1. SRI KRISHNA COLLEGE OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF MECHATRONICS ENGINEERING
Session: Introduction to Transmission
System
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MODULE 2
2. SESSION OBJECTIVES
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On the completion of this session, the students might
be able to understand,
Basic Necessity of a transmission system in Vehicle
How the transmission system provide tractive force
to the vehicle.
3. Topics
Function of Transmission system
Basic Necessity of transmission
Types of gears and Gear train
Types of transmission
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4. FUNCTION OF TRANSMISSION SYSTEM
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Introduction:
Engine is the only source to give
motive force to the vehicle
This will help the vehicle to move on
different driving conditions from start
up to high speed driving
It will ensure by transmission system
The transmission is actually a set of
gears which is used to transfer the
power developed in the engine to
the driving wheels according to the
requirement's.
5. FUNCTION OF TRANSMISSION SYSTEM
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Function of transmission system:
It transfer the engine output power
to the final driven gear from where it
is transmitted to the driving wheels
through the drive shaft (or propeller
shaft)
It provides sufficient torque
It provides low to high speed driving
capability
It is used to change the direction of
the wheel rotation
6. BASIC NECESSITY OF GEAR BOX
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Transmission Necessity :
CAD B
OA – Stabilizing speed
7. TYPES OF GEARS
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Introduction:
Gears are toothed wheels that
transmit power between the shafts.
The teeth my be cut on the edge on
the wheel on the side or inside.
To transmit power, a gear on one
shaft is meshed with gear on
another shaft.
The meaning of mesh is that the
teeth of a gear fit into the space
between the teeth on the another
gear
8. TYPES OF GEARS
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Introduction:
When one gear turns, then it’s teeth
forces the other gear to turn.
The gear that does the turning is the
driving gear.[A - Gear]
The gear that is forced to turn is the
driven gear.[B – Gear]
9. TYPES OF GEARS
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Types of Gears: Spur Gears
The spur gears are the most
common type of gears.
These gears have teeth parallel to
the axis of wheel
10. TYPES OF GEARS
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Types of Gears: Helical Gears
It is very similar to spur gears.
Gears having teeth inclined to the
axis of the wheel
Angle of teeth give gears more tooth
contact in the same area.
Also used to transmit power between
non parallel shaft.
Running is quitter and smoother
than spur gears.
This is Due to the increased number
of teeth in constant contact at any
one period of time.
11. TYPES OF GEARS
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Types of Gears: Herringbone gears
Double helical gears are known as
herringbone gears.
The herring bone gear resemble two
helical gears that have been placed
side by side
Advantage: To eliminate side thrust
issues in helical gears.
12. TYPES OF GEARS
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Types of Gears: Bevel Gears
The Bevel gears are used mostly in
situations that require power to be
transmitted at right angles.
The bevel gears can have different
angle of application but tend to be
90o.
13. TYPES OF GEARS
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Types of Gears: Worm Gears
The worm gears are used to transmit
power at 90o and where high
reduction are required.
It simply resembles a thread that
rides in concave or helical teeth.
Worm Gear
Worm Wheel
14. TYPES OF GEARS
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Types of Gears: Rack & Pinion gears
A rack & Pinion gear is basically used
to transmit power and motion in a
linear movement.
15. TYPES OF GEARS
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Types of Gears: Planetary Gears
The planetary gears consist of one or
more outer gears, revolving about a
central gear (or sun gear).
Typically, the planet gears are
mounted on a movable arm which
itself may rotate relative to the sun
gear.
The planet gear systems also
incorporate the use of an outer ring
gear, which meshes with planet
gears.
16. TYPES OF GEARS
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Gear Ratio:
The gear ratio’s are used to express the mathematical relationship between
the gears.
The actual operation performed by the gear lever in an automobile is to
change the gear size
𝐺𝑒𝑎𝑟 𝑅𝑎𝑡𝑖𝑜 =
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑜𝑛 𝑡ℎ𝑒 𝑑𝑟𝑖𝑣𝑒𝑛 𝑔𝑒𝑎𝑟
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑜𝑛 𝑡ℎ𝑒 𝐷𝑟𝑖𝑣𝑒 𝑔𝑒𝑎𝑟
17. TYPES OF GEARS
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Gear Ratio:
When a larger gear is driven by a smaller gear, the speed of rotation on the
driving gear is reduced on the driven gear while the torque is increase
contrarily.
18. TYPES OF GEARS
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Gear Ratio:
When a small gear is driven by the larger gear, the result will be a decrease in
torque and an increase in speed.
19. TYPES OF GEAR TRAIN
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Gear Train:
Sometimes two or more
gears are made to mesh
with each other to
transmit power.
This is called Gear train
Types of gear train:
Simple Gear train
Compound gear train
20. TYPES OF GEAR TRAIN
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Simple Gear Train:
When there is only one gear on each shaft is known as simple gear train
In here the motion of the driven gear is opposite to the motion of the driving
gear.
21. TYPES OF GEAR TRAIN
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Simple Gear Train:
Speed ratio :
Ratio of the speed of the driving
gear to the speed of the driven
gear and this ratio is inversely
related to the teeth on each
gears.
𝑆𝑝𝑒𝑒𝑑 𝑅𝑎𝑡𝑖𝑜 =
𝑆𝑝𝑒𝑒𝑑 𝑜𝑓 𝑓𝑖𝑟𝑠𝑡 𝑑𝑟𝑖𝑣𝑒𝑟
𝑆𝑝𝑒𝑒𝑑 𝑜𝑓 𝑡ℎ𝑒 𝑑𝑟𝑖𝑣𝑒𝑛
=
𝑁𝑜. 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑜𝑛 𝑑𝑟𝑖𝑣𝑒𝑛
𝑁𝑜. 𝑜𝑓 𝑇𝑒𝑒𝑡ℎ 𝑜𝑛 𝑑𝑟𝑖𝑣𝑒𝑟
𝑁1
𝑁2
×
𝑁2
𝑁3
=
𝑇2
𝑇1
×
𝑇3
𝑇2
𝑁1
𝑁3
=
𝑇3
𝑇1
22. TYPES OF GEAR TRAIN
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Compound Gear Train:
When there are more than one
gear on a shaft it is called a
compound Train of Gear.
𝑆𝑝𝑒𝑒𝑑 𝑅𝑎𝑡𝑖𝑜 =
𝑆𝑝𝑒𝑒𝑑 𝑜𝑓 𝑡ℎ𝑒 𝑓𝑖𝑟𝑠𝑡 𝑑𝑟𝑖𝑣𝑒𝑟
𝑆𝑝𝑒𝑒𝑑 𝑜𝑓 𝑡ℎ𝑒 𝑙𝑎𝑠𝑡 𝑑𝑟𝑖𝑣𝑒𝑛 𝑜𝑟 𝑓𝑜𝑙𝑙𝑜𝑤𝑒𝑟
=
𝑃𝑟𝑜𝑑𝑢𝑐𝑡 𝑜𝑓 𝑡ℎ𝑒 𝑁𝑜. 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑜𝑛 𝑑𝑟𝑖𝑣𝑒𝑛𝑠
𝑃𝑟𝑜𝑑𝑢𝑐𝑡 𝑜𝑓 𝑡ℎ𝑒 𝑁𝑜. 𝑜𝑓 𝑇𝑒𝑒𝑡ℎ 𝑜𝑛 𝑑𝑟𝑖𝑣𝑒𝑟𝑠
𝑁1
𝑁2
×
𝑁3
𝑁4
=
𝑇2
𝑇1
×
𝑇4
𝑇3
𝑁1
𝑁4
=
𝑇2 × 𝑇4
𝑇1 × 𝑇3
23. TYPES OF GEAR TRAIN
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Compound Gear Train: Advantage
Compare to simple gear train much
larger speed reduction is achieved
But simple gear require large size
gear at last for large speed reduction.
24. TYPES OF TRANSMISSION
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Epicyclic or planetary
Type
Selective Type Progressive Type
Types of transmission:
Sliding Mesh
transmission
Constant mesh
Transmission
Synchromesh
transmission
25. TYPES OF TRANSMISSION
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What is selective type transmission :
Any speed may be selected from the neutral
position.
Forward & Reverse gear always starts from
Neutral gear.
Constant Mesh
Sliding Mesh
SYNCHROMESH
26. TYPES OF TRANSMISSION
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What is Progressive type transmission :
It is used in motor cycles
The gears pass through the intervening
speeds while shifting one speed to another.
There is neutral position between two gear
positions
NEUTRAL
NEUTRAL
NEUTRAL
1234
27. TYPES OF TRANSMISSION
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What is Epicyclic or Planetary transmission :
An Epicyclic transmission consists of two
Epicyclic or planetary gear sets.
28. TYPES OF TRANSMISSION
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Sliding Mesh Gear box : Neutral condition
Simplest type of transmission
Name suggests by gears are changed by sliding one gear on the other.
Main shaft not rotate on neutral condition – No power Transmission to wheels
29. TYPES OF TRANSMISSION
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Sliding Mesh Gear box : First Gear condition
The direction of rotation of main shaft is same as that of the clutch shaft.
Main shaft larger gear & Counter shaft smaller gears are meshed
Hence speed reduction is 3:1.
At differential on wheel side achieved as 12:1.
30. TYPES OF TRANSMISSION
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Sliding Mesh Gear box : Second gear condition
The direction of rotation of main shaft is same as that of the clutch shaft.
Main shaft smaller gear & Counter larger gears are meshed
Hence speed reduction is 2:1.
At differential on wheel side achieved as 8:1.
31. TYPES OF TRANSMISSION
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Sliding Mesh Gear box : Third gear condition
The main shaft is slided axially towards the clutch shaft
So that main shaft is directly connected to the clutch shaft.
Main shaft & Clutch shaft runs at same speed.
Speed reduction at gear 1:1 & at differential 4:1
32. TYPES OF TRANSMISSION
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Sliding Mesh Gear box : Reverse gear condition
The larger (reverse) gear of the main shaft meshes with the reverse idler
gear.
The reverse idler gear is always connected to reverse gear on counter shaft.
Idler gear causes the main shaft rotates in opposite direction.
33. TYPES OF TRANSMISSION
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Sliding Mesh Gear box :
Advantages :
It is simple in construction
It has low cost
The mechanical efficiency of sliding mesh gear box is very high
Disadvantage:
The gear noise is very high due to the type of gears (i.e spur gears)
It is difficult to obtain a smooth, quiet and quick change of gears.
34. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : Neutral condition
Drive and driven gear combination for each speed, are constantly engaged
with each other.
It will happen even in the neutral position, all gear combination are in mesh
and turning
No power transmitted, because of gears on main shaft has freely rotate on
main shaft.
35. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : First Gear
Dog clutches can be slided to achieve the power flow.
The axial motion of dog clutch can achieved by providing the splines on main
shaft.
D2 moves left & engage with Gear E to transfer power to wheels through
Main shaft
Power Flow: A-B-
Layshaft-F-E-D2-
Mainshaft.
36. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : Second Gear
D1 moves right & engage with Gear D to transfer power to wheels through
Main shaft
37. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : Third Gear
D1 moves left & engage with Clutch Gear A to transfer power to wheels
through Main shaft
Power Flow : A-D1-Main shaft
38. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : Reverse Gear
D2 moves Right & engage with Gear I to transfer power to wheels through
Main shaft
Power Flow : A-B-Layshaft-G-H-I-D2-Mainshaft.
39. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION :advantage
These have high Mechanical efficiency.
It has helical gears, very quiet power transmission is achieved.
Constant mesh ensure the safeness of gear from damage
Disadvantage:
Dog clutch produce noise & jerk.
40. TYPES OF TRANSMISSION
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CONSTANT MESH
TRANSMISSION : Double
Declutching
Smooth engage of dog
clutches should achieved
for good transmission.
For this speed of the
main shaft gear & the
sliding dog must be
equal.
This requires double
declutching.
41. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : Double Declutching – Working
Clutch is disengaged (First Declutching) and the gear system is brought to
neutral position.
42. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : Double Declutching – Working
Clutch is engaged and accelerator pedal is pressed to increase the speed of
main shaft gears.
43. TYPES OF TRANSMISSION
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CONSTANT MESH TRANSMISSION : Double Declutching – Working
Clutch is disengaged once again (i.e., second declutching). The gear is
moved to the required lower gear and the clutch is engaged.
In this process, the clutch is disengaged twice, therefore, it is called as
double declutching
44. TYPES OF TRANSMISSION
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SYNCHROMESH TRANSMISSIONS :
Kind of constant Mesh transmission
Gears on the main shaft are constant
mesh with gears on lay shaft
The gears on the counter shaft are
fixed where as the gears on the main
shaft are free to rotate on the same
Here instead of Dog clutch, a special
mechanism used called synchromesh
mechanism.
Which is used frictional force during
shifting to mesh the to different
gears rotate at different speed.
45. TYPES OF TRANSMISSION
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SYNCHROMESH
TRANSMISSIONS :
PRINCIPLE
Bringing to the
neutral state: For gear
changing from 3rd to 4th
The clutch is
disengaged to stop
power flow from
the engine
46. TYPES OF TRANSMISSION
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SYNCHROMESH
TRANSMISSIONS :
PRINCIPLE
Start of
synchronization:
The sleeve move
on shifting direction
And strut also
move on same
direction
It forces the ring
into the cone shape
of Gear portion.
47. TYPES OF TRANSMISSION
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SYNCHROMESH
TRANSMISSIONS :
PRINCIPLE
Midway through
synchronization:
Further movement
make the sleeve to
over come the
force of spring
It means sleeve &
projection of key
will disengaged
48. TYPES OF TRANSMISSION
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SYNCHROMESH
TRANSMISSIONS :
PRINCIPLE
End of
synchronization:
The sleeve directly
pushes
synchronizer ring
without key
operation
The ring is strongly
pressed to the third
gear cone part with
great friction
49. TYPES OF TRANSMISSION
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SYNCHROMESH
TRANSMISSIONS :
PRINCIPLE
End of
synchronization:
Now the speed of
the hub sleeve and
the gear becomes
equal.
Results in hub
sleeve splines mesh
with the
synchronizer ring
splines.
50. TYPES OF TRANSMISSION
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SYNCHROMESH
TRANSMISSIONS :
PRINCIPLE
End of shift change:
After the hub
sleeve spline
meshes with
synchronizer ring
splines
Now the hub sleeve
moves further and
meshes with the
gear spline.
51. TYPES OF TRANSMISSION
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FLUID COUPLING:
It is called us
Hydrodynamic Device
Used to transmit
rotating mechanical
power
And an alternative to
Clutch.
Fluid coupling
performs the transfer
of torque in a fashion
which is similar to the
transfer of motion by
fans.
52. TYPES OF TRANSMISSION
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FLUID COUPLING:
Flow of air at outside fan B still
possesses a considerable
amount of energy
And if ducts are used to
redirect this air flow to rear of
the vanes in fan A.
Then the rotation of that fan
will be assisted and torque will
be increased.
53. TYPES OF TRANSMISSION
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FLUID COUPLING: Like Mechanical
Clutch
The pump is typically connected to
the fly wheel of the engine.
The turbine is connected to the input
shaft of transmission
The torque is transferred from the
engine to transmission system with
the help of fluid motion for propelling
the vehicle.
54. TYPES OF TRANSMISSION
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FLUID COUPLING: Construction of
Fluid coupling
Pump : Called as driving impeller,
which will be mounted over the
input shaft.
Turbine : Driven impeller which
will be mounted over the output
shaft.
Housing: Provide the oil tight seal
& Protect the Pump & Turbine
55. TYPES OF TRANSMISSION
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FLUID COUPLING: Working
No mechanical interconnection b/n
Rotor & Impeller.
Power transmitted by the virtue`
of fluid filled in the coupling
Engine drives the impeller, which
imparts the velocity & energy to
the fluid.
Thus will converted into Mechanical
energy in the rotor thus rotating it.
56. TYPES OF TRANSMISSION
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FLUID COUPLING: Working
The fluid flows a closed circuit of flow from impeller to rotor through the air
gap at the outer periphery.
57. TYPES OF TRANSMISSION
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FLUID COUPLING: Working
And then from the rotor to the impeller through the inner periphery.
58. TYPES OF TRANSMISSION
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FLUID COUPLING: Working
As the slip increases more & more fluid can be transferred from the impeller
to the rotor and more torque is transmitted.
𝑆𝑙𝑖𝑝 =
𝐷𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 ℎ𝑒𝑎𝑡 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑡ℎ𝑒 𝑟𝑜𝑡𝑜𝑟 & 𝐼𝑚𝑝𝑒𝑙𝑙𝑒𝑟
𝐷𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑜𝑓 𝑠𝑝𝑒𝑒𝑑 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑟𝑜𝑡𝑜𝑟 & 𝐼𝑚𝑝𝑒𝑙𝑙𝑒𝑟
59. TYPES OF TRANSMISSION
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Torque Converter:
Type of fluid coupling
It increase the torque of
the vehicle by reducing
the speed.
Provides continuous
variation from low to
high.
Key characteristic –
Ability to multiply torque
when there is a
substantial difference
b/n input & output
rotational speed.
60. TYPES OF TRANSMISSION
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Torque Converter:
It is equivalent of a reduction gear.
Helps to automatic transmission to
disengage transmission to change
gear
61. TYPES OF TRANSMISSION
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Torque Converter: Stator
The stator is located b/n
Pump & Turbine.
Modified the direction of
fluid comes out from
turbine
Prevent hard impact of
Pump impeller
The stator vanes catches
the fluid from turbine &
redirects to the pump
impeller, for giving the
added torque
62. TYPES OF TRANSMISSION
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Torque Converter: Stator
The stator is mounted to
the stator shaft, which is
fixed to the transmission
case.
One way clutch mounted
to the stator allows it to
rotate in the same
direction as the engine
crank shaft
Because of the fluid flow,
if the stator rotates in
fluid direction, it will stop
by one way clutch
63. TYPES OF TRANSMISSION
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Automatic
Transmission:
Most advanced system
Reduce the mechanical
efforts very much
Different speeds are
obtained automatically.
Called as hydramatic
transmission.
It contains Epicyclic
gear arrangement, Fluid
Coupling and torque
converter.
64. TYPES OF TRANSMISSION
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Automatic Transmission:
Planetry gearing:
Consists of one or more
outer gears, or planet gears
revolving about a central
Gear.
Different torque ratio can
achieved
Very compact
65. TYPES OF TRANSMISSION
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Automatic Transmission: Working
Planetry gear set contains 2 Input
& One output
Input one – Ring Gear
Input Two – Sun gear
Output – Connected to Planet
carrier, which hold the planet Gear.
66. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Now Ring gear is stationary
Sun gear is rotating, causes the
Planetry gear to rotate
Transmit the power to the
output shaft to drive the wheel.
67. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Now Ring gear is also Rotates.
Planet gears revolves & Spin
So, the output speed further
increases.
68. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Now Ring gear & sun gear
rotates at same speed.
Whole mechanism moves as
a single unit.
Planet gear do not spin, But
revolves around sun gear.
Output speed = Input speed
69. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Ring gear speed is further
increased.
It cause the output speed to
increase more
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Automatic Transmission:
Working
Now sun gear rotates in
opposite direction
Reverse gears occurred.
The operation of automatic
transmission is all about
the different rotational
speed of ring & sun gear.
71. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Clutch packs C1 & C5
used for transmitting
power.
Clutch packs External
teeth connects case &
Internal teeth connects
hub.
Intermediate shaft is
used for connects input
shaft & output shaft.
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Automatic Transmission:
Working
By Engaging C1 & C5,
First gear will engage.
73. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
For increasing the gear
ratio, New Planetry gear
will add with C4.
The second planet carrier
permanently contact with
first one.
Input drives both sun
gear at speed of it
Planet carrier
permanently connect
with first one.
74. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
By enabling the C1 &
C4,the gear two will
occur
This cause the first ring
Gear to rotate.
Gear 2 will occur
75. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Planet carriers always
connect with hollow
shaft.
The hollow shaft engage
by C2 with housing.
For direct drive the ring
& sun gear should rotate
at same speed of input
shaft.
76. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
By engaging the C1 &
C2, the Fourth gear will
occurred.
77. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Input rotational is given
to planet carrier & Ring
gear will stationary.
By enabling the C2 & C4
can achieve the over
drive called 6th gear.
78. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
For achieving remaining
gears, additional
planetary gears are
added (Set 3)
In set 3, the C3 will lock
the 3rd ring gear & driven
the set 2, set 1
By enabling C1 & C3, the
third gear will occur.
79. TYPES OF TRANSMISSION
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Automatic Transmission:
Working
Now C2 & C3 applied for
Gear 5.
80. TYPES OF TRANSMISSION
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Automatic Transmission: Stages
Park(p): Lock the transmission,
restrict the vehicle from moving
Reverse(R): selecting it to allow it
reverse the car.
Neutral(N): Disconnects the
transmission from wheel
Low(L): Selecting it allow you drive
in lower speed ratio – It required in
drive the vehicle in hilly/Midway
areas
Drive(D): By selecting it allow the
vehicle to move and accelerate
through a range of gears
81. TYPES OF TRANSMISSION
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Manual Transmission vs Automatic Transmission
Manual Transmission Automatic Transmission
Cheaper Costlier than manual transmission
Better fuel economy, because of better
mechanical & gear train efficiency
Not have the better fuel economy, because
of not have the better gear train &
mechanical efficiency
It requires more driver control Does not offer more driver control