unit 1.pptx

ELECTIVE – III
AUTOMOBILE ENGINEERING
Prepared By
Prof. A.D. Dharmadhikari
MTech (Automotive Technology), B.E (Mechanical)
1

Vision of the Mechanical Department
“To be regionally, nationally and internationally recognized center of
excellence in all fields of Mechanical Engineering education where
the best of teaching- learning, state of-art research and consultancy
synergize.”
Mission of the Mechanical Department
• To inculcate basic Mechanical Engineering knowledge to students
through effective teaching–learning practices.
• To encourage students for higher studies, research and
entrepreneurship.
• To cater the needs of society in context of Mechanical Engineering
2

TEXT BOOKS:
1. Automobile EngineeringVol. I & II, Kirpal Singh, Standard Publishers.
2. Automotive Mechanics, Joseph Heitner, EastWest Press.
3. Automobile Engineering, R.K.Rajput, Laxmi Publications.
4. Automobile Engineering R.B. Gupta, Satya Prakashan New Delhi
5. Course in Automobile Engineering, Sharma R. P, Dhanpat Rai and Sons.
6.Automobile Engineering, Ramakrishna, PHI Learning Pvt. Ltd.
REFERENCE BOOKS:
1. Automobile Mechanics, Crause,W.H.,Tata McGraw Hill.
2.Vehicle and EngineTechnology, Heinz Heisler,Arnold London.
3. Automotive Engines, Srinivasan S.,Tata McGraw Hill.
4. MotorVehicleTechnology, J.A. Dolan, Heinemann Educational Books.
5. Automobile EngineeringVol. I, II & III, P. S. Gill, Kataria and Sons.
6. Automobile Engineering, K.K. Jain, R.B.Asthana,Tata McGraw Hill.
1
6

What is an ‘Automobile’??
• A vehicle producing power within itself for its
propulsion is known as a Self propelled vehicle.
• Eg. Moped, Scooter, motorcycle, Car, jeep, truck,
tractor, ships, aircrafts, rocket etc.
• A self propelled vehicle used for transportation of
goods & passengers on the ground is called an
Automobile.
• Different from Aeronautical vehicles (planes,
helicopters, rockets) & marine vehicles (ships, boats,
submarines)
8

Definition of Automobile
• Automobile is a “Self Propelled
vehicle” generally driven by IC Engine
and it is used for transportation of
passengers
Crouse.
• Examples :
& goods on ground – W. H.
Car, Bus, Truck, Scooter etc.
9

History of Automobiles
Captain Nicholas Joseph Cugnot – French Army – built the first self propelled vehicle in 1768-70
10

First Automobile
Cugnot SteamTrolley, Steam Engine powered, 1768
11

Karl Benz
Inventor of the first gasoline powered automobile, 1886 12

History
Invention of Wheel is major milestone in human history after fire
13

History – 1869 Captain Nicholas Cugnot
(French) build first Automobile
2.5mph (4.02 Kmph) in 15 minutes – 3 Wheeler
Steam
Piston's
1769 Cugnot Steamer in
HD.mp4
Front Wheel
Rear Wheel /
Axle
Steam
Generator
Steering
15

e is e
1801 – Richard
Carriage
threvithrick – Firs Steam
TREVITHICK'S PUFFING DEVIL
ON TREVITHICK DAY 2017.mp4
Trevithick was born in 1771 in a
mining
England.
village
He
in
was
Cornwall,
terrible
a
student–his teachers thought he
was a “disobedient, slow,
obstinate, [and] spoiled boy” who
anything,
basically
would never amount to
and in fact he was
illiterat
to tinker
h entir life–but he loved
with tools and machines6
.
Puffing DEVIL
Wheels
Steam
Generator
Chimney
16

1885 – Benz Motors in Germany developed
first Vehicle propelled with IC Engine
7
videoplayback.mp4
17

…Contd
• 1897 – Mr. Foster from Crompton greaves,
borrowed first motor car in india
• 1901 -
INDIAN
Mr. Jamshed Ji TA
TA was the first
to own a motor car .
Sir Jamshed Ji TA
TA 18

Classification
• Purpose
• Passenger Carriers – Car, Bus
• Goods Carriers - Trucks
• Fuel Used
• Petrol
• Diesel Gas
• Electric
• Steam – not in use
• Capacity
• HMV – Trucks, Buses
• LMV – Tempo, Jeeps
of Automobiles
• Construction
• Single unit
• Articulated – Eg. Trailers, Tractors
Drive
• Left hand
• Right Hand
Number of Wheels
• Two Wheeler
• Three Wheeler
• Four Wheeler
Body
• hatchback
• Sedan
• Convertibles
• Station Wagons - V
ans
•
•
•
• Special Purpose V
ehicles
19

Engine
SI – Spark Ignition
CI – Compression
Two Stroke
Ignition
Four Stroke
21

Chassis & Other
important Parts
V
ehicle BODY
22

Chassis
Main Supporting
Structure of
vehicle consist of
almost all major
parts except
automobile body
24

Key component of Chassis
Frame Have 3 different types
is Frame
1.
2.
3.
Conventional frame
Integral Frame
Semi Integral Frame
Functions of Frame
• To support chassis components & body
• Withstand the static & dynamic load of different components
of chassis
• To withstand load of the body
• To carry load
• To withstand stresses caused due to uneven road conditions.
• To withstand force caused due to turning of the vehicles &
sudden braking or acceleration.
25

Frame Cross Sections
Channel Section – Good Resistance to Bending
Box Section – Good Resistance to both bending
and torsion
Tubular Section – Good Resistance to torsion.
29

Types of Chassis
• According to layout
• Conventional
• Forward
• Semi forward
• According to mounting of engine and transmission
• Engine at front
• Engine fitted in front but crosswise
• Engine fitted at the center of the chassis
• Engine fitted at the back
30

According to mounting of
Component of Chassis
• Front Engine Rear Wheel Drive
• Front Engine Front Wheel Drive
• Rear Engine Rear Wheel Drive
• All Wheel Drive
31

Conventional Chassis
Affects visibility of driver
Engine is fitted in front of the driver cabin or driver seat such as in
cars.
Chassis portion can not be utilized for carrying passengers and goods
Heavy Engine can be fitted, which can used to give more power
32

Semi Forward Chassis
• Half portion of the engine is in the driver cabin
half is outside the cabin such as in Tata trucks /
& and remaining
Tempos
• In this arrangement a part of the chassis is utilized for carrying
extra passengers
33

Forward Chassis
• Complete engine is mounted inside the driver cabin, Driver seat
is just above the front wheel.
• More Boot SpaceAvailable as full utilization of chassis
34

Engine
Conventionally
at front
• the engines
are fitted at front & drive is
given to
“rear”
the wheels from the
•
•
Advantages
Enough space is available for
luggage behind the rear seat
The weight of vehicles is well
balance
•
• Increased efficiency of
cooling system
24
35

Engine fitted in front but crosswise
• This front engine layout
requires very small space to
fit the engine. Hence, most
compact cars use this layout
which has very small space to
accommodate the engine.
Design is more complicated
•
as compared to the
longitudinally placed engine.
This is because it does not
leave enough space for
accessories.
36

Engine is mounted at center
• Mid-engine, rear-wheel drive
format can be considered the
original layout of automobiles.
Drive is given to the rear.
Equal Distribution of weight.
•
•
• Largest drawback of mid-engine
cars is
space;
restricted rear passenger
• Consequently most mid-engine
vehicles are two-seat vehicles.
The engine in effect pushes the
passenger compartment forward
towards the front axle (if engine is
behind driver).
•
37

Engine Fitted at back
• Flat floor is available since
long propeller shafts are
eliminated
• With
propeller
elimination of
center
giving
shaft the
of gravity lowered
stable driving
Better adhesion
• on road
climbing
specially
hill
when
38

Other important chassis types
• Tabular Space Frame
• Monocoque Frame
• Backbone Frame
28
39

r r h
• Fo highe
y
stre
Tubular Frame
•
•
It is 3-dimensional design
Tubular space frame chassis
employs dozens of circular
section tube, positions in
different directions to
provide mechanical strength
against force from anywhere.
• These tubes are welded &
forms a very complex
structure.
ngt required
b sports cars, tubular space
frame chassis usually
incorporate a strong structure
under both doors. 40

Advantages & Dis advantages
• V
ery strong in any • V
ery complex , costly
and time consuming to
be built.
It engages a lot of
spaces rise the door seal
and result in difficult to
access to the cabin.
direction
with ladder
Monocoque
(compared
chassis and
chassis of •
the same weight)
• Impossible for
robotized production.
41

Monocoque
Monocoque is a one-piece structure which defines
overall shape of the car. while ladder, tabular & backbone
provide only stress members.
Today 99% car produced in this planet are made of
steel Monocoque chassis.
Chassis are made by welding of Several pieces. (Spot
Welding )
Monocoque is made of steel
31 42

Advantages & Disadvantages
• Space-efficiency.
• Monocoque
•
chassis •
It is very heavy.
Impossible for small
volume production.
In case of accidents
benefit crash production
because it uses
metal.
a lot of •
whole structure
obsolete.
become
• Cheap
production
for mass
43

Back
• Similar
design.
Bone Frame
to the body frame
• It consist
backbone
of a strong tubular
(Usually
rectangular in C/s).
• A body is placed on the
structure.
• This type of chassis has been
used in numerous sports cars.
44

licated an
.
d m
,
ore
e
costly However
ll
th m
-
ore
axles with wheel drive
are needed, the cost
benefit turns in f
e sis
• The vulnerable parts of the
drive shaft are covered by a
• Manufacturing
backbone chassis
comp
the
more
is
thick tube. The whole
system is extremely reliable.
However, if a problem
occurs, repairs are more
complicated. avor of
backbon
chas
.
• The modular system enables
configurations of 2-, 3-, 4-,
5-, 6-, or 8-axle vehicles
• The backbone chassis is
heavier for a given torsional
stiffness than a uni-body.
with various wheel bases.
The chassis gives no
side
protection
impacts.
against
34
45

Types of Vehicle
Layout/
Chassis
Layout
35
46

Front Engine Rear Wheel Drive
Engine
Transmission
Drive Shaft
Clutch
Final Drive
47

Front
Drive
Engine Rear Wheel
• Most common type of layout.
• Engine Located at front and driving power is given
to rear wheels.
• Driving Power flows from engine to rear wheel
through various mechanical linkages.
48

ation, making the rear
ltaneous acceleration
es.
• Better handling : - Accelerating force is applied to
the rear wheels, on which the down
due to load transfer in acceler
force increases,
tires better able to take simu
and curving than the front tir ON DRY ROAD ONLY
49

Even weight distribution
• The division of weight between the front and rear
wheels has a significant impact on a car's handling,
and it is much easier to get a 50/50 weight
distribution in a rear wheel drive car.
Steering radius
• As no complicated drive shaft joints are required at
the front wheels, it is possible to turn them further
than would be possible using front wheel drive,
resulting in a smaller steering radius.
50

Less load at front axle
• The driving force is given at rear axle hence there is
no need to provide complex design on front axle.
Effective Cooling of the engine due to
exposure of cooling system to flowing air
51

Disadvantages
Decreased interior space – This isn't an issue in a vehicle
with a ladder frame like a pickup truck, where the space
used by the drive line is unusable for passengers or cargo.
But in a passenger car, rear wheel drive means: Less front
leg room (the transmission tunnel takes up a lot of space
between the driver and front passenger), less leg room for
center rear passengers (due to the tunnel needed for the
drive shaft), and sometimes less trunk space (since there is
also more hardware that must be placed underneath the
trunk).
52

Increased weight
• The drive shaft, which connects the engine at the
front to the drive axle in the back, adds weight.
There is extra sheet metal to form the transmission
tunnel. A rear wheel drive car will weigh slightly
more than a comparable front wheel drive car, but
less than four wheel drive.
54

Higher purchase price
• Due to the added cost of materials, rear wheel
drive is typically slightly more expensive to
purchase
vehicle.
.
than a comparable front wheel drive
55

Front Engine Front Wheel Drive
Engine
Transmission
Final Drive
56

Front
Drive
Engine Front Wheel
• In this type the engine is
mounted on the front side
of the vehicle and the
driving power is given to
the front wheels only.
The power flows from
engine to front axle.
This type of arrangement
•
•
have additional sub type
cross
i.e. front mounted
engine.
57

Advantages
• Interior space:
• Since the powertrain
engine compartment
is a single unit contained in the
of the vehicle, there is no need
to devote interior space for a driveshaft tunnel or
for
rear differential, increasing the volume available
passengers and cargo.
Inner
SPACE
Engine
58

Better handling on slippery
surface
• Slippery-surface traction: placing the mass of the
drivetrain over the driven wheels
improves traction on wet, snowy, or icy surfaces.
Improved drive train efficiency
• The direct connection between engine and
transaxle reduce the mass and
of the drivetrain compared to
mechanical inertia
a rear-wheel drive
vehicle with a similar engine and transmission,
allowing greater fuel economy.
59

Disadvantages
• Less Turning Radius
• The drive shafts may limit the amount by which the
front wheels can turn, they are generally unable to
make the.
• More Weight on front results in rapid wear of
front tires.
• Front-wheel drive has worse acceleration than
rear-wheel drive, which is why most sporty and
race cars use rear-wheel drive.
60

Rear Engine Rear Wheel Drive
63

Advantages
• Weight over rear wheels, increased traction while
accelerating.
• Front axle construction is simplified.
• Absence of propeller shaft results in decrease of
floor height.
• Engine components mounted at rear of rear axle
hence more space is available.
65

Disadvantages
• Separate cooling mechanism is needed for
effective cooling
mounted at rear.
of the engine as the engine is
• More load on rear side may result in overturning
(Over steer) of the vehicle.
• Longer linkages are required to operate clutch,
gears from driver.
66

AWD or 4WD
All wheelsAlways
engaged.
Safe and advantageous
over 4WD
4 wheels can be engaged only
in difficult terrain.
In normal condition power is
given to rear wheels only.
68

Advantages
• 4WD improves traction in dangerous driving
conditions, such as snow,
make
ice, rocks, and other
scenarios that can control difficult. By
engaging both sets of wheels, traction and control
improves.
• Additional weight contributes to better grip on the
road.
• 4WD is great for those who like off-roading.
69

Disadvantages
• The main disadvantage of 4WD is added cost for
purchase, maintenance, and fuel. The extra equipment
(differentials, transfer case, etc.) adds complexity and
weight to the vehicle, increasing initial market value,
tire wear, and the cost of repairs and maintenance.
The added power and weight of 4WD and AWD
systems require more fuel, making them less efficient
than their 2WD counterparts.
Added weight improves traction and control, but it also
increases the braking distance required to make a
complete stop. Lighter vehicles can avoid collision
easier than heavier vehicles.
•
•
70

TRANSMISSION
SYSTEM
D E F I N I T I O N O F T R A N S M I S S I O N S Y S T E M
N E E D O F T R A N S M I S S I O N S Y S T E M
P U R P O S E
T Y P E S O F
PA R T S O F
O F T R A N S M I S S I O N S Y S T E M
T R A N S M I S S I O N S Y S T E M
T R A N S M I S S I O N S Y S T E M
71

Gear Box
An automobile requires high torque when
climbing hills and when starting, even though
they are performed at low speeds. On other hand,
when running at high speeds on level roads, high
torque is not required because of momentum.
So requirement of a device is occur, which can
change the vehicle’s torque and its speed
according to road condition or when the driver
need. This device is known as transmission(Gear
Box) box.
85

Functions of Gearbox
The transmission box which is also known as
the gear box is the second element of the
power train in an automobile.
It is used to change the speed and torque of
vehicle according to variety of road and load
condition.
Transmission box change the engine speed
into torque when climbing hills and when the
vehicle required. Sometimes it is known as
torque converter. Main functions of a gear box
is as follow:
86

Functions of Gearbox
1.Provide the torque needed to move the
vehicle under a variety of road and load
conditions. It does this by changing the gear
ratio between the engine crankshaft and
vehicle drive wheels.
2.Be shifted into reverse so the vehicle can
move backward.
3.Be shifted into neutral for starting the
engine.
87

Types of Gear box
PROGRESSIVE TYPE GEAR BOX
Usually this gear boxes are used in motor cycles. In this gear boxes the
gears pass through the intervening speeds while shifting from one
speed to another. There is a neutral position between two positions.
These gear boxes are a combination of sliding and constant mesh gear
boxes. The various gear speeds are obtained by sliding the dog clutch
or gear to the required position.
EPICYCLIC (OR) PLANETARY TYPE GEAR BOX
The epicylic or planetary type transmission uses no sliding dogs or
gears to engage but different gear speeds are obtained by merely
tightening brake-bands on the gear drums, which simplify gear
changing.
Aplanetary gear set consists of ring gear or annular wheel, sun gear
and planet gears with carrier. In order to obtain different speeds any one
of these three units can be held from rotation by means of brake bands.
88

Types of Gear box
• SELECTIVE TYPE GEAR BOX
• It is the transmission in which any speed may be select
neutral position. In this type of transmission neutral positio
obtained before selecting any forward or reverse gear.
• Some selective type gear boxes are,
1.Constant mesh gear box with positive dog clutch.
2.Constant mesh gear box with synchromesh device.
3.Sliding mesh gear box.
89

Sliding Mesh Gear Box
It is the simplest and oldest type of gear box.
1. The clutch gear is rigidly fixed to the clutch shaft.
2.The clutch gear always remains connected to the drive
gear of countershaft.
3. The other lay shaft gears are also rigidly fixed with it.
4.Two gears are mounted on the main shaft and can be
sliding by shifter yoke when shifter is operated.
5.One gear is second speed gear and the other is the first
and reverse speed gears.All gears used are spur gears.
6.A reverse idler gear is mounted on another shaft and
always remains connected to reverse gear of counter shaft.
91

Gearing ratio of Sliding Mesh Gear Box
The shifting of gears is obtained by the meshing of the gears on the main shaft with the
gears on the lay shaft by right or left sliding of gears on the main shaft in order to
obtain appropriate gears, lets understand the working of 3- speed 1-reverse
transmission used in early automobile vehicles.
First gear First gear provides maximum torque at low speed which is obtained when
the smallest gear on the lay shaft meshes with the biggest gear on the main shaft in
order to provide high torque.
Second gear Second gear provides less torque and higher speed than first gear and is
obtained when the middle size gear of the main shaft meshes with the second smallest
gear on the lay shaft and high speed and second high torque is transmitted to the final
drive.
Third gear Third gear provides maximum speed and minimum torque to the final drive
and is also known as high-speed gear or top gear in sliding mesh gearbox, this gear is
obtained when the smallest gear of the main shaft meshes with the biggest gear of the
lay shaft. Or we can say that the drive obtained a maximum speed of the clutch shaft.
Reverse gear When the reverse gear is selected, the rotation of the output shaft is
reversed which is made possible by using an idler gear between the main shaft and lay
shaft that changes the rotation of the output shaft and the vehicle starts moving in the
reverse direction.
92

Constant MeshGearbox
In this gearbox, all the gears are always in mesh. The
gear remains fixed and not slide
In this gearbox, the sliding mesh was replaced with
constantly meshed pairs of gears and the new shifting
devices named dog clutches were introduced.
93

Main Parts of Constant Mesh Gearbox
1) Shafts – There are 3 shafts present in this gearbox which are :
i)Main Shaft
It is also known as output shaft. It is the splined shaft over which the
dog clutches along with gears are mounted. Gears on this shaft are free
to rotate.
ii) Lay Shaft or Counter Shaft
It is an intermediate shaft between the Main Shaft and Clutch Shaft.
The gears of counter shaft are in constant mesh with gears of main
shaft.Also the gears of counter are shaft are not free to rotate as they
are directly connected to the Counter Shaft.
iii) Clutch Shaft:
The clutch shaft carries the engine output to the gearbox but act as
input for the gearbox. It is also known as input shaft.
95

Main Parts of Constant Mesh Gearbox
2) Dog Clutch:
The dog clutch couples the lay shaft and main shaft by interference and not by friction.
Dog clutches are used to transmit appropriate gear ratio to the main shaft or output
shaft by coming in interference with pair of gears with suitable gear ratio.
There are usually two dog clutches in a Constant Mesh Gear Box.
3) Gears:
Gears of constant mesh gearbox come in pairs.All gears of lay shaft or counter shaft
are always paired with gears of main shaft or output shaft.
This paired gears of counter shaft and main shaft provide different gear ratio which can
be transmitted to main shaft by engaging dog clutch with appropriate gear ratio
required.
Two type of gears are used in constant mesh gearbox:-
i) Helical Gears:
These gears have angular cut teeth over cylindrical cross-section metal
body.
ii) Bevel Gears:
These gears have angular cut teeth over conical cross-section metal body 96

Construction of Constant Mesh Gear box
The output of the engine is carried by clutch shaft. The gear in
clutch shaft is in constant mesh with the gear of lay shaft.
• There are 5 gears in lay shaft, one of which is connected to
gear of clutch shaft and the other 4 are connected with gears of
main shaft.
• All four gears are of different sizes to obtain different gear
ratios.
• An idler gear is present between the gear of lay shaft and gear
of main shaft to form reverse gear.
97

Working of Constant Mesh Gear box
• When the dog clutch is engaged with different gears of main shaft
different gear ratios are obtained as gears of main shaft are always
paired with gears of counter shaft to form different gear ratios.
• If the dog clutch is not in contact with any gear of main shaft the
gears of main shaft rotates freely and does not rotates the main shaft
as they are connected with main shaft using bearings.
• The main shaft rotates only when one of the dog clutch is engaged
with any of the gear of the main shaft.
• Reverse gear is obtained in this gearbox using the same technique
that was in sliding gearbox i.e using the idle gear between main
shaft gear and counter shaft gear.
98

Gearing ratio Constant Mesh Gear
box
First Gear:
First gear is obtained in constant mesh gearbox when dog clutch
gets engage by interference with the largest gear of main shaft
which is in constant mesh with smallest gear of main shaft. This
gear provides maximum torque and minimum speed to the main
shaft.
Second Gear:
Second Gear is obtained when dog clutch gets engage with
second largest gear of main shaft which is in a constant mesh
with second smallest gear of lay shaft. This gear provides higher
speed and lower torque than first gear.
99

Gearing ratio of Constant Mesh Gear box
Third Gear:
Third gear is obtained when dog clutch engages with second smallest gear of
main shaft which is in constant mesh with second largest gear of lay shaft. This
gear more speed and less torque than second gear.
Fourth Gear:
This gear provides the highest or maximum speed in a vehicle using constant
mesh gearbox. This gear is obtained when dog clutch engages with smallest
gear of main shaft which is in constant mesh with largest gear of lay shaft.
Reverse Gear:
In this gear the vehicle goes in reverse direction. Like sliding mesh gearbox,
an idler gear is also used in constant mesh gearbox between the main shaft
gear and lay shaft gear to form reverse gear. Reverse gear is obtained when
dog clutch engages with gear in main shaft which is paired with idler gear. 100

Application of Constant Mesh Gear box
• Constant mesh gearbox was mainly used in farm trucks, motor bikes and
heavy machinery.
• It is also used in cars like Ford Model T.
• Constant Mesh Box was used in motor bikes before the introduction of
synchromesh gearbox in 1928 by General Motors.
https://www.youtube.com/watch?v=8Hb2y06pQy0
101

SynchromeshGearbox
Synchromesh gearbox or transmission system is a type of
transmission system in which the dog clutches from the constant
mesh gearbox is replaced with the special shifting devices known
as synchromesh devices which makes the system compact and
also provide smooth and noise free shifting of gears.
102

MainComponents Synchromesh Gearbox
1) Shafts –
Just like constant mesh gearbox, there are 3 shafts used in
synchromesh gearbox-
(i) Main shaft- Same as constant mesh a splined shaft is used as
the output shaft over which the synchronizers and gears are
mounted.
(ii)Lay shaft- It is the intermediate shaft over which gears with
suitable size and teethes are mounted and is used to transmit the
rotational motion from clutch shaft to the final output shaft.
(iii)Clutch shaft- It is the shaft used as an input shaft in gearbox
as it carries the engine output to the gearbox, same as the constant
mesh gearbox
104

MainComponents Synchromesh Gearbox
2. Gears-
(i) Helical gears- These gears are having angular cut teethes over a
cylindrical metal flank.
(ii)Bevel gears – These gears are having angular cut teethes over a
conical metal flank.
3. Synchronizers –
They are the special shifting devices used in the synchromesh gearbox
which has conical grooves cut over its surface that provide frictional
contact to the gears which is to be meshed in order to equalise the
speed of main shaft, lay shaft and clutch shaft which in turn provides
smooth shifting of gears.
4. Gear lever –
It is the shifting lever operated by the driver and is used to select
the appropriate gear i.e. 1, 2, 3, 4, 5 or reverse gear.
105

Working of Synchromesh Gearbox
Selecting gears in synchromesh gearbox is somewhat same as constant mesh
gearbox that are
First gear
When the driver push or pull the gear lever in order to select the first gear which
gives the maximum torque and minimum speed and is used to move the vehicle from
its initial state ,the synchromesh device attached with the pair of meshed gears having
biggest gear of the main shaft and smallest gear of the lay shaft equalises the speed of
the shafts by making frictional contact with the pair and finally the first gear is
obtained.
Second gear
This is the gear having lower torque and higher speed than first gear and is obtained
when the pair of gears having second largest gear of the main shaft and second smallest
gear of the lay shaft is meshed by the corresponding synchromesh device.
Third gear
This gear having higher speed and lower torque than second gear is obtained when
the corresponding synchromesh device attached to the pair of gear having intermediate
size gear of main shaft and intermediate size of gear of lay shaft makes contact.
106

Working of Synchromesh Gearbox
Fourth gear
It is the second highest speed gear which is obtained when the
corresponding synchromesh device attached to the pair of meshed gears having
main shaft and second largest gear of the lay shaft
second smallest gear of
makes contact.
Fifth gear
It is the highest speed and lowest torque gear which transmit the maximum
speed of the clutch shaft to the main or output shaft and is obtained when the
corresponding synchromesh device attached to the pair of meshed gear having
smallest gear of main shaft and largest gear of lay shaft makes contact.
Reverse gear
It is the gear that reverses the direction of the output shaft which in turn
reverse the direction of the vehicle with the help of the idler gear which is
usually fit in the middle of the lay shaft and main shaft and is obtained when
the idler gear makes contact with the gears on the main shaft and lay shaft.
107

Application of Synchromesh Gearbox
• It has a wide application as almost 50% of the vehicle on the
road used synchromesh gearbox, some of them are-
• In Maruti Suzuki swift it comes with 5-speed 1-reverse manual
transmission configuration.
• It is used in bikes like ktm duke 390cc.
• Most of the race cars like formula-1 uses synchromesh
gearbox with suitable modification in shifting lever as they
required sudden shifting of gears from high torque to high
speed because they have to race onto the zig-zag track having
sharp turns.
https://www.youtube.com/watch?v=rb3_suXXbxY
108

EpicyclicGearbox
An Epicyclic gearbox is an automatic type gearbox in which parallel shafts
and gears arrangement from manual gear box are replaced with more
compact and more reliable sun and planetary types of gear arrangement and
also the manual clutch from manual power train is replaced with hydro
coupled clutch or torque converter which in turn made the transmission
automatic.
109

Components of Epicyclic Gearbox
1. Ring gear-
• It is a type of gear which looks like a ring and have angular cut teethes at its
inner surface ,and is placed in outermost position in en epicyclic gearbox, the
inner teethes of ring gear is in constant mesh at outer point with the set of
planetary gears ,it is also known as annular ring.
2. Sun gear-
• It is the gear with angular cut teethes and is placed in the middle of the
epicyclic gearbox; the sun gear is in constant mesh at inner point with the
planetary gears and is connected with the input shaft of the epicyclic gear box.
• One or more sun gears can be used for achieving different output.
3. Planet gears-
• These are small gears used in between ring and sun gear , the teethes of the
planet gears are in constant mesh with the sun and the ring gear at both the
inner and outer points respectively.
• The axis of the planet gears are attached to the planet carrier which is carrying
the output shaft of the epicyclic gearbox.
• The planet gears can rotate about their axis and also can revolve between the
ring and the sun gear just like our solar system.
110

Components of Epicyclic Gearbox
4. Planet carrier-
• It is a carrier attached with the axis of the planet gears and is
responsible for final transmission of the output to the output
shaft.
• The planet gears rotate over the carrier and the revolution of
the planetary gears causes rotation of the carrier.
5. Brake or clutch band-
• The device used to fix the annular gear, sun gear and planetary
gear and is controlled by the brake or clutch of the vehicle.
111

Working of Epicyclic Gearbox
First gear ratio
• This provides high torque ratios to the vehicle which helps the vehicle
to move from its initial state and is obtained by fixing the annular gear
which in turn causes the planet carrier to rotate with the power supplied
to the sun gear.
Second gear ratio
• This provides high-speed ratios to the vehicle which helps the vehicle
to attain higher speed during a drive, these ratios are obtained by fixing
the sun gear which in turn makes the planet carrier the driven member
and annular the driving member in order to achieve high-speed ratios.
Reverse gear ratio
• This gear reverses the direction of the output shaft which in turn
reverses the direction of the vehicle, this gear is achieved by fixing the
planet gear carrier which in turn makes the annular gear the driven
member and the sun gear the driver member.
112

Application of Epicyclic Gearbox
• Epicyclic gear train is usually used in automatic vehicles with
the hydraulic clutch.
• The epicyclic gearbox is used in the automatic model ofAudi
A4
• It is used in Lamborghini Gallardo.
• It is also used in power transmission between I.C engine and
electric motor, so it also has its uses in hybrid cars.
https://www.youtube.com/watch?v=ARd-Om2VyiE
113

unit 1.pptx

More Related Content

Similar to unit 1.pptx (20)

Recently uploaded (20)

unit 1.pptx