1. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

2. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Basic transmission parts Purpose of a manual transmission Gear fundamentals Manual transmission construction (8 Topics)

3. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission types Transmission power flow Speedometer drive Manual transmission switches

4. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Input shaft Gears Synchronizers Shift forks Shift linkage Gear shift lever Output shaft Transmission case

5. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Basic Transmission Parts

6. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only A manual transmission is designed to change the vehicle’s drive wheel speed and torque in relation to engine speed and torque

7. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Features A manual transmission should: be able to increase torque to the drive wheels for quick acceleration supply different gear ratios to match load conditions provide a reverse gear provide an easy means of shifting gears operate quietly with minimal power loss

8. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gears are discs with teeth machined on their perimeters (rims) They transmit turning effort from one shaft to another When gears are different sizes, output speed and torque change

9. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Drive A small gear driving a larger gear increases torque and decreases speed

10. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Drive A large gear driving a smaller gear decreases torque and increases speed

11. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Ratio The number of revolutions a drive gear must turn before the driven gear completes one revolution Calculated by dividing the number of teeth on the driven gear by the number of teeth on the drive gear Gear Ratio =# of driven gear teeth # of drive gear teeth

12. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Ratio If the drive gear has 12 teeth and the driven gear has 24 teeth, the gear ratio is two-to-one Gear Ratio =# of driven gear teeth # of drive gear teeth =24 12 =2, written 2:1

13. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Ratio

14. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Gear Ratios First gearapproximately 3:1 Second gearapproximately 2:1 Third (high) gearapproximately 1:1 Reverse gearapproximately 3:1

15. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Reduction Occurs when a small gear drives a larger gear Increases turning force (torque) Used in lower transmission gears

16. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Overdrive Ratio Results when a larger gear drives a smaller gear Output gear speed increases Output torque is reduced

17. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Types Two gear types are commonly used in automotive transmissions: spur gears helical gears

18. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Spur Gears Somewhat noisy The teeth are cut parallel to the centerline of the gear shaft Used for sliding gears such as reverse gear

19. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Helical Gears The teeth are machined at an angle to the centerline Quieter and stronger than spur gears Used for main drive gears that are in constant mesh

20. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Types

21. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Backlash Distance between the meshing gear teeth Allows lubricating oil to enter the high-friction area between the gear teeth Allows the gears to expand during operation

22. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Manual Transmission Lubrication Bearings, shafts, and gears are lubricated by oil splash lubrication As the gears rotate, they sling oil around inside the transmission Typically, 80W or 90W gear oil is used

23. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Bearings Bearings reduce the friction between the surfaces of rotating parts Three basic types are used: ball bearings roller bearings needle bearings Used between shafts and housing, or between gears and shafts

24. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Bearings Three types of antifriction bearings are used

25. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

26. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Case Supports the bearings and shafts Provides an enclosure for gear oil Made of cast iron or aluminum A drain plug and fill plug are provided typically, the oil level should be level with the bottom of the fill plug hole at operating temperature

27. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Extension Housing Bolts to the rear of the transmission case Encloses the output shaft Holds the rear oil seal

28. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Front Bearing Hub Covers the front transmission bearing Acts as a sleeve for the release bearing

29. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Manual Transmission

30. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Shafts At least four shafts are commonly used: input shaft (clutch shaft) countershaft (cluster gear shaft) reverse idler shaft output shaft (main shaft)

31. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Input Shaft Transfers rotation from the clutch disc to the countershaft gears Anytime the clutch disc turns, the input shaft gear turns

32. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Countershaft Holds the countershaft gears into mesh with the input gear and other gears Located slightly below and to one side of the input shaft Normally, it is locked in the case and does not turn

33. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Reverse Idler Shaft Supports the reverse idler gear Allows the reverse idler gear to mesh with gears on both the countershaft and output shaft

34. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Output Shaft Holds the output gears and synchronizers Connects to the drive shaft to turn the wheels Gears are free to revolve on the shaft, but the synchronizers are locked on the shaft by splines

35. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Shafts

36. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Transmission Gears The input shaft gear turns the countershaft gears, which then turn the output shaft gears

37. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Gear Ranges Gear reduction Direct driveOutput shaft rotation is reversed

38. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Input Gear A machined part of the steel input shaft

39. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Countershaft Gear Several gears machined from a single piece of steel

40. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Reverse Idler Gear Assembly

41. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Output Shaft Gears

42. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Synchronizers Synchronizers have two functions: prevent the gears from clashing (grinding) during engagement lock the output gear to the output shaft

43. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Synchronizer Theory When the synchronizer is away from an output gear, the gear freewheels (spins freely) on the output shaft When the synchronizer slides against the output gear, it locks the output gear to the output shaft Power flows through the output shaft to the drive wheels

44. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Synchronizer Construction The hub is splined to the output shaft

45. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Synchronizer Operation When the driver shifts gears, the synchronizer sleeve slides on its splined hub toward the output gear The blocking ring cone rubs on the side of the drive gear cone, causing friction between the two The output gear, synchronizer, and output shaft begin to spin at the same speed

46. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Synchronizer Operation

47. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Synchronizer Operation As soon as the speed is equalized, the sleeve can slide over the blocking ring and spur gear teeth on the output gear This locks the output gear to the synchronizer hub and to the shaft Power flows through that gear to the drive wheels

48. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Synchronizer Operation

49. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Fully Synchronized Transmission All the forward output gears use a synchronizer Allows the driver to downshift into any lower gear (except reverse) while the vehicle is moving

50. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Shift Forks Transfer movement from the gear shift linkage to the sleeves

51. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Shift Fork Assembly Movement of the shift linkage moves the shift fork

52. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only External Shift Rod Linkage

53. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Internal Shift Rail Linkage

54. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Internal Shift Rail Linkage

55. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Column Shift Mechanism

56. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only There are several types: three-speed four-speed five-speed Some transmissions have an overdrive in high gear Extra gear ratios are needed for the small, low-horsepower engines

57. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

58. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only First Gear Linkage rods move the shift forks so that the first gear synchronizer is engaged to the first output gear The input shaft gear turns the countershaft gears First gear is locked to the output shaft A small gear on countershaft drives a larger gear on the output shaft The gear ratio is about 3:1

59. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only First Gear

60. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Second Gear The first gear synchronizer is slid away from the first gear The second-third synchronizer is then engaged Power flow is through the second gear on the output shaft The gear ratio is about 2:1

61. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Second Gear

62. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Third Gear The synchronizer is slid over the small teeth on the input shaft gear The synchronizer locks the input shaft directly to the output shaft All the output shaft gears freewheel on the shaft Power flow is straight through the transmission The gear ratio is 1:1

63. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Third Gear

64. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Reverse The synchronizer is moved into the reverse gear on the output shaft, locking the gear to the output shaft Power flows through the countershaft, reverse idler gear, reverse gear, and to the output shaft

65. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Reverse

66. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Neutral All the synchronizer sleeves are located in the center of their hubs All the output shaft gears freewheel on the output shaft No power is transmitted to the output shaft

67. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Neutral

68. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Overdrive In many transmissions, high gear is an overdrive An overdrive gear ratio is less than 1:1 e.g. 0.87:1 Overdrive increases fuel economy

69. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed, Overdrive Transmission

70. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed, Overdrive Transmission

71. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed, Overdrive Transmission

72. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed, Overdrive Transmission

73. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed, Overdrive Transmission

74. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed, Overdrive Transmission

75. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed, Overdrive Transmission

76. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Many transmission design variations are used by the numerous auto manufacturers Whether rear-wheel drive, front-wheel drive, or all-wheel drive, all transmissions use similar principles

77. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Five-Speed Transmission

78. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Front-Engine, All- Wheel Drive Vehicle

79. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only A worm gear on the output shaft drives the speedometer gear and cable The gear on the output shaft turns a plastic gear on the end of the speedometer cable The cable runs through a housing up to the speedometer head

80. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

81. © Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only Back-up Light Switch Closed by the action of the reverse gear shift linkage When shifted into reverse, the linkage closes the switch The switch carries current to the back-up lamps