A

REPORT ON

STUDENTS’ WORK EXPERIENCE PROGRAMME (SWEP)

UNDERTAKEN AT THE

UNIVERSITY OF AGRICULTURE, ABEOKUTA

BY

ODUMOSU TAIWO OLAWALE

MATRIC NUMBER: 070635

OF

THE DEPARTMENT OF

ELECTRICAL/ELECTRONICS ENGINEERING

COLLEGE OF ENGINEERING

UNIVERSITY OF AGRICULTURE, ABEOKUTA

OGUN STATE

APRIL 2009

CERTIFICATION

This is to certify that this project “A TECHNICAL REPORT BASED ON STUDENT WORK

EXPERINENCE PROGRAMME” was carried out by me: ODUMOSU TAIWO OLAWALE with

matriculation number: 070635 of the, DEPARTMENT OF ELECTRICAL/ELECTRONICS

ENGINEERING, UNIVERSITY OF AGRICULTURE ABEOKUTA, OGUN STATE and was thoroughly

supervised by

________________ __________________

Engr. G.A. Bolaji Engr. I. A. Adejumobi

SWEP Co-ordinator Head of Department

DEDICATION

This project is dedicated firstly, to ALMIGHTY GOD for sparing my life till today. My thanks also

go to my loving, caring and active parents Mr. and Mrs. Odumosu, the best brother Kehinde

Odumosu and my loving sisters. Special thanks goes to my loving mother who goes to any

length to see that I get all that is needed in my academic endeavour. Also my sincere

appreciation goes to Mr and Mrs Fayemi, Mrs Odumosu-Ayanu and Mr Laide Osijonwo and my

friends Paul Ogomigo, Aloba Kayode, Seyi Okuselu and Ologun Korede. Also Adeola

Majekodunmi, Dairo Fajuyitan thanks for your never ending support and for being there for me

always and for those who believe in knowledge.

ACKNOWLEDGEMENT

I sincerely show my appreciation to the ALMIGHTY GOD who gave me the opportunity to

participate in this year’s (SWEP) programme. While my unlimited gratitude goes to my loving

caring and active parents for their financial support towards my academic pursuit in this great

institution, what I can say is that “God rewards those that seek progress for others”.

My appreciation is incomplete without thanking the Management of the different units visited

during the SWEP for the knowledge I acquired during the period of working with them,

I also thank the authority of the University of Agriculture Abeokuta especially those in the

Department of Electrical/ Electronics. The H.O.D, Engr.I.A Adejumobi and the other staff, I

thank them for the knowledge they imparted on me.

Also my indebtedness gratitude goes to all 200L engineering students; I thank you all for your

encouragement. You are the best one can have around. I love you all.

Lastly my appreciation goes to my friends and course Mates: Paul Ogomigo, Seyi Okuselu,

Korede Ologun, Aloba Kayode and the others. I pray that you will all succeed in your academic

endeavor.

ABSTRACT

This report covers essentially the knowledge and experience acquired during the course of

training at various units of the SWEP programme such as the ELECTRICAL/ELECTRONICS

LABORATORY, THE TRACTOR UNIT, WORKS AND SERVICES, THE CENTRAL WORKSHOP, and the

PHYSICAL PLANNING UNIT.

TABLE OF CONTENT

TITLE PAGE

CERTIFICATION

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

INTRODUCTION

CHAPTER 1 - TRACTOR UNIT

1.1.0 - INTRODUCTION TO TRACTOR UNIT

1.1.1 - SAFETY PRECAUTIONS

Human safety Machine Safety Care of tools

1.1.2 - INTRODUCTION TO WORKSHOP TOOLS

Spanners Pliers Chisels Screwdrivers Hammer Socket wrench and sockets Toolbox

1.1.3 - MAINTENANCE AND SERVICING OF MACHINE TOOLS

Types of Maintenance Engine oil

Filters

1.2.1 - NUTS AND BOLTS

Bolts Nuts Studs

1.2.2 - WASHERS

Spring Washer Plain Washer Fibre Washer

1.2.3 - BEARINGS

Roller Bearing Tapered Roller Bearing Ball Bearing Plain Bearing Needle Bearing

1.3.1 - METHODS OF TRANSMITTING MOTION IN A MACHINE

Belt and Pulley Chain and Sprocket Shaft and Splines Keys and Keyways Gears

1.3.2 - IDENTIFICATION OF ENGINES

Type of Fuel used Method of Cooling Number of Cylinder Stroke

1.3.3 - FOUR STROKE ENGINE CYCLE

Induction Stroke Compression Stroke Power Stroke Exhaust Stroke

1.4.1 - SYSTEMS ON A TRACTOR / AUTOMOBILE

Ignition System Fueling System Lubrication System Cooling System Electrical System Transmission System Steering System Braking System Hydraulic System

CHAPTER 2 - PHYSICAL PLANNING UNIT

CHAPTER 3 - ELECTRICAL / ELECTRONICS LABORATORY

CHAPTER 4 - CENTRAL WORKSHOP

4.1.1 - SAFETY IN THE WROKSHOP

4.2.1 - BENCHWORK / FITTING SECTION

4.3.1 - MACHINE SECTION

4.4.1 - WELDING SECTION

CHAPTER 5 - WORKS AND SERVICES

INTRODUCTION

The Students’ Work Experience Programme (SWEP) was set up with a view of giving training to students

so that they would be able to appreciate and relate the practical knowledge to the theoretical knowledge

which they have gone through during the course of study in their institution.

Also it exposes us as students to various conditions and guides that are required of us to perform our

duties in a formal way as we were posted to various locations to receive training which will assist in

acquiring knowledge and experience.

Finally, as an individual, the SWEP programme has given me the ample opportunity to learn so much

about the ethics of the engineering profession and mystery.

CHAPTER ONE

TRACTOR UNIT

1.1.O INTRODUCTION TO TRACTOR UNIT

A tractor is a self-powered work vehicle, designed for pulling or pushing special machinery or heavy loads over land. They are widely used in agriculture, building and road constructions, as well as for specialized service in industrial plants, railway freight stations, and docks. Applications also include snowplows and bulldozers.

TYPES OF TRACTORS

There are two types of tractors:

Wheeled tractors Crawler (track-laying) tractors

Wheeled tractors generally have two large rear wheels with pneumatic tyres or ground-gripping metal lugs; they operate much like an automobile with a gearshift drive. Power is usually provided by a diesel or a gasoline engine.

Crawler tractors are used for heavy pulling or pushing or for adverse terrain conditions. These tractors move on heavy, metal tracks that form a loop around large geared wheels; the wheels drive the metal tracks, and the tracks distribute the weight over a wide area. Crawler tractors are well adapted to rough terrain, rice-land cultivation, and tillage operations in loose and sandy soil. Lighter crawler tractors are frequently used for work on the sides of steep hills where they are less likely to overturn than wheeled tractors.

USES OF A TRACTOR

Farm tractors are used for plowing, cultivating, grading, or cutting, or for driving various agricultural machines (see Agricultural Machinery). The use of tractors has revolutionized agriculture. The power capability of the modern tractor has led to higher productivity with a significantly reduced workforce. Early agricultural tractors were lumbering, heavy steam-engine vehicles moving on spiked or cleated metal wheels. The engine, in addition to providing pulling power, also drives a number of power take-off (PTO) shafts that can be used to operate accessory machinery. Large or special purpose tractors may also have a hydraulic power system that can be used to deploy or move various attachments such as bulldozer blades or snowplows. In recent years there has been a trend from four-wheeled to three-wheeled vehicles, where a single, central front wheel can operate more successfully among crops planted or cultivated in rows.

Crawler tractors are employed extensively in the building industry, where cranes or hoists are usually mounted directly on the tractor frame. The small, comparatively low-powered electric tractor, deriving its motor power from a storage battery, has been put to many specialized uses, such as handling freight

and express material at railroad stations and steamship piers, and shifting material in large industrial plants and warehouses. Electric tractors are usually equipped with rubber-tired wheels. Other specialized tractors have been designed for numerous applications. For example, specialized tractors are used in mining operations, for many different forms of earth moving, and in the steel industry, where overhead tractors operate on tracks.

1.1.1 SAFETY PRECAUTIONS

There are three levels of safety. They are:

Human safety Machine safety Safety of tools

HUMAN SAFETY: The personal safety rules include the following;

Consciousness of personal safety and that of others working with you.

Be conscious of what you are doing and the consequence of your actions.

Do not wear loose garments around moving parts of a machine.

Keeping of long nails is prohibited.

Put on covered shoes or protective shoes to prevent legs from been hurt in the event of a tool

falling down.

Always wipe oil or grease from the floor surface to prevent a slip which can cause fracture of

some body parts.

Do not panic, always have self confidence in yourself.

Tomfooling and horse-play should be avoided in the workshop.

MACHINE SAFETY: These rules must be observed when operating machines in the workshop. Machine and industrial safety rules include;

Do not start any machine without properly identifying its ON and OFF button.

Machines must not be operated without having the technical know-how.

Spare parts should be kept clean during servicing.

Dismantled components must be kept in an orderly manner and in a well cleaned compartment.

Oil-spillage must be avoided in the workshop so as to erase the havoc of slippery.

Do not rest against or lie under suspended heavy duty machine.

Always do the routine check on machines before operation is carried out.

Always watch safety signs when in workshop.

CARE OF TOOLS: Tools are indispensable in engineering operations, so they must be well handle to avoid damage, loss and injury. The following are safety rules pertinent to care for tools;

At the end of each day’s work, the tools should be cleaned and properly stored.

Tools must be properly placed on the workbench to prevent them from falling; it could cause

injuries or get damaged.

Always use the right tools for the right job.

Do not hammer on a spanner when trying to loosen a bolt or nut instead put penetrating oil, the

spanner could get damaged if hammered.

Do not place tools on top of each other.

1.1.2 INTRODUCTION TO WORKSHOP TOOLS

Workshop tools are used in the production of machine parts and components. The following are examples of workshop tools:

SPANNERS: They are used to loosen and tighten mechanical fasteners. There are various types of spanners and they vary in sizes from 12-13, 15-17, 19-21 etc. Some examples are

o Combination spanners- is a double ended tool with one open end and the other like a ring. Both ends fit the same size of a bolt or nut.

o Flat spanner- is a one piece spanner with a u-shaped opening that grips two opposite

faces of a bolt or nut. It has a different size opening at each end.

o Ring spanner- has two enclosed openings that grip the faces of the bolt or nut. It hexagonal in shape at its ends.

PLIERS: are hand tools used to hold objects firmly for cutting and bending tough materials such as wires. There are different types

o Gripping pliers: it adjusts automatically to the size of any object within its range.

CHISELS: they are used to cut cold metals. Types are flat chisel, cross cut chisel, half round chisel etc.

SCREWDRIVERS: they are used to drive screws into machine parts. Types of screwdrivers are flat and star.

HAMMER: the hammer consists of a hardened and tempered steel head firmly fixed on a wooden handle. It is used to strike metals or drive nails into wood.

SOCKET WRENCH AND SOCKETS: a long handled wrench with interchangeable heads that fits over nuts and bolts of various sizes.

TOOLBOX: The toolbox contains all the tools (hand tools). A standard toolbox should contain at least 30-50 tools.

Other tools are the Allen key, hacksaw

The Allen key

1.1.3 MAINTENANCE AND SERVICING MACHINE TOOLS

There are various types of maintenance. They are

o Periodical maintenance

o Seasonal maintenance

o Predictive maintenance

o Damage maintenance

o Preventive maintenance

o Daily maintenance

ENGINE OIL

In servicing of machine tools, oil is used to service some machine parts. The viscosity of the oil determines its grade. It is graded in SAE numbers. E.g. SAE 40, SAE 30, SAE 50 etc. The higher the grade number, the thicker the oil. The different types of oils are.

o Petrol engine oil

o Diesel engine oil

o Gear oil

o Steering oil

o Hydraulic oil

o Axle oil

FILTERS: Filters are used to filter oil and remove or prevent dirt from entering the machine. Types are: fuel filter, engine oil filter, hydraulic filter, dry air filter, wet air filter.

1.2.1 NUTS AND BOLTS

BOLTS: A bolt is a hexagonal shaft having external threading at one end. They are used majorly to hold machine parts together. They vary in size from very small to large sizes.

There is a special type of bolt called the u-bolt. It is used to hold axles.

NUTS: A nut is a hexagonal shaft having internal threading. It is used with bolts to fasten mechanical parts together. They vary in size.

STUDS: A stud is a shaft that has threading at both ends of its length. They are used to hold components at both ends together with a bolt.

1.2.2 WASHERS

A Washer is a thin plate with a hole that is normally used to distribute load of a threaded fastener. Washers have two general purposes:

o They are used as spacers to achieve a very good tightening.

o To achieve air tight surfaces which prevent fuel leakage.

There are three types of washers:

o Spring washer

o Plain washer

o Fibre washer: this is made of brass and copper. It is used along fuel lines.

Types of washers

1.2.3 BEARINGS

Bearings are components of a machine or machinery that support the rotating parts in the machines.

Every revolving shaft must have bearing supporting their rotational motion. Bearing (mechanics),

mechanical device for decreasing friction in a machine in which a moving part bears—that is, slides or

rolls while exerting force—on another part. Usually in a bearing the support must allow the moving part

one type of motion, for example, rotation, while preventing it from moving in any other way, for

example, sidewise. The commonest bearings are found at the rigid supports of rotating shafts where

friction is the greatest.

TYPES OF BEARING

The different types of bearings are:

a) Roller bearing; the roller bearing has the same diameter both for it top and the base and it is

being guarded by a Cole. A roller bearing is similar to a ball bearing, except that small steel

cylinders, or rollers, are substituted for the balls. A needle bearing is a roller bearing in which

the rollers are extremely long and thin. An ordinary roller bearing may have 20 rollers, each

twice as long as it is wide; whereas a needle bearing may have 100 needles, each 10 times as

long as it is wide. Needle bearings are particularly useful when space is limited.

b) Tapered roller bearing; The diameter of the top is more than that of its bottom. It is used when

the revolving shaft is expected to speed and carry load. It is usually found at the front wheels of

a vehicle. The position where the wheels are fixed is called a hub. A hub is housing or a unit that

allows component to rotate. All hubs must have two tapered roller bearings and shaft.

c) Ball bearing; it has balls as bearings; example is the life grease ball bearing. It is usually found in

machines where large amount of load is to be carried. It can be found at the rear wheel of a

tractor. In a ball bearing, a number of balls rotate freely between an inner ring, which is rigidly

fixed to a rotating shaft, and an outer ring, which is rigidly fixed to a support. Both balls and

rings are made of hardened alloy steel, usually finished to extremely fine tolerances. The balls

are generally held in position by a cage or separator that keeps them evenly spaced and

prevents them from rubbing against each other. The bearing is lubricated with grease or oil.

d) Needle bearing. This is found at the universal joint of a propeller shaft. It is used when very high

speed is required

e) Plain bearing; it acts as a bearing and spacer to prevent metal to metal contact. It can be found

at the crankshaft as and connecting rod.

f) Bushing; it is made from brass material. It prevents metal to metal contact during rotational

motion. It has groove or shut which helps it to trap down grease.

1.3.1 METHODS OF TRANSMITTING MOTION IN A MACHINE

This involves the methods of transferring motion to movable parts of component machines. There are

five ways of transmitting motion:

a) Belt and pulleys method: this involves transmission of drive from one pulley to another by a

connecting medium called the belt. For example the crankshaft generates drive and it is

transmitted to the pulley of an alternator through the use of a belt. When the belt is twisted the

sense of the drive we change. The types of pulleys are; the groove and flat pulleys. A groove

pulley uses groove belt while a flat pulley uses flat belt. Belt and pulleys method is applied were

less power is to be transmitted. Grinding machine, block-making machine, grain Sheller machine

and milling machine use this method for the transmission of drive.

b) Chain and sprocket method; this is used when great power is to be transmitted. The chain

moves at a lower speed compare to belt. This mechanism can be found in bicycle and

motorcycle. For bicycle, drive is generated by pedaling and it is transferred through the chain to

the sprocket. For motorcycle drive is not generated by pedaling. Also combine grain sheller uses

chain and sprocket and also this method can be found in Xerox machine. Types of chains

include; the needle chain, the roller chain and the Gunter chain.

c) Keys and Key-ways method; this method is often used when drive is to be transmitted from the

shaft to the pulley; the key is locked to the pulley through key-ways. There are different types of

keys for different purposes. These are the Allen key, bolt, flat keys, round key and the half-

round key. The different types of keyways are, the internal and external key ways. This method

can be found in the tractor and slasher.

d) Shaft and splines. A spline is a flat, relatively narrow key that is integral to a shaft, produced by

milling a longitudinal groove while shaft is a rotating rod that provides motion or power. This

method enhances the transfer of power from the source of the power to other part. There are

external and internal splines the power-take-off shaft.

External spline internal spline

e) Gears: Any meshing gears move in opposite direction. The diameters of the two gears involved

may be different or the same. Bevel gears are employed to transmit motion between shafts that

do not have parallel axes and hence can be used to change direction. Gears can be classified into

driving and driven gear.

1.3.2 IDENTIFICATION OF ENGINES

Engines can be identified in four major ways.

1. TYPE OF FUEL USED: the engine may have a petrol engine or a diesel engine.

2. METHODS OF COOLING: the engine can be identified if the engine uses either an air cooling engine or water cooling engine.

3. NUMBER OF CYLINDERS: the number of cylinders in a engine can be used to identify it. This range from 4-12 cylinders.

4. BY THEIR STROKE: some engines are either two or four stroke engines. A stroke is the distance travelled when the piston moves from the top dead centre to the bottom dead centre.

1.3.3 FOUR STROKE ENGINE CYCLE

A four stroke engine must complete four strokes to complete a cycle.

DEFINITION OF TERMS

o Stroke: this is the distance travelled by the piston from the top dead centre to the bottom dead centre and vice versa.

o Top dead centre: this is the highest height the piston can travel to.

o Bottom dead centre: this is the lowest depth the piston can travel to.

o Piston: metal cylinder that slides up and down inside a tubular housing, receiving pressure from or exerting pressure on a fluid, especially one of several in an internal combustion engine.

o Connecting rod: connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates.

o Inlet valve: this allows air to come in and mix with fuel.

o Exhaust valve: this allows gases after combustion to leave the combustion chamber.

The four stages in the completion of the four stoke cycle are

STAGE 1 - INDUCTION STROKE

The inlet valve is opened while the exhaust valve is closed. The open inlet valve allows a mixture of air and petrol to flow in and the piston moves from the top dead centre to the bottom dead centre.

STAGE 2 – COMPRESSION STROKE

The piston moves from the bottom dead centre to Top dead centre where the fuel is compressed, the volume is reduced and pressure is increased and so the fuel mixture temperature is increased. The two valves closed during this stroke.

STAGE 3 – POWER STROKE

In this stroke, the spark plug ignites the fuel. Current is released from the battery and the current tries to jump the two electrodes at the base of the plug thereby producing a spark. The fuel air mixture is combusted or explodes thereby pushing the piston downward from top dead centre to the bottom dead centre.

It should be noted that in compression ignition engines i.e. diesel engines, it is diesel which is sprayed into combustion chamber that acts like a spark plug because it is the air which is compressed that is already at a high temperature. The power stroke is the useful stroke because the crankshaft is turned in this stroke. The inlet valves and exhaust valves are also closed here.

STAGE 4 – EXHAUST STROKE

The gases left by the burned fuel are pushed out of the cylinder and the piston rises again moving from the bottom dead centre to the Top dead centre. The exhaust valves opens to let the fumes escape while the inlet valves remain closed, thereby bringing an end to the cycle and the whole process starts all over again.

1.4.1 SYSTEMS IN A TRACTOR / AUTOMOBILE

Systems are components combined together for a particular purpose in the vehicle. There are nine systems in tractors or automobiles. They are as follows:

Ignition System Fueling System Lubrication System Cooling System Electrical System Transmission System Steering System Braking System Hydraulic System

IGNITION SYSTEM

The system by which the compressed fuel in the cylinder is being ignited is referred to as the ignition system. In the ignition system, the positive terminal of the battery is connected to the kick or starter motor which is like a switch and the negative is earthed. From the positive terminal of the battery is connected a wire to the ignition coil. The ignition coil is made of primary and secondary windings, it serves as a multiplier effect on the voltage supplied. A high tension goes from the ignition coil to the distributor cap. Inside the distributor cap we have the contact set and a rotor, the negative terminal of

the ignition coil is connected to the contact set.

The current in the distributor unit gets to the rotor which has a pointed end and the rotor rotates among the four ends or plug points which later leads to the spark plug. There is a notable distance between the four plug points and

the current that passes through this distance is not useful and is picked up by the contact set and returned back to the coil. The contact also controls the timing of the distribution among the four spark plugs.

Also, there is a condenser whose function is to arrest the current and the noisy sound produced in engines which is always irregular is caused by a damaged condenser. There is also a firing order for the cylinders which could either be “1,3,4,2” or “1,2,3,4” it should be observed that “4” always come at the third position.

FUELING SYSTEM

This is the system that deals mainly with how the fuel in the tank gets to the cylinders of the engine. It consists of a tank, fuel filter fuel pump or lift pump, injection nozzles e.t.c For a tractor the fuel filter comprises of both primary and secondary filter, in this system fuel from the tank goes to the fuel pump (to increase the pressure of the fuel) since a liquid naturally flows from top to bottom but the movement of the fuel is in the opposite direction so a fuel pump is needed.

From the fuel pump or lift pump which has a priming lever that is actuated by cranking the engine, the fuel moves into the primary and secondary filter, the primary filter been the one closest to the lift pump and directly to it. Leaving the secondary filter the fuel goes to the injector pump, the injector pump has four nozzles or pipes coming out of it and then the injector pump then distributes the fuel to the next nozzle to fire. The injection nozzles are also called atomizers as they spray fuel through three tiny holes.

Difference between a carburetor engine and an injector engine

A carburetor mixes fuel with air and releases it in the form of liquid while fuel injectors spray the exact quantity of fuel needed into the cylinders and thus making it more efficient and consistent than a carburetor. All modern cars are equipped with fuel injection systems

Since air goes to the engine through the intake manifold, there is a need for us to ensure that clean air gets to the cylinders and hence the use of air cleaners. There are two types of cleaners 1) dry cleaner 2) wet cleaner

The wet cleaner has oil at its base which traps dust and then goes to the inlet manifold which later goes into the cylinders, while the dry cleaner is devoid of oil.

A major problem with the diesel engine is when the fuel finishes in the tank and air fills the pipe that lead to the injection nozzles. This occurrence is termed ENGINE AIRLOCK or that the engine is “air locked.” The process whereby air is removed from the fuelling system is called “BLEEDING.”

Bleeding

The bleeding process involves;

Fill the tank with fuel

Prime by pressing the priming lever to actuate it.

Open the bolt after secondary filter

Continue priming

Unscrew the bleeding screw

Loosen the number 1 nozzle.

We then continue priming until fuel comes out of the number 1 nozzle. It should be noted that number 1 nozzle is always the longest and if fuel should come out of it, it means that fuel has already replaced the air in the other nozzles and so air has been completely removed from the fuelling system.

LUBRICATING SYSTEM

The lubricating system is a system whereby all the moving parts are oiled. This is to reduce friction and heat generated. The lubricating system has a oil reservoir where the engine oil is put. An oil pump is used in moving the oil from low level to high level. The main lubricant in an automobile engine is the motor oil which is held in an oil pan underneath the engine which is called the sump. From the pump the oil goes through an oil filter which strains particle and dirt thereby giving the oil an exceptional purity. It goes from the oil filter to the rocker shaft. The shaft holding the rockers is called the rocker shaft.

Between the cylinder head and engine block is the top cylinder gasket which prevents oil mixing water. If this happens the water in the radiator becomes a mixture of oil and water but if water mixes with oil the dipstick looks milky. The dipstick is used to check the gauge of oil in the sump. The rubber material found around the rocker cover is called sealant and is to prevent loss of oil. There is a drain plug which is a very big bolt compared to the other bolts which is used to drain oil.

Maintenance cultures

There are basically three types of maintenance culture

Daily maintenance

Weekly maintenance

Periodic maintenance

Daily maintenance: (1) check the water level (2) check the engine oil level

(3) Check the brake oil level.

Weekly maintenance: in addition to the daily maintenance we include checking the gear oil level.

Periodic maintenance: this is mainly about servicing and the vehicle plugs are changed along with the engine oil and the oil filters.

COOLING SYSTEM

It is a system whereby the temperature of the engine is been controlled to prevent overheating. Overheating may result in the melting of the metals that were used in the making of the engine.

The cooling system consists of the radiator, water pump, fan thermostat, water ways e.t.c. The radiator is the water reservoir; it consists of up-tank and bottom tank. The bottom tank has an outlet orifice which goes to the engine. Also, since water is moving in the opposite direction there is need for a pump and specifically a water pump is used to pump the water from low level to high level. The radiator also consists of the radiator tube and the radiator fins which helps in cooling the water. The process involves hot water entering the up-tank and as it goes through the radiator tube, the fan blows it and its cooled, so cooled water enters the engine through the outlet orifice and the cycle continues.

How to diagnose fault on overheating

The two possible reasons are;

The fan is not working

The water pump is damaged.

It should be noted that the radiator cap is different from other caps because it has a spring which enables it to relief pressure from the heat of the vapour of the hot water and hence it does not damage the radiator by flying of suddenly. This cap is called pressure relief cap and it has a relieve hole that gases passes out. The purpose of the thermostat is to conserve heat within engine and not allowing it to get to the top tank very fast. The thermostat is mainly used in the temperate regions not here in the equatorial regions.

ELECTRICAL SYSTEM

Basically, the electrical system can be defined as a system which shows how electricity is transferred to the required components coupled in an automobile. The electrical components can be grouped into three stages; 1) cranking stage 2) lightning system 3) charging system.

Cranking stage/system: Wire comes from the positive terminal of the battery to the kick starter, from the kick starter a tiny wire goes to the ignition key. When the key is switched on 12V is drawn from the battery which is naturally not enough to drive the flywheel. The kick starter is made up of magnets and solenoid that we multiply the 12V to become 1200V and this voltage can now drive the flywheel.

There is a spring attached to the ignition key which returns the key to a particular position after cranking. Thus, the cranking stage is about how the engine comes to live through the ignition key (switch).

Lightning system: All the other accessories that require lightning are involved in this stage. Examples are the horn radio the head lamps trafficator, inner lights e.t.c are all dependent on the battery.

Charging system: The continuous usage of the battery without recharge makes the battery go flat with time. The device solely responsible for recharging the battery is the alternator. There is a pulley of the alternator which is connected to a solenoid and from the alternator there is a red wire that connects back to the kick starter. When the battery has filled back to 12V, There is a device in the alternator called voltage regulator which cuts the recharging process to prevent the battery from over charging. In older cars like the 1967 Volkswagen beetle a generator is used and this voltage regulator is commonly referred to as cut-out. The alternator might not be working sometimes and all the work load comes to the battery which goes flat after two to three days. The ways of checking whether the alternator is working are;

After starting the engine you remove the positive terminal cap of the battery and see if the engine is still working if the engine is still working then the alternator is working but if not then the alternator is not working. This method is used in petrol engines.

CHAPTER 2

PHYSICAL PLANNING UNIT