UNIVERSITY OF CROSS RIVER STATE

TECHNICAL REPORT ON

STUDENT INDUSTRIAL WORK EXPERIENCE SCHEME (S.I.W.E.S)

UNDERTAKEN AT

ARMED FORCES ELECTRICAL AND MECHANICAL ENGINEERING (AFEME)

WORKSHOP
MOGADISHUCANTONMENT, ASOKORO, FCT, ABUJA

BY

ESSIEN EMMANUEL GREGORY

MATRICULATION NUMBER: 19/MEN/064

DEPARTMENT OF MECHANICAL ENGINEERING

FALCULTY OF ENGINEERING

I.T REPORT SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING IN

PARTIAL FULFILLMENT FOR THE AWARD OF B.ENG MECHANICAL ENGINEERING,
UNIVERSITY CROSS RIVER STATE (UNICROSS)

OCTOBER, 2024

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 DECLARATION
I, ESSIEN EMMANUEL GREGORY, hereby declare that this SIWES Report has
been carried out by me. It has not been presented or submitted either in part or full for
award of any degree in any Institution. All sources of information are specifically
acknowledged by means of reference.
________________________ ____________________________

Signature Date

ii
 CERTIFICATION

This SIWES Report by ESSIEN EMMANUEL GREGORY with Matriculation

Number 19/MEN/064 meets the requirements governing the award of the degree of
Bachelor of Engineering in Mechanical Engineering and is approved for its
contribution to knowledge and literary presentation.

_____________________________ ____________________
Engr.Takim Date
SIWES Coordinator

________________________ ____________________
Dr. Oku nyong Date
Head of
Department

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 DEDICATION
This report is dedicated to God almighty for His guidance and protection throughout my SIWES
program and helping me to carry out different activities that were assigned to me and for granting me,
knowledge, and ability to understand all what I did as regards my course of study. Also, special
dedication to my family for their unconditional love and financial support. I also want to appreciate
AFEME workshop Abuja for the training provided over the course of the past 5 month’s program.

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 ACKNOWLEGDEMENTS

My appreciation goes to God almighty, through the help of the Holy Spirit made me to choose
Mechanical Engineering as my discipline.

There are a host of people I will like to thank, starting with the Industrial Training Fund (ITF) for
their foresight in putting this program to place and also to the Mechanical Engineering
department, University of cross river state (unicross) for providing the platform on which I was
engaged in the training.

I am also grateful to the entire mechatronic workshop and school Department for their guidance
and support throughout my Internship Program, starting from the commanding officer in person of
Lt. Col. S.O Ore, my industrial based supervisor Mwo Zaka D. K. Maj. Ibrahim, Capt. Isa Staff
Sergeant Mamman, Leading Seaman Munhanye, Mr Abba and Mr Emmanuel for their support in
various capacities.

My fellow interns are not left out, I appreciate them all for their constant support and
encouragement throughout the course of my internship program.

I consider this to be as a major achievement in my academic and career development. I will utilize
the acquired abilities and information and I will keep on enhancing them to accomplish wanted
profession goals.

I also want to thank my family for encouraging me and also for their moral and financial support
all through my Industrial Training (IT) period.

Finally, to my Institution based supervisor and my lecturers for their advice and support. And to
my friends and colleagues. I say thank you all. I am grateful.

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 ABSTRACT

This report reviews the knowledge, skills and experience acquired during the six months Students
Industrial Work Experience Scheme (SIWES) which took place at Armed Forces Electrical and
Mechanical Workshop, Mogadishu cantonment, Asokoro, Abuja. This report talks about the
Automobile and Mechatronic Departments of the organization where different automobiles (i.e.,
Mercedes Benz, Toyota, Peugeot, BMW etc.) were learnt about and operated on. Different
processes and procedures in which different cars or automobiles are scanned, maintained and
repaired were also stated in the report.

This report gives the information of the company in which the industrial training was carried out,
the experience gained, the problems encountered and solved.

During this period, I acquired practical knowledge on how to repair, replace and install some
mechanical parts and systems also assisted in providing the units the functionality they need.
This report discusses the technical skills gained during the training period and justifying the
relevance of the scheme in equipping students with needed technical competence to thrive in the
real world.

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 TABLE OF CONTENTS
COVER
PAGE...................................................................................................................
...................I
DECLARATION.....................................................................................................
..............................II
CERTIFICATION....................................................................................................
............................III
DEDICATION........................................................................................................
............................IV
ACKNOWLEDGEMENT..........................................................................................
...........................V
ABSTRACT...........................................................................................................
.............................VI
TABLE OF
CONTENT............................................................................................................
...........VII
LIST OF
FIGURE................................................................................................................
...............X
LIST OF
ABBREVIATIONS..................................................................................................
...............XI
CHAPTER ONE – INTRODUCTION
Background of SIWES AND ITF 1
Objectives of SIWES 1
A Brief History of AFEME Workshop 2
CHAPTER TWO – DESCRIPTION OF WORK DONE
2.1.0 Description of Work done 4
2.2.0 Automotive Mechanical Systems 4
2.2.1 The Engine 4
2.2.2 Lubricating System 6
2.2.3 The Cooling System 6
2.2.4 Air Conditioning System
2.2.5 The Electrical system
2.2.6 The Exhaust System
2.2.7 The Transmission (Drive Train) System
2.2.8 The Suspension System
2.2.9 The Steering System

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2.3.0 The Braking System
2.3.1 Battery Ignition System
2.3.2 The Battery Ignition System
2. 3.3The Fuel System
23
2.3.4 Sensors
CHAPTER THREE – REPAIR AND MAINTENANCE PROCESS
3.1.0 Repair and Maintenance Process

3.1.1 Safety Information

3.1.2 Tools Required
3.2.0 Breakdown of some selected Repair and Maintenance Services carried out
3.2.1 Servicing of vehicles
3.2.2 Replacement of Brake Pads
3.2.3 Brake bleeding operation
3.2.4 Replacement of a faulty water pump
3. 2.5Change of shock absorber
28
3.3.0 Vehicle Identification Number (VIN)
3.3.1 ALLDATA Software
3.3.2 OBD Machine
CHAPTER FOUR – CHALLENGES ENCOUNTERED, CONTRIBUTIONS
EXPERIENCE ACQUIRED
4.1 Challenges Encountered
32
4.2 Contributions
32
4.3Experience acquired
CHAPTER FIVE – SUMMARY CONCLUSION AND RECOMMENDATIONS
5.1 Summary
34
5.2 Conclusion
34
5.3 Recommendation
34

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LIST OF FIGURES
FIGURES Page
Figure 1: Overview of AFEME Workshop floor and AMS Workshop 3
Figure 2: Organizational structure of AFEME Workshop 3
Figure 3: Engine Cylinder arrangement 5
Figure 4: Removal and replacement of spark plug. 6
Figure 5: Engine Cooling System 7
Figure 6: Air Conditioning System 12
Figure 7: Transmission (Drive Train) system 14
Figure 8: Suspension System 17
Figure 9: Steering System 18
Figure 10: Some car sensors 25
Figure 11: Pictures of tools 26
Figure 12: Break bleeding operation 28
Figure 13: VIN decoding 30
Figure 14: OBD Machine 30
LIST OF ABBREVIATIONS
SIWES - Students’ Work Experience Scheme
ITF - Industrial Training Fund
AFEME - Armed Forces Electrical and Mechanical Engineering
DTCs - Diagnostics Trouble Codes
OBD - On-Board Diagnosis
VIN - Vehicle Identification Number
AWD - All-Wheel Drive
4WD - 4-Wheel Drive
ECU - Electronic Control Unit
FWD - Front Wheel Drive
RWD - Rear Wheel Drive
MAF - Mass Air Flow
MAP - Mass Air Pressure
VSS - Vehicle Speed Sensor
ABS - Anti-lock Braking System
ESP - Electronic Stability Program
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CAD - Computer Aided Design

x
*

1.0 CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND OF SIWES AND ITF

SIWES was founded in 1973 by ITF (Industrial Training Fund) to address the problem of tertiary
institution graduates' lack of appropriate skills for employment in Nigerian industries. The Students'
Work Experience Scheme (SIWES) was founded to be a skill training program to help expose and
prepare students of universities, Polytechnics and colleges of education for the industrial work situation
to be met after graduation.

The main institutions coordinating the scheme are the ITF, NUC NCCE, NBTE, tertiary educational
institutions and employers of labor. It is funded by the Federal Government of Nigeria. The target
beneficiaries are the undergraduate students of 2 Polytechnics, Colleges of Education and Universities in
disciplines such as Agriculture, Engineering, Technology, Environmental Science, Education, Medical
Science and Pure and Applied Sciences.
This system facilitates the transfer from the classroom to the workplace and aids in the application of
knowledge. The program allows students to become acquainted with and exposed to the experience
required in handling and operating equipment and machinery that are typically not available at their
schools.

Prior to the establishment of this scheme, there was a rising concern and trend among industrialists that
graduates from higher education institutions lacked appropriate practical experience for employment.
Students who entered Nigerian universities to study science and technology were not previously trained
in the practical aspects of their chosen fields. As a result of their lack of work experience, they had
difficulty finding work.

This gives student the opportunity to blend the theoretical knowledge acquired in the classroom and with
practical hands-on application of knowledge required to perform work in the industry. It also prepares
students for employment and makes the transition from school to the world of work easier after
graduation.
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1.2 OBJECTIVES OF SIWES

The Industrial Training Funds policy document no. 1 of 1973, which established SIWES, the
objectives of the scheme are:
• Provide an avenue for students in institutions of higher learning to acquire industrial skills and
experience during their course of study.
• Prepare students for industrial work situation that they are likely to meet after graduation.
• Expose students to work methods and techniques in handling equipment and machinery that may
not be available in their institutions.
• Make the transition from school to the world of work carrier and enhances students contacts for
later job placements.
• Provide students with the opportunities to apply their educational knowledge in real work
situations, thereby bridging the gap between theory and practical.

1.3 A BRIEF HISTORY OF AFEME WORKSHOP

The Armed Forces Electrical and Mechanical Engineering Workshop (AFEME WORKSHOP) located at
Mogadishu Cantonment, Asokoro, FCT, Abuja was commissioned on the 9 th day of March 2004 by His
Excellency DR. DIETMAR KREUSEL, The Ambassador of the Federal Republic of Germany to the
Federal Republic of Nigeria. It’s a workshop for mechanics, fixing and fitting all sorts of military
vehicles. Sometimes civil vehicles come for repair and maintenance at the workshop but it is mainly
military vehicles that are worked upon. There is also a school known as AFEME Mechatronic School
(AMS) established on the 27thday of May, 2015, which is located inside the workshop. It was established
by the Defense Headquarters (DHQ) in partnership with the German Technical Advisory Group (G-TAG)
to meet modern day training of its personnel. They are 3 fuel dump within the facility for the 3 Armed
forces. This workshop is well equipped with top notch auto repair facilities, skillful and well experienced
personnel that handle mechanical and electrical faults and as well as painting, fabrication and bodyworks
(panel beating). They are also in collaboration with INNOSON Vehicle Motor (IVM). The workshop is
located inside Mogadishu Cantonment which is popularly known as Abacha Barracks. They are
basically four major departments at the workshop where activities are being carried out and they are as
follow:
• Mechanical and Electrical Work Floor Department (Repair Bay).
• Mechatronics Department (where we have the Automotive Mechatronics School).
• Welding, Fitting and Fabrication Department.
• Painting and Panel beating Department.
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During the cause of the industrial training, jobs/ activities were majorly carried out in the first two
departments mentioned above.

Figure 1: Picture 1 - Overview of AFEME Workshop floor & Picture 2 – AFEME Mechatronics
School Workshop

Below is the Organization’s organogram showing its chain of command and duties.

Figure2: Organizational structure of AFEME Workshop

`

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 CHAPTER TWO

2.1 DESCRIPTION OF WORKDONE

Automotive Mechatronics is an interesting but intrinsic aspect of Engineering. It comprises of different
Parts which when put together form Components and thus these components assembled together forms
what is known as a System. There are many systems involved in this aspect of Engineering and thus
these various systems will be treated in the course of the technical report and as well jobs/activities
carried out on these Systems will be explained in details with reference to the respective departments
these activities were carried out.

2.1.2 INDUSTRIAL TRAINING EXPERIENCE

After a glamorous reception to the Armed Forces Mechanical and Electrical (AFEME) workshop
week one, we had basic introduction to workshop safety rules(Use of Overall, Safety Boot, Muster Point,
Use of Fire Extinguishers etc.), Workshop Tools and Equipment’s used to Implement Tasks and Jobs e.g.
all Spanner(Socket head, Combinations, extension rod, Screw drivers, etc.), Wrench, Electro-hydraulic
lift, Pneumatic Actuated wheel removal Machine, Crane, Multi-Flex Brake tester Machine, OBD II
Diagnosing Machine, Oil Sucking Machine and also the ALLDATA software. Thereafter in subsequent
weeks, different systems that make up automobile vehicles were highlighted and then series of
Theoretical and practical approach were performed on these systems.

2.2.0 THEORITICAL BACKGROUND OF AUTOMOTIVE MECHANICAL SYSTEMS

2.2.1 THE ENGINE
What is an Engine/Heat Engine?
An Engine is a Device which converts Energy from one form to another. Internal combustion engines run
on a mixture of fuel and air, the core of the engine is the cylinder, with the piston moving up and down
inside the cylinder and this takes place in a four-stroke process, which are intake, compression, Power
and Exhaust. The piston moves down on the intake stroke, the intake valve is open and the fuel air
mixture is admitted into the cylinder, and the piston moves up during the compression with stroke both
valves are closed, compresses the trapped fuel air mixture that was brought during the intake stroke,
thereafter the spark plug fires, igniting the compressed air-fuel mixture which produces a powerful
expansion of the vapor which is used to drive the crankshaft and this is the power stroke. Finally, during
the exhaust stroke, where the piston is at the bottom of the cylinder the exhaust valve opens to allow the
burned gas to be expelled to the exhaust system. The cycle goes over and over and again, very fast,
keeping the engine running and producing power in the order of 1342, as it is for 4 in-line cylinder cars.

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Engine Types
The majority of engines in motor vehicles today are four stroke, spark ignition internal combustion
engines.
There are several engine types which are identified by the number of cylinders and the way the cylinders
are laid. Straight line cylinders have their cylinders in row while the “V” arrangement uses two banks of
cylinders side-by-side and its commonly used in V-6, V-8 configurations.

Figure 3. Engine Cylinder arrangement

Some automobile engine parts include;

 Spark plug: The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can
occur. The spark must happen at just the right moment for this to work properly Valves The intake and
exhaust valves open at the proper time to let in air and fuel and to let out
exhaust.

Figure 4. Removal and replacement of spark plug.

 Piston: Piston is a cylindrical piece of metal that moves up and down inside the cylinder. Piston rings
Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder,
the rings serves two purposes.
• They prevent the fuel/air mixture and the exhaust in the chamber from leaking into the sump during
compression and combustion

5
• They keep oil in the sumo from leaking into the combustion area where it would be burn and lost.
Connecting rod: The connecting rod connects the piston to the crankshaft, it rotates at both ends so
that its angle can change as the piston moves and the crankshaft rotates.

 Crankshaft: The crankshaft turns the piston’s reciprocating motion in the cylinder into circular
motion. Sump (oil pan) the sump surrounds the crankshaft. It contains some amount of oil, which collects
in the bottom of the sump.

 Camshaft: The camshaft in an internal combustion engine makes it possible for the engine’s valve to
open and close, the asymmetrical lobes of the camshaft correspond to the engine valves.

2.2.2 LUBRICATING SYSTEM

Oil is the life-blood of the engine. An engine running without oil will last about as long as human without
blood. Oil is pumped to all the moving parts of the engine by and oil pump. The oil pump is mounted at
the bottom of the engine in the oil pan and is connected by a gear to either the crankshaft or camshaft.
This way, when the engine is running the pump is pumping simultaneously. There is usually an oil
pressure sensor near the oil pump that monitors pressure and sends this information to a warning light on
the dash board (this feature is found in modern cars as it might be in your car), when the ignition key is
turned on, but before the car is started the oil light should light, indicating that there is no oil pressure yet,
but also letting you know that the warning system is working.

2.2.3 THE COOLING SYSTEM

A car engine produces enormous amount of heat when it is running, and must be cooled
continuously to avoid engine damage, generally this is done by circulating coolant liquid usually water
mixed with an antifreeze solution through special passages.
As the name implies, cooling system maintains the working temperature of an Engine.

Figure 5: Engine Cooling System

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There are two types of Engine cooling Systems and they are as follows:
1. Air Cooling System: In this type of cooling system, the heat which is conducted to the outer part of
the engine is radiated and carried by stream of air which is obtained from the atmosphere. For efficient
cooling effect, fins are provided around the cylinder and cylinder head so as to increase the contact area.
These fins are metallic ridges which are formed during the casting of the cylinder and cylinder head. The
amount of heat carried away by the air Cooling depends on the following factor:
• Total area of fin surface.
• Velocity and amount of cooling air.
• Temperature of the fin and cooling air.
Air cooling system is mostly used in tractors of less horsepower, motorcycles scooters, small cars and
small air craft engines where forward motion of the engine gives good velocity to cool the engine.

ADVANTAGES

• Simple Design.
• Lighter weight than water cooled engines due to absence of water jackets, radiator and pump.
• Cost of maintenance is low.
DISADVANTAGES

a. Relatively large amount of power is needed to drive the cooling fan.

b. Engine gives less power output.
c. Cooling is not uniform.
d. Engines are subjected to high working temperature.

2. Water Cooling System: Water cooling Systems is used in engines of cars, buses, trucks etc. In this
system, water is circulated through Water Jackets around each of the combustion chambers, cylinder,
valve seat and valve stem. The water is kept continuously in motion by a centrifugal water pump by
means of serpentine belt through the crankshaft pulley. This cooling process is known as Boundary
Cooling.
Water Cooling System Comprises of these main parts:
• Water Pump.
• Coolant (antifreeze mixture).
• Thermostat.
• Radiator and necessary plumbing hose.
• Coolant Temperature Sensor.
• Radiator Fan.

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 A. Water Pump:
Water pump is the heart of Cooling System which distributes the coolant around the surrounding of the
engine (water jacket). It consists of the following parts:

• Impeller.

• Pulley Flange.

• O-ring.
When an engine is started in the morning, there is conversion of reciprocating motion of the Piston
connecting rod to rotary motion of the crankshaft (crankshaft pulley) which then distribute the motion to
different pulley units of different components e.g., water pump pulley (pulley Flange) through the
serpentine belt. Hence the water pump begins to pump in coolant from the radiator lower tank hose to the
engine block through the water jacket.

B. Coolant:
Its function is to absorb the heat generated from the combustion process and flows toward the thermostat.

C. Thermostat:
Main parts of the thermostat include:
• Main valve.
• Main spring.
• Frame.
• Charge cylinder.
• Bypass valve.
• Secondary spring.
The thermostat is the brain behind the cooling system. It's the main component that regulates and
maintains the working temperature of the engine. A thermostat is a Mechanical actuator which acts like a
valve to open and close as a function of its temperature (designed temperature most times 180°F). It
isolates the engine from the radiator i.e., it restricts the coolant from flowing towards the radiator until the
temperature of the coolant (which is the temperature of the engine) is raised the above working
temperature of the engine and this temperature reaches that of the thermostat, thus the thermostat is
Actuated to open by pushing the bypass valve downward thus realizing the coolant to flow to the upper
radiator tank hose.

D. Radiator.

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Radiator consists of the following parts:
• Inlet port or upper radiator hose.
• Outlet port or lower radiator hose.
• Radiator pressure cap.
• Drain plug.
• Fins.
Radiator is a heat Exchanger used to transfer the excess heat developed by the engine to the atmosphere.
As the hot coolant flows into the radiator through the inlet port, this coolant flows through the various
passages inside the radiator and as well since the pressure of the coolant is very high, it tends to provide
an upward force. This upward pressure force is taken care of by the radiator pressure regulating valve.
When the inbuilt pressure goes beyond the recommended value, it tends to open upward thus realizing
some of the coolant to flow into the expansion tank through the drain plug. Air is blown from the
atmosphere to the radiator tubes and fins as the hot coolant flows from top to bottom of the radiator and
at the button of the radiator, pressure and temperature is expected to have gone back to normal for
another cycle of cooling to take place in the engine.

E. Coolant Temperature Sensor

As the word sensor implies, it’s capable of converting a physical quantity (heat) into Electrical signal.
This sensor consists of the Sensing probe and Electrical connector. Most coolant temperature are
negative temperature coefficient Type in the sense that as temperature increases, its resistance decreases
thus allowing the flow of current. Thus, it monitors the engine temperature (coolant Temperature), sends
that signal (data) to the Electronic Control Unit (ECU) to manage fuel injection and ignition timing and
as well this sensor is used to trigger the radiator fan to start blowing.

F. Radiator Fan.
As the name implies, it's used to create an air suction effect to cool down the temperature of the coolant
inside the radiator. in most vehicles depending on the design, it is triggered by the coolant Temperature
sensor to start blowing in an anti-clockwise manner thus creating the suction effect on the radiator.

This is basically the working system of an engine cooling system. Most times these individual
components can get faulty or start showing symptoms of failure and when this happens, the component
must be replaced by a new one. Looking at only one of the components (Thermostat), a practical session
was demonstrated on how to test the workability of a good thermostat. Two methods were introduced
which can be classified as follows:

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 ▪ Recommended method.
As the name implies, this involves the removal of the thermostat from the car (Engine Compartment),
submerging it inside water while suspended with a non-metallic material (rope) and then heating up the
water. When the temperature of the water reaches the temperature marked on the thermostat (designers'
temperature) by using a thermometer to check, if the thermostat is good, it starts operating i.e., the bypass
valve opens downward as expected. Thus, this performance shows that the thermostat is working fine. If
the reverse be the case, the thermostat is bad and needs to be replaced.

▪ Modern Method.
Testing the thermostat without removing it from the car is very much possible. This is done by measuring
the temperature of the upper and lower radiator hose using an infrared thermometer while monitoring the
engine temperature using a scan tool. This same method was equally achieved by using two hands to feel
the temperature of the two radiator hoses (outlet and inlet). If one hose is hot and the other is cold, it
means that the thermostat is stocked closed (not functioning) but if both are hot it then shows that the
thermostat is functioning.

2.2.4 AIR CONDITIONING SYSTEM.

Comfort is a necessity in automotive vehicles because it deals with the welfare of the Occupant.

Definition: Air conditioning system refers to as a closed loop within the car in which the interior air in a
vehicle in hot weather is been cool down thus producing a better interior environment for the Occupant.
This is made possible by moving a substance known as refrigerant through high/low pressure close loop
system. This system also serves as a means of warming up the interior environment of the car during cold
weather in coldest countries.

Components of Air Conditioning System

• Refrigerant.
• Compressor.
• Condenser.
• Receiver-drier.
• Expansion Valve.
• Evaporator.
• Blower Motor.
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 • Accumulator.
• Pressure sensor.

L
PRINCIPLE OF OPERATION

1. Refrigerant: This is actually a gas that is commonly called Freon which is one of the major
components of A/C system itself.
2. Compressor: This is the heart of the A/C system. This cycle starts with the compressor compressing
low pressure gaseous refrigerant to high pressure gaseous refrigerant and since pressure is directly
proportional to temperature, the temperature of the gaseous refrigerant increases as well. Thus, this high
temperature and pressurized gaseous refrigerant flows into the condenser through the outlet pipe. 3.
Condenser: This looks like a small radiator thus providing condensing effect. i.e., it lowers the
temperature of the pressurized gaseous refrigerant sent by the compressor through a forced convection
provided either by the radiator fan or by separated fan used by the condenser so as to change it phase
from vapor to liquid. This hot gaseous refrigerant enters the top of the condenser and as it flows down to
the button of the condenser, it condenses to liquid with low temperature but high pressure.

4. Expansion valve: This is a device used in the air conditioning system to expand the high pressurized
low temperature liquid refrigerant sent by the condenser to low pressure liquid refrigerant before sending
it to the Evaporator.
5. Evaporator: This device looks like another heat exchanger in the sense that it absorbs the heat from
the passenger's compartment and converts the liquid refrigerant sent by the expansion valve into vapor
which in turns provides cooling effect through the blower inside the passenger's cabin. Recall, heat gain
is equal to heat loss and this is what happens in the evaporator. This blower is found behind the A/C vent
over the dashboard of a car. One major benefit of the Evaporator is that it causes Dehumidification
(removal of excess moisture from air and maintaining a relatively ideal humidity level).
6. Receiver or Dryer: There are chances that some liquid might escape and flow back to the
compressor for compression and since liquids are incompressible, this might damage the compressor.

Thus, the dryer is used in between the evaporator and compressor it converts the remaining liquid in to
vapor before sending it to the compressor for another cycle to take place. Also, the receiver serves three
important functions and they are as follows:
• Most receivers or dryers contain filter that can trap debris that might be in the A/C system.
• It also contains a material called Desiccant used to absorb moisture (water) that may have gotten
inside the A/C system during manufacture or from humidity in the air.
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 • Receiver or Dryer acts as a temporary storage container for oil and refrigerant when neither is
needed for the system Operation i.e., period of low cooling demand and hence, this is the receiver
function of the receiver/dryer.
This is how a typical air conditioning system in automotive vehicles works.

2.2.5 THE ELECTRICAL SYSTEM

The electrical system consists primarily of the battery, starter and alternator. The battery acts as a power
storage unit while the alternator sends power back into the battery from the running engine keeping it
charged.

2.2.6 THE EXHAUST SYSTEM

When the engine is running, it produces a lot of waste also known as exhaust. Some substances within
the exhaust are harmful to both people and the environment. The exhaust system, composted of the
exhaust manifold, oxygen sensors, catalytic converters, resonators, exhaust pipes, muffler, and tailpipe,
works to filter, channel, and push exhaust gasses away from the car.

2.2.7 THE TRANSMISSION (DRIVE TRAIN) SYSTEM

The Transmission system includes the following; Drive train, Transmission (gearbox), driveshaft,
Axles and wheels. These work together with the engine to move the vehicle. The drive train and the
transmission are an essential and integral system of a vehicle.

FUNCTION OF THE TRANSMISSION (DRIVE TRAIN) SYSTEM

Due to the internal combustion taking place in the engine, power is being generated from the process and
thus must be efficiently utilized. Its main function is basically to transmit power from the vehicle's engine
(flywheel) through the transmission to the drive wheels of the vehicle through the propeller shaft to
control the amount of torque needed by the vehicle for different conditions e.g., either climbing a hill or
moving in a straight line (either high torque or low torque with the same power output, note: velocity
varies as well from high to low or vice versa depending on the torque needed). Thus, this keeps the
wheels spinning and the engine within a certain revolution per minute range.

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 Figure 7: Transmission (Drive Train) system

COMPONENTS OF THE TRANSMISSION (DRIVE TRAIN) SYSTEM

• Trans-axle: As its name implies, it does the job of both transmission and axle. It's connected to
the clutch or the torque converter depending on the transmission type used in the car (Manual,
automatic/ semiautomatic). its other gear is connected to either a differential unit or another set of
gears.
• Constant Velocity joint (CV Joint): This is used to transmit power through variable angles at
constant rotational speed. This joint is well lubricated this having low friction.
• Driveshaft: the driveshaft is a long tube of steel that is linked to the car's transmission at one end
and to the wheels at the other end this transferring Mechanical power from the transmission to
other components of the vehicle.
• Half shaft: It comprises of two parts used at both wheels; one is connected to the Differential
while the other is connected to the wheel.
• Universal Joint: This is a flexible pivot point that transmits power allowing for varying angles of
the driveshaft.
• Differential: This is where the power makes it last stop before spinning the wheels.
• Gear box (Transmission): This is a Mechanical device used to increase the output torque or to
increase the speed (RPM) of a motor. The shaft of the motor is connected to one end of the gear
box and through the internal configuration of the gears of the gear box, provides a given output
torque and speed which determines the gear ratio.
• Clutch or Torque converter: This Component transfers engine torque to the gear box. The
torque converter sits between the engine and the transmission. It’s a donut looking thing that sits
inside the big opening of the transmission’s bell case. It has two primary functions in terms of
transmitting torque:

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  Transfers power from the engine to the transmission input shaft.
 Multiplies engine torque output
It performs these two functions thanks to hydraulic power provided by the transmission fluid inside your
transmission. There are four main parts of a torque converter in most modern vehicles:
• Pump (Impeller): This looks like a fan thus having Bunches of blades radiating from its centre.
The pump is mounted directly to the torque converter housing which in turn is bolted directly to
the engine’s flywheel. Consequently, the pump spins at the same speed as the engine’s crankshaft.
• Stator: The stator sits between the pump and turbine. It looks like a fan blade or airplane
propeller. The stator does two things:
 Sends transmission fluid from the turbine back to the pump more efficiently, and
 Multiplies torque coming from the engine to help get the car moving, but then sends less
torque once the car is going at a good clip.
• Turbine: The turbine connects directly to the input shaft of the transmission. It’s not connected to
the pump so it can move at a different speed than the pump. This is an important point. This is
what allows the engine to turn at a different speed than the rest of the drive train.
• Torque converter clutch.
TYPES OF DRIVETRAINS

a. Front Wheel Drive (FWD): Now in this type of drive, the power from the engine is delivered to
the front wheel of the vehicle. I.e., in FWD, the front wheel engages the motion by pulling the
vehicle while the rear wheel becomes the follower because it doesn't receive power of its own.
FWD is of better fuel economy and emits less carbon dioxide as well. Since the weight of the
engine is located over the driving wheel, vehicles with FWD can maintain better traction in snow.
b. Rear Wheel Drive (RWD): This type of drive indicates that power from the engine is delivered
directly to the rear wheel and thus it becomes responsible for moving the vehicle forward. The
front wheel becomes the follower.
c. Four Wheel Drive (4WD): In this type of drive, power from the engine is delivered to the four
wheels. I.e., both can engage motion but it has an option to either operate in FWD or RWD to
conserve fuel. The advantage of 4WD is its versatility and power to withstand any terrain or
weather condition. However, 4WD tends to be more robust than AWD, and this makes that
system a better fit for drivers who go off-road. Also, unlike AWD, 4WD typically offers
driverselectable low- and high-range settings. The low-range setting delivers aggressive traction
and is usually used when ascending steep trails or crawling over boulders.

d. All-Wheel Drive (AWD): This drive train employs front, rear and centre differential to provide
power to all four wheels of the vehicle. Hence, all-wheel drive system powers the front and rear
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 wheel all the time. For AWD system, torque is sent to all four of a vehicle’s wheels automatically.
Drivers typically don’t need to act to start the process, though some systems offer selectable
modes that allow drivers to determine how power is distributed. There are two types of AWD:
full-time and part-time. With a full-time system, torque is sent to all four wheels 24/7. With
parttime AWD, power is typically sent to either the front or rear axle during normal driving.
Sensors determine if there is a need for extra traction, such as when there’s rain, snow or mud on
the ground. Then, the part-time AWD sends power to both axles.
Having explained about the drive train, it can be said that the vehicle is set on motion because power has
reached the wheel. Now this motion has to be controlled and directed and thus bringing us to the next
system as a case of study.

2.2.8 THE SUSPENSION SYSTEM

Every car, truck, and utility vehicle has a suspension system that helps support the vehicle, absorb shock
and bumps, and allows the vehicle to turn. The suspension is comprised of the following basic
Components:

 Wheels and tires

 Springs
 Shock absorbers and struts
 Linkages
 Bushings,
 bearings and
 Joints

Figure 8: Suspension System

2.2.9 THE STEERING SYSTEM

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A vehicle's steering system is a vital part of a vehicle's ability to move. The main functions of the steering
system is to provide vehicle turning per will of the driver, directional stability, it converts the rotary
movement of the steering wheel into an angular turn of front wheels, and absorbs road shock from being
transmitted to a driver's hands. A motor vehicle's steering system contains the following basic parts:
Steering wheel, Steering shaft and Column, Tie rods, rack, idler arms, Pitman arm, and drag or center
link. A power steering system contains additional components such as power
Steering pump, steering yoke/damper, steering coupler, and power steering hoses.

FUNCTION OF STEERING SYSTEM

• Set direction for the car.
• Provides stability to the car while running.
• Prevents vibration from reaching the steering wheel.
• Helps to prevent wear and tear of tyre.
• Provides straightening effect to the front wheel.

Figure 9: Steering system

TYPES OF STEERING SYSTEM
Basically, there are two types of steering systems which are as follows:
1. Manual Steering System.
2. Power Assisted Steering System.
MANUAL STEERING SYSTEM

This is a steering system whereby the steering is connected to the rod that turns the wheel as per steering
direction. Hence, manual steering system is called rack and pinion steering. Rack means rod and pinion
means Gear. A gear is attached to the steering rod and thus when the driver turns the steering wheel, it
turns the gears in circular motion which in turns moves the steering rod which can be seen behind the
clutch, brake and accelerator pedal. The rotational motion of the steering wheel is converted to linear
motion which makes the vehicle move forward. Now, when the vehicle is ideal, the steering is heavy but

16
ones the vehicle (tyres) starts moving, the kinetic energy reduces the weight of the steering and thus the
higher the speed, the lighter the steering.

POWER ASSISTED STEERING

This is a steering system Target at reducing the effort of the driver in turning the steering wheel. Without
power assist, the steering of most vehicles becomes extremely heavy especially during low speeds. E.g.,
turning 90 degrees inside city.

REPLACEMENT OF POWER STEEERING PUMP

Replacement of power steering pump was carried out on C300 Mercedes Benz. This was done because
the of the following reasons:

• Whining noise while turning the steering wheel.  Faulty power steering pump code
and symbol popped up  Steering wheel was slow to respond.
• Stiff steering wheel.
• Application of much force by the driver to turn the wheels which is not supposed to be so.
• Faulty serpentine belt.
So based on the following symptoms and reasons, it was concluded the power steering pump had failed
and needed replacement. The following steps were carried out:
• Surrounding compartment were dismantled so as to have easy access to the pump
• The Adjuster was slacked so as to permit easy removal of the serpentine belt
• Power steering reservoir and connecting hose was dismantled and removed so as to access
the pump because the pump is directly under it.
• Surrounding bolts of the pump were slacked and loosed which comprises of two at the
front and one at the back and spanners such as 10mm socket, extension and handle were
used to slack these bolts and hence the faulty pump was removed.
• The new pump was installed back right away and the various components were assembled
including the serpentine belt.
Thereafter the car’s system was scanned and the faulty code that popped up for the power steering pump
was cleared and then the system became normal. Ignition was turned on and the steering was tested and it
was found working fine.

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2.3.0 THE BRAKING SYSTEM

A brake system is designed to slow and halt the motion of vehicle. To do this, various components within
the brake system must convert vehicle’s moving energy into heat. This is done by using
Friction.
As the brakes on a moving automobile are put into motion, rough-textures brake pads or brake shoes are
pressed against the rotating parts of vehicle, be it disc or drum. The kinetic energy or momentum of the
vehicle is then converted into heat energy by kinetic friction of the rubbing surfaces and the car or truck
slows down. When vehicle comes to stop, it is held in place by static friction. The friction between
surfaces of brakes as well as the friction between tires and roads resist any movement. To overcome the
static friction that holds the car motionless, brakes are released. The heat energy of combustion of in
engine is converted into kinetic energy by transmission and drive train, and the vehicle moves.

TYPES OF BRAKING SYSTEM

There are basically three types of brakes used in automobiles
1. Mechanical brakes
2. Hydraulic brakes
3. Air Brakes and related type of brakes
 Mechanical brakes: Mechanical brakes are used in Hand brakes (or parking brakes). Here, a lever is
provided near the driver seat and through steel wire connections it is connected to brakes at the rear of
the vehicle. When the hand brake is engaged, tension is created at the brakes and the brake shoe holds the
drum from rotating and hence the movement of the vehicle is restricted, even if parked in a slightly
inclined surface.

 Hydraulic brakes: The hydraulic brake system uses brake fluid to transfer pressure from the brake
pedal to the pads or shoe. By exercising the pedal, brake fluid transfers this pressure to the brake pads.
This transfer of pressure is reliable and consistent because liquids are not compressible,
i.e. pressure applied to liquid in a closed system is transmitted by the liquid equally to every other part of.
In brief, when a driver applies pressure at the brake pedal, the mechanical force (stepping of driver on
pedal) is changed to hydraulic pressure which is transmitted through liquid to respective wheel cylinder
and changed back to mechanical force (operation of brake pads, shoe).
 Power Brakes: Power brakes are nothing more than a standard hydraulic brake system with a booster
located between the brake pedal and master cylinder to help activate the brakes. This could be in case the
fluid pressure required would be too high. There are two basic types of power assisted mechanisms used:
vacuum assisted and hydraulic assisted. Vacuum assisted system use engine vacuum pressure to help

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apply the brakes. Hydraulic assist systems are largely found on heavy vehicles. This system uses
hydraulic pressure developed by the power steering pump or other external pump to help apply the
brakes.

 Air brakes: Air brake system consist of components like air compressor, air reserve tank, check
valves, safety valves etc. The working is very similar to the working of hydraulic brakes. The key
difference is that mechanical force is transmitted to wheel ends through air pressure, instead of fluid
pressure. Airbrakes are most preferred in heavy vehicles.

DISC VS DRUM BRAKES

Another brake classification is in terms of disc and drum. This refers to the actual mechanics of
Slowing down the vehicle. Let us take a look at these two systems.

 Drum brakes: A drum brake assembly consists of a cast-iron drum which is bolted to and rotates
with the vehicle’s wheel, and a fixed backing plate to which the shoes, wheel cylinder, automatic
adjusters and linkages are attached. Additionally, there might be some extra
Hardware for parking brakes.

 Disc brakes: In disc brakes, the friction elements are in the form of pads, which are squeezed or
clamped about the edge of a rotating wheel. With automotive disc brakes, there is a separate wheel
unit called the Rotor (commonly called as disc) alongside the vehicle’s wheel. This rotor is made of
cast iron. Since pads clamp against both sides of it, both sides are machined smooth. Usually the
two surfaces are separated by a finned center section for better cooling (such rotors are called
ventilated rotors or in common words as ventilated discs).The pads are attached to metal shoes,
which are actuated by pistons, the same as with drum brakes. The pistons are contained within a
caliper assembly, housing the wraps around the edge of the rotor. The caliper is kept from rotating
by
Way of bolts holding it to the car’s suspension frame work.

FUNCTIONS OF AUTOMOTIVE BRAKING SYSTEM

Below are the functions braking system used in the automotive engine:
• A brake system helps to stop vehicles within the smallest possible distance. This is achieved by
converting the kinetic energy of the vehicle into heat energy.
• It also functions on a mechanical device where motion occurs, the brake is applied to stop it
within a short period of time.

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COMPONENTS OF THE BRAKING SYSTEM

Below are the components used in the automotive braking system:

• Brake pedal: The component of a brake system is used to activate the brake by pressing it down
by foot. It’s located in the middle of the accelerator and clutch pedal inside the vehicle.
• Fluid reservoir: The fluid reservoir is the housing where the brake fluid or brake oil is store.
• Fluid lines: The fluid lines are the pipes through which the brake fluid flows in the vehicle.
• Brake pads: The brake pad is a steel backing plate employed on disc brakes. It’s often made of
ceramic, metal, or other hard-wearing composite materials.
• Brake shoes: Brake shoes are two pieces of sheet steel joined together so it can carry the brake
lining.
• Brake drum: The brake drum is a rotating drum-shaped component used in the drum brake
system.
• Rotor: The rotor is a cast-iron brake disc connected to a wheel or axle, sometimes made of
reinforced carbon-carbon, ceramic metrics, or some other composite.
• Brake lining: A brake lining is a heat-resistant, soft but also tough material with high friction
characteristics. It’s enclosed inside the brake shoe.
• Piston: The piston is a moving component contained by the cylinder.
• Calliper: The calliper carries the brake pads and pistons.
• `Floating calliper or sliding calliper: The part moves relatively with the rotor as it uses a piston
on a single side of the disc to push the inner brake pad into the braking surface. It then pulls the
calliper body in to apply pressure on the opposite side of the disc.
• Fixed callipers: The fixed calliper does not move in relative to the rotor, which works sensitive to
imperfections. It uses one or more single pairs of opposing pistons to clamp from each side of the
rotor.
• Master cylinder: The master cylinder converts the non-hydraulic pressure from the driver’s foot
into hydraulic pressure. it then controls the slave cylinders at the opposite end of the hydraulic
system.
• Vacuum booster: This braking system component is used to improve the master cylinder and
increase pressure to which the driver foot supply through the use of a vacuum in the engine intake.
This is effective while the vehicle’s engine is running.
2.3.1 BATTERY IGNITION SYSTEM
Battery Ignition System is used in Automobile (IC Engine) to produce a spark in the spark plug for the
combustion of fuel.

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A battery ignition system is used in the SI engine for supplying the power to the spark plug for the
generation of spark to burn the air-fuel mixture in the SI Engine system.
PRINCIPLE OF OPERATION
When the ignition switch is turned ON, the primary circuit gets closed and the current starts flowing
through it. This current sets up the magnetic field around the soft iron core of the coil. The current starts
flowing through the condenser when the breaker points open, and when it closes the current is flowing
through the contact breaker. When the current passes through the condenser, the condenser charges, the
primary current falls, and the magnetic field gets collapses. This change in the magnetic field induces a
current in the primary winding that flows in the same direction as the primary current. And charges the
condenser voltage to much higher than battery voltage thus stopping the current flowing from the battery.
Due to these processes, the condenser gets discharged into the battery. Now reverse the direction of the
primary current and magnetic field induces a high voltage in the secondary winding. Now the high
voltage sends to the distributor by the high-tension wire. Between distributor and spark plug an ignition
harness is connected as you can see in the diagram. Now the current passes to spark plug one by one and
it will produce spark for the burning of an air-
Fuel mixture.

PARTS OF THE BATTERY IGNITION SYSTEM

Battery Ignition System consists of the following Main Parts: Battery, Ballast Resistor, Ammeter,
Ignition Switch, Primary Winding, Contact Breaker, Capacitor, Secondary Winding, Distributor and
Spark Plug

2.3.2 FUEL SYSTEM

The fuel system is critical in storing and delivering the gasoline or diesel fuel your engine needs to run.
Think of it as your vascular system, with a heart (fuel pump), veins (fuel lines) and kidneys (filter). A
failure in any of these fuel system components has the same devastating effects as in your body.
COMPONENT OF THE FUEL SYSTEM
 Fuel tank: It is basically a holding tank for your fuel. When you fill up at a gas station the gas travels
down the filter tube and into the tank. In the tank there is a sending unit which tells the gas gauge how
much gas is in the tank. Some fuel thank houses the fuel pump and has more emissions
Controls to prevent vapors leaking into the gas.

21
 Fuel pump: On newer cars the fuel pump is usually installed in the fuel tank. Older cars have the fuel
pump attached to the engine or on the frame rail between the tank and the engine. If the pump is in the
tank or the frame rail then it id electric and is driven by your car battery. Fuel pumps mounted to the
engine use the motion of the engine to pump the fuel, most often being driven by the
camshaft, but sometimes the crankshaft. Fuel filter: clean fuel is critical to engine life and performance.
Fuel injectors and carburetors have tiny openings which clog easily so filtering the fuel is a necessity.
Filters can be before or after the fuel pump. They are most often made from a paper element, but can be
stainless steel or synthetic material and are designed to be disposable in most cases. Some performance
fuel filters will have washable mesh, which eliminated the need for replacement.

2.3.4 SENSORS
Sensors are used in cars to serve as input devices; they react to the environment (remote sensing) and
make diagnosis and faults detection easy. Common sensors include:
 Oxygen Sensors (or O2 Sensors): They sense the amount of oxygen in the vehicle’s exhaust. The
readings from the sensors are sent as input to the ECU to regulate the amount of fuel-air ratio in
the engine. They are found along the exhaust system.
 Mass Air Flow (MAF) Sensor: It records the amount of air coming into the engine and
Regulates the amount of fuel needed to offset it. It found along the air hose between the air filer and
The actuator.
 Crank Angle Position Sensor: It is popularly referred to as the “starting sensor”. Its common
location is above the flywheel. This sensor monitors the position or rotational speed of the
crankshaft. This information is used by the ECU to control the ignition system, the timing, and
other engine parameters like the fuel injection and strokes. Without this sensor the car won’t start!
 Brake Pad Wear Sensor: It monitors the wear of brake pads. When the pads are worn to a low
Level, these sensors give alert for replacement.
 Vehicle Speed Sensor (VSS): It is responsible for sending a signal to the car’s computer that tells
it how fast the car is traveling. The speed is displayed on the speedometer on the dashboard.
Thermostat: it serves as a temperature sensor and one-way-valve at the same time, in the
cooling system. It monitors the flow of coolant flow in the engine until it reaches an alarming
temperature of 180ºF where it can now allow the hot fluid to flow pass it to the radiator and then
actuate the fan via a thermostatic switch.

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 Camshaft Sensor: it is found above the camshaft gear teeth. It determines the position of the
camshaft as it relates to the crankshaft. This data is then sent to the Powertrain Control Module
(PCM) for use with fuel injection and/or ignition system control
 Knock Sensor: it is bolted to the engine block to pick up vibrations and abnormal sounds from the
combustion chamber. The information obtained is used by the ECU to adjust combustion timing
to the correct one and thus avoiding knocking (an inappropriately timed, unplanned, or secondary
Combustion within the combustion chamber).

Figure 10: Some cars sensors

CHAPTER THREE

3.1.0 REPAIR AND MAINTENANCE PROCESS

Mechanical systems in automobiles are a little complex and some problems, may need to be serviced at
the repaired shop.

3.1.1 SAFETY INFORMATION

Most accidents in servicing/mechanical repair involve slips, trips and falls or poor manual handling.
Other causes of incidents sometimes resulting in serious injury or death include working under
inadequately supported vehicles, incidents involving petrol and vehicle movement. Keeping work areas
free of clutter is an important, but often overlooked, step in running a safe and productive workshop.
Requiring appropriate protective gear minimizes eye and finger lacerations, which are common auto
body shop injuries. Shops should purchase appropriate eyewear, and make protective gloves available to
prevent cuts from glass, sheet metal or other jagged objects.

3.1.2 TOOLS REQUIRED

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To effectively carry out repair and maintenance, they are certain tools that an automotive technician must
have and use. Some of them are listed below;
Wrench set, Screw driver set, Ratchet and socket set, Pliers, Torx & Hex wrenches, Hammers, Car
Jack, Jack (Axle) stands, Tire Wrench, Multimeter, OBDII Scanner, Oil Filter Wrench, Drain Pan, Oil,
Funnel, WD-40 Spray, anti-seize lubricant, Torque Wrench and a host of
Others.

3.2.0 BREAK DOWN OF SOME SELECTEDREPAIR AND MAINTENANCE CARRIED OUT

3.2.1 Servicing of Vehicles

Servicing of vehicles is a nominal routine implemented on cars so as to maintain efficiency and good
performance upon usage. Depending on the manufacturers ’specification, a certain range of distance must
be covered before servicing can be performed on the car and this ranges from 5000miles and above. The
following procedures are carried in achieving the task at hand:

• Engine oil was changed

• Oil filter, air filter and fuel filter were replaced.
• Spark plugs were replaced.
• Brake fluid level was checked and refilled.
• Brake pads were checked and were replaced when worn out.
• Power steering fluid was checked and was refilled.
• Timing belt was inspected.
• Conditions of the tires were checked.

3.2.2 Replacement of brake pads

This operation is always carried out when a vehicle is due for servicing. It is essential to change the brake
pad of a vehicle when there is less friction between the pads and the brake disc. The following are the
procedures followed when changing the brake pads;
• The vehicle is jacked up and the tire sere removed so as to access the wheel.
• The caliper that houses the pad are disassembled.
• The clip that holds the pad is removed then the pads are removed afterwards.
• The piston responsible for pushing the pads to grip the wheels is forced back to its original position.
• A new set of pads are properly fixed and the caliper is assembled.

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3.2.3 Brake bleeding operation
This operation is usually carried out to expel air from the system. Also, it is carried out when the master
cylinder has been allowed to fall too low and when the system has been opened for repair. The following
are the procedure:
• The nipple on the caliper is loosed.
• From the driver side, the brake pedal is pumped so that the air in the master cylinder can be
expelled.

• Then the nipple is tightened.

• Brake fluid is added to the master cylinder.
• The above procedures were repeated until the brake pedal attained a sufficient height when pressed.

Normally during the inspection, trouble codes such as ABS (Anti-lock braking system), ESP (Electronic
stability program), are usually seen on the dash board. So, after the maintenance job carried out on the
vehicle, the diagnosing device is usually used to check the system if the job was successfully done and to
confirm that, all those trouble codes will be wiped out from the device and dashboard as well.

Figure12: Break bleeding operation

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3.2.4 Replacement of a faulty water pump

A faulty water pump affects the cooling system of the vehicle. The transfer of water to the engine stop. If
not replaced, the engine will be overheated which can cause burning of the gasket. Procedures include;

• The serpentine belt that connects the water pump to another part (compressor, alternator) of the
engine was removed.
• The faulty water pump was detached from the engine.
• The new fuel filter was installed

3.2.5 Change of shock absorber

It is a component of the suspension system. It isolates the body of the vehicle from shock and vibrations
generated due to irregularities on the surface of the road. A bad shock absorber will not isolate the
vehicle from shock and vibration. When this was observed in a vehicle, the following are the procedures
carried out to change the shock absorber:
• The tire of the wheel where the shock absorber is to be fixed is removed after the vehicle is jacked
to an appropriate position
• Bolts are removed from the shock tower.
• The shock absorber is disconnected from the suspension.
• The shock absorber is removed from the bottom and top bolts.
• The new shock absorber is fitted back onto the suspension control arm.

3.3.0 VEHICLE IDENTIFICATION NUMBER (VIN)

VIN is a 17 alphanumeric code which contains all information provided in a vehicle. It cannot be more or
less than 17 digits. This VIN is broken down into 3 sections:
1. World Manufacturer Identifier (WMI) section: The first section includes 3 digits. This section
tells you the most basic information on the car, such as;  Digit 1 tells what country made the car.
• Digit 2 indicates the car’s manufacturer.
• Digit 3 gives information on the car type, when combined with the first two digits.
2. Vehicle Descriptor Section: The second section includes more specific information on the car,
including technical information about the car type.
 Digits 4 to 8 provide further specifics on the car, such as the car’s model, body and type of engine. 
Digit 9 is the check digit, which is assigned by the manufacturer to ensure VIN accuracy.
3. Vehicle Identifier Section: The third section further identifies the individual vehicle. This section can
include the car’s serial number, and other manufacturer-specific identifying information.
• Digit 10 indicates the car’s model year.
26
• Digit 11 shows which plant assembled the vehicle.
• Digits 12 to 17 generally indicate the individual car’s serial number
Having given a brief explanation about what VIN is, diagnosis and troubleshooting and fault finding can
now be properly discussed about

Figure 13: VIN decoding

3.3.1 ALLDATA SOFTWARE
ALLDATA is a source for automotive original equipment manufacturer information. ALLDATA
provides vehicle manufacturers’ diagnostic and repair information. It was founded in 1986. It provides
details concerning repairs, diagnosis, locations of different components of the vehicle, tightening torque
specifications.

3.3.2 ON BOARD DIAGNOSTICS (OBD) MACHINE

OBD is also a scanner used mainly for detecting and clearing faults and error codes on a vehicle. It also
reveals the VIN number of the vehicle. It is connected to the vehicle through a 16-pin port located
beneath the steering wheel of every vehicle

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 Figure 14: OBD scanner

WHAT IS ON-BOARD DIAGNOSIS

On-board diagnosis (OBD) is an automotive term referring to a vehicle’s self-diagnostic and reporting
capability. It has the following aims:

« To aid technicians access the status of various sub-systems.

« It’s a software targeted at monitoring and regulating vehicles’ emission to zero tolerance or a set of
standards.

« It equally alerts the vehicles’ owner by illuminating a warning light in regards to failure in emission
related component(s).

STEPS FOR ON BOARD DIAGNOSIS

i. Connect the EOBD11 16-pin Bluetooth connector.

ii. Switch on the vehicles Ignition.
iii. Depending on the nature of the job, u can select either the manufacturer or generic software from
the diagnosing machine or gadget.
iv. For manufacturer software, vehicles specification such as whether the car is European, American
or Asian must be rightly selected, vehicles’ brand or make e.g., Mercedes Benz, Toyota, Nissan
must be selected, vehicles’ model will be selected, and other information such as year of
manufacture, engine types etc. will pop up as well
v. For generic connection, a straight forward connection will take place and the following vehicles’
details will pop up for confirmation e.g. VIN, vehicle model, year of manufacture etc.
vi. And finally, from here the vehicles’ system can be observed, analyzed and the corresponding
trouble codes can be interpreted.

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4.0 CHAPTER FOUR

CHALLENGES ENCOUNTERED, CONTRIBUTIONS AND EXPERIENCE ACQUIRED

4.1CHALLENGES ENCOUNTERED

During the period of the training, despite the excitements offered by the program as well as the vast
experience gained, I was exposed to some challenges even before I started the training and in the course
of the training.

They include:

• Adapting to the work environment: Because of the military nature of the environment and how
security conscious they are, it took me time to adjust to their modus operandi but I finally was able to do
so with the help of my industry-based supervisors and fellow IT course mates.

• Operating and handling of some machines: Some training equipment relevant to my course
Mechanical engineering were difficult to operate at first, but it sunk to my understanding eventually e.g.,
OBD machine, tyre removing machine, hydraulic jack.

• Delivery of spare parts from marketers: During the course of the industrial training there was lack
of spare parts at the workshop, so many a times we had to wait for their delivery or go to the market to
get them for the job which brought about delay therefore increased the stay of certain vehicles in the
workshop.

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• Proximity of Workshop from my residential area: I faced a major challenge in transporting
myself to and from the Workshop, I had to travel over 20kilometers and beat heavy gridlock which was
stressful with no financial support from the company.

4.2CONTRIBUTIONS

My contributions were shown in my work done and services given as a Diagnosing / Mechanical
technician in the establishment, which was basically diagnosing and repair of mechanical components of
automobiles. I was able to maximize the job efficiency and work output in my section, because after a
couple of months my section supervisor gave me the access to work directly with the spare parts and
material store department, thereby speeding up the job completion process, as he wasn’t always around to
attend due to official reasons. I was also able to revive the job registration process as it was slightly
overlooked prior to my attachment because of the magnitude of work in the section, but after successfully
reviving it, it became useful in double checking the vehicles that came into the section and technicians
that worked on them.

4.3 EXPERIENCE ACQUIRED

During my Industrial training I acquired new skills in different skill such as:

1. Safety (HSE) skills

2. Project management and Supervision skills
3. Tool maintenance

Safety (HSE) Skills: This include how to use a fire extinguisher, as fire classes were being taught by the
Production Officer (PO), where a formal ‘Permit To Work’ system is in force it must be complied with.
Where there is no such system, it is recommended that a responsible person should know what work is
going on and, where necessary, arrange to have an assistant whose primary responsibility is safety and
proper handling of fabrication tools to achieve zero hazards.

Tool maintenance: During my Industrial training I maintained some tools such as the wrench, spanners,
hydraulic jacks etc. To maintain proper working condition of tools, Good House Keeping is required by:
• Clean the store tools properly.
• Fix or report broken tools.
• Store materials properly.
• Clean and maintain machine properly.
• Keep work place clean.
• Maintain adequate lightening.
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Automotive repair and maintenance skill: During my 6 months Industrial Training, I was able to learn
the art of automotive repair and maintenance. Below are some of the skills I acquired.
• Scan and diagnose difficulties on range of cars, trucks and other vehicles using OBDII device.
• Replace significant components in transmissions, brake systems and suspension assemblies.
• Make road calls to perform repairs and change tires for customers.
• Overhaul gasoline and diesel engines by taking apart engines, identifying and replacing faulty
parts and rebuilding engine to increase vehicle power and performance.

5.0 CHAPTER FIVE

SUMMARY, CONCLUSION AND RECOMMENDATIONS

5.1 SUMMARY

The Student Industrial Work Experience Scheme (SIWES) provided me with extensive exposure to a
practical learning environment, allowing me to apply the knowledge gained in the classroom. Engaging
in various activities such as on-board diagnosis, vehicle servicing and maintenance, and the replacement
of various parts afforded me the chance to witness the real-world application of mechanical and
electronics systems/concepts.

5.2 CONCLUSION
My five-month industrial attachment at AFEME Workshop proved to be highly successful, serving as a
significant period of knowledge and skill acquisition. Throughout my training, I developed a deeper
appreciation for my chosen course of study, as it afforded me the opportunity to integrate theoretical
knowledge from school with practical, hands-on applications. This integration was instrumental in
carrying out crucial tasks that contributed significantly to my productivity within the company.

In conclusion, my training at AFEME Workshop has provided me with a broader perspective on the
importance and relevance of Mechanical Engineers in both the immediate society and the global context.
As I approach graduation, I eagerly anticipate making a positive impact in these spheres.

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5.3 RECOMMENDATIONS
To ensure the successful implementation of the SIWES program, the following measures should be
Taken:

• Enhance the teaching of workshop practices courses by allowing students to utilize all workshop
tools and machines for a comprehensive learning experience.

• The school authorities should establish carefully crafted programs aimed at fostering the career
development of students.

• Promote the use of Computer-Aided Design (CAD) software among all Engineering students prior
to their Industrial training.

• School supervisors should maintain contact with industry-based supervisors during their visits to
facilitate a positive relationship between the department and the firms. This proactive approach
will greatly assist students in securing placements in the future.

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