Ingles Tecnico Para Mecanica Automotriz

MANUAL DE APRENDIZAJE

CÓDIGO : 89000032

Técnico de Nivel Operativo

AUTORIZACIÓN Y DIFUSIÓN

MATERIAL DIDÁCTICO ESCRITO FAMILIA OCUPACIONAL OCUPACIÓN NIVEL

MECÁNICA AUTOMOTRIZ MECÁNICO AUTOMOTRIZ TÉCNICO OPERATIVO

Con la finalidad de facilitar el aprendizaje en el desarrollo de la formación y capacitación en la ocupación del MECÁNICO AUTOMOTRIZ a nivel nacional y dejando la posibilidad de un mejoramiento y actualización permanente, se autoriza la APLICACIÓN Y DIFUSIÓN de material didáctico escrito referido a INGLÉS TÉCNICO PARA MECÁNICO AUTOMOTRIZ. Los Directores Zonales y Jefes de Unidades Operativas son los responsables de su difusión y aplicación oportuna.

Registro de derecho de autor: 7032-2003

AUTOMOTIVE SPECIALIZED ENGLISH COURSE

CONTENTS

TABLE OF CONTENTS INTERNAL COMBUSTIONEÑGiÑžS¥FÞUhSTKOKÉCYÈLE Page

01

OBJECTIVES

LESSON A 1. COMPONENTS 02 2. FOUR STROKE CYCLE : INTAKE STROKE

03

3. FOUR STROK. CYCLE COMPRESSION STROKE

CLASSWORK ASSIGMENT LESSON A

06

LESSON B 1. FOUR STROKE CYCLE : POWER STROKE

09

2. FOUR STROKE CYCLE : EXHAUST STROKE 10

CLASSWORK ASSIGMENT : LESSON B

11

OBJECTIVES

12

page

LESSON A 1. STATIONARY PARTS 13 2. ENGINE COOLING

14

CLASSWORK ASSIGMENT : LESSON A

LESSON B 1. BASIC ENGINE TYPES : IN-LINE ENGINES

17

15

2. BASIC ENGINE TYPES : V - ENGINES 18 3. BASIC ENG. TYPES : HORIZONTAL OPPOSED

19

CLASSWORK ASSIGMENT: LESSON B

20

Page

22

OBJECTIVES

LESSON A 1. MOVING PARTS 23 2. THE CRANKSHAFT 24


26


LESSON B 1. VALVE SYSTEMS 2. VALVE IN-BLOCK ENGINES 3. VALVE IN-HEAD ENGINES 4. F-HEAD VALVE ENGINES 5. OVERHEAD CAMSHAFT (OHC)

29 29 30 31 31


32

UNITFOUR FUEL -AIR EXHAUST SYSTEMS Page

35

OBJECTIVES LESSON A 1. FUEL AIR SYSTEMS, GENERAL 2. THE FUEL SYSTEM

36

37

3. THE AIR SYSTEM 38

39


LESSON B 1. THE FUEL AIR MIXING SYSTEM (CARBURATOR)

42

2. THE EXHAUST SYSTEM 43


44

STARTfAND page

46

OBJECTIVES LESSON A 1. SMALL ENGINES : START AND IGNITION


49

LESSON B 1. MULTI-CYLINDER ENGINES : START AND IGNITION CLASSWORK ASSIGMENT : LESSON B


SIX

52 55 CONTB•.rrs

COOLING SYSTEMS Page

59

OBJECTIVES LESSON A 1. SIMPLE AIR COOLING SYSTEM

60

2. WATER COOLING SYSTEMS 61 CLASSWORK ASSIGMENT : LESSON A

62

LESSON B 1. AUTOMOTIVE WATER COOLING SYSTEMS 2. FORCED AIR COOLING SYSTEMS

64

65

CLASSWORK ASSIGMENT •. LESSON B

66

Page

OBJECTIVES

69

LESSON A 1. LUBRICANTS

70

2. SPLASH LUBRICATION SYSTEM

71

3. PRESSURE LUBRICATION SYSTEMS

72


73

LESSON B 1. OIL COOLING

76

2. INSTRUMENTS

77


78

OBJECTIVES

81

Page

LESSON A 1. FUEL

82

2. INJECTION PUMP (DISTRIBUTOR TYPE) FUEL SYSTEM 83 CLASSWORK ASSIGMENT : LESSON A

85

1. FUEL INJECTION (UNIT INJECTOR TYPE) FUEL SYSTEM

88


90

LESSON B

UNIT NINE GEARS OBJECTIVES LESSON A 1 . GEARS

Page 93

94


LESSON B 1. TRANSMISSIONS 2. DIFFERENTIAL

CLASSWORK ASSIGMENT: LESSON B

100 102 103

AUTOMOTIVE SPECIALIZED ENGLISH COURSE AUTOMOTIVE SPECIALIZED ENGLISH COURSE

Page 1

UNIT TEN Page

OBJECTIVES

106

ENGINE SPECIFICATIONS

107


112

LESSON A

UNIT ONE

THE INTERNAL COMBUSTION ENGINE: THE FOUR STROKE CYCLE

OBJETIVES 1. Given a picture of a simple one cylinder internal combustion gasoline engine, the student will orally and/or in writing correctly identify the following components: cylinder

- piston - wrist pin or piston pin - flywheel

- crankshaft - crank pin - crankshaft gear - camshaft - camshaft gear - cam - valve - valve spring - tappet - port 2. Given a task of identifying the four strokes of a four stroke cycle internal combustion engine, the student will oraly and/or in writing state that: - The intake stroke is the piston movement that brings the fuel-air mixture into the cylinder - The compression stroke is the piston movement that compresses the fuel-air mixture in the top of the cylinder.


Page 2

- The power stroke is the downward piston movement caused by the expansion of the burning fuel-air mixture.

- The exhaust stroke is the piston movement that pushes the burned gases or exhaust out of the cylinder. 3. Given pictures of internal combustion engines showing the four strokes, the student will orally and/or in writing correctly describe the position of each component.

UNIT ONE THE INTERNAL COMBUSTION ENGINE: THE FOUR STROKE CYCLE

LESSON A 1. THE COMPONENTS

4

2

Figure 1.- Simple internal combustion engine Figure 1 illustrates a simple one cylinder internal combustion gasoline engine. It is easier to understand the operation if you think of the parts in groups as shown in the ilustration.

AUTOMOTIVE SPECIALIZED ENGLISH COURSE Group 1

Group 2

Group 3

Group 4

cylinder

flywheel

piston

crankshaft

camshaft camshaftgear

valve valve springs

Page 3

wrist pin tappet crank pin cam connecting rod crankshaft gear port The words tappet añd port are new to us. A tappet is a short metal piece that fits between the end of the valve stem and the cam. It is used to adjust how far the valve moves. The opening or hole that the valve opens and closes is called the port.

2. THE FOUR STROKE CYCLE: THE INTAKE STROKE

c

-

ENTERING

MOVIN DOWN

TAPPET VALVE

b CAM

LOBELIFTING TAPPET

Figure 2.- Intake stroke Figure 2 shows the intake stroke. The intake stroke is the piston movement that brings the fuel-air mixture into the cylinder. Look at a. As the flywheel turns, the crankshaft is rotated. This causes the connecting rod to pull the piston down. When the piston moves down, the space in the cylinder is increased. This creates a negative pressure in the cylinder.


Page 4

Now look at h. When the crankshaft turned, the crankshaft gear also turned and caused the camshaft gear to turn. The camshaft gear turned the camshaft so that cam lobe lifted the valve tappet. The tappet lifted the intake valve to the open position. Now look at C. When the intake valve is opened, the outside air is pulled through the carburator to fill the increased space in the cylinder. The carburator is a device that mixes the fuel, gasoline, with the air as it enters the engine. Summary: As the piston moved down it pulled air through the carburator, where it was mixed with fuel. The fuel-air mixture was then pulled through the intake port into the cylinder.

3. FOUR STROKE CYCLE: THE COMPRESSION STROKE

c FUEL BEING

COMBUSTION CHAMBER

PISTON

MOVING

a

Figure 3.- Compression stroke Figure 3 shows the compression stroke. The compression stroke is the piston movement that compresses the fuel-air mixture into a small space at the top of the cylinder, called the combustion chamber. Look at a. The flywheel has continued to turn the crankshaft. The crankpin has pushed the connecting rod-piston unit back into the cylinder.


Page 5

Look at h. The crankshaft gear continued to turn the camshaft gear. The camshaft has turned so the cam does not hold the valve open. The valve spring has pushed the intake valve down so that the intake port is closed. Now look at g. Both valves are closed and the piston is rising in the cylinder. The space in the cylinder is decreasing and the fuel-air mixture is being compressed. Summary : When the piston began to move up, the intake valve closed. The fuel-air mixture was pushed into a smaller and smaller space. This stroke compressed the fuel-air mixture.


Page 6

UNIT ONE

CLASSWORK ASSIGMENT: LESSON A The following comprehension exercises should be completed in class with the instructor's

assistance.

Figure 1.

Figure 2.

1. Look at figure 1. Fill in the blanks below a indicates the b the indicates the

indicates the c indicates the piston moves in.

2. Look at figure 2. Fill in the blanks below: a indicates the b g

indicates indicates indicates

the the the


b

Figure 3

Figure 4

3. Look at figure 3. Fill in the blanks below: a indicates the b indicates the indicates the

c indicates the

4. Look at figure 4. Fill in the blanks below: a is the b is the c is the d is the e is the f is the g is the h is the

Page 7


Page 8

Page 9


b

b Figure 5.- Intake stoke

Figure 6.- Compression stroke

5. Figure

5 showsstroke a indicates the it is closed. indicates the, it is movingc indicates the intake . It lifts d, the intakeThe intake tappet lifts e, the intake When the intake valve is lifted, the intakeis open. f indicates the entering the carburator. h indicates the mixture being pulled into the

6. Figura 6 shows the stroke. a indicates the It is moving b indicates the valve and

the

valve.

Both

valves

are

the c mixture. It is in the top of the cylinder. The section it is compressed into is called the chamber.

UNIT ONE

LESSON B


Page 10

1. THE FOUR STROKE CYCLE: THE POWER STROKE ELECTRIC SPARK BOTH VALVES a IGNITES MIXTURECLOSED

PISTON MOVING

DOWN

b

Figure 1 .- The power stroke Figure 1 shows the power stroke. The power stroke is the piston movement that provides the power or force to turn the crankshaft flywheel. Look at a. When piston reached the top of the cylinder, the engine electrical system caused an electric spark to occur suddenly in the top of the cylinder. The hot spark caused the compressed fuel-air mixture to ignite, or begin burning. The compressed mixture burns very rapidly and expands in all directions with a strong force. Look at b. The very strong force of the rapidly expanding gas pushes the piston down in the cylinder. This causes the crankshaft and the flywheel to turn rapidly. This movement is what provide the output power or force. Summary : When the piston compresses the fuel-air mixture in the top of the cylinder, the mixture is ignited and burns rapidly. The force of the burning expanding gases pushes the piston down with a strong force. The crankshaft changes this force to a rotating movement.

2.


Page 11

THE FOUR STROKE CYCLE: EXHAUST STROKE EXHAUST VALVE OPEN CLOSED

INTAKE VALVE

VALVE TAPPET LIFTING VALVE CAM LOBE LIFTING VALVE TAPPET

a

Figure 2.- The exhaust stroke Figure 2 shows the exhaust stroke. The exhaust is the piston movement that pushes the burned gases, or exhaust, out of the cylinder. Look at a. The flywheel continues to turn the crankshaft and the crankshaft gear with the force it received from the power stroke.

Look at b. and g. The camshaft gear has turned the camshaft so that the lobe of the second cam lifts the other valve tappet. This causes the exhaust valve to rise and open the exhuast port. Now look at d. As the piston rises, it forces the exhaust gases out through the exhaust port. Summary: When the piston reached the bottom of the cylinder during the power stroke, the flywheel continued to turn and caused the piston to start back up into the cylinder. When the piston began to move up into the cylinder, the second cam on the camshaft lifted the exhaust valve and opened the exahust port. As the piston rose, it forced the exhaust gases out of the cylinder UNIT ONE


The following comprehension exercises should be completed in class with the instructor's

assistance:

c

b

d

a

Figure 1.- Power stroke

Figure 2.- Exhaust stroke

1. Figure 1 shows the •stroke. the mixture has been

by the electric spark. The burning mixture is expanding and pushing against g, the a indicates the They are b oth . The piston is pushing down quickly with a strong . This provides the power thaf rotates d, the and e, the

2. Figure 2 shows the strokþ. a indicates the cam; it has lifted c, the . The exhaust is now open. d, the the

valve, is closed. e the or burned gases out of the cylinder.

3. The four strokes a four-stroke cycle engine are: a.b. c.

d.

UNIT rwo

is rising and forcing


Page 12


Page 13

STATIONARY PARTS / ENGINE COOLING / BASIC ENGINE TYPES

OBJETIVES 1.

Given the question: What are fixed or non-moving parts called ? the student will orally and/or in writing state the fixed or non-moving parts are called stationary parts.

2.

Given a picture of a simple one cylinder engine with carburator indicated, the student will orally and/or in writing correctly identify the following terms:

- intake manifold - exhaust manifold - crankcase - cylinder block - cylinder head - single cylinder engines - water cooled - absorb - circulate - air cooled - cylinder barrel - multi-cylinder - flat 3. Given pictures of the different basic engine types the student will orally and/or in writing identify each kind of engine, as follows: - two cylinder in-line engine as an in-line or straight engine. - two cylinder V-engine as a V engine - two cylinder horizontal opposed engine as a a horizontal opposed or flat engine.

UNIT Two STATIONARY PARTS / ENGINE COOLING / BASIC ENGINE TYPES

LESSON A 1. STATIONARY PARTS It is useful to separate engine parts into two types, the moving parts and the fixed or stationary parts. In this lesson we will talk about the stationary parts.

AUTOMOTIVE SPECIALIZED ENGLISH COURSE exhaust

d

Page 14

•aifllt

e

canrebr

Figure 1.- Single-cylinder internal combustion gasoline engine The simple engine shown in figure 1 contains the five main stationary parts found in most engines. a indicates the crankcase. The crankcase encloses or contains the crankshaft. þ indicates the cylinder block, The block is the section above the crankcase that contains the cylinder. C indicates the cylinder head. The cylinder head is the piece that covers the top of the cylinder. indicates the exhaust manifold. The exhaust manifold is the tube that carries the exhaust gases away from the cylinder. e indicates the intake manifold, The intake manifold is the tube that carries the fuel-air mixture from the carburator to the cylinder.

2. ENGINE COOLING The engine shown in figurel is a water cooled engine. Look at the figure 2. The cool water is passed near the cylinder so that it absorbs (takes) some of the heat from the cylinder block. The heated water is then taken from the block to another part of the system where it is cooled. Then the water is returned to cool the cylinder again. The circulation (moving in a circle) of the water cools the engine. Engine cooling is necessary because of the heat produced by the combustion of the fuel air mixture.


air

Page 15

teat

cyliller

Figure 2.- Water cooled engine

Figure 3.- Air cooled engine

The engine shown in figure 3 is an air cooled engine. Cool air passes around the cylinder barrel (cylinder unit) and cylinder head, and absorbs heat from the engine. Air cooled engines are often used in airplanes because there is a constant circulation of air past the engine when the aircraft is moving. When air cooled engines are used for other purposes, it is usually necessary to have a method of forcing air past the engine. The cooling system will be explained in more detail in a later lesson.

UNIT TWO CLASSWORK ASSIGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance:

1. Look at figure 1. Fill in the blanks below.

a

indicates

indicates

the the

d

indicates the c indicates the e indicates the

The ilustration shows a cylinder cycle gasoline It is a cooled engine. Water moves around the and the head. The water heat from the cylinder and cylinder The heat is caused by the of the fuel-air mixture.


Page 16

c

a

Figure 2 2. Figure 2 shows a

Figure 3 cylinder

cooled engine.

The white arrows indicate the air. As it passes the barrel and head, it the heat. The black arrows indicate the it leaves the engine.

a

indicates b

indicates

the the C

indicates the

3. Figure 3 shows a

a

indicates where the and indicate where the water

cooled engine. water enters the engine. heat.

air as


Page 17

d indicates where the water leaves the engine. e indicates the part of the system where the hot water is The water in this system moves in a circle; we say it

4. What are fixed or non-moving parts called? UNIT Two

LESSON B 1. BASIC ENGINE TYPES : IN-LINE ENGINES

Figure 1 ilustrates an in-line engine. In an in-line engine, the cylinders are in a row one after the other. Each piston and connecting rod unit acts on its own throw of the crankshaft. A typical in-line engine may have 2, 4, 6, 8, or more cylinders. Figure 2 shows the pistonvalve arrangement of a 4 cylinder in-line engine. Figure 3 shows the cylinder block of a 6 cylinder in-line engine. In-line engines are also called straight engines.

valves

camshaft gear

crankshaft

Figure 2.- Piston-valve unit, 4 cyl. in-line engine. Figure 3. Cylinder block, 6 cyl, in-line engine.

2. BASIC ENGINE TYPES : «V» ENGINES

rods pistons cylinder head

cylinder barrel

connecting

Figure 4.- «V» engine.


Page 18

The engine shown in figure 4 is a V - engine. V -engines have the cylinders in pairs at an angle to each other. A small 2 cylinder V-block engine such as the one in figure 4 usually has separate cylinder barrels. Small air cooled 2 cylinder V-engines of this type are frequently used to power motorcycles.

cylinder head

cylinder block

Figure 5.- V-8 engine Large V-engines often have the two rows of cylinders manufactured as a single cylinder block. Figure 5 ilustrates a typical V-8 (V-block, 8 cylinder) engine such as is used in automobiles and light trucks. These engines are usually water cooled engines. One of the advantages of a V-block engine -is that it does not require as much space as a comparable in-line engine. A straight 8 (in-line, 8 cylinder) engine would be much longer than the V-8 illustrated. The opposite pair of pistons may use the same throw of the crankshaft or each piston may have its own throw.

3. BASIC ENGINE TYPES : HORIZONTAL - OPPOSED ENGINES c linder block

crankshaft

rod cylinder block

cylinder head cylinder head


Page 19


Page 20

crankcase

Figure 6.- Opposed engine

The engine shown in figure 6 is a horizontal-opposed engine. The cylinders are located on opposite sides of the crankcase. The opposing pair of pistons may use the same crankshaft throw or each piston unit may have its own throw. Horizontal opposed engines are sometimes called flat engines or 180* V-engine. Figure 7 shows the top view of a 6 cylinder air cooled horizontal opposed engine of the type used in some aircraft.

crankcase Figure 7.- Horizontal opposed 6 cylinder engine Horizontal opposed engines also are made as water cooled engines. The cylinder block system similar to that of the V-engine is used when the engine is water cooled. UNIT Two


b

Figure 1 1 . Figure 1 shows a cylinder called a

Figure2 cooled

engine. It also be

two.

a indicates the indicates the g indicates the

2. Figure 2 shows a

cylinder engine. It could be called a

a indicates indicates the

the

cooled two.

indicates the C indicates the indicates the e


Page 21

a

c

Figure 3

3. Figure 3 shows a

a indicates

cylinder engine. the

cooled

indicates

the right

C

indicates

the

right indicates the

right

e

indicates the right t indicates indicates the left h indicates the left j indicates the left i left

the

g

indicates the

UNIT THREE

MOVING PARTS / VALVE SYSTEMS


Page 22

OBJECTIVES 1 . Given a picture of a piston unit, the student will orally and/or in writing correctly identify the following features: - head

- skirt - grooves - compression rings - oill rings - wrist pin 2. Given a picture of a crankshaft, the student will orally and/or in writing correctly identify the following parts: - main journals - intermediate main journals

- connecting rod journals - flywheel - crankshaft gear - camshaft gear - counterweights - throws 3. Given the task of identifying the valve systems, the student will orally and/or in writing identify each properly. 4. Given a picture of an overhead valve unit showing the crankshaft, camshaft and valve mechanism, the student will orally and/or in writing correctly identify the following features: - crankshaft

- camshaft gear - camshaft - camshaft lobe - push rod - rocker arm - valve spring - valve - valve cover UNIT THREE

MOVING PARTS / VALVE SYSTEMS


Page 23

LESSON A 1. MOVING PARTS The main moving parts of an engine are shown in figure 1. It is helpful to think of them in the following four units: a The piston-connecting rod unit. b The flywheel-crankshaft unit.

c The camshaft unit d The valve unit

compression rings oil ring rings head

grooves

skirt

wrist pin

2. PISTON CONNECTING ROD UNIT Figure 2 shows the piston assembly. The top of the piston is called the head. The head receives the force of the expanding burning gases. The side of the piston is called the skirt. The skirt guides the piston up and down in the cylinder. The rings fit in the grooves in the piston. The upper rings, called

bolts crank

The compression rings

oil rings wrist pin

in

connecting

rod

to pin

crankshaft

Figure 3.- Connecting rod

(piston pin)

Figure 2.- Piston unit

compression rings, prevent the hot gases from passing between the piston and the cylinder. lower rings, called oil rings, prevent lubricants from entering the combustion chamber. The complete pistonconnecting rod unit is shown in figure 3. As you learn previously, the piston pin passes through the hole the upper end of the connecting rod and locks it the piston. The hole in the lower end of the connecting rod has a removable section called the cap. The cap fits around the crankpin and is bolted to the end of the connecting rod.


Page 24

3. THE CRANKSHAFT journals main

intermediate main main journal journal

connecting rod journals

Figure 4.- Crankshaft journals The crankshaft shown in figure 4 is the type used in a four cylinder engine; It has four throws. The crankshaft is suppored and held in place by sections of the crankcase. The surfaces of the crankshaft that contact these supports are called journals and, as we learned earlier, they are protected by journal bearings. The journals at each end of the crankshaft are called main journals. If the center section of the crankshaft is also supported, the journals that contact the center supports are called intermediate main journals. The crankpins at the end of the throws are also journals. The connecting rods are attached to the crankpins and, as we know, this attachment is protected by journal bearings. The crankpin surfaces that the connecting rods are attached to are called connecting rod journals. See figure 4.


main journal

Page 25

connecting

main journal flywheel

crankshaft gear counterweights

Figure 5.- Complete crankshaft unit. A complete crankshaft unit is shown in figure 5. The complete unit includes the flywheel and the crankshaft gear. This crankshaft has only one intermediate main journal located between the second and third throws. This crankshaft has counterweights located opposite the crankpins. The counterweights equal or balance the weight of the throw so that the crankshaft turns smoothly. UNIT THREE

CLASSWORK ASSIGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance.

Page 26


1. Look at figure 1. Fill in the blanks below • Figure 1 shows the

a

parts of a

cylinder engine.

indicates the unit. Þ indicates

the

a Figure 2 unit. C indicates the

unit. d indicates the unit.

2. Look at figure 2. Fill in the blanks below : Figure 2 shows a unit.

Page 27


a

indicates the

indicates the c indicates the

d indicates the e indicates the

of the piston.

of the piston. f

indicates

g indicates the

the rings.

indicates thering.

3. What are the upper rings of a piston called ?

4. What are the lower rings of a piston called?

it receives the force of indicates the piston ; it guides the

down

in

the expanding as it moves up and

the i and k indicate the ; they fit in the in the piston. The rings the space

between the

and

j

AUTOMOTIVE SPECIALIZED ENGLISH COURSE the cylinder

Page 28

k indicates the upper rings, they are

I indicates the lower rings, they are

6. Look at figure 4. Fill in the blanks below : Figure 4 shows the from a cylinder engine. The sections of the crankshaft that are supported by the crankcase are called Journals are protected by bearings. The a at each end of the crankshaft are called Journals that support the middle of the crankshaft, b, are called journals. The crankpins, c, are also ; they are called journals.

b

g

e

Figure 5 7. Look at figure 5. Fill in the blanks below.

h

AUTOMOTIVE SPECIALIZED ENGLISH COURSE Figure 5 shows a complete a indicates

Page 29 unit.

the b indicates the

gear. c indicates a journal. d ine rates the other journal. e inajcates anjournal. f, g, b, and y indicate the journals. g indicates the that balance the weight of the throw.

UNIT THREE

LESSON B 1. VALVE SYSTEMS

TOP VIEW

F-

o SIDE VIEW L - head

I - head

Figure 6.- alve systems

head

Figure 1 ilustrates the three main types of valve systems. Valves in L-head engine are located in the side of the engine block. Valves in I-head engine are located in the cylinder head over the cylinder. This is also called an overhead value system (OHV). The valve system in an F-head engine combines the two systems; one valve is located in the engine block, the other valve is located in the cylinder head.

2. VALVE IN BLOCK (L-HEAD) ENGINES Figure 2 shows the valve systems used in L-head or valve in block engine. It is the system you are already familiar with. The crankshaft gear turns the camshaft gear. As the camshaft rotates, the lobes of the cams lift the tappets. This lifs the different valves so that the valve ports will be opened or closed at the correct time for intake or exhaust. The valve springs (not shown) hold the valves closed until they are lifted.

valves

camshaft gear

crankshaft Xcrankshaft gear

Figure 2.- L-head valve system AUTOMOTIVE SPECIALIZED ENGLISH COURSE

Page 30

3. VALVE IN HEAD (I-HEAD) ENGINES rocker arm rocker arm

sh aft

valve

crankshaft

gear crankshaft gear

Figure 3.- I-head valve system Figure 3 shows the valve system used in I-head or overhead valve engine. The crankshaft gear turns the camshaft gear and causes the camshaft to rotate. The camshaft lobe lifts a long rod called push rod. The push rod is attached to one end of the rocker arm. The rocker arm is pivoted on the rocker arm shaft. When the push rod lifts its side of the rocker arm, the rocker arm pivots and the other side pushes the valve down so the valve port is opened. When the camshaft has turned and the cam lobe does not lift the push rod, the valve spring pushes the valve closed by lifting the valve side of the rocker arm.


Page 31


Page 32

rocker arm

valve spring4—-valvecover

Figure 4.- Overhed valve system Figure 4 illustrates a cylinder head with an overhead valve system for a four cylinder engine unit. The valve mechanism is usually covered with a light metal unit called the valve cover. The valve cover protects the valves from dirt and dust and keeps the lubricating oil from leaving the engine unit.

4. F-HEAD VALVES Since the valve system of F-head engine combines the system used in L-head and I-head, it will not be illustrated here. The single overhead valve for each cylinder (usually the intake valve) is operated by a pushrod moving a rocker arm as in I-head engine. The valve in the block (usually the exhaust valve) is operated by a tappet lifting the valve as in the L-head engine.

5. OVERHEAD CAMSHAFT (OHC) In some engines with overhead valves, the camshaft is in the cylinder head also. In this mechanism the pushrod is not necessary because the cam lobe lifts the rocker arm directly. The camshaft gear and the crankshaft gear are connected by a chain. UNIT THREE

CLASSWORK ASSIGMENT : LESSON e

The following exercises should be completed in class with the instructor's assistance

top view

c side view

Figure 1 1. Look at figure 1. Fill in the blanks below: Figure 1 shows the three main types of valve engine arrangements.

a

shows

the

-head in

b

shows the

it

is

-head engine; it is also called a

called

a

in

-head valve engine.

shows an -head engine. It is a combination of the -head and

head. The

also

engine.

engine or an

c

engine;

valves are located in the cylinder , and the

are located in the cylinder

-


c

ab

Figure 2 2. Look at figure 2. Fill in the blanks below .

3.

at figure 3. Fill the blanks below Figure 2 shows the valve mechanism from a

cylinder

Page 33

Figure 3 shows the cylinder engine.

from

an

over

Over head valve engines are also called valve in- engines. We also call this an

-head indicates the ; it protects the valves from 4. Look at figure 4. Fill in the blanks below

engine. a indicates the and damage.

Figure 4 shows the valve mechanism from a valve in-head engine. a indicates the indicates a C indicates ajournal.

d

indicates theshaft.

e indicates theshaft

c

Figure 4


Page 34 Page 35

f indicates the g indicates a h indicates the j

indicates therod.

i indicates the

k indicates thearm I indicates the valve m indicates the n indicates the valve

UNIT FOUR

FUEL - AIR - EXHAUST SYSTEMS OBJECTIVES 1. Given pictures of a simple one-cylinder internal combustion engine, the student will orally and/or in writing correctly identify the following components of the fuel - air - exhaust system:

- fuel tank - fuel line - sump - fuel cap - filler neck - fuel line - air cleaner - fuel filter - carburator body - fuel air - intake manifold - exhaust manifold - exhaust line (pipe) - muffler 2. Given a cutaway illustration of a simplified carburator and air cleaner, the student will orally and/or in writing identify the following parts . - float chamber

- venturi

AUTOMOTIVE SPECIALIZED ENGLISH COURSE - needle valve

discharge nozzle

- float

- throttle valve

Page 36

UNIT FOUR

FUEL - AIR - EXHAUST SYSTEMS LESSON A 1. FUEL - AIR - EXHAUST SYSTEMS, GENERAL Internal combustion engines burn a fuel-air mixture. After the mixture has been burned, the burned gases, called exhaust, are forced out of the engine. Three different systems work together to accomplish this process. A system is the combination of all of the parts necessary to do one thing. The engine has a fuel system, an air system and an exhaust system. Figure 1 shows these system, on the small gasoline engine we are familiar with. c fuel filter air cleaner

f carburetor throttle valve

j muffler

manifold

e air filter

Figure 1.- Small engine fuel air exhaust systems Fuel Sistem fuel tank (a) fuel line (b) fuel filter (c)

Air System air cleaner (d) air filter (e) air filter cartridge *


Page 37

fuel pump* Fuel-Air Mixture carburetor (F) throttle valve (g)

Exhaust System exhaust manifold (i) exhaust line*

intake manifold (h)

muffler (k)

2. THE FUEL SYSTEM The fuel system stores (holds) the fuel oil and gasoline, and delivers it to the carburator where it is mixed with air.

Figure 2 shows the fuel system of the one- cylinder gasoline engine. The fuel is stored in the container called the fuel tank (a). The fuel is put into the tank through the opening or tube called the filter neck (b). The filter neck usually has a removable cover called the cap (c). The fuel line (d) is a tube that carries the fuel from the fuel tank to the carburetor. Before the fuel reaches the carburetor, it must pass through a fuel filter (e). The fuel filter contains a material that has many very small openning or holes. The liquid gasoline can pass through the small holes but particles of dirt in the gasoline can not pass through the holes. We say the material filters or cleans the gasoline. The fuel system shown in figure 3 is the type that is found in a typical automobile. The bottom of the tank has a lower section called the sump. Dirt or water in the gasoline will collect in the sump because it is the lowest section of the tank. A fuel pump is attached to the fuel line. The fuel pump forces the fuel to the carburetor. The small engine in figure 2 does •not need a fuel pump because the fuel line is short and the fuel tank is higher than the carburetor. Gravity force pulls the fuel to the carburetor in the small engine fuel system.


Page 38

3. THE AIR SYSTEM The engine air system provides the air to be mixed with the fuel. In small engines the air system only consists of an Air cleaner attached to the top of the carburetor; it removes dirt and dust from the air. a air cleaner

air cleaner

carburetor

fuel filter

Figure 4.- Small engine air system

Figure 5.- Small engine air system

The air cleaner of the single-cylinder gasoline engine in figure 4 consits of a small metal frame attached to the top of the carburetor. The air filter is a cloth-like material made from wire. The spaces between the wires are very small. Often the filter is coated with oil. When the air is pulled through the filter to the carburator, the dirt in the air cannot pass through the holes in the filter and the dust sticks to the oil on the filter. The filter can be removed and cleaned. The system shown in figure 5 is used on small multi-cylinder engines. The air cleaner is in the form of a metal cover that is bolted to the carburetor. The air is pulled in through the air intake opening. Inside the air cleaner is a repaceable air filter cartridge like the one shown in figure 6. The air filter cartrigde is often made of folded paper that has many small holes in it. When the out side surface of the filter becomes dirty, the filter is removed and replaced with a new one. UNIT FOUR

Figure 6.- Air filter cartridge


Page 39

CLASSWORK ASSIGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance :

1. Look at figure 1. Fill in the blanks below • Figure 1 shows a a indicates the

C

cylinder gasoline engine. indicates

the

indicates

the indicates the

e indicates the f indicates the the

g indicates b

AUTOMOTIVE SPECIALIZED ENGLISH COURSE indicates the

Page 40

j indicates the i indicates the manifold.

k indicates manifold.

the I

indicates

the

e

Figure 2

b

2. Look at figure 2. Fill in the blanks below : a indicates the

b

indicates

the

C indicates the indicates the

e

indicates the

f

indicafes the replaceable


Page 41

d

a

Figure 3

Figure 4

3. Look at the figures 3 and 4. Fill in the blanks below : Figure 3 shows a simple fuel tank to the

The indicates f indicates

The fuel is moved from the by

force.

is higher than the a indicates the indicates the C indicates the d the e indicates the the

Figure 4 shows an automotive-type the fuel to the

fuel indicates the the d the f

indicates

system. The fuel is moved from by an electric a b indicates the C indicates indicates the e indicates the electric


Page 42 FOUR

LESSON B 1. THE FUEL -AIR MIXNG SYSTEM (CARBURATOR) The fuel and the air are mixed in the carburator. The carburator changes the liquid fuel into very small particles that are mixed with the air as it passes through the carburator.

air

fuel discharge nozzle chamber

valve

fuel-air

line (a)

intake

Figure 1.- Carburator The main feature of a simplified carburator are shown in figure 1. The fuel from the fuel line (a) enters the small space called the float chamber (b). As a more fuel enters, the float (a) rises because it is lighter than the fuel. When the float rises the connecting arm pivots and pushes the needle valve (d) down so it closes the inlet to the float chamber. When fuel is taken from the float chamber, the float goes down and causes the needle valve to rise and open the inlet so more fuel can enter the chamber. Air is pulled into the top of the carburator by the negative pressure that occurs when the piston goes down. As air rapidly passes through the narrow section called the venturi, it pulls small particles of fuel from the fuel discharge nozzle. These small particles of fuel mixed in the air are carried into the cylinder. The throttle valve is a round disc in the center of the carburetor opening. It can be turned vertically so the air passes rapidly, or it can be turned horizontally so the air passes more slowly. The throttle valve controls how fast the fuel air mixture enters the engine. It controls the speed of the engine.

UNIT


Page 43


Page 44

2. THE EXHAUST SYSTEM After the fuel - air mixture has been burned, the piston pushes the burned gases or exhaustout of the cylinder into the exhaust system.

Figure 2.- Exhayst systems The exhaust system of the simple single - cylinder engine only consists of the exhaust manifold and the muffler. The muffler is a cylindrical pipe that contains material to slow the speed of the exhaust gases to reduce the engine noise.

filter neck

Figure 3.- Automotive fuel -air-exhaust systems The automotive fuel - air - exhaust system shown in figure 3 has a longer exhaust system. The muffler is connected to the exhaust manifold by a long tube called the exhaust. line or the exhaust pipe. There is often a shorter piece of tubing after the muffler called a tail pipe. It carries the exhaust from the muffler to the rear of the vehicle.

FOUR

CLASSWORK ASSIGMENT : LESSON B The following exercises should be completed in class with the instructor's assistance :

air

Figure 1 1. Look at figure 1. Fill in the blanks below Figure

1

shows

the

main

features

a

indicates

the

C indicates the d

indicates

of

a

simple

indicates

the

chamber. the

e f g

indicates

the

indicates

the

indicates

the indicates the

j

indicates

the

UNIT

SENAn


Page 45

a

b

Figure 2 2. Look at figure 2. Fill in the blanks below • Figure 2 shows an automotive type a indicates the b indicates the C indicates the d indicates the e indicates the f indicates the g indicates the i indicates the j indicates the k indicates the I indicates the m indicates the n indicates the o indicates the

FIVE

START AND IGNITION SYSTEMS

, air,

system.


Page 46 Page 47

OBJECTIVES 1. Given pictures of internal combustion engines, the student will orally and/or in writing correctly identify the following starting systems :

- rope starter system - hand crank starter system - automotive electrical starter system 2. Given a picture of automotive electrical starting and ignition systems, the student will orally and/or in writing identify the following features :

- battery - starter motor - generator - ignition or booster coil - distributor unit 3.

Given cutaway picture of an engine with a magneto ignition system, the student will orally and/or in writing correctly identify the following components: - magneto ignition wire - booster coil spark

plugs - breaker points

- cam lobe 4. Given a cutaway picture of a spark plug, the student will orally and/or in writing identifiy the following parts • - insulation - side electrode - center electrode - gap UNIT FIVE

STARTING AND IGNITION SYSTEMS

LESSON A 1. SMALL ENGINES : STARTING AND IGNITION SYSTEMS Most internal combustion engines have the same basic starting system. The flywheel is rotated by an outside force. This causes the crankshaft to turn so that the intake and compression movements of the piston take place. When the fuel - air mixture is

UNIT compressed, the ignition system releases an electric spark that ignites the mixture. At this time the power stroke takes place and the engine begins to run on its own power. Small engines can be started manually (by hand). Figure 1 shows a rope - starting system. The end of the starter rope is wound around the pulley on the flywheel and pulled quickly. This rotates the flywheel and causes the intake - compression - ignition cycles to take place. Figure 2 shows a crank starting system. The hand crank is inserted into the crank fitting on the flywheel and turned. The crank fitting is similar to a spiral jaw clutch; when the engine starts, the crank is automatically disengaged from the fitting.


Page 48

The fuel-air mixture is ignited by an electric spark. The ignition system must have a source of electricity to provide the spark. Small engines usually use magnets to create the electricity. The system is called a magneto system. The magnets are attached to the flywheel. When the flywheel is turned to start the engine, the rotating magnets create a weak electric current in the booster coil. At the end of the compression cycle a cam on the camshaft separates two small pieces of metal called the breaker points. When the breaker points separate, the booster coil releases a strong electric current that flows through the ignition wire to the spark plug at the top of the cylinder. The electric current flows through the center electrode of the spark plug; it cannot pass through the insulator. The current jumps the gap or space between the center electrode and the side electrode in the form of a spark. This is the spark that ignites the fuelair mixture. This process continues as long as the engines runs. See figure 3.

gnition wire Ireaker points

electrode

electrode

Figure 3.- Magneto ignition system


Page 49

UNIT FIVE CLASSWORK ASSiGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance :

1. Look at figures 1 and 2. Fill in the blanks below. system. Figure 1 shows a starter

a

indicates

the

When the rope is wound around the pulley and pulled, the cycles take place. Figure 2 show a starter system. a indicates the indicates the . When the hand crank is inserted into the crank fitting and turned, the cycles take place.

2. Look at figure 3. Fill in the blanks below. Figure 3 shows

ignition system.

a indicates the b indicates the


Page 50 Page 51

C indicates the

d indicates the e indicates the below.

wire is attached to electrode. The electric flows through the There is a the in the form of a jumps the mixture.

between the electrode. The current jumps the The electrical ignites the

The current electrode and that


Page 52

c

Figure 5 4. Look at the figure 5. Fill in the blanks below : Figure 5 shows the a indicates indicates the C indicates the d indicates the

When the cam

-points and the booster the

b

moves so that the

are

, the booster

an

current to the spark

points releases

UNIT FIVE

LESSON B 1. MULTI-CYLINDER ENGINES : STARTING AND IGNITION SYSTEMS Larger engines can not be started by hand. Medium-size engines like those in cars and trucks are usually started by an electric motor. A gear on the starter motor shaft engages gear teeth cut around the edge of the flywheel. The starter motor turns the flywheel so that the intake-compression-ignition cycles take place. When the engine starts, the starter motor gear is automatically disengaged from the flywheel gear.

See figures 1 and 2.


Page 53

starter

gear

ear* starter motor

Figure 1

Figure2

The electric current to operate the starter motor is provided by the battery. The battery is a strong unit. When the engine is running, a pulley and belt connected to the crankshaft turn the generator. The generator produces electrical energy. Some of the electrical energy produced by the generator is stored in the battery. When the engine is stopped the generator does not produce electricity. Electrical energy must be taken from the battery to operate the starter motor to start the engine again. See figure 3 on the next page.

generat01

battery

Figure 3.- Electrical starting system When an engine has more than one cylinder, each cylinder is in a different cycle than the others cylinders. This means that the ignition must take place in the different cylinders at different times. The breaker points release the electricity at the correct time, then the

point

c distyributor hou§ing

Figure 4

distributor directs the electricity to the correct spark plug. When the breaker points open, the booster or ignition coil releases electricity to the distributor. The rotor (rotating switch) in the distributor makes the connection to the ignition wire leading to the spark plug in the cylinder that is in the compressionignition stroke. The distributor housing is attached to the top of the breaker point housing. They are usually located at the side of the engine. See figure 4.


Page 54

3

rotor

breaker

Figure 5.- Ignition system, 6 cylinder engine. Figure 5 is an illustration of the ignition system for a 6 cylinder engine. The ignition controls the flow of electricity from the battery to the system. In the illustration the breaker point housing has been separated from its position under the distributor housing so that the parts can be seen easily. The distributor has six connection points that the rotor contacts as it rotates (note that the firing order is 3-6-24-1-5). A separate ignition wire connects each spark plug to the correct switch point in the distributor. Cylinder 3 is shown in the drawing to illustrate the cylinder, piston, combustion chamber and and valve.

UNIT FIVE

Page 55


CLASSWORK ASSIGMENT : LESSON B The following exercises should be completed in class with the instructor's assistance .

v-belt

a

Figure 1 1. Look at figure 1. Fill in the blanks below : Figure 1 shows a a

starting system.

indicates

the indicates the C indicates the d indicates the

The

does not produce

energy when the engine is stopped. The provides electrical to start the engine.

a storage unit motor


Page 56

a

Figure 2 2. Look at figure 2. Fill in the blanks below : Figure 2 shows how the

a is the bis the starter motor

starting system operates. motor.

It engages gear

on the flywheel. When the starter

turns, the

gear causes the flywheel to When the flywheel turns, the

(d) also turns. This causes the cycles to take place.

3

6

Figure 3 3. Look at figure 3. Fill in the blanks below :


AUTOMOTIVE SPECIALIZED ENGLISH COURSE Figure 3 shows the a

system for a

Page 57 Page 58

cylinder engine.

indicates

the indicates the C indicates the d indicates the

e indicates the

(rotary switch).

f indicates the

chamber.

g indicates the

cid

a

Figure 4 4. Look at figure 4. Fill in the blanks below :

Figure 4 shows the

system of a

-cylinder engine.

a is the is the C and indicate the e the

indicates f

indicates the g is a

and the


Page 59 UNIT

COOLING SYSTEMS

OBJECTIVES 1 . Given a picture of an air cooled engine, the student will orally and/or in writing correctly identify the following parts:

- fins - heated air - cool air 2. Given a picture of a simplified radiator and core unit with the direction of flow indicated, the student will orally and/or in writing correctly identify the following features: - inlet - outlet - radiator cap - radiator - radiator core 3. Given pictures of various water cooling systems the student will orally and/or in writing identify the following features : - water pump - thermostat - inlet hose - outlet hose - water jacket - radiator core - radiator fan - strainer - cooler - antifreeze 4. Given a picture of a simplified forced-air cooling system, the student will orally and/or in writing identify the following features : - fan unit - fan housing - thermostat

- air ducts UNIT

COOLING SYSTEMS


Page 60

LESSON A 1. SIMPLE AIR COOLING SYSTEM The purpose of a cooling system is to remove heat from the engine. The heat is produced by the combustion process.

Figure 1 shows a simple air cooling system that we are already familiar with. As the cool air passes around the cylinder barrel it absorbs the heat from the metal. The metal is raised into fins so that more surface will be exposed to the cool air and more heat will be absorbed from the surface. See figu-

2. WATER COOLING SYSTEMS A simplified water cooling system is shown in figure 2. Heated water from the engine is forced into the inlet at the top of the Figure 1.- Air cooling radiator and through a series of small metal tubes that make up the radiator core. The tubes absorbs the heat from the water. Cool air passing between and around the tubes absorbs the heat from the surface of the metal tubes. By the time the water reaches the end of the tubes it has been cooled. The cooled water is returned through the outlet to the engine and is circulated around the cylinder and combustion chamber where it absorbs more heat. At that time it is circulated through the radiator again. See figure 2. heated (from

water i engine}letSIDE VIEW

heated


Page 61

core

cooled water Qulet (to engine)

cool air

Figure 2.- Water cooling

A simplified small engine water cooling system is shown in figure 3. The camshaft gear (or a crankshaft pulley in other engines) drives the water pump. The water pump pulls cooled water from the bottom of the radiator through the radiator hose and forces it into the engine. The water moves through the radiator jacket that carries the water around the cylinders and the combustion chamber. As the water passes through these areas it absorbs heat from the metal surfaces. The heated water is then forced through the upper radiator hose to the top of the radiator and through the radiator core. As the water passes through the radiator core it is cooled again and returned to the engine. See figure 3.

———-radiator cap

inlet hose

radiator

water acket radiator

Figure 3.- Water cooling (small engine) Cooling systems like one shown in figure 3 usually have an engine driven fan that moves air through the radiator core. As the air passes through the core, it absorbs the heat from the tubes that carry the water. The fan provides a continuous flow of air through the radiator core. UNIT SIX

CLASSWORK ASSIGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance


Page 62

1. Look at figure 1. Fill in the blanks below Figure shows 1 shows the main parts of a The radiator is used with acooled engine.

a indicates the indicates the c indicates the d indicates the e indicates the

Now look at the side view. Hot water from theenters the at the top of the the

It the metal absorbs from the The white arrows represent air. The cool passes around the metal and absorbs When the water reaches theof the radiator, it is much than it was when it entered at the The cooled

Page 63


back to the

is pumped from the engine. d

Fi ure 2 2. Look at figure 2. Fill in the blanks below a indicates the

It carries water

from the to the indicates the . It is removed if you want to add to the C

indicates the . It moves a continuous flow of through the radiator the water.

e indicates the . It carries water from the

to

the

f It pulls

indicates

the water

from


Page 64

and forces it through the g indicates the waterIt drives the water that circulates the water. water circulates water and absorbs from the walls and the

indicates the The through the chamber. UNIT SIX

COOLING SYSTEMS

LESSON : B 1. AUTOMOTIVE WATER COOLING SYSTEMS thermostat

inlet hose

adiator core

water oulet hose pump (cooled water)

Figure 1 Automotive cooling system The water cooling system used with automobile and truck engines is very similar to the small engine cooling system. The engine driven water pump pulls the cooled water from the radiator into the engine and circulates it through the water jacket. The heated water is then forced back into the radiator and through the core to be cooled again. The flow of water is controlled by the thermostat. The thermostat is an automatic control that releases water from the engine to the radiator when the engine is hot. When the engine is cold the thermostat holds the water in the engine until the engine reaches the correct operating temperature. The fan attached to the front of the engine is driven by a V-belt. See figure 1 and 2.

Water cooling systems for engines are limited by the characteristics of water. As you know, water boils and turns to steam, a gas, at 212* F, and freezes and turns to ice, a solid, at 32* F. The cooling system functions to keep the water from boiling by keeping the temperature of the water below 212* F. It does this by circulating the water through the radiator. The system can be protected

driven

Figure 2.- Engine driven fan


Page 65 from freezing by adding a liquid chemical, anti-freeze, to the water in the cooling system. The chemicals in the anti-freeze lower freezing point (temperature that a liquid freezes) of the water.

2. FORCED AIR COOLING SYSTEMS When we first talked about air cooled engines, we mentioned that they were frequently used in small airplanes. They are practical in this situation as there is a constant flow of cool air around the engine. However, air cooled engines are also used in automobiles, small trucks, boats and in small power tools. Since these engines do not move rapidly through the air like an airplane engine, it is necessary to mechanically force cool air to move around the engine. This is called forced air cooling because the air is forced to pass over the engine. An engine driven fan either pushes or pulls air into the large metal tubes called ducts. The ducts guide the air around and over the cylinder barrels and crankcase so that the engine is cooled. In some systems a thermostat unit controls how much air passes through the ducts. When the engine is hot the ducts are opened so more air can pass to cool the engine. See figure 3.

thermostat fan unit

crankcase

cylinder barrels

Figure 3.- Forced air cooling UNIT SIX

CLASSWORK ASSIGMENT : LESSON B The following exercises should be completed in class with the instructor's assistance ass istance

Page 66


b

Figure 1 1. Look at figure 1. Fill in the blanks below Figure 1 shows an water system.

type

a indicates the indicates the

from the to the

b

C indicates the It is an automatic control that releases to the when the engine isand holds water in the engine until the correct temperature is reached when the engine is d indicates the from the to indicates the f indicates the g indicates the

the

e

2. Water and turns to a gas at 212* F. The system operates to keep the water temperature below Water and turns to a solid, ice, at 32*F. When the engine is used in cold weather we add to the water. Anti-freeze is a chemical that the freezing point of water. If the water has at 32*F. the in it, it will not temperature will have to be before it freezes.


Figure 2

Page 67

Figure 3

3. Look at figures 2 and 3. Fill in the blanks below . Figure 2 shows an

cooled engine. The white arrows

indicate air. When the cool passes around the cylinder it absorbs

from the engine. The black arrows indicate theair.

a indicates

the The fins expose more to the air. This type cooling is often used forused in airplanes.

As the plane flies, Figure 3 also shows an not move through the system to move air cooling.

air passes around the engine. It does like an airplane engine, it needs a around the engine. This is called

AUTOMOTIVE SPECIALIZED ENGLISH COURSE a

indicates

the c It goes to the engine.

d indicates the

They guide the around the

Page 68

b indicates the indicates the controls how much


Page 69 Page 70 UNIT SEVEN

LUBRICATION SYSTEMS OBJECTIVES 1 . Given pictures of a splash lubrication system and of an automotive type pressure lubrication system, the student will orally and/or in writing correctly identify the following features : filler neck -

drain plug

-

oil

-

dipstick

-

sump

-

filter - thermostat - cooler

-

by pass - oil lines

-

oil passages

-

oil temperature gage - oil temperature gage

-

oil level

-

spray

-

grease

2. Given a task of explaining the main functions of a lubricant system, the student will orally and/or in writing state that the main function of any lubrication system is to reduce friction and as a second main function to cool the internal parts of an engine. UNIT SEVEN

LUBRICATION SYSTEMS

LESSON A 1. LUBRICANTS Lubricants are materials that reduce friction. The lubricants that are used in internal combustion engines are usually petroleum products such as oil or grease. The moving parts


Page 71

that contact each other are coated with lubricant to reduce friction. The lubrication system of the engine circulates oil to the moving parts so that they are continuously lubricated.

2. SPLASH LUBRICATION SYSTEM Most small engines such as the shown in figure 1, use a splash lubrication system. Lubricating oil is poured in the crankcase through the filler neck, until the crankcase is partially filled with oil. The dipstick, figure 2, is used to check that the amount of oil is correct. When the crankshaft turns the crankshaft throw (or certain kind of spoon) hits the oil and splashes (throws) oil around the inside of the crankcase and the lower part of the cylinder. Since the crankshaft rotates 2000 or 3000 revolutions per minute (RPM) the splashing is continuous and oil covers all surfaces. After certain length of time, 50-150 hours of engine operation, the drain plug is opened and the old oil is removed and replaced with clean oil.

cap and filter neck dipstick

full mark add 1 qt add 2 qt

oil

drain plug

Figure 1.- Splash lubrication

Figure 2.- Dipstick

3. PRESSURE LUBRICATION SYSTEM An automotive type lubrication system circulates oil to the various moving parts. Look at figure 3. The engine driven oil pump, a, pulls oil from the sump, h, through the oil strainer; c. The oil pump then forces the oil under high pressure (40-80 psi) through the oil filter, d. The oil filter removes dirt and small particles from the oil. The lines carry the high pressure oii to the parts that require lubrication. The oil sprays from small holes in the oil lines onto the parts that are to be lubricated. Special oil passages carry oil directly to the crankshaft

journals. The oil passages are holes in the metal of the engine block that lead to the journals. The oil forms a coat on the moving parts; the excess or extra oil falls from the parts and flows through holes in the block, back to the sump. The pumps pulls the oil from the sump and circulates it again. This type system is called a pressure lubrication system. The oil pump creates the pressure. • oil line to rockerarm shafts and rocker arms

oil line to

camshaft

oil passage

oil returning to the sump

Figure 3.- Oil flow in an utomobile engine


Page 72


Page 73

Much of the lubrication system is located inside the engine and can not be seen unless the engine is taken apart. The parts on the exterior or outside of engine are easy to see. Look at figure 4. Oil is added or replaced through the filler neck, a. When the oil is to be changed, the drain plug, b, in the sump, g, is opened so the old dirty oil can run out. The dipstick, d, is used to check the oil level to be sure that the engine has the correct amount of oil. The filter, e, is removed and replaced after a specific period of time. a and cap

sump

Figure 4.- Automotive lubrication UNIT SEVEN

CLASSWORK ASSIGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance.

2-3000

cb

Figure 1

Figure 2

1. Look at figures 1 and 2. Fill in the blanks below Figure 1 shows a lubrication system. When the crankshaft rotates, the of the crankshaft hits the oil and the oil around the inside of the and lower cylinder. a indicates the indicates the C indicates the the

level. d is

Oil is added to the system through the Oil is removed from the system by opening the

The

is used to check the

level.

Figure 2 shows a The mark indicated by a is the mark. If the oil is at this level, the amount of oil is in the engine. When the oil level is at mark b, quart should be to the oil. When the oil level is at mark C, quarts should be


Page 74

Figure 3 2- Look at figure 3. Fill in the blanks below . Figure 3 shows the

of an engine. This engine uses a lubrication system. The oil pump moves the oil under

a

indicates

the

The oil pump pulls oil from the Then the

indicates the g indicates the indicates the engine driven e indicates the f indicates the g indicates oil being from small holes in the oil lines. through the forces the oil through the

filter.

AUTOMOTIVE SPECIALIZED ENGLISH COURSE The The oil

removes dirt and small carry the oil to the parts that need

Extra oil runs off the parts; it returns to the the cylinder.

Page 75

through holes in


Page 76


Page 77 UNIT SEVEN

LUBRICATION SYSTEMS

LESSON B 1. OIL COOLING Oil reduces heat in an engine because it is a lubricant and it reduces friction that causes heat. Oil has a second cooling function. It is a liquid and it circulates through out the engine. As it circulates it absorbs heat from the metal part it contacts. This action contributes to the engine cooling procces. However, as the oil becomes heated it loses some of its lubricating characteristics. Some engines are built with an oil-cooling system so that the temperature of the oil can be controlled. Simple systems used in automotive-type engine may use an air-cooled cooler to cool the oil, larger engines may use a water cooled cooler. The system shown in figure 1 uses an air - cooler. The thermostat unit directs the oil through cooler when the oil is too hot. When the oil is not over-heated it does not go to the cooler, but is directed through the bypass and into the normal lubrication system. The thermostat and bypass are shown outside the engine in the illustration. The cooler usually is located in the front of the engine area, so that cool air will pass around the tubes in the core. oil pressure gage

oil temperatursgage

cooler

auto atic temperature control (thermostat)

Figure 1.- Air cooled oil cooler 2. INSTRUMENTS Large engines usually have instrumentc to show the temperature and pressure of the lubricating oil. The gage or instrument that shows pressure is called the oil pressure gage. It indicates whether the oil pump is maintainig the correct pressure in the oil lines. The gage that shows the oil temperature is called the oil temperature gage. It indicates whether the


Page 78

oil cooling system is functionig correctly or not. The oil pressure gage reads in PSI. The oil temperature gage may marked either in degress Fahrenheit or degrees centigrade.

Figure 2.- Pressure gage

Figure 3.- Temperature gage UNIT SEVEN


1. The oil in the lubrication system is a liquid. It is circulated through the The oil is in contact with parts. The oil heat from the metal it lubricates. The oil helpsthe engine.

Too much heat changes the

When it is too hot, it does not

the parts as well as it should. Some engines have an oil

to reduce he temperature of the oil.

a

Figure 1 2. Look at figure 1. Fill in the blanks below : This engine has the oil a g indicates the indicates the f indicates the

anto cool indicates the indicates the d indicates the oilgage. e indicates g indicates the b


Page 79


Page 80

Figure 2 3. Look at figure 2. Fill in the blanks below : Figure 2 shows theof an engine that has an oil a indicates

the indicates the C indicates the d

indicates the

oil

e

indicates the or automatic

f

indicates the

g indicates the

indicates

the

h

i

indicates

When the oil is too hot the the thermostat directs the so it enters thesystem and does not go through the

the

oil

directs the oil to the If the oil temperature is not hot, through the


Page 81 UNIT EIGHT

DIESEL FUEL SYSTEMS OBJECTIVES

1 . Given the task to describe fuel oil, the student will orally and/or in writing state that fuel oil is a liquid petroleum product that is thicker and heavier than gasoline.

2.

Given a picture of a distribuion- type diesel fuel system the student will orally and/or in writing correctly identify the following features . - tank - fuel supply lines - fuel supply pump - injection nozzles - filter

- fuel pipe

- injection pump - excess fuel return line 3. Given the task to identify the main functions of the injection pump, the student will orally and/or in writing state that: - It pressurizes the fuel for injection. - It meters or measures the fuel. - It distributes the fuel. - It controls the timing of the injection/ignition. - It provides pressure to atomize the fuel. 4. Given pictures of the fuel injector unit and unit injector fuel system, the student will orally and/or in writing identify the following features: -

fuel injector - fuel supply tank or service tank

-

inlet line

- strainer

-

outlet line

- fuel filter - tip

-

plunger

- injectors

- fuel supply pump UNIT EIGHT

DIESEL FUEL SYSTEM


Page 82 Page 83

LESSON A 1. FUEL Diesel or compression engines do not use gasoline as a fuel. Diesel engines use fuel oil for fuel. Fuel oil, or diesel oil as it is sometimes called, is a liquid petroleum product that is thicker, heavier, and usually cheaper than gasoline. Gasoline is made so it will mix easily with air in the cylinder and produce a fuel air mixture that is easy to ignite with the small, quick electrical spark from the spark plug. This feature, which makes gasoline a good fuel, also makes it an extremely dangerous liquid. It is easy to ignite; it is a flammable liquid. Gasoline evaporates (changes to a vapor) quickly and easily. The gasoline vapors, or gasoline fumes, mix with air and produce a fuel air mixture that can be ignited by a spark, flame, cigarrette, or hot surface. When ignition occurs, the gasoline fuel-air mixture explodes and burns just as it does in the engine cylinder. There is always a posibility of fire or explosion any where that gasoline is used or has been used recently. gasoline vapor fumes

or

Figure 1 Diesel oil or fuel oil, is not a dangerous fuel. It is not flammable in the same sense as gasoline; fuel oil will burn but it is difficult to ignite. Fuel oil fumes or vapors are not easy to ignite like gasoline. Diesel oil or fuel oil is a safe fuel; this and other advantages of diesel engines makes them advantageous for use in trucks, buses, trains, and ships. Diesel engines are used in comercial vehicles and factories because they are le ss costly to operate. The fuel itself is cheaper than gasoline and the diesel engines consume or use less fuel than gasoline engines. The fuel cosumption of a diesel engine is usually much less than a similar size gasoline engine.

2. INJECTION PUMP (DISTRIBUTOR TYPE) FUEL SYSTEM

The fuel system of a diesel engine is easy to understand if it is compared to the fuel system and the ignition system of a spark-ignition gasoline engine. The diesel fuel system performs both functions. h excess fue; return line

fuel

injection pump

supply lines

Figure 2.- Diesel engine fuel system (distributor type) Figure 2 shows one type of diesel engine fuel system. a, the tank; b, the fuel supply pump; g, the fuel line; and d, the fuel filter are all similar to the fuel system of the gasoline engine. The fuel supply pump moves fuel oil from the tank through the fuel line to the fuel filter. e the injection pump; f the fuel supply line and g the injection nozzles, are similar to the ignition system of the gasoline engine. The injection pump, Wich resembles a distributor, functions like a distributor. It sends the correct amount of fuel oil to the correct cylinder at the correct time form ignition. The fuel supply line function like ignition wires; they carry the fuel oil from the injection pump to each cylinder. The injection nozzles are placed in each cylinder. The injection nozzles spray the fuel oil into the cylinder at the correct time for ignition by the compressed air. b the excess fuel return line carries the extra unused fuel back to the fuel tank.


fuel supply pump

strainer

filter

Page 84

fuel supply lines

nozzles

Figure 3.- Schematic drawing of diesel fuel system Figure 3 is a schematic drawing of a diesel fuel system like the one shown in figure 2. A schematic drawing does not directly show the real system, it just indicates how the components work in the system. The system above is a dual (two) pressure system. The low pressure fuel supply pump pulls fuel from the tank and forces it through the strainer and the filter to the high pressure injection pump. The high pressure injection pump is the most important unit of this type system. It performs the following function. A - B. The injection pump pressurizes (puts under pressure) the fuel oil. The fuel oil must have higher pressure than the compressed air in the cylinder so it can be forced into the cylinder. The pressure of the compressed air in the cylinder of a diesel engine is very high (500-600) PSI or more); the fuel pressure must be higher. The high pressure is also necessary to atomize, or break the fuel intto small particles as it is sprayed into the combustion chamber. When the fuel is forced through the small holes in the tip or end of the injection nozzle under high pressure it is atomized and mixes with the air. C.

The injection pump meters or measure the fuel so that the correct amount of fuel is sprayed into the cylinder.

D.

The injection pump distributes the fuel to each of the cylinders.

E.

The injection pump cont?ols the timig of the injection so that ignition takes place at the correct time. The injection nozzles are simple one way or check valves that atomized and spray the fuel into the cylinder. UNIT EIGHT

ÃUTOMOTIVE SPECIALIZED ENGLISH COURSE AUTOMOTIVE SPECIALIZED ENGLISH COURSE

Page 85 Page 86

CLASSWORK ASSIGMENT : LESSON A The following exercises should completed in class with the instructor's assistance:

1. Look at the figure 1. Fill in the blanks below :

b.

Gasoline

a. Spark ignition engines use

dangerous than diesel oil. When gasoline is in a open container it will or change to a vapor. The vapors are also called Gasoline easily. The

ignites it can

mix with air quickly and

fume-air mixture can be ignited, with a spark, , cigarrete or hot When it

and burn like it does in a combustion

of an engine. Gasoline vapors are dangerous because they Gasoline and its fumes arematerials the are easy to ignite. The situation in figure 1 is very

some one must put the


Page 87

He should open a door orso the will blow away.

h

Figure 2

a

e

2. Look at figure. fill in the blanks below :

Figure 2 shows a

a is

type diesel engine fuel system.

the

is

is a is the

the e is f indicates the g indicates the

h indicates the The injection pump is very important.

a. It b. It c. It

the fuel for injection (puts under pressure). the fuel (messure). the fuel to the correct cylinder.

b It controls the of the ignition / injection. e. It provides the pressure to

the fuel when it is sprayed into the cylinder.

the

The fuel supply pump is a The fuel injection pump is a

pressure pump. pressure pump.


Page 88 UNIT EIGHT

DIESEL FUEL SYSTEMS LESSON B 1. FUEL INJECTOR (UNIT INJECTOR TYPE) FUEL SYSTEM The injection pump or distributor-type fuel system isn't used on all diesel engines. A few engines use a unit injector-type fuel system. See figure 1. The unit injector system is a low-pressure system. The low pressure fuel supply pump moves the fuel from the tank through the filters to the fuel injectors in each cylinder. The fuel injectors are small mechanically operated pumps that pressurize, meter, and atomize the fuel as it is injected into the cylinder. As each cylinder has its own fuel injector unit that performs these functions, it is called a unit injector type system.

rocker arm

unit

The fuel injectors are operated mechanically by cams on the camshaft that lift pushrods to move the camkshaft gear rocker arms. The distribution and timing, or gear injection into the correct Figure 1.- Unit injector cylinder at the correct time, is controlled by the camshaft much like the opennig and closing of the valves is controlled. One advantage of the system is that the fuel oil is not under high pressure until it is actually injected into the cylinder. The fuel supply line, the small inlet and outlet lines, and the excess fuel return line can be made of lighter materials because they don't have to withstand high pressure.

line

plunger

outlet line

Figure 2.- Fuel injector

Figure 3.- Unit injector fuel system


Page 89

Page 90

Figure 2 shows an enlarged view of a fuel injector. The outlet line carries the excess fuel from the injector. Fuel is sprayed from the tip into the cylinder when the plunger is pushed by the rocker arm. Figure 3 shows a schematic of a unit injector fuel system. The low pressure fuel supply pump moves the fuel from the tank through the strainer and filter to the injectors. The small inlet lines carry fuel from the fuel supply line to the injector. The small outlet lines the excess fuel from the injector to the excess fuel return line. The mechanical system that operates the plungers is shown in figure 1. UNIT EIGHT


1. Look at figure 1. Fill in the blanks below :

AUTOMOTIVE SPECIALIZED ENGLISH COURSE Figure 1 shows the mechanical parts of a type diesel engine fuel system. a indicates the indicates the C indicates the indicates the e indicates the f indicates the g indicates the

j indicates the

gear. gear. d

h indicates the line i indicates the line. of the fuel injector. d

Figure 2 shows an enlarged view of a a indicates the line. indicates the g indicates the line. d indicates the

When the rocker arm pushes the fuel it is injected into the

Figure 2

Page 91


Page

92

Fi ure 3 Figure 3 shows the fuel system of a type diesel fuel system. a

is

the is the is the d is the

e is the f and g are

h is an

line.

j is anline. i is the

UNIT NINE


Page 93

GEARS AND TRANSMISSIONS

OBJECTIVES 1. Given a composite picture showing the different sets of gears, the student will orally and/ or in writing state the four main functions of gears as follows:

- Gears are used to change direction. - Gears are used to increase force. - Gears are used to magnify speed. - Gears are used to change direction of rotation. 2. Given pictures of various kind of gears, the student will orally and/or in writing identify the following features . drive gear - driven gear idler gear

gear train

-

gear case

gear box bevel gear

3. Given cutaway pictures of a typical three speed transmission and of a differential, the student will orally and/or in writing identify the following parts :

-

clutch shaft propeller shaft shifter shaft countershaft

-

countershaft gears sliding gears shifting forks - gear shift lever pivot

axles bevel drive gear bevel ring gear differential gear unit UNIT NINE



Page 94


Page 95

LESSON A 1. GEARS Gears are often used in series. A series in gears is called a gear train. See figure 1.

driver

Figure 1.- Gear train In figure 1, gear a, the driver gear, turns gear h. Gear g is attached to the side of gear and turns with it. As gearþ turns, gear causes gear d to rotate. Gear d then turns gear e. Arrangements of this type allow large changes in speed or force to be made in relatively small space. If you look ciosely at the arrows in figure 1 , you can see that each driven gear turns in the opposite direction of the gear that drives it. When it is desire that the drive gear and the driven turn in the same direction, an idler gear is put between them. See figure 2. idler driver gear gear

driven

Figure 2.- Idler gear Gear trains and series of gears are usually enclosed in a case that supports the gear shaft, protects the gears from dirt, and holds the lubricant that lubricate the gears. This container is called a gear box or gear case. See figure 3.


Page 96

Figure 3.- Gear box (top removed) Gears are used to perform four main functions :

1. Gears are use to change direction of rotation. As we have already seen, when two gears are meshed they turn in opposite directions. See figure 4a. 2.

Gears are use to magnify, or increase, force. When a drive gear is smaller than the driven gear, the force of the driven gear is increased. See figure 4b.

3.

Gears are used to magnify, or increase speed. When a drive gear is larger than the driven gear the speed of the driven gear is increased. See figure 4c.

4.

Gears are used to change the angle of rotation. When gears are cut on a bevel the rotation force of the one shaft can be converted to rotation force on another shaft that extends at a different angle. See figure 4d.

a. Idler gear used to change direction of rotation.

. Magnifying force with gears.

c. 'creasing speed with gears

. Changing angle of rotation with gears. Figure 4 UNIT NINE

CLASSWORK ASSIGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance •

AUTOMOTIVE SPECIALIZED ENGLISH COURSE 1. Lookat figure 1. Fill

Page 97

the

below.

output

input

Figure 2 Gear a provides the input, it is called thegear.

Gear provides the output; it is called the Gear g is called an Gear g is use so that gear will rotate in the same direction as gear

The of rotation.

gear is used to change the

gear.


Page 98

a input

Figure 3

Figure 4

3. Look at figure 3. Fill in the blanks below. Gear a is called thegear. Gear b is called the

gear.

The gear is larger than the This arrangement is use to

gear.

4. Look at figure 4. Fill in the blanks below. Gear a is called the Gear is called the The

gear. gear. gear is larger than the

gear.

This arrangement is use to

5. Look at figure 3 and 4. Fill in the blanks below. The gears in figure 3

The gears in figure 4 If the speed is increased, the

decreased.

force.

speed. per revolution is

AUTOMOTIVE SPECIALIZED ENGLISH COURSE AUTOMOTIVE SPECIALIZED ENGLISH COURSE If the force is increased, the

Page 99 Page 100

per revolution is

In figure 3 and 4, the driven gears rotate in the direction of the drive gear. The gears have changed the of rotation.

6. Look at figure 5. Fill in the blanks below. Figure 5 shows a pair of gears. When bevel gears are used, theof

the

rotation

is changed. The driver, gear is smaller than the gear. This set increases and changes the angle of

Figure 5

Gears are used to perform four main functions:

b. To

UNIT NINE


LESSON B 1. TRANSMISSION The gear box of an automobile is called a transmission. Figure 1 shows a simplified three-speed automobile transmission or gear box. At the left side of the picture is the clutch


Page 101

shaft. The clutch shaft is rotated by the engine. There is a gear attached to the clutch shaft inside the transmission. The gear on the clutch shaft is meshed with the gear on the countershaft. The countershaft is the shaft at the bottom of the transmission. When the gear on the clutch shaft turns, it causes all of the countershaft gears to turn. Now look at the right of the transmission. The shaft at the right is the propeller shaft. The propeller shaft delivers the turning force to the wheels. There are two gears attached to the propeller shaft inside the transmission. They are called the sliding gears. The sliding gears can move or slide forward and backward on the splined propeller shaft. Now look at the top of the picture. The pivoted lever that is used to move the slinding gears is called the gear shift lever. If the top of the gear shift lever is pushed forward, the bottom of the lever will move to the rear. The bottom of the gear shift lever to the shifter forks. When the bottom of the gear shift lever moves, it slides the shifter forks on the shifter shaft. The shifter shaft is the shaft in the top of the transmission. Then when the shifter fork moves to the rear, it slides the sliding gear to the rear so it meshes with the countershaft gear. When the two are meshed, the rotation of the countershaft gear will be transmitted to the propeller shaft.

countershft gears

Figure 1.- Transmission


Page 102

clutch

rear wheels

Fi ure 2 2. DIFFERENTIAL Figure 2 shows the typical location of the transmission in a car or a truck. The propeller shaft connects the transmission to the differential located between the rear wheels. The differential is a special gear unit that adjusts for the difference in the speeds of the two rear wheels that occurs when the car or truck makes a turn. When the vehicle turns, the outside rear wheel travels a longer curve than the inside wheel. As it travels the longer distance in the same length of time, it in fact travels faster. The main parts of a differential are shown in figure 3. The bevel drive gear is attached to the end of the propeller shaft inside the differential case. The bevel drive gear turns the bevel ring gear. The bevel ring gear rotates the differential gear unit. The differential gear unit turns the axle shafts that the rear wheels are attached to.

differential gear unit

drive gear

Figure 3

shaft

UNIT NINE


Page 103


Page 104


rear wheels

b

front wheels

Figure 1 1. Look at figure 1. Fill in the blanks below. Figure 1 shows a typical truck frame. a indicates the b indicates the and d indicates the two delivers

the

shaft, g indicates the

shafts. The

power

from the The diferential is used to turn the for the difference in wheel

wheels. It also

when

vehiclesmakes

2. Look at figure 2. Fill in the blanks below. Figure 2 shows a typical a indicates the indicates the C the d indicates the e indicates the f indicates the

g indicates the

indicates

h indicates the i indicates the i indicate the

d

Figure 2


Page 105 Page 106

Figure 3 3. Look at figure 3. Fill in the blanks below. Figure 3 shows a simplified a indicates the indicates the g indicates the d indicates the e andf indicate

that provides the power.

UNIT TEN

ENGINE SPECIFICATIONS OBJECTIVES 1. Given schematic drawings of piston-cylinder units, the student will orally and/or in writing correctly identify the following terms.

-

specifications

AUTOMOTIVE SPECIALIZED ENGLISH COURSE -

bore - OHV - inch

-

stroke

-

TDC (top dead center) BDC (bottom dead center)

-

firing order

-

net brake horsepower

-

net torque

-

regular gasoline

Page 107

engine displacement - compression ratio

UNIT TEN

ENGINE SPECIFICATIONS

LESSON A 1. SPECIFICATIONS, GENERAL Internal combustion engines are usually described by listing certain information about the engine. This information is referred to as the specifications of the engine, or the engine specifications. It is a list of the specific (exact) technical information that describes the important features of the engine. Figure 1 illustrates part of the engine specifications of a typical automotive type engine.

Specifications Engine Type

4 cycle, water cooled

(2) No. Cylinders 6 cyl. inline OHV 3. 750" (3) Bore (4) Stroke (5) Displacemnet 232 cu. in. 8. 0 : 1 (6) Compression ratio

1 (7) Firing order (8) Net brake horse power

-5-3-6-2-4 100

3600 RPM

(9) Net torque 185 lb-ft @ 1800 RPM Regular gasoline (10) Fuel

Figure 1 (l) Type

4 cycle. water cooled

The engine is a four-stroke cycle, water-cooled engine.

AUTOMOTIVE SPECIALIZED ENGLISH COURSE (2) No. cylinders

Page 108

6 cyl. inline. OHV

No. is the abbreviation for number, the entry reads number (of) cylinders. This is a 6 cylinder engine. The cylinders are arranged inline. OHV is the abbreviation for overthead valves. The full line tells you this is a six cylinder inline overthead valve type of engine.

(3) Bore 3. 750" Bore refers to the diameter of the cylinder. "is the mark that indicates the measuremnet is in inches. The diameter of the cylinder is 3. 750 inches.

(4) Stroke 3. 50" Stroke refers to the distance the piston moves in the cylinder. The piston of this engine moves 3. 50 inches. The stroke is measured from the piston position when the piston is at the lowest point in the cylinder, to the piston position when the piston is at the highest point in the cylinder. The lowest point piston position is called bottom dead center (abbreviation BDC). The highest piston position is called top dead center (abreviation TDC). The stroke is the distance the piston moves from the bottom dead center position to the top dead center position.

Top dead center

BOC Bottom dead center

Figure 2 (5) Displacement

232 cu. in.


Page 109

The word displacement, or engine displacement, refers to volume of the cylinders, measuring from the bottom dead center position to the top dead center position. The displacement of an engine can be calculated by using the specifications of the bore and the stroke. The displacement of this engine is 232 cubic inches. The formula for determining the volume of a cylinder is shown in figure 3. 3,750

cylinder

3.50"

displacement of cylinder

BDC

Volume- xr 2 x height 3.750 = 1.875 (radius) x 1.875" 3.516 x 3.14 ( 7 ) 11.040 (area of bore) x 3.50 (stroke) 38.640 (vol. 1 cyl.)

(no cyl.) 231.84" (vol 6 cyl.) (displacement)

Figure 3.- calculation of displacement. Note: In the countries that use the metric system, bore and stroke measurements are stated in centimeters (cm) millimeters (mm). Engine displacement is stated in cubic centimeters or in liters. The displacement of this engine would be 3803 cubic centimeters or 3. 803 liters in the metric system.


Page 110

(6) Compression ratio 8.0 : 1 A ratio is a mathematical comparison. If one object is 10 inches long and the other object is 2 inches long, we can say the first object is five times as long as the second object, or we can write the ratio 5 : 1. The compression ratio of an engine compares the amount of space in the cylinder when the fuel air mixture is compressed in the combustion chamber (TDC) with amount of space in the cylinder when the piston is at the lowest point (BDC). The compression ratio tell us how much the fuel air mixture is compressed in the cylinder. The amount of space at TDC ia always given the value of 1. In this engine 8.0 is the volume at BDC and 1 is the volume TDC. Eigth volume units of fuel air mixture are compressed into the space of one volume unit. Figure 4 shows the relationship for an engine having a 6 : 1 compression ratio. combustion

combustion chamber

TOTAL VOLUME

chamber total volume at T.D.C.

AT D.D.C.

a Start of compression

b End of compression atroke (BDC) stroke (TOC)

Figure 4.- Compression ratio 6.0 : 1

(7) Firing order 1 - 5 - 3 - 6 - 2 - 4 Firing order tell us the order or sequence of ignition in the six cylinders. Cylinders are usually numbered starting from the front of the engine in this engine, cylinder No. 1 receives ignition first, then cylinder No. 5, then cylinder No. 3 etc. The order of ignition is distributed so that the engine will vibrate or shake as little as possible. The order of ignition also tells us how the ignition wires are arranged in the distributor. (8) Net brake horsepower 100 HP @ 3600 RPM You learned that horsepower is a measurement of power equal to 33,000 foot-pound of work in one minute. Although the figure for horsepower is fixed, the method for measurement can vary. In our lessons on simple machines we talked abauttheorical mechanical advantage, and we mentioned that friction reduces the actual amount of output work. Net horsepower refers to one method of measuring the actual, not theorical, output of work. The engine develops 100 hp when it is operating at a speed of 3600 revolutions per minute. The symbol @ means at.


Page 1 1 1


Page 112

(9) Net torque 185 lbs-ft @ 1800 RPM When you studied the simple wheel and axle and crank and axle machines you learned that turning force is called torque. We know that this type of l.c. engine delivers power in the form of a rotating shaft, the crankshaft. Net torque is the actual not theorical amount of power delivered through the crankshaft. This crankshaft provides 185 lbs-ft of turning force or torque when the engine is operating at 1800 revolutions per minute.

(10) Fuel Regular gasoline The fuel used in this engine is regular gasoline. Gasoline is made in several different mixtures so it can be used in different types of engines. Regular gasoline is one of the mixture that is made. It is important that the correct fuel be used in an engine. The type of fuel used is one of the important engine specifications. UNIT TEN

CLASSWORK ASSIGMENT : LESSON A The following exercises should be completed in class with the instructor's assistance :

1. What do we call the list of specific thechical information that describes an engine ?

2. The first two line of an engine specifications reads as follows : Type No. cylinders

4 cycle water cooled 8, V-block, OHV

Write out the full description based on the information given.

3. What does the word "bore" mean in reference to an engine?

4. The engine specification reads: Bore Write out what this means.

5. Look at figure 1. Write your answer in the spaces provided. Figure la shows the piston in the center position; the abbreviation for this

Figure 1b shows the piston in the center position; The

abbreviation for this is

in figure la:

(1) indicates the (2) indicates the (3) indicates the The space indicated by (4) is the The word "stroke" refers to moves from the

thethe

center position (abbr.

to the

center position (abbr.

The arrow at (5) indicates the The arrow at (6) indicates the Figure lc shows the cylinder that would be represented by the

piston


Page 113


Page 114

and

of the engine cylinder. (7) indicates the diameter or , (8) represents the height or

(9) is the formula for calculating theof a cylinder.

If we know the bore or

of the cylinder, and the stroke or of the cylinder, and we have the formula given, we can calculate

the volume or

of one cylinder. If we multiply the displacement

of one cylinder by the number of cylinders the engine has, we will have the

of the engine.

6. If a V-8 engine has a displacement of 320 cubics inches, each cylinder has a displacement of

7. Look at the figure 1. Fill in the blanks below. The compression ratio an engine compares the volume of thewhen the piston is in the bottom

position.

If the compression ratio of this engine is 8.0 : 1, figure 1b shows the space represented by the numberand figure la shows the space represented by the . (The volume chamber at T always equals of the1 in the ratio).

8. If the firing order of a V-6 engine is 1-5-3-6-2-4, Which cylinder receives ignition firts? No. Which cylinder receives ignition last ? No. Which cylinder receives ignition after cylinder number 4? No.

9. Does net horsepower refer to the theorical : horsepower or to the actual output?

Ingles Tecnico Para Mecanica Automotriz

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