VISVESVARAYA TECHNOLOGICAL UNIVERSITY

BELGAUM, KARNATAKA

A Seminar Report on

Dual clutch transmission

Submitted in partial fulfilment of the requirements for the award of degree
BACHELOR OF ENGINEERING
In
MECHANICAL ENGINEERING
Submitted by:
AKASH PALLAV PAUL
(1BY11ME005)

For Academic year 2015-2016

Under the Guidance of
Mr. Kiran M D

Assistant Professor, Dept. of ME,

BMSIT&M.

DEPARTMENT OF MECHANICAL ENGINEERING

BMS INSTITUTE OF TECHNOLOGY AND MANAGEMENT
DODDABALAPUR MAIN ROAD, AVALAHALLI
YELAHANKA, BENGALURU-560064

Dual clutch transmission

BMS INSTITUTE OF TECHNOLOGY AND MANAGEMENT
DODDABALAPUR MAIN ROAD, AVALAHALLI, YELAHANKA, BENGALURU560064

DEPARTMENT OF MECHANICAL ENGINEERING

Certificate
Certified that the seminar work entitled Dual clutch transmission is bonafied work
carried out by Akash Pallav Paul (1BY11ME005), in partial fulfilment of the
requirements for the award of the degree of Bachelor of Mechanical Engineering of
Visvesvaraya Technological University, Belgaum, during the year 2015-2016. It is
certified that all the corrections/suggestions indicated for internal assessment have been
incorporated in the report. The Seminar report has been approved as it satisfies the
academic requirements in respect of seminar (10ME86) prescribed for the Bachelor of
Engineering degree.

Signature of the Guide

Signature of the HOD

Mr. Kiran M. D

Dr. H K

Govindaraju
Assistant Professor,

Professor and head

Dept. of ME, BMSIT&M

Dept. of ME, BMSIT&M

Name of the Examiners:

Signature with date:

1. .

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2. .

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ABSTRACT
With fuel price increasing, it became obvious long ago that the trend for the future
must be toward smaller engines driving light weight cars. This stimulated automotive
products to re-examine the prospects for developing a simpler and more efficient
automatic transmission based on the traditional, highly efficient, manual gearbox.
The primary requirement for the development of Dual clutch transmission was to
change gears without interrupting the power flow to the wheels. This will in turn increase
the overall efficiency of the engine and also the power delivery will be constant.

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Table of figures
Figure 2.1 : Block diagram of DCT9
Figure 2.2: Dual clutch...10
Figure 2.3: Dual clutch transmission shafts.....11
Figure 3.1: Dual clutch transmission system..13
Figure 4.1: Torque transfer comparison.........................15
Figure 4.2: Aluminium crash graph.17

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CONTENTS
PAGE NO
Certificate
Abstract

List of figures

Chapter 1...........................................................................................................................6
Introduction.......................................................................................................................6
1.1. Transmission........................................................................................... 6
1.1.1. Purpose of transmission...................................................................6
1.2. Clutch..................................................................................................... 7
1.2.1. Basic function of clutch....................................................................7

Chapter 2...........................................................................................................................8
Dual clutch transmission..................................................................................................8
2.1. Basic parts of dual clutch transmission system......................................9
2.1.1. Dual clutch....................................................................................... 9
2.1.2 Dual clutch transmission shafts.......................................................10

Chapter 3.........................................................................................................................12
Working of dual clutch transmission............................................................................12
Chapter 4.........................................................................................................................14
Advantage and disadvantage of dual clutch transmission..........................................14
4.1. Advantages:......................................................................................... 14
4.2. Disadvantages:..................................................................................... 15

Chapter 5.........................................................................................................................16
Applications.....................................................................................................................16
5.1. Trucks and busses................................................................................16
5.2. Formula one cars..................................................................................16
5.3. Automobiles......................................................................................... 16

Conclusion.......................................................................................................................17
References........................................................................................................................18

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Chapter 1

Introduction
1.1. Transmission
Transmission is the mechanism through which the driving torque of the engine is
transmitted to the driving wheel of the vehicle so that the motor vehicle can move on the
road. The reciprocating motion of the piston turns a crankshaft rotating a flywheel
through the connecting rod .The circular motion of the crankshaft is to be now transmitted
to the rear wheels .It is transmitted through the clutch, gear box, universal joints, propeller
shaft or the drive shaft, differential and axles extending to the wheels .The application of
the engine power to the driving wheels through all these parts is called POWER
TRANSMISSION .The power system is usually the same on all modern passenger cars
and trucks, but its arrangement may vary according to the method of drive and type of
transmission units.

1.1.1. Purpose of transmission

It enables the engine to be disconnected from the driving wheels.

It enables the running engine to be connected to driving wheel smoothly and

without shock.

It enables the leverage between the engine and the driving wheels to be varied.

It enables the reduction of engine speed in the ratio of 4:1 in case of passenger
cars and in greater ratio in case of Lorries.

It enables the driving wheels to be driven at different speeds.

It enables turning the driving through 90 degrees.

It enables the relative movement between the engine and the driving wheel.

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1.2. Clutch
In all vehicles using a transmission, a coupling device is used to separate the
engine and transmission when necessary. The clutch accomplishes this in manual
transmissions. Without it, the engine and tires would at all times be inextricably linked,
and anytime the vehicle stopped the engine would perforce stall. Without the clutch,
changing gears would be very difficult, even with the vehicle moving already: deselecting
a gear while the transmission is under load requires considerable force, and selecting a
gear requires the revolution speed of the engine to be held at a very precise value which
depends on the vehicle speed and desired gear. In a car the clutch is usually operated by a
pedal; on a motorcycle, a lever on the left handlebar serves the purpose.

1.2.1. Basic function of clutch

When the clutch pedal is fully depressed, the clutch is fully disengaged, and no
torque is transferred from the engine to the transmission. In this uncoupled state it

is possible to select gears or to stop the car without stopping the Engine.
When the clutch pedal is fully released, the clutch is fully engaged, and practically
all of the engine's torque is transferred. In this coupled state, the clutch does not
slip, but rather acts as rigid coupling, and power is transmitted to the wheels with

minimal practical waste heat.

Between these extremes of engagement and disengagement the clutch slips to
varying degrees. When the clutch slips it still transmits torque despite the
difference in speeds between the engine crankshaft and the transmission input.
Because this torque is transmitted by means of friction rather than direct

mechanical contact.
Considerable power is wasted as heat (which is dissipated by the clutch). Properly
applied, slip allows the vehicle to be started from a standstill, and when it is
already moving, allows the engine rotation to gradually adjust to a newly selected
gear ratio.

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Chapter 2

Dual clutch transmission

A DUAL CLUTCH TRANSMISSION uses two separate clutches for odd and
even gear sets.

It can fundamentally be described as two separate manual

transmissions (with their respective clutches) contained within one housing, and working
as one unit. They are usually operated in a fully automatic mode, and many also have the
ability to allow the driver to manually shift gears in semi-automatic mode, albeit still
carried out by the transmission's electro-hydraulics.
Elaborated form of manual transmission in which two internal shafts, each
connected to the input via an electronically controlled clutch, are coordinated such as to
achieve an uninterrupted flow of torque to the driven wheels during gear changes. As well
as reducing acceleration times, a dual clutch transmission also enhances refinement over a
convectional manual or manual gearbox.
Most people know that cars come with two basic transmission types: manuals,
which require that the driver change gears by depressing a clutch pedal and using a stick
shift, and automatics, which do all of the shifting work for drivers using clutches, a torque
converter and sets of planetary gears. But there's also something in between that offers the
best of both worlds -- the dual-clutch transmission, also called the semi-automatic
transmission, the "clutch less" manual transmission and the automated manual
transmission.
In the world of race cars, semi-automatic transmissions, such as the sequential
manual gearbox (or SMG), have been a staple for years. But in the world of production
vehicles, it's a relatively new technology -- one that is being defined by a very specific
design known as the dual-clutch, or direct-shift, gearbox.

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Fig. 2.1 block diagram of DCT

2.1. Basic parts of dual clutch transmission system

2.1.1. Dual clutch
A dual clutch is a type of clutch which houses two clutches in the same housing.
These clutches are used to operate two separate sets of transmission shafts. One shaft
turns the odd number of gears and the other even number of gears. The clutches are
controlled by hydraulic actuators.
In this type of clutch the driver is free from using the clutch pedal as the on board
computer does this for him. A simple block diagram showing the working of the dual
clutch is shown below. In this diagram the GREEN clutch drives the even gears and the
RED clutch drives the odd gears. From the diagram we can see that when green clutch is
engaged the red is disengaged and vice versa. This simple switching of the clutch leads to
the changing of gears.

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Fig 2.2 dual clutch

2.1.2 Dual clutch transmission shafts

A two-part transmission shaft is at the heart of a DUAL CLUTCH
TRANSMISSION. Unlike a conventional manual gearbox, this houses all of its gears on
a single input shaft, the DCT splits up odd and even gears on two input shafts. The outer
shaft is hollowed out, making room for an inner shaft, which is nested inside. The outer
hollow shaft feeds second and fourth gears, while the inner shaft feeds first, third and
fifth.
The diagram below shows this arrangement for a typical five-speed DCT. Notice
that one clutch controls second and fourth gears, while another; independent clutch
controls first, third and fifth gears. That's the trick that allows lightning-fast gear changes
and keeps power delivery constant. A standard manual transmission can't do this because
it must use one clutch for all odd and even gears.

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Fig. 2.3 Dual clutch transmission shafts

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Chapter 3

Working of dual clutch transmission

A dual-clutch transmission offers the function of two manual gearboxes in one. To
understand what this means, it's helpful to review how a conventional manual gearbox
works. When a driver wants to change from one gear to another in a standard stick-shift
car, he first presses down the clutch pedal. This operates a single clutch, which
disconnects the engine from the gearbox and interrupts power flow to the transmission.
Then the driver uses the stick shift to select a new gear, a process that involves moving a
toothed collar from one gear wheel to another gear wheel of a different size. Devices
called synchronizers match the gears before they are engaged to prevent grinding. Once
the new gear is engaged, the driver releases the clutch pedal, which re-connects the
engine to the gearbox and transmits power to the wheels.
So, in a conventional manual transmission, there is not a continuous flow of
power from the engine to the wheels. This problem is solved by using dual clutch
transmission.
A dual-clutch gearbox, uses two clutches, but has no clutch pedal. Sophisticated
electronics and hydraulics control the clutches, just as they do in a standard automatic
transmission. In a DCT, however, the clutches operate independently. One clutch controls
the odd gears (first, third, fifth and reverse), while the other controls the even gears
(second, fourth and sixth). Using this arrangement, gears can be changed without
interrupting the power flow from the engine to the transmission.
Sequence of operation of the DTC is as follows:

A car travelling in second gear is controlled by the inner clutch .Power is sent to
second gear along the outer transmission shaft

As the car increases speed, the computer detects the next gearshift point and the
third gear is pre-selected.

When the driver changes gears, the inner clutch disengages and the outer clutch is
activated.

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The power is transferred along the inner transmission shafts to the pre-selected
gear.

Drivers can also choose a fully automatic mode that relinquishes all gear-changing
duties to the computer. In this mode, the driving experience is very similar to that
delivered by a conventional automatic. The gear change takes place under load so that a
permanent flow of power is maintained. An ingenious two-shaft construction separating
the odd and even gears makes all of this possible.

Fig 3.1 Dual clutch transmission system

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Chapter 4

Advantage and disadvantage of dual clutch

transmission
4.1. Advantages:

It's got input and auxiliary shafts to house gears, synchronizers and a clutch. It
doesn't have a clutch pedal, because computers, solenoids and hydraulics do the
actual shifting. Even without a clutch pedal, the driver can still "tell" the computer

when to take action through paddles, buttons or a gearshift.

Driver experience is just one of the many advantages of a DCT. With upshifts
taking a mere 8 milliseconds, many feel that the DCT offers the most dynamic

acceleration of any vehicle on the market.

It certainly offers smooth acceleration by eliminating the shift shock that
accompanies gearshifts in manual transmissions and even some automatics. Best of
all, it affords drivers the luxury of choosing whether they prefer to control the

shifting or let the computer do all of the work.

Perhaps the most compelling advantage of a DCT is improved fuel economy.
Because power flow from the engine to the transmission is not interrupted, fuel
efficiency increases dramatically. Some experts say that a six-speed DCT can
deliver up to a 10 percent increase in relative fuel efficiency when compared to a

conventional five-speed automatic.

There is very less torque variation as compared to manual transmission. This can
be shown by this simple graph.

Fig 4.1 Torque transfer comparison

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4.2. Disadvantages:

Many car manufacturers are interested in DCT technology. However, some

automakers are wary of the additional costs associated with modifying production
lines to accommodate a new type of transmission. This could initially drive up the

costs of cars outfitted with DCTs, which might discourage cost-conscious consumers.
DCTs are heavy than normal transmissions so the mountings of the transmission

assembly must be robust.

DCTs require high amount of maintenance due to its complex working and
construction.

Chapter 5

Applications
5.1. Trucks and busses
Semi-automatic transmissions have also made its way into the truck and bus
market in the early 2000s. Volvo offers its I-shift on its heavier trucks and buses, while ZF
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markets its ASTronic system for buses and coaches. These gearboxes have a place in
public transport as they have been shown to significantly reduce fuel consumption

5.2. Formula one cars

In the recent years of development of technology the use of dual clutch
transmission in formula one race is widely accepted. Though the use of full automatic
shifts is banned in formula one, they still use dual clutch transmission which helps the
drivers to shift in a millionth of second.

5.3. Automobiles
The use of dual clutch transmission has been widely accepted in todays
automobiles. Through ever increasing technology the manufacturing of DTCs are getting
cheaper and are now used in almost all cars.

Conclusion
In todays world of ever increasing of fuel price and pollution, the dual clutch
transmission system is the clear winner over other types of transmission system.
The dual clutch transmission server best of both worlds namely practicality and
environment friendly. This has led to more and more automobile companies to start using
dual cutch transmission.

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References
1. J. J. Uicker; G. R. Pennock; J. E. Shigley (2003). Theory of Machines and
Mechanisms(3rd ed.). New York: Oxford University Press. ISBN 9780195155983.
2. B. Paul (1979). Kinematics and Dynamics of Planar Machinery. Prentice Hall.
3. Stiesdal, Henrik (August 1999), The
operation (PDF), retrieved 2009-10-06
4.

wind

turbine:

Components

and

"From the Hele-Shaw Experiment to IntegrableSystems: A Historical

Overview" (PDF). University of Bergen. Retrieved August 9, 2012.

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5.

Analdo M. English, Friction-Clutch, US 255957, granted Apr. 4 1882.

6.

Charles C. Tillotson, Power-Transmission Clutch, US 850981, granted Apr. 23,

1907.

7. Frank Wheeler, Clutch and stop mechanism for presses, US 470797, granted Dec.
14, 1891.
8.

"Powertrain

transmissions:
Shift
in
power
to
the
gearbox" (PDF).AMS (UnofficialBMW.com).
SeptemberOctober
2003.
Retrieved 31 October 2009.

9. "Automatic-shifting dual-clutch transmissions are poised to grab share from

traditional transmissions thanks to their combination of efficiency and
convenience" (PDF). AEI-online.org (DCTfacts.com). June 2009. Retrieved31
October 2009.
10. "Patent GB2101243 - Control system
gearbox". Espacenet.com. Retrieved 2012-06-14.

for

vehicle

automatic

11. "Dual clutches take the lead". Eureka Magazine. Findlay Media Ltd. 13 March
2009. Retrieved 31 October 2009.

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