1. The document discusses various components of automobile transmission systems including the clutch, gearbox, driveshaft, differential, and rear axle. It describes the purpose and basic workings of components like the clutch, constant mesh and synchromesh gearboxes, torque converter, and limited-slip differential. 2. Various types of clutches, gearboxes, differentials, and rear axle designs are defined and compared, including single plate, multi-plate, and cone clutches. Manual, automatic, and hydromatic gearboxes as well as live and dead rear axles are also covered. 3. The key functions of the transmission system are to connect or disconnect the engine from the wheels, reduce engine

1. UNIT-III
TRANSMISSION SYSTEMS

2. Transmission System
• Transmission System is the system by means
of which power developed by the engine is
transmitted to road wheels to propel the
vehicle.
• In Automobile the power developed by the
engine which is used to turn wheel. Therefore
the engine is connected to the transmission.

3. Transmission Arrangement

4. Purpose of Transmission system
• It enables the running engine to be connected
or disconnected from the driving wheel
smoothly and without shocks.
• It enables the reduction of engine speed.
• It enables the driving wheels to driven at
different speeds.

5. CLUTCH
Characteristics of a clutch
• Transmission of torque
• Gradual engagement
• Dissipation of heat
• Dynamic balancing
• Vibration damping
• Size of the clutch
• Free pedal clutch play
• Non-exertive operation of disengagement

6. Clutch
• Clutch is a mechanism used to connect or
disconnect the engine from the rest of
transmission elements.
• It is located between engine and gear box.
• During normal running and stationary
position, it is always in engaged condition.
• It is always in engaged condition.

7. Principle of Operation of friction clutch

8. TYPES OF CLUTCH
1. Friction clutch
a) single plate clutch
b)Multi plate clutch
• Wet type
• Dry type
c) cone clutch
2. Centrifugal clutch
3. Semi centrifugal clutch
4. Coil pressure spring clutch
5. Conical spring clutch or diaphragm clutch
a) Tapered
b) Crown spring
6. Positive clutch- dog and spline clutch
7. Hydraulic clutch

9. Single plate clutch

10. Single plate Clutch
• It is most commonly used in motor vehicle
such as cars, trucks and tractors.
• Various parts of Single plate Clutch-
1. Fly wheel.
2. Pilot Bearing.
3. Clutch plate.
4. Pressure plate.
5. Clutch cover assembly.

13. Multi-plate Clutch
• Multi-plate clutch are used in heavy vehicles
racing cars and motorcycles for transmitting
high torque.
• They are smooth and easy to operate due to
their assembly of friction surface’s contact.
• This clutch are of two types wet type and dry
type.

14. MULTI PLATE CLUTCH

15. Multi-plate clutch
• The wet type clutch plate are oil immersed
clutch this types of wet clutches are generally
used in conjunction with a part of automatic
transmission.
• advantages –
1. It is highly reliable.
2. It is suitable for heavy vehicles.
3. Increased torque transmission capacity could
be obtained .

16. Cone clutch
• The cone surface of this type of clutch are in
form of cone. It is called cone clutch.
• It consist of two cones having two leather
facing.
• This cones are known as male and female
cone.
• One cone is fixed to the driving member and
other cone is fixed to the splined driven shaft.

17. CONE CLUTCH

18. Cone clutch
Advantages-
• Normal force acting on the contact surface is
larger than the axial force which reduces the
effort required to operate the clutch.
Disadvantages-
• If the angle of cone is smaller than 20’, the
male cone tends to bind or joint in the female
cone.

19. Centrifugal clutch
• Centrifugal clutch is controlled by the engine
speed through an accelerator. When the
speed decrease the clutch gets disengage.
• When the speed rises above the
predetermined value the clutch is engaged.
Greater is the centrifugal force due to higher
engine speed, more will be powerful contact.

20. CENTRIFUGAL CLUTCH

21. Semi centrifugal clutch
• In this clutch plate the pressure between
plates is increased as the speed of rotation of
the clutch in proportional to the pressure
requirements.
• As speed increases, the rotating weights will
tend to move the pressure plate towards the
flywheel.

22. • The ends of release levers are also moved
back against the throw out bearing along with
this movement of the pressure plate.

23. SEMI CENTRIFUGAL CLUTCH

24. DIAPHRAGM CLUTCH

25. POSITIVE CLUTCH OR DOG AND SPLINE
CLUTCH

26. HYDRAULIC CLUTCH

27. ELECTROMAGNETIC CLUTCH

28. Gear box
• Gear box is a speed and torque changing
device. It changes speed and torque between
engine and driving wheels.
• More power is required to keep an
automobile in motion when compared to
power required for keeping it rolling after
starting.

29. Gear box
• Necessity of Gear box-
When the vehicle is running, various
resistance oppose it. In order to keep vehicle
moving at uniform speed , a driving force or
tractive effort is equal to the sum of all opposing
force.

30. Purpose of transmission
• It helps the engine to disconnect from driving
wheels.
• It helps the running engine to be connected to
the driving wheel smoothly and without
shock.
• It provides the leverage between engine and
driving wheels to be varied.
• It helps the driving wheels to be driven at
different speed.

31. Tractive effort
• The torque available on the wheel produce a
driving force which is parallel to the end known
as tractive effort.

32. GEAR BOX
TYPES OF GEAR BOX
1.Manual transmission
a) Sliding mesh gearbox
b) Constant mesh gear box
c) Synchromesh gear box
2. Epicyclic gear box
3. Automatic gear box
a) Hydromatic gear box
b) Torque converter gear box

33. Sliding mesh Gear Box
• Sliding mesh gear box is a transmission system
that consist of various sets of gears and shafts
that are arranged together in an organized
fashion and the shifting or meshing of
different gear ratios is done by the sliding of
gears towards right and left over the splined
shaft with the help of a gear lever operated by
the driver.

34. Need of sliding mesh transmission
• Fuel consumption of an automobile increased
as the load on the engine is decreased.
• Due to varying torque ratio provided by this
gearbox, the automobile vehicle is made to go
to the hill stations which is possible earlier.
• Reverse of the car made possible with the
introduction of this transmission system.

35. Sliding mesh gear box

36. First Gear

37. Second Gear

38. 3rd gear

39. 4th gear

40. Application
• Alfa 12HP used sliding mesh gearbox with 4 -
speed manual transmission.
• Fiat 6HP used 3-speed manual transmission.
• Mercedes 35HP used 4-speed manual
transmission
• Renault Voiturette used manual 3-speed
transmission.

41. Constant Mesh Gear Box
• Constant Mesh Gearbox is type of transmission in
which all or most of the gears are always in mesh
with one another, as opposed to a sliding gear
transmission, in which engagement is obtained by
sliding some of the gears along the shaft into
mesh.
• In constant mesh gear box, Gear ratios are
selected by the small clutches that are connect
the various gear sets to their shaft so power is
transmitted through them.

42. Constant mesh gear box

47. Constant mesh gear box

48. Synchromesh Gear Box
• To simplify the operation of changing of gear
without the occurrence of clashes and their
consequent damage, synchromesh is used in
different motors.
• The main feature of this gear box is
The main shaft or output gear is freely
rotated on the bushes of the output shaft.

49. Advantages and Disadvantages
• Gear Changing is very much simplified.
• Less wear in gear.
• It allows the usage of helical gear that run
directly.
Disadvantages
The design is very much complex.

50. Automatic Gear Box
• Various speed are obtained automatically in
gear boxes are known as automatic gear box,
generally the driver selects the car condition
such as neutral , forward or reverse.
• Such Gear box are of two types
• Hydramatic Transmission.
• Torque convertor transmission.

51. AUTOMATIC GEARBOX
HYDROMATIC TRANSMISSION

52. First Gear
• The power transmitted from the flywheel to
the torus covers, then to the internal gear and
to the planet cage with the sun gear when the
front unit is locked thus the engine is running.
• The planet cage usually moves around the
stationary sun gear with reduced speed. The
power is transmitted by the cage to the
driving torus through the front section of the
intermediate shaft.

53. Second Gear
• The power is first transmitted to the torus
covers and then to the locked front unit from
the flywheel.
• The front section of the intermediate shaft
transmit the power directly to the fluid
flywheel. Then it is transmitted back to sun
gear of the rear section.

54. Third gear
• Now the gear is 1.45 :1, similarly the front unit
is engaged, the planet cage is driven by the
driven internal gear.

55. Fourth Gear
• The direct Drive is obtained by controlling the
transmission in the front unit.
• The power is transmitted from the flywheel
through the torus covers to the locked front
unit. Now the power is transmitted from the
flywheel through the torus covers to the
locked front unit. The power is transmitted in
two paths.

56. Shift or Selector Mechanism
• For Gear Changing and selecting a particular
gear train to operation, the selector
mechanism is implemented to obtained the
same easier.
• In this case, the gear are shifted by a gearshift
Lever. In Manually operated selective
transmission system, the gear shift lever is
mounted either on the steering column or
floor board.

57. SHIFT OR SELECTOR MECHANISM
(a) FLOOR MOUNTED SHIFT MECHANISM

58. (b) MECHANISM WITH GEAR LEVER AS STEERING
COLUMN

59. Over drive Mechanism
• In this the high gear mechanism produces 1:1
ratio Between clutch gear and transmission
output shaft.
• There is neither gear reduction nor gear
increase through the Transmission. It is the
direct drive.
• It produces the high cruising speed with
comparative low engine speed.

60. Over drive Mechanism
• The shift to overdrive can be obtained when
the car is running above a predetermined cut
in speed from 32 to 51 km/hr by lifting the
foot momentarily from the accelerator. The
action of the overdrive is controlled by a
centrifugally operated switch.

61. OVERDRIVE MECHANISM

62. Transfer Box
• Transfer Box is a part of a four wheel drive
system used in four wheel drive or all wheel
drive vehicles. It is also called as transfer gear
case.
• Function of Transfer Gear box-
1. It receives power front the transmission and
sends to both front and rear axles.
2. It provides low and high range of speed.

63. TRANSFER BOX

64. Transfer Box
• Type of transfer Box-
• Gear driven type transfer box.
• Chain driven type transfer box.
• Housing type gear box.
• Transfer case shift typee.

65. Fluid flywheel
• It is also known as fluid clutch, which couples
the driving members with driven member
through the media of fluid.
• Advantages-
• It is simple design.
• No need of adjustment is required.
• No skill is required for operation.

66. FLUID FLYWHEEL

67. Torque convertor
• The only difference is that it has an additional
stationary member called ‘ Stator or reaction
member”.
• But the operation is not similar. In the case of
flywheel, the same torque is transmitted as
given by the engine shaft.

68. Torque Convertor
• Single stage torque convertor-
1. Impeller or driving member- This is driving
member is connected to the engine.
2. Turbine or Driven member- This driven
member is connected to the road wheels
through the transmission gears and the drive
line and
3. Stator- It is connected to the frame through a
free wheel.

69. TORQUE CONVERTER

71. UNIVERSAL JOINTS

72. Propeller Shaft
• The propeller Shaft is connected between
transmission shaft (i.e. gear box output shaft and
pinion shaft) of the differential at the wheel axle.
• The propeller shaft also called as driveline shaft
or drive shaft.
• The propeller shaft takes power from the engine
and a transmits to clutch, transmission gear box
unit and driving wheels of the vehicle through the
final drive and differential units.

73. PROPELLER SHAFT

74. SLIP JOINTS

75. Differential
• Differential is a system that transmits an
engine’s torque to the wheels. The differential
takes the power from the engine and splits it,
allowing the wheels to spin at different
speeds.
• Major Components of differential-
1. Drive pinion or bevel pinion.
2. Ring Gear or Crown wheel.
3. Differential Case.
4. Differential side gear or Sun gears.

76. Type of Differential
• Conventional Differential.
• Limited Slip Differential.
• Non Slip Differential.
• Double Reduction differential

77. DIFFERENTIAL

78. DIFFERENTIAL

79. Limited Slip Differential or Self Locking
Differential

80. Non Slip Differential
• The differential is a torque controlled
differential. Preloading the system is possible.
• The Differential is operated by resultant
moments. Preload can be adjusted.
Advantages-
I. Maximum Traction can be achieved for all
grip levels.
II. Fuel Consumption is reduced.

81. Non Slip Differential

82. Rear Axle
• The power transmitted through rear axle to
driving wheels. On Modern passenger cars
almost all rear axles are live axles.
• It includes revolving shafts for driving wheels.
In ordinary cars, the live axle will be at the
front and the rear axle will be dead which
simply remains stationary.

83. Rear Axle
• All live axle shafts are splitted into two parts in
modern cars. Each part is driven by one of the
differential gears through a spline connection.
• Types of Rear Axle-
1. Dead Axle.
2. Live Axle.

84. CONSTRUCTION OF REAR AXLES

85. TYPES OF REAR AXLES
(i) SEMI FLOATING AXLE

86. (ii)FULL FLOATING AXLE

87. (iii) THREE QUARTER FLOATING AXLE

88. REAR AXLE DRIVES
(i) HOTCHKISS DRIVE

89. (ii) TORQUE TUBE DRIVE