Lab report

ThermodynamicsLABReport
1
ENGINEERING
THERMODYNAMICS LAB
(ME-106L)
Submitted to:
Submitted by:
Section: A
Class# 11
MechanicalEngineering
Submission Date: 11-jul-2017
Book Assigned: AUTOMOTIVE MACHINES (Edition 10)
(WILLIUM H. CROUSE and DONALD L ANGLIN)

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Lists of experiments:
i. Introduction to thermodynamics lab and layout of
the lab.
ii. Demonstration of main components of IC engine and
its functions.
iii. Demonstration of two and four strokes IC engine.
iv. Demonstration of petrol and diesel engine.
v. Demonstration of ignition system of IC petrol engine.
vi. Demonstration of cooling system of IC engine.
vii. Demonstration of lubricating system of IC engine.
viii. Demonstration of fuel system of IC petrol engine.
ix. Demonstration of carburetor circuits of IC petrol
engine.
x. Demonstration of transmissionsystem of a car.
xi. Demonstration of automobile brakes system.
*****

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LAB NO 1:
INTRODUTION TO THERMODYNAMICS LAB AND
LAYOUT OF LAB.
 Introduction:
Thermodynamics lab deals with the practical study of all the thermodynamic processes
their importance and application in normal life. Especially the study of engines and its working in
detail.
 Layout Of The Lab:
InjectionPump Disc and Drum
TestingMachine Brake System
Penetrometer Assembly
Apparatus
Adiabatic Bomb
Calorimeter Turbo Charger
Cut Section Cut Section
Petrol Engine Diesel Engine
Junker Gas Winkle
Calorimeter Rotatory Engine
DOOR TEACHER STAGE Two Stroke
Cycle Engine

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LAB NO 2:
DEMONSTRATION OF MAIN PARTS OF IC ENGINE
AND ITS FUNCTIONS.
 Objectives:
The main objectives of this lab are:
o To know about the names and general introduction of the basic parts of IC engine.
o To know about the function of the basic parts of IC engine.
 Historical Background:
The principle of spark ignition (SI) engines was invented by Nicolas A. Otto in 1876.
The principle compression ignition engine (CI) was found out by Rudolf Dieselin 1892.
 Theoretical Background:
 ENGINE:
An engine or motor is machine designed to convert one form of energy
Into mechanical energy
TYPES OF ENGINES: Two types
o IC ENGINES:
Internal combustion engines are those in which combustion take place internally
e.g. automotive engines.
In this the combustion of a fuel (generally, fossil fuel) occurs with an oxidizer
(usually air) in a combustion chamber.
o EC ENGINES:
External combustion engines are those in which combustion take place externally
e.g. steam engines.
It is one where a working fluid, contained internally, is heated by combustion in
an external source, through the engine wall or a heat exchanger.
TYPES OF IC ENGINE ON THE BASIS OF IGNITION SYSTEM:
o SPARK IGNITION ENGINE (SI):
A spark-ignition engine is an internal combustion engine, where the combustion
process of the air-fuel mixture is ignited by a spark from a spark plug.

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o COMPRESION IGNITION ENGINE (CI):
A compression-ignition engine is an internal combustion engine in which ignition
of the fuel that has been injected into the combustion chamber is caused by the
high temperature which a gas achieves when greatly compressed.
 BASIC PARTS OF IC ENGINE:
Are given below:
 CYLENDER BLOCK/ASSUMBLY:
A cylinder block is an integrated structure comprising the cylinder(s) of a
reciprocating engine and often some or all of their associated
surrounding structures. It is made of aluminum alloy.
 CYLENDER HEAD:
It is a covering of cylinder block and cylinder and the end cover of a cylinder in an internal
combustion engine, against which the piston compresses the cylinder's
contents
 CYLENDER:
A cylinder is the central working part of a reciprocating engine
or pump, the space in which a piston travels. The combustion occurs in this part.
 PISTON:
A piston is a component of reciprocating engines It is he moving part of engine that is
contained by a cylinder and is made gas-tight by piston rings. Its function is
to compress air mixture.
 CONNECTING ROD:
Connecting rod or conrod connects the piston to the crank or crankshaft.
Together with the crank, they form a simple mechanism that converts
reciprocating motion into rotating motion.
 PISTON PINS:
Piston Pins or Gudgeon Pins are used in all combustion engines and are one
of the most highly stressed components of an engine. The piston pin is a hollow rod with
a small diameter that is typically made of an alloy steel.
 PISTON RINGS:
A piston ring is a split ring that fits into a groove on the outer diameter
of a piston in a reciprocating engine.

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TYPES OF PISTON RINGS: Two types:
o COMPRESSION RINGS:
The main functions of compression rings are to sealthe combustion chamber from
the crankcaseand transfer heat from the piston to the cylinder and does not allow
air-fuel mixture to be leaked.
o OIL CONTROL RINGS:
It lubricates the walls of cylinder, avoid wear and tear and controls the amount of
lubricating oil passing up or down the cylinder walls. These rings are also called
scraper rings as they scrap the oil off the cylinder walls and send it back to the
crankcase.
 SPARK PLUG:
A spark plug is a device for delivering electric current from an ignition system
to the combustion chamber of a spark-ignition engine to ignite the compressed
fuel/air mixture by an electric spark.
 FUEL INJECTER:
Fuel injector is used for the introduction of fuel in an internal combustion
engine. All diesel engines use fuel injection by design
 WATER PUMP:
The water pump is a simple centrifugalpump driven by a belt connected to the crankshaft
of the engine. The pump circulates fluid whenever the engine is running.
 DIP STICK:
It is used for the measurement of lubricant.
 CAM SHAFT:
It operates engine poppet valves, it has cam profiles. It consists of a
cylindrical rod and lobes which force the valves open as they rotate.
Camshafts can be made out of several types of material. These
include Chilled iron castings and Billet Steel.
 CRANK SHAFT:
A crankshaft is a mechanical part able to perform a conversion
between reciprocating motion and rotational motion. It’s connected
to piston through connecting rods.
 OIL FILTER:
Oil filter - as the name implies - is a filter designed to remove contaminants from engine
oil, transmission oil, lubricating oil, or hydraulic oil.
 INJECTOR PUMP:
An Injection Pump is the device that pumps diesel (as the fuel) into the cylinders of a
diesel engine.

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 OIL PUMP:
The oil pump is used to circulate engine oil under pressure to lubricate the rotating
bearings, the sliding pistons and the camshaft of the engine to allow the use of higher-
capacity fluid bearings and also assists in cooling the engine.
 FUEL FILTER:
A fuel filter is a filter in the fuel line that screens out dirt and dust particles from the fuel,
normally made into cartridges containing a filter paper.
 ENGINE VALVES/POPPET VALVES:
Poppet valves are used in most piston engines to open and closethe intake and
exhaust ports in the cylinder head.
TYPES OF ENGINE VALVES:
o INTAKE VALVES:
It is used to bring in air-fuel mixture to the cylinder. It’s bigger in size
then other.
o EXHUST VALVES:
It is used to bring out combusted air-fuel mixture from the cylinder.
 CLUTH:
A clutch istwo metal plates in the engine. When you press the clutch pedal down the plates
come apart separating the engine from the drive wheels allowing you to change gear.
Bringing the pedal back up re-engages the plates which in turn connect the engine to the
drive wheels.
 VALVE LEFTER:
A valve lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for
maintaining zero valve clearance in an internal combustion engine.
 GEAR BOX:
Gearbox uses gears and gear trains to
provide speed and torque conversions from a rotating power
source to another device.
 GEAR LEVER:
A gear stick / gear lever is a metal lever attached to the shift assembly in
a manual transmission-equipped automobile and is used to change gears.
 FLY WHEEL:
A flywheel is essentially a very heavy wheel that takes a lot of force to spin
around. It's the kind of wheel you have to push really hard to set it spinning.
When it's spinning at high speed, it tends to want to keep on spinning which
means it can store a great deal of kinetic energy.

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 CRANK CASE/OIL SUMP/OIL CHAMBER:
The crankcase is the housing for the crankshaft. The enclosure forms the largest cavity in
the engine and is located below the cylinder(s).
 TIMING BELT and TIMING PULLEY:
A timing belt, timing chain or cam belt with timing pulley are used to synchronize the
rotation of the crankshaft and the camshaft(s).
 INTAKE MINIFOLD:
An inlet manifold or intake manifold is the part of an engine that supplies the fuel/air
mixture to the cylinders.
 EXHAUST MINIFOLD:
An exhaust system is usually piping used to guide reaction exhaust gases away from a
controlled combustion inside an engine or stove.
 PUSH ROD:
A metal rod in an overhead-valve engine that is part of the linkage used for transmitting
the reciprocating motion that open and close the valves.
 ROCKER ARM:
A rocker arm is an oscillating lever that conveys radial movement from the cam lobe into
linear movement at the poppet valve to open it.
 IGNITION COIL:
An ignition coil (also called a spark coil) is an induction coil in an
automobile's ignition system that transforms the battery's low voltage to the
thousands of volts needed to create an electric spark in the spark plugs
to ignite the fuel.
 RADIATOR:
Radiators are heat exchangers used for cooling internal combustion engines.
 DISTRIBUTER:
A distributor is an enclosed rotating shaft used in spark-ignition that have
mechanically-timed ignition. The distributor's main function is 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.
 SELF STARTER:
A starter (self-starter) is a device used for rotating an internal-combustion engine so as to
initiate the engine's operation under its own power.

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 SUPER TURBO CHARGER:
A turbocharger, or colloquially turbo, is a turbine-driven forced
induction device that increases an internal combustion engine's efficiency
and power output by forcing extra air into the combustion chamber.
 IDLER PULLEY:
An idler-wheel drive is a system used to transmit the rotation of
the main shaft of a motor to another rotating device,

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 Procedure:
The principle of working of both SI and CI engines are almost the same, except the
process of the fuel combustion.
In the cylinder head the fuel is compressed due to which its combustion takes place
which produce mechanical energy.
The process direct force to some component of the engine. This force moves the
component over a distance, transforming chemical energy into useful mechanical energy.
 Comments:
The lab was very helpful I learned so many introductory things, which are discussed:
 We learned about basics and introductory knowledge of engines its
types and its working.
 We get knowledge about the basic knowledge of IC engine and its
parts names.
 We learned about the basic structures of engine parts and its
introductory functioning.

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LAB NO 3:
DEMONSTRATION OF TWO AND FOUR STROKE IC
ENGINE.
 Objectives:
o To study basic terms regarding piston cylinder arrangement.
o To know about the introduction of the two and four stroke engine and its basic
ideas, working and operations.
o To know its importance’s and comparison of both.
Some important terms related to stroke systemand will be used frequently are described
below:
 STROKE:
Each cycle of piston consists of two opposite motions: there is a motion in one direction,
and then a motion back in the opposite direction. Each of these is called a stroke.
 TOP DEAD CENTRE:
In a reciprocating engine, the dead center is the position of a
piston in which it is farthest from the crankshaft is known as top
dead Centre (TDC).
 BOTTOM DEAD CENTRE:
In a reciprocating engine, the dead center is the position of a
piston in which it is nearest to the crankshaft is known as
bottom dead Centre (BDC).
 BORE:
The Bore or cylinder bore is a part of a piston engine. The bore also represents the size,
in terms of diameter, of the cylinder in which a piston travels.
 STROKE BORE RATIO:
In a reciprocating piston engine, the stroke ratio, defined by either bore/stroke
ratio or stroke/bore ratio, is a term to describe the ratio
between piston stroke and cylinder bore diameter.
Stroke free ratio = Stroke (L) /Bore (D).

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 SWEPT VOLUME:
Swept volume is defined as the volume of fluid through which a piston or
plunger moves when it makes a stroke in an engine.
Vs = Area of cross section * Height
 CLEARENCE VOLUME:
Clearance volume is the difference between the total volume and the swept volume,
basically the gap that remains between the piston head and the cylinder head when at
top dead center.
 COMPRESSION RATIO:
The compression ratio of an engine is a value that represents
the ratio of the volume of its combustion from its largest
capacityto its smallestcapacity.It is a fundamental specification
for many common combustion engines.
For diesel engine ratio is up to 22 : 1
For diesel petrol ratio is up to 8 : 1
 DIFFERENT STAGES OF STROKE:
A four-stroke cycle engine is an internal combustion engine that utilizes four distinct
piston strokes (intake, compression, power, and exhaust) to complete one operating
cycle. The action of piston stroke can be divided into four different stages which are
described below:
 INAKE STROKE:
o The intake event is when the air-fuel mixture is
introduced to fill the combustion chamber.
o The intake event occurs when the piston moves from
TDC to BDC and the intake valve is open.
o The movement of the piston toward BDC creates a low
pressure in the cylinder. Ambient atmospheric pressure
forces the air-fuel mixture through the open intake valve

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into the cylinder to fill the low-pressure area created by the piston movement.
o The cylinder continues to fill slightly past BDC as the air-fuel mixture continues to
flow by its own inertia while the piston begins to change direction.
o The intake valve remains open a few degrees of crankshaft rotation after BDC.
Depending on engine design.
o The intake valve then closes and the air-fuel mixture is sealed inside the cylinder.
 COMPRESSION STROKE:
o The compression stroke is when the trapped air-fuel mixture is compressed inside
the cylinder.
o Compressing the air-fuel mixture allows more energy to be
released when the charge is ignited.
o Intake and exhaust valves must be closed to ensure that the
cylinder is sealed to provide compression.
o Compression is the process of reducing or squeezing a
charge from a large volume to a smaller volume in the
combustion chamber.
o The flywheel helps to maintain the momentum necessary
to compress the charge.
o When the piston of an engine compresses the charge, an increase in compressive
force supplied by work being done by the piston causes heat to be generated.
o Too high a compression can cause detonation, which is undesirable compared
with a smooth, controlled burn.
o Too low a compression may result in the fuel/air mixture still burning when the
piston reaches the bottom of the stroke and the exhaust valve opens.
Ignition Event The ignition (combustion) event occurs when the charge is ignited
and rapidly oxidized through a chemical reaction to release heat
energy. Combustion is the rapid, oxidizing chemical reaction in which afuel chemically
combines with oxygen in the atmosphere and releases energy in the form of heat.
 POWER STROKE:
o The power stroke is an engine operation Stroke in which
hot expanding gases force the piston head away from the
cylinder head.
o Piston force and subsequent motion are transferred through
the connecting rod to apply torque to the crankshaft.
o The torque applied initiates crankshaft rotation.
o The amount of torque produced is determined by the
pressure on the piston, the size of the piston, and the throw of the engine during
the power Stroke, both valves are closed.

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 EXHAUST STROKE:
o The exhaust stroke occurs when spent gases are
expelled from the combustion chamber and released to
the atmosphere.
o The exhaust stroke is the final stroke and occurs when
the exhaust valve is open and the intake valve is closed.
o Piston movement evacuates exhaust gases to the
atmosphere.
o As the piston reaches BDC during the power stroke
combustion is complete and the cylinder is filled with
exhaust gases.
o The exhaust valve opens, and inertia of the flywheel and other moving parts
push the piston back to TDC, forcing the exhaust gases out through the open
exhaust valve.
At the end of the exhaust stroke, the piston is at TDC and one operating cycle
has been completed.
 FIRING ORDER:
The firing order is the sequence of power delivery of each cylinder in a multi-cylinder
reciprocating engine. This is achieved by sparking of the spark plugs in a gasoline engine
in the correct order, or by the sequence of fuel injection in a Diesel engine.
Firing order affects the balance, noise, vibration, smoothness, cooling, and sound of the
engine.
Even and unevenfiring order:
Evenlyspacedfiringorder(alsocalledevenfiringorderorevenfiringinterval)meansthatthe angle
betweeneachfiringisequal.Infour-strokeengines720°dividedbythe numberof cylinders.A six-
cylinderenginemusthave 720° / 6 = 120° firinginterval.
Engines with unevenly spaced firing order (sometimes called odd firing order) not all angles between
firings are equal, for example a six-cylinder engine with unevenly spaced firing order can have a
combination of 90° and 150° firing intervals.

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 Four stroke engine:
 INTRODUCTION:
A four-stroke engine (also known as four cycle) is an internal combustion (IC)
engine in which the piston completes four separate strokes while turning a
crankshaft.
 DEMONSTRATIVE WORKING
The fourstrokesof the cycle are intake,compression,power,andexhaust.Each
correspondstoone full stroke of the piston;therefore,the completecycle requirestwo
revolutionsof the crankshafttocomplete.
Intake
During the intake stroke, the piston moves downward, drawing a fresh charge of
vaporized fuel/air mixture. A poppet intake valve which is drawn open by the vacuum
produced by the intake stroke
Compression
As the piston rises, the poppet valve is forced shut by the increased cylinder pressure.
Flywheel momentum drives the piston upward, compressing the fuel/air mixture.
Power
At the top of the compression stroke, the spark plug fires, igniting the compressed
fuel. As the fuel burns it expands, driving the piston downward.
Exhaust
At the bottom of the power stroke, the exhaust valve is opened by the cam/lifter
mechanism. The upward stroke of the piston drives the exhausted fuel out of the
cylinder.

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 Two stroke engine:
 INTRODUCTION:
A two-stroke, or two-cycle, engine is a type of internal combustion engine which
completes apower cyclewith two strokes of the piston during only one crankshaft
revolution. In a two-stroke engine, the end of the combustion stroke and the
beginning of the compression stroke happen simultaneously, with the intake and
exhaust functions occurring at the same time.
 DEMONSTRATIVE WORKING:
The two stroke engine employs both the crankcase and the cylinder to achieve all the
elements of the Otto cycle in only two strokes of the piston.
Intake
The fuel/air mixture is first drawn into the crankcase by the vacuum that is created during
the upward stroke of the piston.
Crankcase compression
During the downward stroke, the port is forced closed by the increased crankcase
pressure. The fuel mixture is then compressed in the crankcase during the remainder of
the stroke.
Transfer/Exhaust
Toward the end of the stroke, the piston exposes the intake port, allowing the
compressed fuel/air mixture in the crankcase to escape around the piston into the main
cylinder. This expels the exhaust gasses out the exhaust port, usually located on the
opposite side of the cylinder. Unfortunately, some of the fresh fuel mixture is usually
expelled as well.
Compression
The piston then rises, driven by flywheel momentum, and compresses the fuel mixture.
(At the same time, another intake stroke is happening beneath the piston).
Power
At the top of the stroke, the spark plug ignites the fuel mixture. The burning fuel expands,
driving the piston downward, to complete the cycle.(At the same time, another crankcase
compression stroke is happening beneath the piston.)

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Differentiation between 2 stroke and 4 stroke engine:
2 stroke 4 stroke
No cam shaft Have cam shaft
Not good for economy Good in fuel economy
More power generation Not more
Oriented in many direction Not properly
Not proper lubrication Proper lubrication system
Not proper cooling Having proper cooling system
Simple construction Not simple
Gives Sox, NOx etc. Environment friendly
Not properly Air-fuel mixture is properly burnt
Not too Crankshaft runs smoothly.
Not continues continuous flow of power.
Energy lost Energy will not be lost.
More chief Not as much
Produces more noise. Not as much
Used in cars, buses, trucks etc. Used in mopeds, scooters, motorcycle.
More wear and tear of moving parts. Less wear and tear of moving parts.
It consumes more lubricating oil. It consumes less lubricating oil.
Less thermal efficiency. More thermal efficiency.
Engine consists of inlet and exhaust
ports.
Engine consists of inlet and exhaust
valve.
Simple lubricating system. Complicated lubricating system.
Engine requires less space. Engine requires more space.
Less output due to mixing of fresh
charge with the hot burnt gases.
More output due to full fresh charge
intake and full burnt gases exhaust.
More mechanical efficiency due to less
friction on a few parts.
Less mechanical efficiency due to more
friction on many parts.
Engine designissimple due to absence
of valve mechanism.
Engine designiscomplicateddue tovalve
mechanism.
Lighterflywheel isrequired and engine
runs balancedbecause turningmoment
is more even.
Heavy flywheel is required and engine
runs unbalanced because turning
moment on the crankshaft is not even.
Has one power stroke for each
revolution of the crankshaft.
Has one power stroke for every two
revolutions of the crankshaft.

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 Comments:
 We learned about basics and introductory knowledge of the working
of strokes process and working.
 We learned about the different working of 2 and 4 stroke.
 We get knowledge about the differences between 2 stroke and 4
stroke engines their advantages and disadvantages.

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LAB NO 4:
DEMONSTRATION OF PETROL AND DIESEL ENGINE.
 Objectives:
o To know detailed information about the petrol and diesel
o To know its basics of operating, working and basic ideas.
o To study its importance and comparison of both on different basis.
 Historical Background:
The first practical petrol engine was built in 1876 in Germany by Otto. The original
cycle proposed by Rudolf Diesel in 1892 was a constant temperature cycle.
Petrol anddiesel enginesare the twomostcommonlyusedinternalcombustionengines.
Eventhoughtheiroperationseemssimilar,theyhave some interestingdifferences,andeach
has advantagesoverthe other.
 DIESEL ENGINE:
 INTRODUCTION:
The diesel engine is an internal combustion engine in which ignition of the fuel
that has been injected into the combustion chamber is caused by the high temperature
which a gas achieves when greatly compressed.
Inthe true dieselengine,onlyairisinitiallyintroducedintothe combustionchamber.The
air is then compressed with a compression ratio typically between 15:1 and 23:1. This high
compressioncausesthe temperature ofthe airtorise.At aboutthe topofthe compressionstroke,
fuel is injected directly into the compressed air in the combustion chamber. The fuel injector
ensures that the fuel is broken down into small droplets, and that the fuel is distributed evenly.
Combustionoccursat asubstantiallyconstantpressure duringthe initial partof the powerstroke.
Whencombustioniscomplete the combustion,gasesexpandasthe pistondescendsfurther;the
high pressure in the cylinder drives the piston downward, supplying power to the crankshaft.
 PETROL ENGINE:
 INTRODUCTION:
A petrol engine is an internal combustion engine with spark-ignition, designed to run on
petrol and similar volatile fuels.

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In most petrol engines, the fuel and air are usually pre-mixed before
compression (although some modern petrol engines now use cylinder-direct petrol
injection). The pre-mixing was formerly done in a carburetor, but now it is done by
electronically controlled fuel injection, except in small engines where the
cost/complication of electronics does not justify the added engine efficiency. The process
differs from a diesel engine in the method of mixing the fuel and air, and in using spark
plugs to initiate the combustion process.
 Major differences between diesel and petrol engine:
 Difference between petrol and diesel:
Petrol is a volatile fuel, is readily evaporates, so it gets mixed with the air
efficiently. As a result, just a spark is sufficient to produce smooth combustion
in a well pre-mixed petrol engine. On the other hand, diesel being a less
volatile fuel does not properly mix with air
 Difference between combustion:
This means that in petrol engines, the fuel and air should be pre-mixed, while
in diesel engines, mixing happens only during the combustion. Due to this
reason diesel engines use a fuel injector while petrol engines use a spark plug,
and because of this the combustion type is different as shown in figure.
 Difference of fuel injector and spark plug:
Due to this the difference between fuels diesel engines use a fuel injector
while petrol engines use a spark plug for their main process control.
 Difference of heaviness:
Petrol engines are less noisy and vibrate less compared to diesel
engines. This is because the combustion process in a pre-mixed mixture
is smooth and propagates well but in a diesel engine, the combustion
could begin anywhere in the combustion chamber, and it turns out to
be an uncontrolled process.

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For this reason, to reduce the excessive vibration and noise problem, diesel engines require a
more rugged structural design than petrol engines. To normalize the heavy unbalanced power
production of diesel engines a heavy fly wheel is often required. This is why petrol engines are
always preferred for light-weight applications, such as in 2-
wheeler or portable devices
 Difference of fuel economy:
Diesel engine is compressing only the air, it can achieve a good
compression ratio without risk of self-ignition. But, in a pre-mixed
petrol engine, such a high compression ratio is not possible. As we
increase compression ratio of petrol engine the mixture becomes
more prone to self-ignition. This is known as knocking. Over the period of operation knocking
badly damages the engine.
 Table showing differencesbetween petrol and diesel
engine:
Diesel engine Petrol engine
Diesel is used Petrol is used
Efficiency (Thermal Efficiency) is 45% Efficiency (Thermal Efficiency) is 35%
Less Chances of pre-ignition More Chances of pre-ignition
Initial cost is More Initial cost is Less
Running cost is less Running cost is more
Maintenance cost is More but not frequent Maintenance cost is Less but frequent
For spark ignition Heat of compressed air is
required
For spark ignition Plug is there
Fuel is supplied by Fuel injector Fuel is supplied by Carburettor
Its compression ratio is 22 : 1
Compressionratiois higherindiesel engine.
Due to higher compression ratio, more
power is produced.
Its compression ratio is 8 : 1
Compression ratio is low.
Less power is produced due to lower
compression ratio.
Its working cycle is at Constant Pressure
(diesel cycle)
Its working cycle is at Constant Volume
(Otto cycle)
Irregular Combustion Smooth Combustion
More Vibration and Noise Less Vibration and Noise
Used for Heavy duties Used for Light duties
More Pressure and Temperature Less Pressure and Temperature
More Weight and Size and Bulky Less Weight and Size and not Bulky
Fuel consumption in diesel engine is less. Fuel consumption in petrol engine is high.

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Diesel engine Petrol engine
Greater starting problem.
The starting of the diesel engine is slightly
difficult due to higher compression ratio
compared to a petrol engine.
Lesser starting problem.
The starting of petrol engine is easy due to
low compression ratio.
The pressure at the end of the compression
is about 35 bar.
The pressure at the end of the compression
is about 10 bar.
Diesel engines are relatively low-speed
engines
Petrol engines are high-speed engines.
 THE HORSE POWER EQUITION :
When R.P.M decreases, the torque (T) increases. The equation for horsepower is
given as:
𝐇𝐏 =
𝐓 × 𝐫. 𝐩. 𝐦
𝟓𝟐𝟓𝟐
 Comments:
 We studied about basics and introductory knowledge of the engine
processes and its working.
 We learned about the different working of petrol and diesel stroke.
 We get knowledge about the differences between petrol and diesel
engines their advantages and disadvantages.

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LAB NO 5:
DEMONSTRATION OF THE IGNITION SYSTEM OF IC
ENGINE.
 Objectives:
o To know detailed information about the ignition system of IC engine.
o To know basics of operating, working and basic ideas of the ignition system of IC
engine.
o To study the importance and different types of the ignition system of IC engine.
 IGNITION SYSTEM:
An ignition system generates a spark or heats an electrode to a high temperature
to ignite a fuel-air mixture in spark ignition internal combustion engines or other
Engines. It is an array of components that are all involved in the process of igniting
the air/fuel mixture in an internal combustion engine.
TWO MAIN TYPES:
o Contact Point Ignition System.
o Electronic Ignition System.
CONTECT POINT IGNITION SYSTEM:
 INTRODUCTION:
It is actually a type of ignition system that is based on contact point’s type transmission
of current for ignition and further for sparking.
 MAIN COMPNENTS:
The main components are described below:
 BATTERY:
An automotive battery is a rechargeable battery that supplies electrical energy to
a motor vehicle. It is also known as an SLI battery (abbreviation of starting-lighting-
ignition) and its main purpose is to start the engine.

24
 IGNITION SWITHES:
An ignition switch or starter switch is a switch in the control system of
an internal combustion engine motor vehicle that activates the main
electrical systems for the vehicle
 IGNITION COILS:
An ignition coil (also called a spark coil) is an induction coil in
an automobile's ignition system that transforms the battery's low
voltage to the thousands of volts needed to create an electric spark in
the spark plugs to ignite the fuel.
 CONTECT BRAKERS:
A contact breaker (or "points") is a type of electrical switch, and the term
typically refers to the switching device found in the distributor of the ignition
systems of spark-ignition system.
 DISTRIBUTERS:
A distributor is an enclosed rotating shaft used in spark-
ignition internal combustion engines that have mechanically-
timed ignition. The distributor's main function is 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
 .SPARK PLUGS:
A spark plug is a device for delivering
electric current from an ignition system
to the combustion chamber of a spark-
ignition engine to ignite the
compressed fuel/air mixture by
an electric spark, while containing
combustion pressure within the engine.
 CONDENSER:
The function of a condenser in a
coil ignition circuit is to reduce the
spark at the contact points as they open
in the distributor and thus minimize burning and pitting of the points. Arcing as caused by
the effect of self-induction in the coil as the points interrupt the flow of current.

25
 DEMONSTRATIVE WORKING:
The breaker point ignition system circuit starts and ends with the battery. When the
engine is running, the battery is continuously being recharged by an alternator or, on
older systems, a generator.
Current flows from the positive terminal of the battery to the ignition switch and an
ignition coil. The ignition coil is really a transformer that steps up the 12-volt current of
the battery to somewhere in the neighborhood of 25,000 volts. In engines of medium to
high compression this kind of voltage is necessary to reliably arc across the gapon a spark
plug and make enough fire to ignite the fuel/air mixture in a cylinder.
The coil has two circuits in it; the primary, which runs from the positive coil terminal to
the negative coil terminal; and the secondary circuit, which goes from the positive
terminal on the coil to the ignition wire in the center of the distributor cap. The negative
wire on the primary circuit runs from the coil to the base of the distributor and the
breaker points inside.
The breaker points open and closeas the distributorshaft rotates.The distributor shaft
has lobes that contact the rubbing block. These lobes act as cams to push the points open,
thereby breaking the electrical connection between the points. The points have a spring
clip that acts to hold the points shut, and this spring causes the moveable point to snap
back into contact with the stationary point mounted to the distributor plate when the
cam rotates out of contact.
When the points are touching each other, electricity runs from the battery, through
the coil and to the engine block, which is grounded to the negative terminal on the
battery. The current running through the windings in the ignition coil builds up apowerful
electricalfield that is unleashed when the points separate. No longer able to go to ground
through the points, the electricity, which is seeking the easiest path to ground, rushes
through the secondary circuit to the coil wire to the top of the distributor cap where it is
transmitted to the distributor rotor.

26
ELECTRONIC IGNITION SYSTEM:
 INTRODUCTION:
An ignition system using electronic switching devices to eliminate the mechanical breaker
points . An automotive ignition in which electrical pulses are generated electronically,
usually by transistors controlled by sensing devices, without the use of mechanically
actuated breaker points. Also called breaker less ignition.
 MAIN COMPNENTS:
The main components are described below:
 TRIGGER WHEEL:
The trigger wheel, pole piece or armature, is connected to
upper end of the distributor shaft. The trigger wheel replaces
the distributor cam. Like the distributor cam lobes, the teeth on
the trigger wheel equal the number of engine cylinders.
 ELECTRONIC IGNITION MODULE:
An ignition control module (ICM) is a computer that controls the ignition coil or the
ignition coil's firing time. The ignition control module is the heart of an automobile's
ignition system, because it regulates spark generation within
the engine.
 PICKUP COIL:
The pickup coil, also known as a sensor assembly, produces
tiny voltage surges for the ignition systems electronic control
unit. The pickup coil is a small set of windings forming a coil.
 ELECRTONIC CONTROL UNIT AMPLIFIER
The ignition system electronic control unit amplifier is an electronic
switch that turns the ignition coil primary current ON and OFF. The ECU performs the
same function as the contact points. The ignition ECU is a network of transistors,
capacitors, resistors, and other electronic components sealed in a metal or plastic
housing.
 VACCUM ADVANCE:
There’s a tiny silver cane on the side of most distributors that
is easily the most misunderstood component of any
distributor-based ignition system. With less air and fuel in
each cylinder, the air-fuel mixture is not too densely packed.
This less-dense mixture requires more ignition timing to
complete the combustion because it takes longer to complete

27
the combustion process. So we need a way to increase the amount of timing based on
the load on the engine. At part throttle, high manifold vacuum moves the diaphragm in
the vacuum advance canister on the distributor to add more timing. So based on this,
you can see that having a curve in the distributor along with vacuum advance is a good
thing.
With the engine running, the trigger wheel rotates inside the distributor. As a tooth of
the trigger wheel passes thepickup coil,the magneticfield strengthens around the pickup
coil. This action changes the output voltage or current flow through the coil. As a result,
an electrical surge is sent to the electronic control unit, as the trigger wheel teeth pass
the pickup coil.
The electronic control unit increases the electrical surges into ON/OFF cycles for
the ignition coil. When the ECU is ON, current passes through the primary
windings of the ignition coil, Thereby developing magnetic field
then, when the trigger wheel and pickup coil turn OFF the ECU, the magnetic field
inside the ignition coil collapses and fires a sparkplug.
IGNITION TIMING DEVICES
Ignition timing refers to how early or late the sparkplugs fire in relation to the
position of the engine pistons. Ignition timing must vary with engine speed, load, and
temperature. Timing advance happens when the spark plugs fire sooner than
the compression strokes of the engine.
The timing is set several degrees before top dead center (TDC). More time advance is
required at higher speeds to give combustion enough time to develop pressure on
the stroke. Timing retard happens when the spark plugs fire later on the compression
strokes. This is the opposite of timing advance.
Spark retard is required at lower speeds and under high load conditions. Timing
retard prevents the fuel from burning too much on the compression stroke, which
would cause spark knock roping.

28
Differentiation between Contact Point Ignition System and
Electronic Ignition Systems:
 CONTACTPOINT IGNITION SYSTEM:
While thisiscalleda“conventional”ignitionsystem, it’ssomethingof amisnomer.Thisisanolderstyle
of ignitionsystemthatusespoints,adistributor,andanexternal coil.They’re high-maintenance,but
easilyfixedandprettycheap.
 ELECTRONIC IGNITION SYSTEM:
An electronic ignition is a modification on the conventionalsystem, and you’llfind
these in widespread use today. In an electronic system, you still havea
distributor, but the points have been replaced with a pickup coil, and there’s an
electronic ignition control module. These are far less likely to breakdown than
conventional systems, and providevery reliable operation.
 Comments:
 We studied and learned about basics and introductory knowledge of
the ignition system and its working.
 We learned about the different types of ignition system.
 Weget knowledgeaboutthedifferences between electronic and point
ignition system their advantages and importance.

29
LAB NO 6:
DEMONSTRATION OF THE COOLING SYSTEM OF
AUTOMOBILE.
 Objectives:
o To know detailed information about the cooling system of automobile.
o To know basics of operating, working and basic ideas of the cooling system of
automobile and its parts.
o To study different methods of cooling system in automobile.
o To study the importance of the cooling system of automobile.
 COOLING SYSTEM:
A coolingsystemmustmaintainthe engine at a constanttemperature whetherthe outside
airtemperature is110degreesFahrenheit or10 below zero. If the enginetemperatureistoolow,
fuel economywill sufferandemissionswill rise. If the temperature canget too hot for too long,
the engine will self-destruct. Coolingwater isthe waterremovingheatfromamachine orsystem.
Coolingwatermay be recycledthrougha recirculating systemorusedin a single pass once-
through cooling (OTC) system.
TYPES OF COOLING SYSTEM: Two types
o AIR COOLING SYSTEM (ACS):
Air cooling is a method of dissipating heat. It works by expanding the surface area
of or increasing the flow of air over the object to be cooled, or both. Air cooled
engines are found on a few older cars. Many modern motorcycles still use air
cooling, but for the most part, automobiles and trucks use liquid cooled systems
and that is what this article will concentrate on.
o WATER COOLING SYSTEM (WCS):
Water cooling isa methodof heat removal fromcomponentsand industrial equipment.
As opposed to air cooling, water is used as the heat conductor. Water cooling is
commonly used for cooling automobile internal combustion engines and large
industrial facilities.

30
WATER COOLING SYSTEM (WCS) :
Cooling water is the water removing heat from a machine or system. This system
is described below:
 BASIC PARTS OF WATER COOLING SYSTEM (WCS):
Are given below:
 RADIATOR:
Radiators are heat exchangers used to
transfer thermal energy from one medium to
another for the purpose of cooling. The
radiator is always a source of heat to its
environment, although this may be for either
the purpose of heating this environment, or
for cooling the fluid as for engine cooling.
 WATER PUMP:
The purpose of a car water pump is to push coolant through the car's
engine block, radiator and hoses to get the engine heat away from the
system. Most frequently, the water pump is driven off by the engine
itself by a belt.
 FANS:
The cooling fan must be controlled so that it allows the engine to
maintain a constant temperature. The fans are controlled either with
a thermostatic switch or by the engine computer, and they turn on when the temperature
of the coolant goes above a set point.
 THERMOSTATIC VALVE:
A thermostatic radiator valve (TRV) is a self-regulating valve fitted to
hot water heating systemradiator, to control the temperature of a
room by changing the flow of hot water to the radiator.
 COOLENT TEMPERATURE SENSER:
The coolant temperature sensor is used to measure the temperature of the engine
coolant. The readings from this sensor are then fed back to the Engine control unit (ECU),
which uses this data to adjust the fuel injection and ignition timing.
 ANTI FREEZE:
An antifreezeisanadditivewhichlowersthe freezingpointof awater-basedliquid.Anantifreeze
mixture is used to achieve freezing-point depression for cold environments and also
achieves boiling-point elevation to allow higher coolant temperature.
Coolant=anti-freeze +water
Most antifreeze is made by mixing distilled water with some kind of alcohol.

31
Methanol
Its chemical formula isCH3OH, At room temperature, it is apolar solvent and is used as
an antifreeze, solvent, fuel, and as a denaturant for ethyl alcohol. It is not popular for
machinery, but may be found in automotive windshield washer fluid, de-icers,
and gasoline additives.
Ethylene glycol
Its formula is .Ethylene glycol solutions became available in 1926 and
were marketed as "permanent antifreeze" since the higher boiling points provided
advantagesfor summertime use aswell asduringcold weather.Theyare usedtoday for
a variety of applications, including automobiles, but gradually being replaced
by propylene glycol due to its toxicity.
Propylene glycol
Its formula is .Propylene glycol, on the other hand, is considerablyless
toxic than ethylene glycol and may be labeled as "non-toxic antifreeze". It is used as
antifreeze where ethylene glycol would be inappropriate.
Glycerol
Once used for automotive antifreeze, glycerol has the advantage of being non-toxic,
withstands relatively high temperatures, and is noncorrosive. Glycerol was historically
used as an antifreeze for automotive applications before being replaced by ethylene
glycol, which has a lower freezing point. While the
minimumfreezingpointof a glycerol-watermixtureis
higher than an ethylene glycol-water mixture.
 WATER JACKETS:v
A water jacketis a water-filled casing surrounding a device,
typicallyametal sheathhavingintake andoutletventstoallow
waterto be pumped through and circulated. The flow of
waterto an external heating orcoolingdevice allowsprecise
temperature control of the device.
 RADIATOR PRESSURE CAP:
Radiator's pressure cap will keep your cooling system at a higher psi to
increase the boiling point of your coolant allowing it to absorb more heat
from your engine.
 BYPASS SYSTEM
The bypass hose, is used to circulate the coolantthrough the
engine, bypassing the radiator, when the thermostat is closed.
 FINS:
The rows of finson both the steel cylinder barrel and the aluminum cylinder head provide
additional surface area for air to pass over the cylinder and absorb heat.

32
 FREEZE PLUGS:
Whenwaterfreezes,itexpands.If waterfreezesinsideyourengine block,itcanexpandandcrack
the block, destroying the motor. Freeze plugs (or expansion plugs) will and supposedly prevent
this.
 GASKETS:
Gasketsare usedthroughoutyourwhole coolingsystem,includingonthe waterpump,
thermostat, coolantbypassesandothervital components.Overtime,it'sinevitable that
your gasketswear out and become damaged, which leads to a potential coolantleak
and engine overheating.
A water-cooled engine block and cylinder head have interconnected coolant channels
runningthroughthem.Atthe topof the cylinderheadall the channelsconvergetoasingle outlet.
A pump,drivenbya pulleyandbeltfromthe crankshaft,driveshot coolantout of the engine to
the radiator, which is a form of heat exchanger.
Unwanted heat is passed from the radiator into the air stream, and the cooled liquid then
returns to an inlet at the bottom of the block and flows back into the channels again.
Usuallythe pumpsendscoolantupthroughthe engine anddownthroughthe radiator,taking
advantage of the fact that hot waterexpands,becomeslighterandrisesabove cool waterwhen
heated. Its natural tendency is to flow upwards, and the pump assists circulation.
The radiatorislinkedtothe enginebyrubber hoses,andhasatopandbottomtankconnected
by a core a bank of many fine tubes.
The tubes pass through holes in a stack of thin sheet-metal fins,so that the core has a very
large surface area and can lose heat rapidly to the cooler air passing through it.
The extra pressure is limited by the radiator cap, which has a pressure valve in it. Excessive
pressure opens the valve, and coolant flows out through an overflow pipe.
Later cars have a sealed system in which any overflow goes into an expansiontank, from
which it is sucked back into the engine when the remaining liquid cools.
How the fan helps
The radiatorneedsaconstant flow of airthroughits core to cool it adequately.Whenthe car
is moving, this happens anyway; but when it is stationary a fan is used to help the airflow.
The fan may be driven by the engine, but unlessthe engine is working hard, it is not always
needed while the car is moving, so the energy used in driving it wastes fuel.
Usually carshave anelectricfan,alsoswitchedonandoff byatemperature sensor.To letthe
engine warmupquickly,the radiatorisclosedoff bya thermostat,usuallysitedabove the pump.
The thermostat has a valve worked by a chamber filled with wax.
When the engine warms up, the wax melts, expands and pushes the valve open, allowing
coolantto flow through the radiator. When the engine stops and cools, the valve closes again.
Water expandswhenitfreezes,andif the waterinanengine freezesitcanburstthe blockor
radiator. So, antifreezeusually ethyleneglycol isaddedtothe watertolowerits freezingpoint to

33
a safe level. Antifreeze shouldnotbe drainedeach summer;it can normallybe leftinfor twoor
three years.
 Comments:
 We studied about basics and introductory knowledge of the cooling
system and its working.
 We learned about the different types of cooling system.
 We get knowledge about the differences between different parts of
cooling system their advantages and importance.

34
LAB NO 7:
DEMONSTRATION OF THE LUBRICATING SYSTEM
OF IC ENGINE.
 Objectives:
o To know detailed information about the lubricating system of IC engine.
o To know basics of operating, working and basic ideas of the basic components of
lubricating system of IC engine.
o To study the theory and back ground of lubricating system of IC engine.
o To study the different types of lubricating system of IC engine.
 LUBRICATION AND LUBRICATING SYSTEM:
The action of applying a substance such as oil or grease to an engine or component to
minimize friction and allow smooth movement.
A lubrication system (LS) is a system that delivers controlled amounts of lubricant to
multiple locations on a machine while the machine is operating.
 TRIBOLOGY:
The science of friction, lubrication and wear is called tribology.
 NEED AND USE:
Lubrication is used to reduce friction, heat, and wear when introduced as a film between
solid surfaces. Using the correct lubrication system helps maximize the life of your
bearings and machinery, therefore saving money, time, and manpower, thus making
operations more efficient and more reliable.
TYPES OF LUBRICATING SYSTEM: Two types
o SPLASH TYPE LUBRICATING SYSTEM:
In the splashsystem, there isadipperonthe bottomof the connectingrod. Thisdipper
splashes the oil all overthe inside of the engine.
All the movingpartsare lubricated bythe oil splashed onthemby the dipper.
Expertsagree thatsplashlubricationissuitable forsmall enginessuchas
those usedinlawnmowersandoutboardboatmotors,butnot for
automobile engines.

35
o FULL PRESURE TYPE LUBRICATING SYSTEM:
Pressure feed lubricatingsystem- mechanical systemof lubricatinginternal combustion
engines in which a pump forces oil into the engine bearings.
It is one where a working fluid, contained internally, is heated by combustion in an
external source, through the engine wall or a heat exchanger.
 VISCOSITY:
A quantityexpressingthemagnitude of internalfrictioninafluid,
as measured by the force per unit area resisting uniform flow.
 VISCOSITY INDEX:
Viscosity index (VI) is an arbitrary measure for the change
of viscosity withvariationsintemperature. The lowerthe VI,the
greater the change of viscosity of the oil with temperature and
vice versa. It is used to characterize viscosity changes with
relation to temperature in lubricating oil.
 GRADES:
The Society of Automotive Engineers (SAE) has established a numerical code system for
grading motor oils according to their viscosity characteristics. SAE viscosity grade numbers
refertotwotypesof measurements - one setwhichmeasurescoldtemperatureperformance
(0W, 5W, 10W, 15W and 20W). The second set of measurementsis for high temperature
performance (8, 12, 16, 20, 30, 40, 50).
 MULTIPLE VISCOSITY OIL:
Many engine oilshave aviscosity-indeximproveradded.Itallowsthe oil viscositytoremain
relativelyunchanged,hotorcold.A multiple viscosity(“multi-viscosity”) oil gradedSAE5W
30 has the viscosityof anSAE 5W oil whencoldandan SAE 30 oil whenhot.Automotive
manufacturersrecommendmulti-viscosityoil formostdrivingconditions.
 ANTI WEAR AGENT:
An additive thatminimizeswearcausedbymetal-on-metal contactbyformingafilmonthe
metal surfaces,typicallyactivatedbyheatandpressure.
 BASIC PARTS OF LUBRICATING SYSTEM:
Are given below:
 OIL SUMP:
The lubrication system is fed by the oil sump that forms the
lowerenclosure of the engine.Oil is takenfromthe sumpby a
pump, filter and delivered under pressure to a system of
passages or channels drilled through the engine.
OIL STAINER AND OIL PICK UP:
The oil pickupisa tube witha strainer, the strainerhasa mesh
screensuitable forstraining large particlesfromthe oil andyet
passes a sufficient quantity of oil to the inlet side of the oil
pump.

36
 PICK UP TUBE:
It’s a tube that extends from the oil pump to the bottom of the oil pan. One end of the pickup
tube boltsor screwsintothe oil pump or to the engine block. The other end holds the strainer.
 OIL PUMP:
The oil pump in an internalcombustion enginecirculatesengine oil
underpressureto the rotating bearings,thesliding pistonsand the
camshaftof theengine.This lubricatesthe bearings,allowstheuse
of higher-capacityfluid bearings and assists in cooling the engine.
 PRESSURE RELEIF VALVE:
The oil pressure relief valve is usually located at the pulley end of
the engine,rightaroundthe oilpump.Whenthe engineiscold,the
oil becomes cold and thick. It is now that the oil pressure relief
allows oil to flow directly to the bearings from the oil pump.
As the engine heatsup,the oil becomesthinnerandhot. Without
the oil pressure relief valve, too much oil would flood the engine
parts and spray onto the cylinder walls, resulting in excessive oil
consumption and a reduction in overall engine power.
 OIL FILTER:
An oil filteris a filter designed to remove contaminants from
engine oil, transmission oil, lubricating oil, or hydraulic oil.
 OIL GALLERIES:
A pipe or drilledpassagewayinthe engine thatisusedto carry engine oil fromone area
to another.
 SPROUTS:
Anoil sproutconnectedwiththe oil lines spraysoil upwardstolubricate piston.Afterlubrication,
oil begins to flow through a separate passage to sump.
 LUBRICANTS:
A lubricantis an organic substance introduced to reduce frictionbetween surfaces in mutual
contact, which ultimately reduces the heat generated when the surfaces move.
The property of reducing friction is known as lubricity.
The lubricant can be a solid, (e.g. Molybdenum disulfide MoS2) a solid/liquid dispersion, a liquid
such as oil or water, a liquid-liquid dispersion (a grease) or a gas
 Properties of lubricants:
A good lubricantgenerally possessesthefollowing characteristics:
i. high boiling pointand low freezing point (to stay liquid within a wide range of temperature)
ii. high viscosityindex.
iii. thermalstability.
iv. hydraulicstability.
v. corrosion prevention.
vi. high resistance to oxidation.

37
The engine lubricatingsystemsuppliesoil toall movingparts.
The oil pumppicksup oil fromthe oil pan andsendsit upthroughthe oil passagestothe main
bearingsof the crankshaft.Oil fromthe mainbearingsmovesthroughoil holesdrilledinthe
crankshaftto the rod bearings.
Oil thenpassesthrough anoil line tothe cylinderheadwhere itflowsthroughanoil galleryto
camshaftbearingsandvalve trainparts.The pistons,pistonrings,andpistonpinsreceive oilthrown
off the connecting-rodbearings.
Thisoil fallsonthe cylinderwallstherebyreachesthe pistons,ringsandpins.Thenthe oil drops
back downinto the oil pan.
Lubricationof bearingsisnecessarytoachieve maximumservicelifeof the engine.However,their
lubricationisquite simple andiseasilymetthroughproperlydesignedbearingsandbyusingoil with
the correct viscosity.The highestunitpressuresandthe mostdifficultlubricationoccurbetweenthe
cam lobesandvalve lifters.Presentdaymotoroil formulationisbased onthe oil’sabilityto
minimize lifterscuffingandwear.
Cam lobesare notlubricatedwithpositive pressure butdependonoil thrownfromthe connecting
rods andon oil,whichdrainsbackfrom the rockerand lifterchambers.Valve assemblies,pistons,
pistonpins,oil pump-distributordrivesandcamdrivesrequire onlyasurface filmof oil.Since the
loadsare relativelylightthe oil receivedfromsplashisusuallyadequate.

38
Oil underslightpressure isusuallysenttothe rockerarms. It isnot the amountof pressure,butthe
definitedeliveryof oil tothe movingsurface needinglubricationisimportant.Someenginesprovide
an oil flowtothe cam drive.Thisoil helpstocushionthe drive andreduce noise.Automobile
enginesalsoutilize engineoil tooperate hydraulicvalve lifters,whichrequiresthe engine oiltohave
a differentkindof characteristic.Hydraulicliftersare manufacturedwithextremelyclosetolerances
to minimize leakage.The engineoil keepsthe lifterclean,minimizingdepositformationtoavoid
liftersticking.
One of the functionsof the engine lubricationsystemistomaintainapositive andcontinuousoil
supplytothe bearings.Engine oil pressure ishighenoughtogetthe oil to the bearingwithsufficient
force to produce adequate oil flowforpropercooling.Normal engineoil pressure range isfrom207
to 414 kPawhile the hydrodynamicfilmpressuresdevelopedinthe high-pressure areasof the
engine bearingmaybe over6895 kPa.
 Comments:
 We studied about basics and introductory knowledge of the
lubricating system and its working.
 We learned about the different types of lubricating system.
 We get knowledge about the different important properties of
lubricating oil.
 We learned about parts of lubricating system in detail.

39
LAB NO 8:
DEMONSTRATION OF THE FUEL SYSTEM OF IC
PETROL ENGINE.
 Objectives:
o To study detailed information about the fuel system of IC engine.
o To know basics of operating, working and basic ideas of the fuel system of IC
engine.
o To study the importance and different types of the fuel system of IC engine.
o To study the sub systems and the main component of fuel engine that is
carbonator its circuits and demonstrative working.
 FUEL SYSTEM:
The functionof the fuel systemisto store and supplyfuel to the cylinderchamberwhere
it can be mixed with air, vaporized, and burned to produce energy. The fuel, which can be
either gasoline or diesel is stored in a fuel tank.
A fuel pump drawsthe fuel fromthe tankthroughfuel lines anddeliversitthroughafuel filterto
either a carburetor or fuel injector, then delivered to the cylinder chamber for combustion.
 TYPES OF FUEL SYSTEM: There are different fuel supply systems for spark ignition
(petrol) and compression ignition (diesel) engine.
o CARBURATED FUEL SYSTEM:
In petrol engine, the combustible mixture of fuel is prepared outside the combustion
chamber.Properair-fuelratioismaintainedwiththehelpof adevice knownascarburetor
and this mixture is inducted into the combustion chamber.
The fuel fromthe tank is deliveredto the float chamberattachedto the carburetor with
the helpof fuel pump.The fuel pumpmaintainsthe constantpressure.Incarburetorfuel
is mixed with air in required proportion.
After that the mixture of fuel and air is inducted into the combustion chamber.
o FUEL INJECTED FUEL SYSTEM:
In diesel engine onlyairisinjectedduringthe suctionstroke andit is compressed during
compression stroke. Fuel is injected into the combustion chamber in the form of fine
spray at the end of compression stroke. fuel pump takes the fuel from fuel tank and
delivers it to the fuel filter.

40
Whenthe pressure isdevelopedinthe injectionpumpthe fuelflowsfrominjectionpump
to the fuel injector under pressure.
The fuel injector is either a single hole nozzle or multi-hole nozzle.
SUB SYSTEMS IN FUEL SYSTEM: Two systems
o FUEL SUPPLY SYSTEM:
The fuel system of an internal combustion Engine is intended to produce combustible
mixture composedof thefuel storedinthefuel tank andatmosphericair,andthendeliver
bothto the cylinders.Petrolengine use lightgrade gasoline fuel while the DieselEngines
utilize heavy diesel fuel, therefore fuel supply systems and they differ greatly in petrol
and diesel engine.
o FUEL METERING SYSTEM:
A fuel meteringsystemforaninternal combustionengine fordetermininga desiredfuel
flowrate baseduponthe mass of air flow intothe engine anda desiredair-to-fuel ratio,
the engine havingapassage through whicha mixture of air and fuel is inductedinto the
combustion chamber or chambers of the engine.
 BASIC PARTS OF FUEL SYSTEM: Are given below:
 FUEL TANK:
The fuel tankcontainsthe fuel,whenthe engineneedsfuelitistakenfromthe tankthroughfuel
linesbyfuel pumpordirectlydue to gravity. Thisstore andprotectsfuelpriortoenteringthe fuel
system. Normally slightly pressurized to aid in fuel delivery.
 FUEL PUMP:
A fuel pump is a frequently (but not always)
essential component in internal combustion
engine devices. Many engines do not require any
fuel pumpat all,requiringonlygravityto feedfuel
from the fuel tank or under high pressure to
the fuel injection system. The fuel pumpisusedto
pump the fuel fromthe fuel tank,viathe fuel lines.
There are two types,mechanical fuel pumps(used
in carburetors) and electronic fuel pumps (used in
electronic fuel injection).
Mechanical fuel pumps:
These are driven normally by auxiliary belts or chains from the engine.
Electronic fuel pumps:
These are controlled by the electronic fuel injection system, these are normally more
reliable and have less reliability issues then their mechanical counterparts.

41
 FUEL FILTER:
The fuel filterhasthe job of makingsure no contaminants enterthe
fuel pump, fuel lines. Rust, dirt and paint can be present in the fuel
tank and will cause premature wear or damage to the vital parts of
the fuel system, also it can impact the engines efficiency to make
power.
 FUEL LINES:
Fuel istransportedfromthe fuel tankto the Injectorsandunusedfuel isreturnedtothe tankvia
the fuel lines.
 FUEL INJECTORS
(only in FUEL INJECTED SYSTEM):
These are not used incarburetedsystembut are in fuel
injectedmethod. The injectorsthroughwhichthe fuel is
sprayed are screwed, nozzle-first, into either the inlet
manifoldorthe cylinderheadandare angledsothatthe
spray of fuel is fired towards the inlet valve.
 CARBORATER:
 INTRODUCTION:
Carburetor is a device that blends air and fuel for an internal combustion engine in the
proper ratio for combustion.
 BASIC COMPONENTS:
The basic components are:
o Air horn
A velocity stack, orair horn is a trumpet-shaped device of differing lengths which is
fittedtothe air entryof an engine'sintake system, carburetor. Itisdesigned toallow
smooth and even entry of air at high
velocities into the intake tract.
o Venturi
Incarburetorasthe airflowsdownthe
pipe, it must pass through a narrow
kink in the middle, which makes it
speed up and causes its pressure to
fall. This kinked section is called
a Venturi.
o Float bowl
To ensure a ready mixture, the
carburetor has a "float chamber" (or
"bowl") thatcontainsa quantityof fuel at near-atmosphericpressure,readyforuse.
This reservoir is constantly provided with fuel supplied by a fuel pump.

42
o Choke
A choke valve is sometimes installed in the carburetorof internal combustion
engines.Itspurpose istorestrictthe flow ofair,therebyenrichingthefuel-airmixture
while starting the engine.
o Throttle valve
In a petrol/gasoline internal combustion engine, the throttle is a valve that directly
adjusts the amount of air entering the engine, indirectly controlling the charge
(fuel +air) burnedoneachcycle due to the fuel-injectororcarburetor maintaininga
relatively constant fuel/air ratio.
o Diaphragm chamber
A flexible diaphragm formsone side of the fuel chamber and is arranged so that as
fuel isdrawnoutintothe engine,the diaphragmisforcedinwardbyairpressure.The
diaphragm is connected to the needle valve and as it moves inward it opens the
needle valve toadmitmore fuel,thusreplenishingthe fuel asitis consumed.Asfuel
is replenished the diaphragm moves out due to fuel pressure and a small spring,
closing the needle valve. A balanced state is reached which creates a steady fuel
reservoir level, which remains constant in any orientation.
 WORKING OF CARBURETOR:
Thisdevice isusedtodrawairandfuel mixture intothe engine,thistransportedviatheintake
manifold. The device works by creating a
venture effect, air entering the device is at
pressure, when air travels along the
carburetor’s internal structure, it decreases in
pressure and speeds up, due to the pipe
narrowing.Thisnarrowingiswhatcausestheair
to speed up and drop in pressure (Bernoulli
effect).
Thisdrop-inpressure sucksfuel intothe air
froma fuel reservoir,creatingthe airandfuel
mixture forthe intake of the engine.The
reservoirisatair pressure andisconstantly
suppliedwithfuel viaafuel pump.A sensor

43
monitors airflowandpressure anddeliversthe airtofuel ratio,dependingonthe airflow
rates.
 CARBORATOR CIRCUITS:
There are many circuits in carburetors some of them are:
 FLOATING CIRCUIT.
 CHOKE CIRCUIT.
 IDLE SPEED CIRCUIT.
 LOW SPEED CIRCUIT.
 MAIN METERING CIRCUIT.
 FULL SPEED CIRCUIT.
 ACCELERATE CIRCUIT.
 THIS WILL BE DISCUSSED IN NEXT LAB.
Whenwe fill the fuel tank fill upit travelsdownthe fillertube andintothe tank.In the tank,there is
a sending unit which tells the gas gauge how much fuel is in the tank.
Fuel pumps mountedtothe engine use the motionof the engine topumpthe fuel,mostoftenbeing
driven by the camshaft, but sometimes the crankshaft.
Fuel filter cleans the fuel. It is critical to engine life and performance because fuel injectors and
carburetors have tiny openings which clog easily so filtering the fuel is a necessity.
A carburetor takes the fuel and mixes it with air without computer intervention. While simple in
operation,theytendtoneedfrequent tuningandrebuilding. Therefore, newercarshave done away
with carburetors in favor of fuel injection.
After this the fuel moves to engine for combustion and energy production.

44
 Table showing differencesbetween fuel injected and
carbureted fuel system:
Fuel injectedfuel system Carburetedfuel system
It has Fuel injector. It has carburetor.
Fuel injector could be pure mechanical or
electrical device
Carburetor is a pure mechanical device
The fuel consumption can be optimized to
suit the performance of the engine in fuel
injectors,whichincreasingthe efficiencyand
reducing the emissions.
in carburetor fuel consumption cannot be
optimized as much as fuel injector because
of its working phenomena.
inelectric control fuel injection, the air fuel
mixture isprepared after electronic devices
have made all calculation according to
engine requirement
involvesthe Venture effect taking place in a
narrow section, where increase in the air
speed result in a drop of pressure in the air
flow. Due to which fuel is sucked out of a
supply container through a small opening
The electronics used in the system will
calculate informationand constantly adjust.
no automatic or computerized adjustments
Do least longer then carburettor carburetorsdo lastlongerthanfuel injection
systems and are favored in motor sports.
One of the mainissuesisthatthese will cost
much more than a carburetor.
The carburetor is currently much less
expensive than the electronic fuel injection
systems.
Installationismore complicatedasituses an
electrical component and custom cylinder
head configuration.
Carburetors are also much simpler to install
than fuel injection systems, because there
are no electrical components.
of the electricfuel injector allows problems
to be diagnosed simply by connecting the
ECU to a diagnostic device or a computer.
in carburetors, a specific experience is
required for maintenance and tuning
because it must be done manually.
 Comments:
 We studied about basics and introductory knowledge of the fuel
system and its working.
 We learned about the different types and sub systems of fuel system.
 We get knowledgeaboutthe workingof different partsof fuel system.

45
LAB NO 9:
DEMONSTRATION OF THE CARBURETOR CIRCUITS
OF IC PETROL ENGINE.
 Objectives:
o To know detailed information about the carburetor circuits of IC engine.
o To know basics of operating, working and basic ideas of the carburetor circuits.
o To study the importance and different types of the carburetor circuits of petrol
engine.
 CARBURATER:
o INTRODUCTION:
Carburetor is a device that blends air and fuel for an internal combustion engine in the
proper ratio for combustion.
 COMPONENTS AND WORKINGOF CARBORATOR IS DISCUSSED IN
DETAIL HERE IS ONLY A TOUCH TO IT’s WORKING. MAINLY WE
WILL DISCUSS CARBORATOR CIRCUITS.
o WORKING OF CARBURETOR:
This device is used to draw
air and fuel mixture intothe
engine, this transported via
the intake manifold. The
device works by creating a
venture effect.
This drop-in pressure sucks
fuel into the air from a fuel
reservoir, creating the air
and fuel mixture for the
intake of the engine

46
 CARBURATER CIRCUITS:
 INTRODUCTION:
A seriesof passagewaysandunitsdesignedtoperforma specificfunction likeidlecircuit,full
power circuit, etc. OR these are circuits, or passages, forthe fuel toflow to the Venturi or
to other points in the carburetor bore.
These circuitsare necessary because differentengine operatingconditions require different
fuel-air mixtures.
 CARBURATOR CIRCUITS:
There are many circuits in carburetors some of them are:
 FLOAT CIRCUIT.
 CHOKE CIRCUIT.
 IDLE SPEED CIRCUIT.
 LOW SPEED CIRCUIT.
 MAIN METERING CIRCUIT.
 FULL SPEED CIRCUIT.
 ACCELERATE CIRCUIT.
 FLOAT CIRCUITS:
The floatcircuitisverysimple.Asthe fuel level increases,the floatrisesandeventuallycloses
a simple needle-and-seatthatpreventsadditional fuel fromenteringthe floatuntil the level
drops
The reservoirof fuel sitsinthischamberandfeedsall the othercircuitsinthe carburetor.It’s
important to remember that as the float level rises, the overall fuel curve becomes richer.
Accordingly, as the float level falls, the fuel curve becomes leaner.
The purpose of the floatsystemisthe maintenanceof the fuel atapredeterminedlevelinthe
carburetor always, under any operating conditions.
If the float is set too low, the engine will starve for fuel at higher speeds.
On the other hand, should the float be set too high, too much fuel will flow through the
carburetor circuits and the engine will load or a mileage complaint will be the result.

47
 CHOKE CIRCUITS:
The choke system is incorporated in the carburetor, for richening the mixture
ratio for cold and semi-warm engine starting and operation. The choke is
built into the carburetor air horn and consists of a round flat valve that has
almost the same circumference as the inside of the air horn. It is mounted
on a shaft that reaches from side to side in the air horn.
One end of the shaft extends out of the air horn and has a linkage at tached
to it for either manual or automatic operation.
By closing the choke valve and restricting the flow of air to the minimum in
the air horn, the mixture is richened for cold engine starting. As the engine
gradually becomes warm the choke valve is gradually opened.
After the engine reaches operating temperature the function of the choke
circuit ceases. On a carburetor having a hand or manually operated choke
system, this action is controlled by the operator of the vehicle.
With the automatic choke, it is just what the name implies, completely
automatic. Of course, the automatic choke can only operate properly when
it is clean and calibrated to specifications.

48
 IDLE SPEED CIRCUITS:
Fuel usedduringcurbidle andlow-speedoperationflowsthroughthe mainmeteringjetinto
the main well.
A connectingidle well intersectsthe mainwell.Anidle tube is installedinthe idle well.Fuel
travelsup the idle well andmixeswithair whichentersthroughthe idle air bleedlocatedin
the bowl cover.Atcurbidlethe fuel andairmixtureflowsdownthe idlechannelandisfurther
mixed or broken up by air entering the idle channel through the transfer slot above the
throttle plate. The idle system is equipped with a restrictor in the idle channel, located
betweenthetransferslotandthe idleport,whichlimitsthe maximumattainableidlemixture.
Asthe throttle platesare openedfurtherandengine speedincreases,the airflow throughthe
carburetor also increases. This increased air flow creates a vacuum in the Venturi and the
main metering system begins to discharge fuel.
 LOW SPEED CIRCUITS:
At idle and low speeds , the carburetorsystem suppliesenoughfuel to the engine to keep it
running.Whenthe vehiclegetsupto speed (usuallyabout24 mphor 15 mph) the idle circuit
kicks out of operation so that fuel is supplied by the main metering system. Also called the
"low-speed circuit."
As there are two throttle valves and two idle adjusting needles or screws,
care must be used in setting both the throttle screw and the idle needles.

49
If a smooth idle cannot be obtained by adjusting the needles, which should
be set one at a time, sometimes increasing the engine speed by setting the
throttle screw will help. Usually a 3/4 turn open on Stromberg is the idle
needle setting. Carter in most cases calls for 1 to 1-1/4 turns open.
Using a tachometer when possible to set the idle speed is a wise procedure,
as trying to guess the engine R.P.M. is very difficult. Most mechanics watch
the fan when setting engine idle speeds. This is a poor policy . The eye cannot
distinguish the change in the revolutions of the fan from as little as fifty
R.P.M. to as much as one hundred fifty R.P.M. Of course, on some engines
this does not matter but on cars equipped with automatic transmissions it
will positively make a difference in the automatic shifting of the gears. Also,
it is impossible to know at what height the vacuum is in the manifold by using
the "guess" method.
During low speed operation, the throttle plate moves exposing the transfer slot and fuel
begins to flow through the transfer slot as well as the idle port.
 MAIN METERING CIRCUITS:
As the throttle valve(s) continue opening, the air flow through the carburetor increases and
createsa low-pressureareainthe Venturi.Thislow pressurecausesfuel toflowfromthe fuel
bowl through the main jets and into the main wells.Air from the main air bleedmixes with
the fuel throughholesinthe sidesofmainwelltube.The mixtureisthendrawnfromthe main
well tube and discharged through the Venturi nozzle. As air flow through the carburetor
increases, the amount of air/fuel mixture discharged also increases.

50
On feedbackcarburetors,amixture control solenoidorvacuummodulatorisusedtocontrol
the air/fuel mixture.Thiscanbe done by regulatingthe amountof air bleedorfuel (insome
casesbothare controlled) available tothe maincircuit.The solenoidormodulatoractuatesa
steppedortaperedneedle inthe airbleedor mainjetsto do this.By controllingthe amount
of fuel released or air bled, the solenoid/modulator regulates the total air/fuel mixture.
 HIGH SPEED CIRCUITS:
Having two high speed systems operating together in a dual carburetor,
means proper balance must be maintained between them, for all hi gh sped
engine operation. To insure this proper balance and operation, main
metering jets should be installed in matched sets (also metering rods on
Carter) and main nozzles should be carefully examined for wear or damage.

51
On Carter Dual carburetors, the mechanism that operates the metering rods
and anti-percolating valves should be thoroughly checked for correct
operation. Any changes in the high-speed system must be the same for each
half of the carburetor. One half cannot be changed without the other and
still have correct carburetor and engine operation.
 ACCELARATE CIRCUITS:
Whenthe throttle platesare openedsuddenly,the airflow throughthe carburetorresponds
almost immediately. However, there is a brief time interval or lag before the additional fuel
can move into the system and maintain the desired air/fuel ratio. The accelerating pump
provides a measured amount of fuel necessary to insure smooth engine operation upon
acceleration.
Whenthe throttle isopened,the pumpplungeractuates the pumppistonordiaphragm.This
closesthe intake checkvalve,forcingfuel outthroughthe dischargepassage andoutthrough
the pump jets. At higher speeds, pump discharge is no longer necessary to insure smooth
acceleration. The external pump linkage is so constructed that less pump stroke is available
when the throttle is in the higher speeds positions.

52
As the throttle isclosed,the pumppistonordiaphragmreturnstoitsrest positionandfuel is
drawn into the pump well as the check valve opens.
 Comments:
 We studied about basics and introductory knowledgeof thecircuits of
carburetor.
 We learned about the different types in detail.
 We get knowledgeaboutthe working of differenttypes of circuits and
its effects and importance.

53
LAB NO 10:
DEMONSTRATION OF THE TRANSMISSION SYSTEM
OF CAR.
 Objectives:
o To know detailed information about the transmission system of car.
o To know basics of operating, working and basic ideas of the main parts of
transmission system of car.
o To know about the detail working of different parts of transmission system.
o To study the importance of all the parts.
 TRANSMISSION SYSTEM:
The mechanismthattransmitsthe powerdevelopedbythe engine of.automobile tothe engine
to the driving wheels is called the. TRANSMISSION SYSTEM (or POWER TRAIN).
 PURPOSE OF TRANNSMISSION SYSTEM:
Main purposes are:
o To provide for disconnecting the engine from the driving wheels.
o When the engine isrunning,to enable the connectionto the drivingwheelstobe made
smoothly and without shock.
o Speed reduction b/w engine and the drive wheels in different ratios
o To enable power transmission at varied angles and varied lengths.
o To drive the driving wheel at different speeds when required.
o To enable diversion of power flow at right angle.
 MAIN COMPONENTS:
Main components are:
o Clutch
o Gear box
o Drive shaft
o Differential

54
 GEAR RATIO:
Input speed relative to the output speed.
𝐺. 𝑅. =
𝑁𝑜. 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑜𝑛 𝑑𝑟𝑖𝑣𝑒𝑛 𝐺𝑒𝑎𝑟
𝑁𝑜. 𝑜𝑓 𝑡𝑒𝑒𝑡ℎ 𝑜𝑛 𝑑𝑟𝑖𝑣𝑒𝑟 𝐺𝑒𝑎𝑟
.
 SOME TYPICAL VALUES FOR GEAR RATIO are given
below:
1st Gear - 2.5: 1
2nd Gear - 1.88: 1
3rd Gear - 1.46: 1
4th Gear - 1: 1
Reverse Gear - 2.59: 1
 TYPES OF GEAR BOX: Two types
o DOG CLUTCH MECHANISM:
A dogclutch isa type of clutch thatcouplestworotatingshaftsor otherrotating
componentsnotby friction butby interference.
The two parts of the clutchare designedsuchthatone will pushthe other,causingboth
to rotate at the same speedandwill neverslip.
Dog clutchesare usedwhere slipisundesirable and/orthe clutchisnot usedto
control torque.Withoutslippage,dogclutchesare notaffectedbywearinthe same way
that frictionclutchesare.
o SLIDING MESH MECHANISM:
A sliding-meshgearbox is similar to a constant-mesh gearbox, but differs in the way the
individual gears are engaged.
In the sliding-meshgearbox, the individual gear ratio is chosen by sliding the selected
gearwheel axially along the splined main output shaft until it meshes fully with the
corresponding lay shaft gear cluster.
The sliding main shaft gearwheels and their corresponding lay-shaft gearwheel clusters
have to be of the spur straight-toothform, sothat whenengagedthere isno side thrust
unlike helical-cut teeth.
 COMPONENTS ARE EXPLAINED BELLOW INDIVISUALLY.

55
 CLUTCH:
 INTRODUCTION:
A clutchis a mechanical device which engages and disengages power transmission
especially from driving shaft to drive shaft
o Fly wheel
The clutch flywheel is connected directly to the engine crankshaft and, therefore,
spins with the engine’s motions.
o The pressure plates
Bolted to the clutch flywheel is the second major component: the clutch pressure
plate. The spring-loadedpressure plate has two jobs: to hold the clutch assembly
together and to release tension that allows the assembly to rotate freely.
o Clutch disk
Between the flywheel and the pressure plate is the clutch disc. The clutch disc has
friction surfaces like a brake pad on both sides that make or break contact with the
metal flywheel and pressure plate surfaces, allowing for smooth engagement and
disengagement.
o Clutch bearing and release system
These components work together simultaneously and are key to the engaging and
disengaging process. They are the release, or throw-out bearing, and the release
system itself.
The clutch release bearing is connected to one end of the hydraulic (or clutch fork
mechanism) andridesonthe diaphragmspringof the clutch.Dependingonthe type
of release system, the throw-outbearingeitherpullsorpushesonthe pressure plate
diaphragmspringto engage or disengage the pressure plate'sgriponthe clutchdisc
when the clutch pedal is depressed and released.

56
 WORKING OF CLUTCH:
The clutch is based on the friction. When two friction surfaces are brought intocontact and
pressed, then theyare united due to friction force between them. This is the basic principle
of clutch. The frictionbetweenthese twosurfacesdependsonthe area of surface,pressure
applied upon them and the friction material between them.
The driving member of a clutch is the flywheel mounted on the engine crankshaft and the
driven member is pressure plate mounted on the transmission shaft. Some friction plates,
sometimes known as clutch plates are kept between these two members. This whole
assembly is known as the clutch.
While the clutchisengaged,everythingspinsasone unit.Whenyoupressthe clutchpedal in,
the clutch assembly is disengaged. The shaft and clutch disc spin independently of the
flywheel and pressure plate.
An automobile clutch has following function:
1.It can be disengaged. This allows engine cranking and permits the
engine to run without delivering power to the transmission.
2. While disengaging it permits the driver to shift the transmission
into various gear according to operating condition.
3. While engaging, the clutch slips momentarily. this provides smooth
engagement and lessens the shock on gears, shaft and other parts
of automobile.
4. While engaging, the clutch transmits the power to the wheel
without slipping, in idea condition.

57
 GEAR BOX:
 INTRODUCTION:
An automobile requireshightorque whenclimbinghillsandwhenstarting,eventhough
theyare performedatlow speeds.Onotherhand,whenrunningat highspeedsonlevel
roads,high torque isnot requiredbecause of momentum. Sorequirementof adevice is
occur, whichcanchange the vehicle’storqueanditsspeedaccordingtoroadconditionor
when the driver need. This device is known as transmission box.
o Counter shaft/Lay shaft
Countershaft isa shaft whichconnectswith the clutchshaft directly.Itcontainsthe
gearwhichconnectsittothe clutchshaftaswell asthe mainshaft.Itmaybe runruns
at the engine speed or at lower than engine speed according to gear ratio.
o Main shaft/Output shaft
It isthe shaftwhichrunsat the vehicle speed.Itcarriespowerformthe countershaft
by use of gearsand according to the gear ratio, itruns at differentspeedandtorque
compares to counter shaft. One end of this shaft is connecting with the universal
shaft.
o Gears
Gearsare usedtotransmitthe powerformoneshafttoanother.Theyare mostuseful
componentof transmissionbox because the variationistorque of countershaft and
mainshaftis dependingonthe gearratio.The gearratioisthe ratioof thedrivengear
teethtothe drivinggearteeth.If gearratio islarge thanone,the mainshaftrevolves
at lowerspeedthanthe countershaftandthe torque of the mainshaftishigherthan
the countershaft.Onotherhandif the gearratioislessthanone,thanthe mainshaft
revolves at higher speed than the counter shaft and the torque of the main shaft is
lowerthanthe countershaft.A small car gear box containsfourspeedgearratioand
one reverse gear ratio.
o Bearing
Wheneverthe rotarymotion,bearingsare required tosupportthe revolvingpartand
reduce the friction.Inthe gearbox bothcounterandmainshaftare supportedbythe
bearing.
o Synchronizer
Modern cars use synchronizers to avoid the
need for double-clutching. A synchronizer, or
"synchro," lets the collar and gear synchronize
theirspeedswhilethey're alreadyincontactbut
before the dog teeth engage. Each
manufacturer'ssynchroisslightlydifferentthan
the others, but the basic idea is the same. For
instance,acone onone gear will fitintoacone-
shaped depression on the collar.

58
The gear and collarsynchronize theirspeedsthankstothe frictionbetweenthe cone
andcollar.Thenthe outerpartof the collarmovesoutof the waysothatthe gearcan
be engaged by the dog teeth.
 WORKING OF GEARBOX:
In a gear box, the counter shaft is mashed to the clutch with a use of a
couple of gear. So, the counter shaft is always in running condition. When
the counter shaft is bringing in contact with the main shaft by use of
meshing gears, the main shaft starts to rotate according to the gear ratio.
When want to change the gear ratio, simply press the clutch pedal which
disconnect the counter shaft with engine and change connect the main
shaft with counter shaft by another gear ratio by use of gearshift lever.
The working of differentgearboxes is:

59
 SLIDE MESHING GEARBOX:
Whenwe talkabout typesof gearbox,thisisone of the oldesttype.Itthis,gearsonthe main
shaft are moved right or left for meshing them withappropriate gears on the counter shaft
for obtaining different speed. This type of gear box derives its name from the fact that the
gearsare meshedbysliding.One disadvantage of itisthat,special skillisrequired tooperate
this gear box.
 DOG CLUTCH MECHANISM:
This is one of the famous type used in twenty century. It this gearbox, all the gears are in
constantmeshwitheachotherall the time.The gearsonthemainshaftrotatesfreelywithout
rotating the main shaft. Constant mesh gear box consists two dog clutches. These clutches
are provided on the main shaft, one between the clutch gear and the second gear and the
otherbetweenthe firstgearandreverse gear.Whenthe leftside dogclutchismade to slide

60
left by means of gearshift lever, it meshes with the clutch gear and the vehicle runs on top
speed. If this clutch slide right and mesh with second gear, the vehicle runs on second gear
speed.Soinconstant meshgearbox we can change the gearratio by shiftingthe dogclutch.
Thistype of gear box ismore popularthan slidingmeshbecause itcreateslow noiseandless
wear of gears.
 SYNCHROMESH GEARBOX:
One big problemoccurin constantmeshgear box is that whenthe driverengage the dog clutch,
the mainshaftandgearto be meshedrunningatdifferentspeed.Sowhenengagethisgearcause
wear and tear of dog clutch. This problem is solved by a synchromesh gear box. Thisgear box is
same as the constant mesh gear box except dog clutch is replaced by synchromesh devices.
Synchromeshgeardevicesworksonthe principle thattwo gearsto be engagedare firstbrought
into frictional contact which equalizes their speed after which they are engaged readily and
smoothly.The synchromeshlookslike asthe cone clutchwhere the outersurface of cone consist
the frictional surface. This type of gear box is widely used in automobile.

61
 DRIVE SHAFT (U JIONT):
 INTRODUCTION:
A universal joint (universalcoupling, U-joint,Cardanjoint,SpicerorHardy Spicerjoint,or
Hooke's joint) is a jointor coupling in a rigid rod whose axis are inclined to each other,
and is commonly used in shafts that transmit rotary motion.
 BASIC COMPONENTS TERMINOLOGIES:

62
 DIFFERENTIAL:
 INTRODUCTION:
A differentialis a gear trainwith three shafts that has the property that the angular
velocity of one shaft is the average of the angular velocities of the others, or a fixed
multiple of that average.
o Pinon gear
Piniongearis a smaller gearin a pair of meshing gears,oris
the cylindrical gear used in a rack and pinion mechanism.
o Bevel ring gear
Within the gearbox of an vehicle,the function of the ring
gear is to transport the torque coming from the secondary
shaft to the differential. This is a crucial component, since
exactlythe transmissionof the engine torque tothe wheels
make the automobile move.
o Side gear
These are two in number, revolving around sun gear.
o Sun gear
A planetarygearset(alsoknownasan epicyclicgearset) consistsof asungearinthe
center, planet gears that rotate around the sun gear, a planet carrier that connects
the planet gears, and a ring gear on the outside that meshes with the planet gears
o Differential case
This is the outer cover around the whole system.

63
 WORKING OF DIFFERENTIAL:

64
Thisdevice isusedtodrawairandfuel mixture intothe engine,this transportedviatheintake
manifold.The deviceworksbycreatingaventureeffect,airenteringthe deviceisatpressure,
whenairtravelsalongthe carburetor’sinternalstructure,itdecreasesinpressureandspeeds
up, due to the pipe narrowing.This narrowingiswhatcausesthe airto speedupanddrop in
pressure (Bernoulli effect).
Thisdrop-inpressure sucksfuel intothe airfroma fuel reservoir,creatingthe airandfuel
mixture forthe intake of the engine.The reservoirisat air pressure and isconstantly
suppliedwithfuel viaafuel pump.A sensormonitorsairflowandpressure anddeliversthe
air to fuel ratio,dependingonthe airflow rates.
LAB NO 11:
DEMONSTRATION OF THE AUTOMOBILE BRAKES
SYSTEM.
 Objectives:
o To know detailed information about the braking system of automobile.
o To know basics of operating, working and basic ideas of the braking system of
automobile.
o To study the configuration and different types of the braking system.
o To study the difference importance and working of front and rear brakes system.

65
 Braking system:
A brake is a mechanical device that inhibits motion by absorbing energy from a
moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to
prevent its motion, most often accomplished by means of friction.
TYPES OF BRAKING SYSTEM: Two types
o SERVICE BRAKES (HYDRAULIC BRAKES):
The servicebrake is the systemthat is designed to slow down the vehicle and bring
it to a stop. The hydraulic brake is an arrangement of braking mechanism which
uses brake fluid to transfer pressure from the controlling mechanism to the
braking mechanism.
o PARKING BRAKE (MECHANICAL BRAKES):
The parking brake is a latching brake usually used to keep the vehicle stationary.
It is sometimes also used to prevent a vehicle from rolling when the operator
needs both feet to operate the clutch and throttle pedals.
 SERVICE BRAKES OR HYDRAULIC BRAKES:
The hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically
containing ethers or diethylene glycol, to transfer pressure from the controlling to the braking
mechanism.
TYPES OF CONFIGURATION IN HYDRAULIC BRAKES: Two types
o DAIGNOL SPLIT:
It is a dual-circuit braking system in which each circuit brakes one front wheel and the
diagonally opposite rear wheel, so that in case of failure of one circuit reasonably
balanced braking can be achieved
WORKING
The right front and left rear are served by one actuating piston while the left front and
the right rear are served, exclusively, by a second actuating piston. If either circuit fails,
the other,
with at least
one front
wheel braking
(the front
brakes
provide most
of the braking

66
force, due to weight transfer), remains intact to stop the mechanically damaged vehicle.
o FRONT/REAR SPLIT:A compression-ignition engine is an internal combustion
engine in which ignition of the fuel that has been injected into the combustion
chamber is caused by the high temperature which a gas achieves when greatly
compressed.
WORKING
Front / Rear hydraulic split also called axle by axle, vertical, and sometimes “black and
white”. The type of split is only significant in the event of a hydraulic system failure. In a
diagonal split system, one brake line is run to each rear brake and one to each front
brake.
 BASIC PARTS OF BRAKING SYSTEM:
Are given below:
 BRAKE PEDAL:
Brake pedal is a pedal used by the driver of a vehicle to
operate the brakes.
 BRAKE FLUIDS:
Brake fluid is a type of hydraulic fluid used in hydraulic brake and hydraulic clutch
applications in automobiles. It is used to transfer force into pressure, and to
amplify braking force.
 POWER BRAKE BOOSTER:
The power brake booster is mounted on the firewall directly
behindthe mastercylinderand isdirectlyconnectedwiththe
brake pedal. Its purpose is to amplify the available foot
pressure appliedtothe brake pedalsothatthe amountof foot
pressure requiredtostopeventhe largestvehicleisminimal.

67
 MASTER CYLENDER:
The master cylinder is a control device that converts
non-hydraulic pressure (commonly from a driver's
foot) into hydraulic pressure. This device
controls slave cylinders located at the other end of
the hydraulic system.
 HYDRAULIC LINES/CIRCUITS:
A circuit whose operation is analogous to that of an
electric circuit except that electric currents are replaced by currents of fluids, as in
a hydraulic control. It’s rigid.
 BRAKE HOSE:
Brake hoses transfer the brake fluid from the master cylinder (brake fluid reservoir) to
the brake calipers or wheel cylinders. It’s flexible.
 ANTI-LOCK BRAKEING SYSTEM:v
An anti-lock braking system or anti-skid braking
system(ABS) is an automobile safety system that
allows the wheels on a motor vehicle to maintain
tractive contact with the road surface according
to driver inputs while braking, preventing the
wheels from locking up (ceasing rotation) and
avoiding uncontrolled skidding.
 FRONT DISK BRAKES:
 INTRODUCTION:
A disc brake is a type of brake that uses calipers to squeeze pairs of pads against a disc in
order to create friction that retards the rotation of a shaft, such as a vehicle axle, either to
reduce its rotational speed or to hold it stationary.
 BASIC COMPONENTS:
o Rotor
The brake disc is the component of a disc brake against which the brake pads are applied. The
material is typically iron, a form of cast iron.
o Caliper
The brake caliperistheassemblywhichhousesthebrake padsandpistons.The pistonsare usually
made of plastic, aluminum or chrome-plated steel.
There are two types of calipers: floating calipers and fixed calipers.
A floating caliper can compress itself and contains only one piston.
A fixed caliper doesn’t move; so, it contains two pistons located on each side of the rotor.

68
o Brake pads
Brake pads are a componentof discbrakes usedinautomotive andotherapplications.Brakepads
are steel backingplateswithfrictionmaterialboundtothe surface thatfacesthediscbrake rotor.
 WORKING:
Discbrakesare responsibleforstoppingyourvehicle.Brake padsare locatedoneachside of the rotor
and are actuallypushedagainstthe rotor to stop the wheel andtherebystopyour vehicle.The pads
create the necessary friction to stop the vehicle. The caliper is a device located over the top of the
rotor and containsbothbrake pads.The rotor isan irondiscconnectedtothe tire’shub.Rotorswork
hand-in-hand with brake pads to stop your vehicle. This friction enables your vehicle to stop while
alsocreatinga tremendousamountof heat.Rotorsconsistof twoirondiscsconnectedbyribs.These
ribsallowthe hotairto ventfromthe rotor andalsodirectair into cool the rotor.It isveryimportant
for rotors to be able to dissipate the large amount of heat so they can work properly.
 REAR DRUM BRAKES:
 INTRODUCTION:
A drum brake is a brake that uses friction causedby a setof shoes or pads that press outward
against a rotating cylinder-shaped part called a brake drum.
 BASIC COMPONENTS:
o Drum
The brake drumis generallymade of aspecial type of castironthat isheat-conductiveandwear-
resistant. It rotates with the wheel and axle.
o Brake shoes
Brake shoes are typically made of two pieces of steel welded together. The friction material is
either riveted to the lining table or attached with adhesive.The crescent-shaped piece is called
the Web and contains holes and slots in different shapes for return springs.
o Wheel Cylinder

69
Wheel cylinder operates the brake on each wheel. Two pistons operate the shoes, one at each
end of the wheel cylinder. The leading shoe (closestto the front of the vehicle) is known as the
primary shoe other is the secondary shoe.
o Self-Adjustment System
As the brake works, the shoes must travel a greater distance to reach the drum. When the
distance reachesacertainpoint,aself-adjustingmechanismautomaticallyreactsbyadjustingthe
rest position of the shoes so that they are closer to the drum.
o Adjustable springs
Drum brakeshave returnspringstoreturnthe shoestoarestposition.The shoesreturntoafully
retracted or rest position when the master cylinder releases pressure to the wheel cylinder.
 WORKING:
A drum brake system consists of hydraulic wheel cylinders, brake shoes and a brake drum.
When the brake pedal is applied the two curved brake shoes, it’s forced by hydraulic wheel
cylinders against the inner surface of a rotating brake drum. The result of this contact
produces friction which enables the vehicle to slow down or stop.

70
 Table showing differencesbetween drum and disk
brakes:
Drum brake Disk brake
less cooling better cooling
less efficiency more efficiency
since less cooling tamp change is more temp change is less
initial pressure is less initial pressure is more
Brake fade so effectiveness is less. brake fade occurs slowly
Water gets collected in the drum. The water does not get collect inside the
drum.

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