shaft • One spline is larger than others (Ford)

  35. Torque-Tube Drive • Torque-tube drive is designed to control rear-end torque • Drive shaft connects to transmission output shaft through U-joint • Other end of shaft connects to drive pinion gear through coupling or splined connection • U-joint at only one end

  36. Torque-Tube Drive (Cont.) • Drive shaft assembly can flex only at U-joint between transmission and drive shaft • Rear axle assembly moves up and down in arc as it pivots about U-joint • Distance between transmission and rear axle assembly is always the same, so no slip yoke is needed

  37. Two-Piece Drive Shaft • Two-piece drive shaft • Two drive shafts • Steel tubes with yokes on all four ends • Three universal joints • Identical to those on one-piece drive shaft • Drive shaft assembly angles are reduced at each U-joint, reducing vibration

  38. Two-Piece Drive Shaft (Cont.)

  39. Center support bearing keeps drive shafts aligned Slip yoke usually installed behind support bearing Some designs have two slip yokes Two-Piece Drive Shaft (Cont.) (Fiat)

  40. Two-Piece Drive Shaft (Cont.) • Two-piece drive shafts: • Were used when vehicle frame design prevented use of single drive shaft • Were discontinued during 60s and 70s except on large trucks and some long-bed pickups • Became common again with increased popularity of large SUVs

  41. Drive Shaft Assembly Angles • All rotating parts have axial centerline, or rotational axis • When rotating parts are coupled together, centerlines must be closely matched

  42. Drive Shaft Assembly Angles (Cont.) • Perfect alignmentis seldom achieved

  43. Drive Shaft Assembly Angles (Cont.) • Drive shaft assembly angle(also called operating angleor U-joint angle)

  44. Drive Shaft Assembly Angles (Cont.) • On front-engine, rear-wheel drive vehicles, drive shaft assembly angle exists between centerlines of: • Transmission output shaft and drive shaft • Drive shaft and drive pinion gear shaft

  45. Drive Shaft Assembly Angles (Cont.) • Angles are measured at front and rear U-joints • Manufacturer’s specification is usually about 1° or 2° • If angle is greater than specified: • Speed fluctuations of shaft tube increase • Shaft may have objectionable vibration • Joint can break

  46. Drive Shaft Assembly Angles (Cont.) • Angles are affected by: • Added weight to vehicle • Road surface condition • Vehicle acceleration or deceleration • Suspension system wear or alterations • Original angles must be kept as close as possible to specifications

  47. Review Questions To compensate for rear axle movement, the driveshaft ___ and ___ must change. Answer: angle, length

  48. Review Questions The ___ slides on the transmission output shaft whenever the rear assembly moves. Answer: slip yoke

  49. Review Questions True or False? A slip yoke has external splines. Answer: False. A slip yoke has internal splines.

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