Automotive Mechanical Training

Prepared by:
Ezzeldine Yahia Hammad Ahmed
20160549
Assigned to:
Dr. Saied Zolfakar

2022

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Acknowledgment

Special Thanks for Ghabour Academy and all my colleagues who

attended this training as they offered the proper learning

circumstances and environment.

I want to Thank also Higher Technological Institute and all the

professors who helped me attending and passing this course

Special thanks to Dr. Saied Zolfakar for Following up with us every

week and making sure every one is getting the proper information

and help.

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Abstract

In the following report we will discuss deeply the Automotive vehicle

mechanical systems, the operation method and the basic concept idea of
each and every component or substance in the vehicle and illustrating the
secondary systems and their role in the automotive system.
describe the principle of converting fuel and heat to mechanical energy, identify
the basic types of power units used for motor vehicles, briefly outline the
historical development of the internal combustion piston engine and explain
its operating principles, describe and relate the systems, parts, components,
and mechanisms essential to the mechanical operation of modern piston
engines, disassemble, examine, measure, adjust, align, refit, machine, and
reassemble components and mechanisms from practice engines,. Included
with the course outline are transparency masters and a reference guide,
illustrating the transmission mechanism with every component and it’s role
in the system,
describe the Electrical System of the vehicle with its components and showing
the application of every device
study the braking system and how the hydraulic circuit operate with each
component role. Anti lock Braking Systems with full illustration, Traction
control System and Electronic Stability Programs.
Finally We will study The Wheel Alignment Basics.

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Acknowledgment 2
Abstract 3
Introduction 8
I. Engine Mechanical Basics 9
a. Engine Basics. 9
II. Maintenance and its types 12
Maintenance strategies: 13
Reactive / Run-to-failure maintenance 13
Advantages of reactive maintenance 14
Disadvantages of reactive maintenance 14
Preventive maintenance 14
Advantages of preventive maintenance 15
Disadvantages of preventive maintenance 15
Predetermined maintenance 16
Advantages of predetermined maintenance 16
Disadvantages of predetermined maintenance 16
Condition based maintenance 17
Advantages of condition based maintenance 17
Disadvantages of condition based maintenance 18
Predictive maintenance 18
Advantages of predictive maintenance 18
Disadvantages of predictive maintenance 19
Preventive maintenance vs predetermined maintenance 19
Condition based maintenance vs predictive maintenance 20
III. Engine overhauling 21
a. Disassembly 21
b. Measurements 22
Tools: 22
Steps: 22
c. Assemble 23

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IV. Transmission System. 25
1.Manual Transmission 26
Manual transmission Components: 27
Clutch. 27
Gearbox. 27
Propeller shaft. 27
Differential. 28
Live Axle. 28
Advantages of Manual Transmission 28
Disadvantages of Manual Trasmission 28
2. Automatic transmission (AT) 29
Automatic Transmission Components: 29
Transmission Casing 29
Torque Converter 29
Planetary Gears 30
Clutch Plates 30
Oil Pump 30
Advantages of AT 31
Disadvantages of AT 31
3. Continuously variable transmission (CVT) 32
Advantages of CVT 32
Disadvantages of CVT 32
4. Dual-clutch transmission (DCT) 33
Advantages of Dual-clutch Transmission 33
Disadvantages of Dual-clutch Transmission 34
V. Automotive Electrical System Basics 34
series circuit 35
parallel circuit 35
Volts 36
Ampere 37
Ohms 38
Ohm’s Law 38
Fuses 39

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 Ignition switch 40
Charging system light 40
Alternator 40
Battery 40
Main fuse: 41
Common Problems in Automotive Electrical Circuits : 41
Shorts 41
Intermittent shorts 42
Opens 42
Overloads 42
Some Specific Examples of Automotive Electrical Circuit Problems 43
Voltage Drop in Diagnosis 44
Automotive Wiring Diagram 45
Ignition System 47
Powertrain control module: 47
Spark plug 47
Distributor 47
Coil 48
Ignition control module 48
distributor cap 49
VI. Braking Systems 49
Braking System Components: 50
Brake pedal. 50
Brake booster. 50
Master cylinder. 50
Lines and Hoses. 51
Brake Calipers. 51
Brake Pads. 51
Disk Brake Rotors. 51
Brake Drums & Brake Shoes. 52
Anti-lock braking system (ABS). 52
The advantages of Anti-lock braking system: 53
Traction Control System (TCS): 53

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 Electronic Stability Program (ESP): 56
ESP Components: 56
Advantages Of ESP 57
VII. Wheel Alignment 58
Camber 58
Caster 59
Toe-In 60
Summary 61

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Introduction

In this report we will firstly study the engine mechanical systems and the
components of every device and name,
Secondly, we will study the engine overhauling and the right steps to dissemble
The engine and how to dismantle every part then we will make our checking
test on every part before assembling the engine again.
We will also illustrate the transmission system whether its manual transmission
system or automatic transmission system operating principles, describe and
relate the systems, parts, components, and mechanisms essential to the
mechanical operation of modern piston engines, disassemble, examine,
measure, adjust, align, refit, machine, and reassemble components and
mechanisms from practice engines,. Included with the course outline are
transparency masters and a reference guide, illustrating the transmission
mechanism with every component and it’s role in the system,
describe the Electrical System of the vehicle with its components and showing
the application of every device
study the braking system and how the hydraulic circuit operate with each
component role. Anti lock Braking Systems with full illustration, Traction
control System and Electronic Stability Programs.
Finally We will study The Wheel Alignment Basics.
After that we will discuss the braking system of the vehicle and the mechanical
concepts and components used in the braking system

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 I. Engine Mechanical Basics

a. Engine Basics.
In this chapter our aim is illustrate the operation method of the engine I correct
way, illustrate the cooling system of the vehicle and how it works, study the

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● Engine Block This is the very core of the engine. Often made of aluminum
or iron, it has several holes to contain the cylinders as well as provide water
and oil flow paths to cool and lubricate the engine. Oil paths are narrower
than the water flow paths. The engine block also houses the pistons,
crankshaft, camshaft, and between four and twelve
● cylinders—depending on the vehicle there are several cylinder arrangement
inline, flat or in the shape of a V.
● Pistons Are a cylindrical apparatus with a flat surface on top. The role of the
piston is to transfer energy created from combustion to the crankshaft to
propel the vehicle. Pistons travel up and down within the cylinder twice
during each rotation of the crankshaft. Pistons on engines that rotate at 1250
RPM, will travel up and down 2500 times per minute. Inside the piston, lie
piston rings that are made to help create compression and reduce the friction
from the constant rubbing of the cylinder
● Crankshaft The crankshaft is in the lower section of the engine block,
within the crankshaft journals (an area of the shaft that rests on the
bearings). This keenly machined and balanced mechanism is connected to
the pistons through the connecting rod. Like how a jack-in-the-box operates,
the crankshaft turns the pistons up and down motion into a reciprocal
motion.
● Cylinder Head Attached to the engine through cylinder bolts, sealed with
the head gasket. The cylinder head contains many items including the valve
springs, valves, lifters, pushrods, rockers, and camshafts to control
passageways that allow flow of intake air into the cylinders during the intake
stroke as well as exhaust passages that remove exhaust gases during the
exhaust stroke.

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● Timing Belt/Chain The camshaft and crankshafts are synchronized to
ensure the precise timing for the engine to run properly. The belt is made of
a heavy-duty rubber with cogs to grasp the pulleys from the camshaft and
crankshaft. The chain, like your bicycle chain wraps around pulleys with
teeth.

● Camshaft Varying from vehicle to vehicle, the camshaft may either be

located within the engine block or in the cylinder heads. Many modern
vehicles have them in the cylinder heads, also known as Dual Overhead
Camshaft (DOHC) or Single Overhead Camshaft (SOHC) and supported by
a sequence of bearings that are lubricated in oil for longevity. The role of the
camshaft is to regulate the timing of the opening and closing of valves and
take the rotary motion from the crankshaft and transfer it to an up and down
motion to control the movement of the lifters, moving the pushrods, rockers,
and valves.

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II. Maintenance and its types
Why are there different types of maintenance strategies? One of the answers is
that because there are different types of assets, there are different strategies.
Different machines break down for different reasons and in different ways,
so you need tailored ways to keep them up and running. It seems a bit
obvious to say not all assets and equipment are the same. But it’s worth
remembering that there are even different kinds of differences.

● Age
● Manufacturer
● Repairs and maintenance histories
● Relative criticality

And because of these differences, you could conceivably have two similar units
that each need a different maintenance strategy. That’s one of the answers.
Another is that new technologies make new strategies possible. When new
tech gives us a new ability, we can leverage it into a new strategy. For
condition
based maintenance and predictive maintenance, for example, sensors mounted
on your assets and equipment capture a constant stream of data that you can
use to help determine when to schedule next maintenance inspections and
tasks. What are the maintenance strategies? Generally, there are six main

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Maintenance strategies:

● Reactive (run-to-failure)
● Predetermined maintenance
● Preventive maintenance
● Corrective maintenance
● Condition-based maintenance
● Predictive maintenance

Let’s look at each in more detail

Reactive / Run-to-failure maintenance

Yes, this is a real strategy, even though it’s easy to confuse it with having no
strategy at all. Basically, you wait for things to break before you fix them.
The trick is choosing the right assets for the strategy. You need things that are
cheap to carry in inventory, easy to replace, hard to inspect or maintain, and
have a low criticality. Light bulbs are the classic example. Because they
don’t require a special environment and aren’t too big, they’re relatively
cheap to carry in inventory. When they burn out, screwing in a new one
takes almost no time at all. Even if you wanted to swap them out just before
they died, it’s hard to accurately check how much longer any given filament
can last. And they are not generally critical to your operations. It’s hard to
imagine a manufacturing facility having to shut down the line because of a
burnedout light bulb. Run-to-failure also sometimes makes sense when you
have duplicates of the same asset, making any given one of them redundant.
You can wait for one to break down knowing that when you’re fixing it, you
have all the others still running. The maintenance strategy can also make
sense for continuous production facilities that use assets that almost never
break down. Instead of periodically shutting down the line for proactive
maintenance, guaranteeing additional costs, you keep going until something
breaks. Because breakdowns are so rare, your total cost of ownership is less.

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Advantages of reactive maintenance

One of the overarching goals of maintenance is to get the most value out of
your assets and equipment. You want maximum return on your investment,
so you

need to squeeze out every drop of value. With something like light bulbs, the
only way to get all the possible value is to keep going until they burn out.
But it’s more than just getting the most value. You want to get the most value
for the least amount of money. And run-to-failure can save you money
because it usually requires a smaller maintenance team. Because you’re not
running a schedule of planned maintenance, you only ever need a small
number of techs. Another way you save money is on training. While other
strategies require special prep and training, even the most
stuck-in-their-ways tech can understand reactive maintenance. “If it ain’t
broke, don’t fix it” is a clear, simple concept.

Disadvantages of reactive maintenance

Although there’re many assets where reactive maintenance is the best choice,
there are even more where you’re simply courting disaster. If you use the
strategy on the wrong assets and equipment, you’re suddenly dealing with a
lot of unscheduled downtime and expensive repairs.

Preventive maintenance
Here, you use a schedule of inspections and tasks to find and fix small issues
before they have a chance to develop into big problems. Preventive
maintenance is basically the idea behind the old saying that “An ounce of
prevention is worth a pound of cure.”
How do you develop the schedule? It can depend on where you are in the
asset’s life span and what sorts of problems you’re seeing. When an asset is
new, it makes more sense to schedule everything according to the
manufacturer’s recommendations. They’re the ones who designed and built

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 it, so they know the asset best. But as time goes on, your senior techs likely
have a better understanding of the asset’s common problems, and so you can
adjust the schedule as needed.
It’s worth noting that “scheduling” comes in two forms, based on time or use.
For some PMs, you perform them according to calendar dates. So, for
example, you have a tech look at the AC units in early spring, checking for
any damage that happened over the winter. You might also have seasonal
PMs for the roof. But for something like a hydraulic press, you can schedule
PMs to trigger based on use. So, after X number of cycles, you have a list of
inspections and maintenance for the team.

Advantages of preventive maintenance

One way to understand the benefits of preventive maintenance is to look at all

the hassles you avoid.

Because you know what work the maintenance team is going to do on any given
day, you have more than enough lead time to ensure they have the right parts
and materials. No more scrambling to find the right inventory. No more
expensive rush deliveries. And it’s not just inventory.
Because you’ve scheduled the work in advance, you can easily schedule the
right people to be there at the right times. No more calling in that one special
tech for overtime because they’re the only one who’s good at
troubleshooting that one tricky asset.
And because you can choose when things get done, you can easily schedule
around peak production times. No more idle operators standing around
watching the maintenance team. That’s a lot of stress you just avoided.

Disadvantages of preventive maintenance

It’s possible to stray over into over-maintenance, where you’re doing more than
you need. Can you have too much of a good thing? In maintenance, you can.
The two big issues are extra waste and added risk. If you’re changing the fan
belts on an engine too soon, you’re throwing out perfectly good inventory.
And every time you open the hood and have a technician pulling things apart

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 and putting them back together, you’re increasing the risk of accidental
damage. The tech might strip a bolt or drop a metal tool across the terminals
on the battery. Even something as simple as checking the oil could introduce
foreign objects into the engine.

Predetermined maintenance
When is it a good idea to have someone else set up your maintenance program?
When they know your assets and equipment better than you do, which might
be only right after you get them or could also be long into the asset and
equipment life cycle.
Predetermined maintenance is when you simply follow the manufacturer’s
recommendations for maintenance, including when to do inspections and
maintenance.

Advantages of predetermined maintenance

All the work’s been done for you, so all you need to do is follow the schedule
and do the work. And the schedule should be good because the manufacturer
has based it on both their knowledge of their products and continuing
research.

Disadvantages of predetermined maintenance

The program is based on averages, so it’s not always an exact match for your
assets.
Stats can be both true and unhelpful. Imagine you’re sitting in a regular
restaurant enjoying a nice meal. Bill Gates walks in, and suddenly, every
single person in that restaurant is, on average, a multimillionaire. But do you
feel any richer?

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Condition based maintenance
Just like the name suggests, condition based maintenance is based on the asset
or equipment’s condition. So, instead of setting up a schedule to periodically
check on an asset, here you’re constantly monitoring it, looking for any
deviations that suggest the start of trouble.
For example, you have an engine you want to maintain. You can set up a
schedule where you check the temperature every three hours. Or you can just
attach a sensor that constantly reads the temperature, setting of an alarm
when things fall below or jump above set perimeters. The idea is your sensor
is set to always be on the lookout for a hint of smoke. As soon as it sees it,
the sensor lets you know, and you can make sure those bits of smoke never
have a chance to develop into a full-fledge fire.
Temperature is just one of the conditions you can monitor. Others include:
● Vibration
● Speed
● Power Moisture (both too much and too little)

Advantages of condition based maintenance

Condition based maintenance is done while the assets is up and running, saving
you on overall downtime. Now, instead of turning the equipment off to
inspect it, you can keep it running and let the sensors do the work for you.
You also save on overall maintenance because you don’t have to schedule as
many inspections, and you only perform tasks when you know you need
them.
Being able to “see” inside an asset without having to shut it down and then lock
it out saves you more than just time and effort. For many assets, it also saves
you from the risk of damage to the asset and injury to technicians. Having a
sensor on the fan over the welding stations means you have to send up a
technician to check on it only when you already know there’s a problem.

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Disadvantages of condition based maintenance

Cost. Both for the required equipment as well as the additional training you
need for your technicians, who now need to know how to set up and
calibrate the sensors. In a way, you’ve created a new class of equipment for
them to worry about maintaining.
That said, if you pick the right assets for the strategy, you can see concrete
returns on your investment. But you have to choose the right assets and set
up the sensors to look for the right things.
Even with the “right” sensors, though, you can still run into trouble if the
environment is a harsh enough to eventually break them. And even if they
all survive, it’s generally hard for them to detect certain types of failures,
including those caused by fatigue or uniform wear.

Predictive maintenance
Basically, it’s the same as condition-based maintenance except that the data is
analyzed to make accurate predictions about future failures.
For example: with condition-based, you have an engine that usually runs at
temperature X. As soon as it goes above X plus Y, you know it needs
maintenance. There’s a constant stream of data coming from the sensor, but
the software only really cares if it’s within the preset ranges.

But with predictive, the engine never has a chance to get to X plus Y because
now that constant stream of data is being looked at closely by the software.
In fact, it’s not simply looking, it’s analyzing it, pushing it through complex
algorithms, hunting for clues. So, your engine might be well within the
parameters for temperature, but the software still triggers maintenance after
“decoding” the data and finding hints that something bad is going to happen.

Advantages of predictive maintenance

It’s nice to live inside a sci-fi movie where computers can tell you the future.
You get all the benefits of condition based but you see them even faster.

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Disadvantages of predictive maintenance

Cost. Now you have all the same costs of condition-based maintenance plus the
added expensive of even more sophisticated software requiring even more
specialized training for your staff.
And you have all the other drawbacks, too, including worrying about keeping
your sensors properly calibrated and up and running.
Which maintenance strategy is right for me? It’s a trick question. You don’t
have to choose the one that’s best for you. Instead, choose the right strategy
for each asset. For some, run-to-failure. For others, preventive. The question
should be “What’s the right combination of maintenance strategies for my
facility, assets, and equipment?”
Instead of thinking about strategies in isolation, you might be able to better
understand them by seeing how they’re different from one another.
Reactive maintenance vs preventive maintenance It’s not that one is better than
the other. Instead, it’s that some assets match better with one than the other.
For reactive maintenance, an asset or piece of equipment needs to check some
of these boxes:
● Impractical or impossible to maintain
● Cheap to buy and carry in inventory
● Easy to replace
● Low relative criticality

For assets that don’t fit any of these descriptions, it likely makes more sense to
use preventive maintenance.

Preventive maintenance vs predetermined maintenance

Both strategies use a schedule of inspections and tasks to find and fix small
issues before they become big, costly problems. The only real difference
between the two is who’s writing out the schedule, you and your department
or the manufacturer and their team of experts.
Just like with a lot of the other strategies, you don’t have to make a hard choice
between strictly one or the other. When an asset is newer, you can use
predetermined maintenance. Later, when you’ve built up a history of

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 maintenance and repairs, you can start to fine-tune the schedule to better
meet your specific situation.

Condition based maintenance vs predictive maintenance

How do you know which one to use? Both have additional costs connected to
equipment and training, but predictive is generally going to be the more
expensive of the two. The way to choose between the two is to carefully the
value of your asset, both its cost and how much it would cost you in time,
money, and frustration if it unexpectedly failed.
Imagine you’ve decided to build yourself a garage but you’re not sure how
much to invest. Your first step should be to look at your car, using its relative
value to help you decide on the structure that’s going to protect it. Simple,
reliable four-door sedan perfect for runs to the grocery store? You need a
simple, reliable garage. Fancy imported vintage sports car? It’s better to
build something with all the possible garage bells and whistles, including a
built-in lift and security system.
Maintenance Types Summary Choosing the right maintenance strategy starts
with understanding your options, their benefits, and drawbacks.
Run-to-failure tends to get a bad name, but for a specific class of assets and
equipment, it’s the best choice. Use it when things are hard or impossible to
maintain, cheap to carry in inventory, easy to replace, or non-essential to
your operations. Preventive maintenance helps you find problems early by
scheduling inspections and tasks. It also saves you money and frustration
because you can plan everything in advance. For predetermined
maintenance, everything is basically the same as with preventive, except
you’re following a schedule set up by the manufacturer, not your
department. Condition based and predictive by rely on sensors and special
software to collect and look at data from sensors installed directly on or near

your assets. For condition based, the software is looking for readings outside
preset parameters. For predictive, the software analyzes the data to predict
future failures long before they start to develop. In the end, there is no
one-sizefits-all, all-time perfect strategy. You need to choose the

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 combination that works best for your assets, fine-tuning your approach as
your assets age and your department collects data.

III. Engine overhauling

Engine overhauling consists of three basic steps

1. Disassembly
2. Measurements
3. Assembly

a. Disassembly
Ascertain and select tools and materials for the job and make this available for
use in a timely manner.
Remove a petrol engine from the vehicle as per vehicle manufacturer standard
Procedure
We begin by removing electrical feed wires and we take care of the bolts for
reassembly
1. Dismantle exhaust manifold and its gasket
2. Dismantle the group functioning drivebelt then remove the dynamo
3. Dismantle the water pump and air conditioning compressor from the
engine block
4. Dismantle the water hoses and the thermostat
5. Dismantle intake manifold and the fuel injectors
6. Dismantle the Starter of the engine
7. Dismantle the spark plugs connectors and the spark plugs
8. Dismantle the crank shaft pulley
9. Remove the oil pan and the oil filter
10.Dismantle the secondary oil strain
11.Remove the chain cover and the timing belt
12.Remove the oil pump from Chain cover
13.Remove the cam shaft assembly
14.Dismantle the cylinder head of the engine and its gasket
15.Uptight the piston connecting rods

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 16.Remove pistons from the cylinder
17.Remove the crank case and the crank shaft
18.Remove the crank bearings

b. Measurements
In this stage we test every component and it’s characteristics
We need measurement tools to be calibrated and ready for the job and make this
available for use in a timely manner as we need to measure different types of
measurements like inner diameter, outer diameter, depth, clearance and
angels

Tools:
1. Vernier caliper
2. Clearance Filler
3. Micrometer
4. Degree gauge
5. Endplay gauge
6. Torque wrench
7. Bore gauge

Steps:
• We begin with measuring the clearance of piston rings, we start with pressure
rings and then oil rings and we make sure their clearance is in acceptable
range
• We test the piston measurements and make sure there are in acceptable
range otherwise we replace all the cylinders together
• After that we test the piston-cylinder clearance and we make sure that they
are in acceptable range
• After that we make the end gape test and in that test, we measure the
opening of the piston rings while mounted in the cylinder
• We test the endplay of the cam shaft and measure all its points for bending

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• We test the bore of the pistons from the measurements recorded by the
micrometer and from the cylinder itself and differentiate the changes
between different stroke levels
• At the end we test the crank shafts measurements and make sure that teres
no longitudinal degree of freedom.

c. Assemble
In this stage we’re assemble the parts of the engine with specific torques and
angles using the torque gauge and angle gauge we may assemble some parts
more than one time to test its fits and tolerance using plast gauge
1. We begin with assembling crank case.
2. Assemble pistons with the right position using mark on it.
3. Assemble piston connecting rods with making sure that we lubricated its
bearings.
4. Assemble the secondary oil strain.
5. Assemble the oil pan.
6. test the valves and cleaning its clearance and its springs.
7. test the flatness of the cylinder head.
8. assemble the gasket of the cylinder head and test its flatness also.
9. Assemble the cylinder head.
10.Assemble the cam shaft.
11.Assemble the cam chain.
12.Assemble the chain cover.
13.Assemble the oil thermostat.
14.Assemble the starter.
15.Assemble the dynamo.
16.Assemble the air conditioner compressor.
17.Assemble the water pump pulley.
18.Assemble the crank shaft pulley.
19.Place the group functioning drivebelt and tighten it.
20.Assemble the intake manifold.
21.Assemble the injectors.
22.Assemble the valve cover.
23.Assemble the exhaust manifold after testing its gasket clearance.

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IV. Transmission System.

The mechanism that transmits the power developed by the engine of automobile
to the engine to the driving wheels.
The output from the engine is available in the form of rotation of the crankshaft.
The friction between the road and the surface of the wheel makes possible the
movement of the automobile. Transmission system performs this function.
The automobile transmission system consists of several components. These
components work together to transmit the rotary motion at the crankshaft
smoothly and efficiently to the road wheels.
A sudden change of state, from rest to motion or vice versa is not desirable. It
may be uncomfortable, or even dangerous, to the occupants of the
automobile.
Therefore, the rotary motion of crankshaft should be transmitted gradually and
not suddenly. Another aspect of transmission is that the motion from the
crankshaft should not be transmitted as soon as the engine starts.
t is not desirable that as soon as the engine starts, the vehicle begins moving.
The motion is required to be transmitted only ‘when desired.’
The rotary motion of the crankshaft gives rise to torque and transmission of this
torque to road wheels give rise to a propulsive force or tractive effort
causing the movement of wheels on the road.
When starting from rest, a great tractive effort is needed. The engine produces
almost the same torque. This torque has to be enhanced so that enough
tractive effort is produced.
This necessitates the introduction of `leverage’ between the engine and the road
wheels.
A variation in the leverage is essential because if the same leverage is used for
climbing as well as moving on the level road, the maximum possible speed
would be unduly low.
Large leverage implies a large reduction in speed between the engine and the
wheels, and at a quite moderate road, the engine speed would be very high.
But at high engine speeds, the engine torque falls off so that tractive effort
available would be less thereby reducing the road speed.

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 Types of transmission systems Commonly used in automotives

1.Manual Transmission

A manual transmission system is the original type of transmission system for

automobiles. It requires the driver to do more work because they much shift
a gear stick around as they’re driving. You’re basically switching gears
manually while the vehicle is in motion. There is a stick shifter that is
mounted in the central console area, and it sticks out vertically, making it
easy to grab and move. The gear stick is connected to the transmission
system. That is how you’re able to change gears with it.
In between the internal combustion engine and transmission, there is a clutch
disc. To the left of the brake pedal is the clutch pedal. The driver presses the
clutch pedal to release the clutch disc and remove the power connection
between the engine input shaft and transmission. By doing this, the engine
will still be running, but it won’t be powering the vehicle. This is important
for when you want to make stops with your vehicle without the engine
stalling.
The manual transmission system is also called the manual gearbox. There are at
least 5 gears in the gearbox of different sizes. Bigger gears slow down the
vehicle, and smaller gears speed up the vehicle. You need to switch gears at
the appropriate times while driving, according to how fast you need to go.

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 Figure 13: Manual Gear Box

Manual transmission Components:

1. Clutch.
This component enables the engine to keep disconnected from road wheels.
The rotary motion available at the crankshaft is not transferred to road wheels.
It allows the transfer of motion when desired by the driver of the
automobile.
clutch also allows the transfer of motion gradually so that the vehicle starts
moving gradually. It works on the principle of friction.
2. Gearbox.
It consists of some pairs of gear wheels. These transmit the motion available
from the crankshaft, through the clutch, at different speeds.
This provides required leverage between the engine and the road wheels. This
leverage is variable to cope up the different conditions encountered during
the movement of the vehicle.
3. Propeller shaft.
The third component of the automobile transmission system, which transfers
motion from the gearbox end to the differential end. The distance between
the two can be large, and therefore, it is a shaft which is thin and long to
connect the two.

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4. Differential.
One of the requirements of the transmission system is to turn the motion
through 90 degrees as the axis of the propeller shaft and live axle are at a
right angle to each other. This is performed by the differential through wheel
and pinion arrangement.
Another function performed by the differential is the variation in the speeds of
inner and outer wheels when the vehicle is taking a turn.
5. Live Axle.
The axle where motion from the crankshaft of the engine is transferred is
known as a live axle. The other axle takes up only the load of the vehicle and
therefore is termed as dead axle or simply the axle.
The motion is generally transferred to the rear axle, but it can be transferred to
the front axle or both the axles. When the motion is transferred to both the
axles, it is known as four-wheel drive.
Finally, motion is transferred to the road wheels at the two ends of the live axle.
The wheels rotate, and friction between their surface and road surface makes
possible the movements of the vehicle on the road.

Advantages of Manual Transmission

● Manual transmission is considered better for off-road purposes.

● This type of transmission system provide high torque load.
● These are much more reliable and easier to service than other types.

Disadvantages of Manual Trasmission

● Not everyone can drive

● Higher learning curve.
● These are require more work during driving.

27
2. Automatic transmission (AT)

It is a multi-speed transmission utilized in vehicles that do not require any

driver to change forward gears under normal driving situations. It is
consists of a planetary gearset, hydraulic controls, and a torque converter.

The engine is connected to a torque converter which is then connected to a gear

system and
then to the transmission. Inside the torque converter, some parts work in tandem
with each other. The outermost part houses the flywheel which spins the
whole structure.
The rotation pushes the fluid out of the pump at high speed, causing the
turbine to spin. The fluid continues to circulate in the two sections
separately and through the stator. The turbine is connected to the shaft
which connects to the rest of the system and then energy is transferred to
the gear system.

Automatic Transmission Components:

Transmission Casing

A transmission casing houses all the parts of the transmission. It sort of looks
like a bell, so you’ll often hear it referred to as a “bell casing.” The
transmission casing is typically made of aluminum. Besides protecting all
the moving gears of the transmission, the bell casing on modern cars has
various sensors that track input rotational speed from the engine and output
rotational speed to the rest of the car.

Torque Converter

28
Ever wonder why you can turn on your car’s engine, but not have the thing
move forward? Well, that’s because power flow from the engine to the
transmission is disconnected. This disconnection allows the engine to
continue running even though the rest of the car’s drivetrain isn’t getting any
power. On a manual transmission, you disconnect power from the engine to
the drivetrain by pressing in the clutch.

Planetary Gears

On an automatic transmission, gear ratios increase and decrease automatically.

And this can happen thanks to the ingenious design of planetary gear.
A planetary gear consists of three components:
● A sun gears. Sits at the center of the planetary gear set.
● The planet gears/pinions and their carrier. Three or four smaller gears
surround the sun gear and are in constant mesh with the sun gear. The planet
gears (or pinions) are mounted and supported by the carrier. Each one of the
planet gears spins on their own separate shafts that are connected to the
carrier. Planet gears not only spin, but they also orbit the sun gear.
● The ring gears. The ring gear is the outer gear and has internal teeth. The
ring gear surrounds the rest of the gear set, and its teeth are in constant mesh
with the planet gears.

Clutch Plates

Clutch Plates are made of metal that is lined with organic friction material. The
brake bands can be tightened to keep the ring or sun gear stationary, or
loosened to allow them to rotate. Whether a brake band tightens or loosens is
controlled by a hydraulic system.

Oil Pump
The pump looks like a fan. It has a series of blades extending from its center.
The pump is mounted directly on the torque converter housing, which in turn
is bolted directly to the engine flywheel. As a result, the pump rotates at the

29
 same speed as the engine’s crankshaft. The pump “pumps” transmission oil
from the center to the outside.

Advantages of AT

● The main advantage of automatic transmissions is that they are simply

convenient and easy to use.
● They provide comfortable driving for the driver and passengers.
● ATs naturally have more power than any equivalent manual transmission.

Disadvantages of AT

● It is a complex system where many different items can fail.

● Very expensive to main and repair compared to manual transmission.

Figure 14: Automatic Gear Box

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3. Continuously variable transmission (CVT)

These are pulley-based transmissions primarily used in small vehicles with

smaller engines and they can change gears seamlessly through a constant
gear ratio. This is in opposition to other transmissions that offer a limited
number of gear ratios in fixed stages.
The CVT uses two pulleys between which a steel belt runs. To continuously
change its gear ratio, the CVT simultaneously adjusts the diameter of the
“drive pulley” which transmits torque from the engine, and the “drive
pulley” which transfers torque to the wheels.
The width of these pulleys changes depending on the power required as one
gets bigger and the other gets smaller. Hence this allows delivering strong
and smooth acceleration. Currently, the use of CVTs in their cars includes
Toyota, Nissan, and Honda.

Advantages of CVT

● They can provide you a smoothest ride because it eliminates the feeling of
shifting.
● It has greater fuel efficiency because the engine is always running
efficiently.
● It can give you a faster response to a change in driving conditions.

Disadvantages of CVT

● They are considered unusable in off-road conditions.

● There is no engine braking capability as seen in the manual transmission.

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 Figure 15: CVT Transmission

4. Dual-clutch transmission (DCT)

This transmission employs two separate clutches for odd and even gear sets
which allow for especially quick shifts. The design is often similar to two
separate manual transmissions, in that their respective clutches are within a
housing, and operate as a single unit.
The DCT operates like an automatic transmission, requiring no driver input to
change gears. This type of transmission can generally be operated in fully
automatic mode or can be moved manually with the pedals on the steering
wheel.
Currently, these gearboxes are mainly found on race cars and high-end sports
cars and they are quite expensive.

Advantages of Dual-clutch Transmission

● DCTs offer better fuel economy and better performance than automatic
transmissions.
● Since they shift smoothly and with a high degree of accuracy, they are often
preferred in the field of performance driving.

32
Disadvantages of Dual-clutch Transmission

● They are expensive, this disadvantage is compounded by their complexity

which leads to more frequent and costly repairs.
● When driving at low speeds, such as in a parking lot or on the opposite side
of the car, it tends to pull and lock.

Figure 16: DCT

V. Automotive Electrical System Basics

The battery is the backbone of your vehicle’s electrical system. It provides the
electrical current that allows the vehicle to start and powers the other
components, like the ignition and fuel systems, which in turn create the
combustion needed for the engine to operate.
Although the battery supplies the car’s power, the starter is what actually
activates the engine. It is connected to the ignition switch, which is typically
activated by key. Receiving a punch of energy from the battery, the starter
rotates the flywheel, which turns the crankshaft, which moves the pistons of
the engine.
The alternator is necessary for endurance; without it, the battery would not be
able to run for an extended period of time. The alternator keeps the battery
charged and the electrical system running, but it isn’t necessary for the car to

33
 start. Some older cars have a generator instead, but modern alternators are
preferable because they are lighter, stronger, and more efficient.
The electricity in your vehicle powers other important features as well. Most
significantly, it allows the headlights and brake lights to function and the
windshield wipers to wave across the window. Both of these features provide
greater visibility (one in darkness, the other in rain or snow), increasing the
driver’s safety and security. Other important electrical assets include the
speedometer and dashboard gauges (fuel gauge, temperature gauge), interior
lights, and heating and air conditioning.
All of these electrical components are connected to the battery through wires,
which carry electrical current, and fuses, which protect the wiring. The wires
vary in thickness depending on their role within the electrical system. They
must be the appropriate size in order to handle the amount of current
transferred or they could overheat, blow a fuse, or burn out.

There are essentially two kinds of automotive electrical circuits:

series circuit
is one in which all the circuit elements are connected end-to-end in chain-like
fashion. The current has only one path to follow so the amount of current
passing through it will be the same throughout. The total resistance in a
series circuit is equal to the sum of the individual resistances within each
circuit element. If one element in a series circuit goes bad, continuity is
broken and the entire circuit goes dead because the current cannot complete
its journey through the circuit.

parallel circuit
is one in which circuit elements are connected next to or parallel to one
another. This creates multiple branches or pathways through which current
can flow. The resistance in any given branch will determine the voltage drop
and current flow through that branch and that branch alone. One of the
advantages of a parallel circuit is that the various segments or pathways of

34
 the circuit can operate independently of one another. If one element goes
open (breaks continuity), it won't disrupt the function of the other. Some
circuits combines elements of both a series and parallel circuit. These would
be called a series-parallel electrical circuit. In this type of circuit, part of the
circuit might have loads in series while in another part the loads would be
parallel.

Figure 17: Circuit Types

Troubleshooting automotive electrical circuits often requires measuring volts,

amps or ohms. These are three basic units of measurement that are used to
describe what goes on inside an electrical circuit.

Volts
Voltage is the difference in electrical potential between two points, or the
amount of "push" that makes the electrons flow. It's also called the
Electromotive Force (EMF). It is like the pressure that forces compressed air
through a hose, but instead of being measured in pounds per square inch,
voltage is measured in units called Volts. You can measure volts with a
digital or analog voltmeter. For late model vehicles, a digital voltmeter is
recommended because the voltage levels you are measuring often have to be
read down to tenths of a volt (0.1 volt). All passenger car and light truck
electrical systems are 12 volts and have been since the mid-1950s. The

35
 electrical systems are all Negative (-) ground, with the body usually serving
as the ground connection for many electrical circuits. The battery negative
cable is attached to the metal body or chassis, while the positive battery
cable (+) is connected to the power side of the vehicle's electrical circuits
and charging system. Many sensors and sensor circuits use a lower voltage,
typically 5 volts, while the ignition coils generate a very high voltage (5,000
to 35,000 volts) to fire the spark plugs. Hybrid vehicles use a high voltage
(140 to 300 volt) battery, generator and electrical motor for their stop-start
systems and electric drive.

Figure 18: Circuit Testing

Use extreme caution when working around hybrid electrical components (which
are usually color coded ORANGE, and avoid making contact with the
ignition coils or spark plug wires when your engine is running to reduce the
risk of being shocked. A shock from a spark plug wire can be painful, but
not fatal because the current (amperage) is low. But a shock from a hybrid
battery can be fatal!

Ampere
Current is the amount or volume of electrons that flow through a conductor or a
circuit. It is a measure of volume, and is specified in units called amperes or
amps. The analogy with an air hose would be the number of cubic feet per

36
 minute of air passing through the hose. One amp is equal to 6.3 million
trillion electrons (6.3 with 18 zeros after it) flowing past a point in one
second! That's a lot of electrons, but a relatively small current in many
automotive circuits. A starter, for example, can draw several hundred amps
while cranking the engine. Amps are measured with an ammeter, or a
multimeter that has an amp function. Measuring amps usually requires using
an inductive pickup that is clamped around a wire to measure the current
flowing through it, though very small currents (100 milliamps or less) can
often be measured directly through the meter itself without having to use an
inductive pickup.

Ohms
Electrical resistance is the opposition to the flow of current, or the restriction
that impedes the flow of electrons. Resistance is measured in units called
ohms. The flow of air though a hose can be reduced by pinching it, by
reducing the diameter of the hose or by holding your finger over the outlet.
Likewise, current flow through a wire can be slowed or controlled by adding
resistance. Resistance can be created by altering the composition of the
material, by decreasing the size of the conductor or wire (smaller wire has
more resistance than larger wire), or by adding heat (heat increases
resistance). Resistance is measured with an ohmmeter or a multimeter with
an ohms function. Caution: Do NOT attempt to measure resistance (ohms) in
any circuit that has voltage or is on as this may damage the ohmmeter.
Resistance is measured when the current is OFF.

Ohm’s Law
One volt equals the amount of force needed to push a one amp current through a
circuit with a resistance of one ohm. This is Ohm's Law, and is named after
the scientist who first figured it out. Ohms Law can be expressed in various
ways: Understanding Ohms Law and the relationships between volts,ohms
and amps is the key to understanding electrical currents and what is
happening inside an automotive electrical circuit. Ohms Law explains why
high resistance in a circuit chokes off the current and causes a voltage drop.

37
 It also explains why an electrical short can cause a wire to rapidly overheat
and burn because of a runaway current.

Fuses
Fuses are used to protect electrical circuits from dangerous overloads that could
cause them to overheat, melt or catch fire. Fuses are rated according to how
many amps they can handle before the fuse blows and stops the flow of
current through the circuit. A blown fuse, therefore, is often an indication of
an overloaded circuit or a fault such as a short that is causing excessive
current flow in the circuit. For more information, see the related article on
Power Centers: Relays & Fuses
Caution: If a fuse has blown, replace it one that has the SAME amp rating as the
original. DO NOT substitute a replacement fuse with a higher amp rating as
this may allow the circuit to overheat or suffer damage. And NEVER replace
a blown fuse with a solid wire or conductor as this will prove no overload
protection at all.

Figure 19: Fuse

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Ignition switch
An ignition switch, starter switch or start switch is a switch in the control
system
of a motor vehicle that activates the main electrical systems for the vehicle,
including "accessories" (radio, power windows, etc.). In vehicles powered
by internal combustion engines, the switch provides power to the starter
solenoid and the ignition system components (including the engine control
unit and ignition coil), and is frequently combined with the starter switch which
activates the starter motor

Charging system light

If something is not right with the charging system, you'll see a warning light. ...
If
this warning lamp lights up while the engine is running, it means that there is a
problem in the charging system, usually that the battery has gone bad or the
the alternator has stopped working.

Alterantor
An alternator is a type of electric generator used in modern automobiles to
charge the battery and to power the electrical system when its engine is
running.[22]
Starter: A starter or starter motor is an electrical device that used to rotate
(crank) internal combustion engines so as to initiate the engine’s operation
under its own power. As soon as the engine begins to run, it got
disconnected from the engine, which now relies on the combustion process.
The component is mounted on the engine’s gearbox housing, and the starter
motor gear meets flywheel’s teeth.

Battery
An automotive battery or car battery is a rechargeable battery that is used to
start a motor vehicle. Its main purpose is to provide an electric current to the
electricpowered starting motor, which in turn starts the chemically-powered

39
 internal combustion engine that actually propels the vehicle. Once the engine
is running, power for the car's electrical systems is still supplied by the
battery, with the alternator charging the battery as demands increase or
decrease.

Main fuse:
All cars have at least one main fuse or fusible link. It's usually installed at the
positive battery terminal or in the fuse box, connected to the battery positive
cable. Often the main fuse blows when accidentally touching the wrong
battery terminal when boosting a dead battery.[25].

Common Problems in Automotive Electrical Circuits :

Shorts

Shorts are a type of fault that can occur if the current traveling through an
electrical circuit does not pass through the component powered by the
circuit, but finds another path to ground. This can happen if a wire rubs
against a sharp edge and shorts to ground, or the insulation on adjacent wires
rubs through or is damaged allowing current in one wire to jump to an
adjacent wire. A short can result in a runaway current because of reduced
resistance in the circuit. This can cause a wire to rapidly overheat, possibly
melting or burning the insulation around it and starting an electrical fire. A
short will usually cause the circuit fuse to blow
Note: If a circuit has a blown fuse and a new fuse blows as soon as you replace
it, the circuit most likely has a short.
Shorts most often occur where wiring rubs against a sharp metal edge, as where
wiring passes through a bulkhead, the firewall between the engine
compartment and passenger compartment, or door or other body cavity.
Rubber grommets are typically used to protect the wiring in places where the
wiring passes through metal panels. But if the grommet is damaged or

40
 missing, the wiring my rub against a sharp edge and short out. Shorts can
also occur between adjacent wiring if the insulation around the wires is
damaged or cracked. Insulation can become brittle with age and may crack
or flake off the wiring, allowing the bare metal underneath to make electrical
contact with adjacent wires or the body.

Intermittent shorts

can occur when wires make intermittent contact as a result of temperature

changes that cause metal to expand and contract, or as a result of vibration.
Finding intermittent shorts can be difficult because the problem comes and
goes. Wiggling and shaking wires, or blowing hot air on them with a hot air
gun may be necessary to simulate the conditions that cause the short to
occur. Shorts can be repaired by wrapping exposed or damaged wiring with
electrical tape, or replacing the damaged wiring.

Opens

Opens are another type of fault that can occur in automotive electrical circuits.
An open is just what the name implies: an open in the wiring that stops the
flow of current and kills the circuit. An open will not blow a fuse, but it will
prevent the circuit from functioning. An open may occur if a wire breaks, a
wiring connector is loose or unplugged, or severe corrosion inside an
electrical connector has created so much resistance that current cannot flow
through the circuit. Opens can also occur in electronic circuits if microcracks
form in soldered connections or on printed circuit boards. The circuit may
pass current normally when cold, but as it heats up and expands, the
microcracks may open up causing an intermittent open.

Overloads

Overloads are a condition that may occur in a circuit when an electric motor or
other device experiences operating conditions that cause it to draw more

41
 current than normal. An example would be a temporary overload in the
windshield wiper motor circuit if the wipers become jammed with ice or
heavy snow. An overload may cause the circuit fuse to blow.

Some Specific Examples of Automotive Electrical Circuit Problems

● A common example of Ohms Law causing an electrical problem in your car

or truck would be a loose or corroded battery cable. The poor connection
creates electrical resistance that prevents the battery from delivering normal
current flow to the vehicle's electrical system. This, in turn, may prevent the
starter from cranking the engine fast enough to start it, or it may prevent the
starter from working at all. The loose or corroded battery connection might
also prevent the alternator from keeping the battery fully charged, causing
the battery to run down.

● Another example of Ohms Law in action would be a fuel pump circuit with
a poor ground connection. The poor ground connection creates high
resistance that reduces the current flowing through the fuel pump. This
causes the pump to spin much slower than normal, causing a drop in fuel
volume and pressure that may cause the engine to lose power or run roughly.

● Low system voltage due to a low battery or low charging output can play
havoc with a vehicle's electronic control modules. Many modules will not
function normally if they are not being supplied with 12 volts of power.
This, in turn, may cause various kinds of driveability or performance
problems. Corrosion is a common cause of high resistance in electrical
circuits.

● Corrosion can be caused by moisture and oxidation that attacks electrical

connectors and terminals in the electrical system. This is one reason why
insurance companies total many vehicles that have been flooded. Once water
gets into the wiring inside a vehicle, it can cause corrosion and numerous
electrical problems down the road.

42
● Vibration can also cause high resistance in electrical connectors and wiring.
The motion the occurs when a vehicle is being driven can cause rubbing and
microscopic wear in electrical connectors that are not properly supported.
Over time, this can result in a poor electrical connection and circuit
problems due to a crop in current within that circuit.

Voltage Drop in Diagnosis

A voltage drop occurs when current flows through a component in a circuit. The
resistance created by the device produces a corresponding drop in voltage
which can be calculated using Ohms Law if you know the resistance of the
component and current flow.

VOLTAGE DROP = RESISTANCE x CURRENT

You can measure voltage drop in a circuit or across a connection with a digital
voltmeter. The voltmeter's leads are connected on either side of the circuit
component or connection that is being tested. If a connection is loose or
corroded, it will create resistance in the circuit and restrict the flow of
current causing an excessive voltage drop. As a rule of thumb, a voltage
drop MORE than one tenth volt (0.1v) across a low voltage or low amperage
connection means trouble. Circuits that handle higher voltages or currents
(such as the voltage output circuit for the charging system) can tolerate
voltage drops up to half a volt (0.5 volts), but 0.1 volts or less is best.

43
Measuring voltage drop is an effective means to quickly pinpoint automotive
electrical circuit problems such as loose or corroded connectors, wires,
switches, etc. It's more accurate than just measuring voltage in a circuit or
using a simple test light to see if there is power or not because it tells you if
there is excessive resistance that might restrict the current in the circuit.

Automotive Wiring Diagram

Vehicle manufacturers publish wiring diagrams for all of the various electrical
circuits in the vehicles they make. These may be obtained from the Vehicle
Manufacturer Technical Websites or from an automotive aftermarket source
such as AlldataDIY for a small fee. Having the correct wiring diagram is an
absolute must for troubleshooting electrical circuit problems. Wiring
diagrams use symbols (see below) to identify various circuit components.
Individual circuits are usually numbered, and the wires in the circuits are
color-coded to make identification easier. When there is a two-color code for
a wire, it means the wire is one color and there is a colored stripe of a
different color on that same wire

44
45
Ignition System
The ignition system is the system, which consists of devices that serve to create
an electric spark of high voltage. The ignition system is generating a very
high voltage (from 20 to 30 thousand volts) from the car 12Volt battery. This
voltage is necessary to igniting the fuel-air mixture in the engine combustion
chambers. The spark plugs are supplying a high voltage spark to the
combustion chambers in determine time.

Powertrain control module:

The powertrain control module is a component and control unit that exists in all
motor vehicles. Combined with a control unit, called the engine control unit,
and the transmission control unit, this powertrain control module plays a
huge part in the inner systems of your car. The system that uses the
powertrain control module is an integrated, and computerized system. This
system is in charge of controlling a vehicle’s engine, transmission, and other
driveline components that are dependent on the make and model of your car.

Spark plug

Spark plug is a device that generates electric spark to the combustion chamber
of a spark ignition engine to ignite the compressed air-fuel mixture. Spark
plug should be strong and durable. Spark Plugs have the best thermal
properties. The normal work of a spark plug is provided by using the next
insulate materials: alumina (Al2O3), and a very hard ceramic material with
high dielectric strength.

Distributor

A distributor is an enclosed rotating shaft used in spark-ignition internal

combustion engines that have mechanically timed ignition. The distributor's

46
 main function is to route secondary, or high voltage, current from the
ignition coil to the spark plugs in the correct firing order, and for the correct
amount of time. Except in magneto systems and many modern computer
controlled engines that use crank angle/position sensors, the distributor also
houses a mechanical or inductive breaker switch to open and close the
ignition coil's primary circuit.

Coil

An ignition coil is an induction coil in an automobile's ignition system that

transforms the battery's voltage to the thousands of volts needed to create an
electric spark in the spark plugs to ignite the fuel. Some coils have an
internal resistor, while others rely on a resistor wire or an external resistor to
limit the current flowing into the coil from the car's 12-volt supply. More
recent electronic ignition systems use a power transistor to provide pulses to
the ignition coil. A modern passenger automobile may use one ignition coil
for each engine cylinder, eliminating fault-prone spark plug cables and a
distributor to route the high voltage pulses. Ignition systems are not required
for diesel engines which rely on compression to ignite the fuel/air mixture.

Ignition control module

The ignition control module switches transistors on and off based on input from
the magnetic pulse generator in the distributor. The magnetic pulse generator
transmits an AC voltage signal that corresponds with engine speed and the
position of the crankshaft position. The ignition control module converts the
analog signal into a digital signal, which essentially is used as an on/off
switch by the ignition control module.

47
distributor cap

The distributor cap is the cover that protects the distributor's internal parts and
holds the contacts between internal rotor and the spark plug wires. ... The
rotor is attached to the top of the distributor shaft which is driven by the
engine's camshaft and thus synchronized to it.

VI. Braking Systems

A brake system is designed to slow and halt the motion of a vehicle. To do this,
various components within the brake system must convert the vehicle's
moving energy into heat. This is done by using friction.
The basic idea behind any hydraulic system is force applied at one point is
transmitted to another point using an incompressible fluid. Brake fluid is the
incompressible fluid used in the brake system. Brake fluid efficiently
operates under high pressure and high temperature and is the hydraulic fluid
responsible for actuating the brake calipers or wheel cylinders at all four
wheels.
energy.: and there are many more individual parts within the above component
groups.

Figure 20:Braking System

48
Braking System Components:
a. Brake pedal.
The brake pedal is designed in such a way that it can multiply the force from
your leg several times before any force is even transmitted to the brake fluid.
The brake pedal provides instant control over the brakes being applied and
released. as you press the brake pedal, the force generated by your leg is
amplified several times by mechanical leverage and then amplified further
by the action of the brake booster. The mechanical force of pressing the
pedal is converted into hydraulic force by the brake master cylinder which
forces hydraulic brake fluid around the entire braking system within a
network of brake lines and hoses. This force is transmitted to all four tires
and creates friction between brake pads and disc brake rotors.

b. Brake booster.
The brake booster, also known as the brake servo, increases the force applied by
the brake pedal via either vacuum from the engine (or a vacuum pump on
diesels), or via a hydraulic pump. Without the brake booster, the brakes feel
very hard and require much more effort to slow the car. The booster only
works when the engine is running.

c. Master cylinder.
The master cylinder then converts the action of you pressing on the brake pedal
into hydraulic pressure. As you press the pedal it moves pistons within the
cylinder which in turn applies pressure to the brake fluid forcing it around
the system. The master cylinder has a brake fluid reservoir attached to the
top of it to ensure there is always an adequate supply of fluid in the system
whether the brakes are applied or released.

49
d. Lines and Hoses.
Brake lines and hoses consist of a series of thin metal pipes which connect the
various components together to transfer the brake fluid around the system.
Most of the pipes are made of metal, however, the area where the pipes meet
the brake calipers needs to consist of flexible rubber hoses to allow the
wheels to turn.

e. Brake Calipers.
Brake calipers come in many shapes and sizes and employ one or more
hydraulically actuated pistons which force the brake pads into contact with
the disc rotor when the brake pedal is pushed. The more pistons a caliper
has, the more evenly distributed the braking force is across the pad, and the
larger the pad surface can be. The larger the pad, the greater the friction
acting on the disc rotor, which equals better stopping power.

f. Brake Pads.
Brake pads are fitted in pairs to each disc brake rotor. They are made of a
hard-wearing compound that provides excellent heat resistant properties and
the ability to provide a high level of friction against the brake disc. Brake
pads gradually wear away every time you apply your brakes. In addition to
normal wear, brake pads can become loose, cracked, broken, and unevenly
worn.

g. Disk Brake Rotors.

Disc brake rotors are metal discs, which also wear, but at a much slower rate.
These metal discs are located between the wheel and hub and provide the
friction surface for the pads to act against. Brake rotors can either be solid
(one piece) or vented (effectively two discs joined by a series of veins)
which aids in cooling. Vented discs are commonly used on the front of cars
where the braking forces are higher and are subject to greater temperatures.
Disc brake rotors can become grooved, rusted, pitted, glazed, cracked, and
warped from the continual heat and pressure from the braking.

50
 h. Brake Drums & Brake Shoes.
Brake drums and shoes are not common on modern vehicles, but they are still
fitted to the rear of some vehicles. The brake shoes are housed within the
drum, and pressing the brake pedal actuates a wheel cylinder which forces
the shoes outward onto the inner edge of the drum and slows down the
vehicle.

Anti-lock braking system (ABS).

The anti-lock brake system (ABS) detects when a wheel locks up when braking.
The system consists of a control module, wheel speed sensors, valves, and a
pump. The ABS control module monitors each wheel speed sensor and
detects when one or more wheels are no longer rotating. The module uses
valves and a pump to pulse the brakes on-and-off incredibly quickly (up to
15 times per second). You feel this sensation through the pedal as a hard
vibration or pulsing sensation.

The ABS works as per the following steps:-

1. When the driver presses the brake pedal, the piston presses the brake fluid &
then ECU sends a signal to the solenoid valve & pump to start the flow of
brake fluid towards the brake drum. Hence Brake fluid flows from – Master

51
 cylinder -> Pump -> Accumulator -> Solenoid valves -> Brake drum and
wheel stops.
2. When the wheel stops due to a brake, the speed sensor sends a signal to
ECU. ECU sends a signal to the pump & solenoid valve to stop brake fluid
flow & release pressure on the wheel (by returning the brake fluid through
the return line). Therefore brake fluid flows from the Brake drum ->
Solenoid valves -> Accumulator and the resulting wheel again starts to
rotate.

3. Again speed sensor sends a signal to the ECU about wheel speed. Again
ECU sends a signal to the solenoid valve & pump to start the flow, Hence
Again brake fluid flows from – Pump -> Accumulator -> Solenoid valves ->
Wheel Drum, This step occurs rapidly till vehicle speed reduces or the
vehicle stops without skidding.

The advantages of Anti-lock braking system:

● Less braking distance

● Good steering control, so the vehicle can turn in the desired direction
● Avoids accidents.

Traction Control System (TCS):

A Traction Control System is used to prevent wheel spin from occurring due to
acceleration. This usually happens on a slippery surface, such as snow or a
pool of water, where the wheels are not able to generate enough traction to
move the vehicle. Traction Control systems and Anti-Lock braking systems
(ABS) are often paired together as they help improve the vehicle's stability
by working in tandem. The major difference between an ABS and a Traction
Control system is that while ABS stops the wheel from spinning while
braking, Traction Control stops the wheel from spinning while the vehicle is
accelerating. A Traction Control System is also known as an Anti-Slip
Regulation (ASR).

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The Traction Control system (TCS) uses wheel speed sensors to measure the
vehicle's speed with the rate at which the drive wheels are spinning, to detect
if there is any slip occurring between the tire and the road. If a slip is
detected between the road and the wheel, the Traction Control system
ensures that only the minimum amount of torque is supplied to the slipping
wheel to generate the required amount of friction for the vehicle to move.

The primary input of the TCS is the wheel speed sensor. These sensors
continuously monitor the speed of each driven wheel and send the data to the
ABS and Traction Control System ECU. When a slip is detected between the
tire and the road, the TCS regulates brake pressure on the slipping wheel.
This process of slowing down the wheel helps it regain traction.
Simultaneously, torque is shifted through the differential to the opposite
wheel that has a better traction when compared to the slipping wheel.

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The brake pressure is applied by routing the pressure from the ABS pump and
through the ABS modulator. The pressure applied is regulated through a
high pressure accumulator. The TCS includes an extra solenoid valve in the
ABS modulator, for each individual drive wheel's brake circuit. This
arrangement allows the system to apply brake pressure to slow down the
spinning wheel in order to regain traction. The continuous usage of brakes in
TCS generates a lot of heat in the brake calipers. To prevent overheating of
these calipers, TCS automatically discontinues after a certain length of time.

If both the driven wheels are losing traction, the TCS slows both the slipping
wheels equally to slow them down until they regain traction. Otherwise, the
systems send a signal to the Powertrain Control Module (PCM) to reduce the
engine torque to the wheels until traction is regained.
When the TCS is activated in a vehicle, it is shown to the driver through the
instrument cluster. In a lot of performance vehicles, there is an option of
switching on/off the Traction Control System. When this system is disabled,
a warning light glows to notify the driver that the TCS is switched off.
Switching off the TCS does not switch off the ABS in the vehicle, even
though they are interrelated.
BOSCH invented the Anti-Lock Braking system in 1978 and the Traction
Control System in 1985. Traction Control is used in cars as well as bikes.

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Electronic Stability Program (ESP):
The electronic stability program (ESP) supports the driver in nearly all critical
driving situations. It comprises the functions of the antilock braking system
(ABS) and the traction control system, but can do considerably more. It
detects vehicle skidding movements, and actively counteracts them. This
considerably improves driving safety.

ESP Components:
● ESP Module
● Wheel Speed Sensor
● Steering Angle Sensor
● Inertial Measurement unit

On the basis of the steering angle, the system recognizes the desired direction of
travel. Speed sensors on each wheel measure wheel speed. At the same time,
yaw-rate sensors measure vehicle rotation around its vertical axis, as well as
lateral acceleration. From this data, the control unit calculates the actual
movement of the vehicle, comparing it 25 times per second with the desired
direction of travel. If the values do not correspond, the system reacts in an
instant, without any action on the part of the driver. It reduces engine power
in order to restore vehicle stability. If that is not sufficient, then it
additionally brakes individual wheels. The resulting rotary movement of the
vehicle counteracts the skidding movement – within the limits of the laws of
physics, the vehicle remains safely on the desired course.

The ESP® system offers value-added functions that increases comfort and
safety. As for example, hill hold control assists the driver when starting off
on inclines by independently applying the brakes for around two seconds
after the driver has released the brake pedal. The system can also protect
vehicles with a high center of gravity from the risk of rolling over.

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Advantages Of ESP
● Counteracts vehicle skidding
● Provides effective support in critical driving situations
● Value-added functions provide additional driving safety, and enhanced
driving comfort and driving agility

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 VII. Wheel Alignment
In its most basic form, a wheel alignment consists of adjusting the angles of the
wheels so that they are perpendicular to the ground and parallel to each
other. The purpose of these adjustments is maximum tire life and a vehicle
that tracks straight and true when driving along a straight and level road. .
We will cover various levels of detail with the deepest levels containing
information that even a wheel alignment technician will find informative.
Wheel Alignment is often confused with Wheel Balancing. The two really
have nothing to do with each other except for the fact that they affect ride
and handling. If a wheel is out of balance, it will cause a vibration at
highway speeds that can be felt in the steering wheel and/or the seat. If the
alignment is out, it can cause excessive tire wear and steering or tracking
problemsIf you know anything about wheel alignment, you've probably
heard the terms

Camber
Camber is the angle of the wheel, measured in degrees, when viewed from the
front of the vehicle. If the top of the wheel is leaning out from the center of
the car, then the camber is positive,if it's leaning in, then the camber is
negative. If the camber is out of
adjustment, it will cause tire wear on one
side of the tire's tread. If the camber is too
far negative, for instance, then the tire will
wear on the inside of the tread. Camber
wear pattern If the camber is different
from side to side it can cause a pulling
problem. The vehicle will pull to the side
with the more positive camber. On many
front-wheel-drive vehicles, camber is not
adjustable. If the camber is out on these
cars, it indicates that something is worn or
bent, possibly from an accident and must
be repaired or replaced.

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Caster
When you turn the steering wheel, the front wheels respond by turning on a
pivot attached to the suspension system. Caster is the angle of this steering
pivot, measured in degrees, when viewed from the side of the vehicle. If the
top of the pivot is leaning toward the rear of the car, then the caster is
positive, if it is leaning toward the front, it is negative. If the caster is out of
adjustment, it can cause problems in straight line tracking. If the caster is
different from side to side, the vehicle will pull to the side with the less
positive caster. If the caster is equal but too negative, the steering will be
light and the vehicle will wander and be difficult to keep in a straight line. If
the caster is equal but too positive, the steering will be heavy and the
steering wheel may kick when you hit a bump. Caster has little affect on tire
wear. The best way to visualize a caster is to picture a shopping cart caster.
The pivot of this type of caster, while not at an angle, intersects the ground
ahead of the wheel contact patch. When the wheel is behind the pivot at the
point where it contacts the ground, it is in a positive caster. Picture yourself
trying to push the cart and keep the wheel ahead of the pivot. The wheel will
continually try to turn from straight ahead. That is what happens when a car
has the caster set too far negative. Like camber, on many front wheel-drive
vehicles, the caster is not adjustable. If the caster is out on these cars, it
indicates that something is worn or bent, possibly from an accident, and
must be repaired or replaced.

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Toe-In
The toe measurement is the difference in the distance between the front of the
tires and the back of the tires. It is measured in fractions of an inch in the US
and is usually set close to zero which means that the wheels are parallel with
each other. Toe-in means that the fronts of the tires are closer to each other
than the rears. Toe-out is just the opposite. An incorrect toein will cause
rapid tire wear to both tires equally. This type of tire wear is called a
saw-tooth wear pattern as shown in this illustration. If the sharp edges of the
tread sections are pointing to the center of the car, then there is too much
toe-in. If they are pointed to the outside of the car then there is too much
toe-out. Toe is always adjustable on the front wheels and on some cars, is
also adjustable for the rear wheels.

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Summary

So we have discussed firstly the Mechanical system components

Including Engine basics then we explained the Maintenance and

it’s types with a comparison between each type of maintenance,

Engine Overhauling Steps and measurements with devices,

Secondly we will study the basic electrical systems including the

Components and the Main Concepts then we explained the

Principle of diagnosing and troubleshooting, Automatic

transmission Basic concepts and types with the advantages and

disadvantages of every type and the ideal use , braking systems

with it’s components and devices with the main idea of every

device and it’s way of operation, Anti-Lock braking System and

it’s operation and basic idea, Traction control system and it’s

operation and basic idea, Electronic Stability program and it’s

operation and basic idea And wheel alignment with the Basic ideas

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References:

1. Ghabour Auto Academy Advanced Mechanical Course

2. Higher technological Institute

3. Mechcontent.com

4. Clemsonuniversity.com

5. polarisuniversity.com

6. AA1car.com

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