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TCE, Dept. Mech. EngineeringBasic Mechanical Engg. Course material (Private Circulation only)

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THIAGARAJAR COLLEGE OF ENGINEERING, MADURAI625 015.(A Govt. Aided Autonomous Institution Affiliated to Anna University)

DEPARTMENT OF MECHANICAL ENGINEERINGCOURSE PLAN

Degree: B.E./B.Tech. Semester: I Branch: All Branches Section: All

Sub. Code: H15 Subject Name: Basics of Mechanical Engineering

Dept. of Staff: Mechanical Engineering

OBJECTIVE: To impart knowledge on basic concepts of energy sources, I.C.Engines,

packaged power plant and design and manufacturing of automotive transmission system.

Sl.No. Topics No. of

Periods

Methodology Dates

engaged

1. History and Evolution of Mechanical

Engineering

1 BB

2. IntroductionStress, strain, factor of safety 1 BB

3. Elements of Transmission Systems -

Fundamentals

1 BB

4. Clutch - Concept design 1 BB

5. Clutch - Manufacturing 1 BB

6. Gear Box - Concept design 2 BB

7. Gear Box ( Housing ) - Manufacturing 1 BB

TEST - I8. Propeller ShaftConcept design 1 BB

9. Propeller Shaft - Manufacturing 1 BB

10. Final Drive - Concept design 1 BB

11. Final Drive - Manufacturing 1 BB

12. Differential - Concept design 1 BB

13. Differential - Manufacturing 1 BB

14. Axle - Concept design 1 BB

15. Axle - Manufacturing 1 BB

TEST - II

16. Laws of Conservation of Energy & Sources

of Energy

1 BB


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17. IC Engine - 2 Stroke IC Engine (Petrol &

Diesel)

2 BB

18. IC Engine - 4-Stroke IC Engine (Petrol &

Diesel)

2 BB

19. Packaged Power Plant 1 BB

20. Petrol / Diesel Engine Power Plant 1 BB

21. Electrical Generator 1 BB

TEST - III

* - ( BB- Black board; OHPOver Head Projector; PP-Power Point;)

OUTCOME:At the end of the course the students should be able to,

Explain the history and evolution of mechanical engineering

Design the transmission system of an automobile

Suggest a suitable method of manufacture of automotive transmissionelements

Explain the construction and operation of packaged power plant.

REFERENCES:

1. N.K. Giri, Problems in Automotive Mechanics, Khanna Publishers, New Delhi, 20042. N.K. Giri , Automotive Mechanics, Khanna Publishers, New Delhi, 19893. Kirpal Singh, Automobile Engineering, Volume I, Standard Publishers, New Delhi,

1997

4. V. Ganesan, Internal Combustion Engines, Second Edition, Tata McGraw HillPublishing Co Ltd, New Delhi, 2003

5. B.L. Theraja, Elements of Electrical and Mechanical Engineering, S. Chand & CoLtd, India, January 1999.

6. Shanmugam G. and Palanichamy M.S., Basic Civil and Mechanical Engineering,

Tata McGraw Hill Publishing Co., New Delhi 1996.7. Mohan Sen, Basic Mechanical Engineering, Laxmi Publications ( P ) Ltd, New Delhi,2006

8. Hajra Choudhury, Elements of Workshop Technology, Vol.I and II, KhannaPublishers, New Delhi, 1988.


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1. History of Mechanical Engineering

The words engine and "ingenious" are derived from the same Latin root,

"ingenerate", which means "to create". The early English verb engine meant "to

contrive". Thus the early "engineers" were the people who contrived (i.e. invented) new

things.

The history of mechanical engineering can be traced directly to the ancient world,

to the designers and inventors of the first mechanisms which were powered by human or

animal labour, water or wind energy, or a combination of these. Although many of the

mechanisms had a purely peaceful application, such as for flight, irrigation or building,

the word "engineer" originally meant "military engineer" because it was derived from the

term "engines of war". These were machines such as catapults, floating bridges and

assault towers. The invention of the steam engine in the latter part of the 18th century

provided a key source of power for the Industrial Revolution and gave enormous impetus

to the development of machinery of all types. As a result, a new major classification of

engineering dealing with tools and machines, namely mechanical engineering, received

formal recognition in 1847.

Today's mechanical engineer is heavily involved in the development and use of

new materials and technologies, especially in computer aided engineering. A rapidly

growing field for mechanical engineers is environmental control, comprising the

development of machines and processes that will produce fewer pollutants, as well as the

development of new equipment and techniques to reduce or remove existing pollution.

Although mechanical engineers may occasionally work alone on a small project, they are

more likely to be working on large, multi-disciplinary projects, liaising with specialists

from other areas.

In almost every sphere of modern life, from the air-conditioned office or home to

the modern industrial plant or mode of transport, one sees the work of mechanicalengineers who continue to develop and apply new knowledge and technology to improve

the quality of life for society as a whole.

What Does a Mechanical Engineer Do?

The professional discipline of mechanical engineering is concerned with the design,

development and manufacture of machines and mechanical engineering systems. These


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include engines and turbines of various kinds, land transport vehicles, ships, aircraft,

pumps and fans, air-conditioning and refrigeration systems, building services, industrial

plants, and manufacturing processes. However, practically all areas of engineering make

use of the skills of the mechanical engineer to some extent. Mechanical engineers offer

expertise in the fields of energy technology, combustion, acoustics, noise and vibration

control, biomedical engineering, fluid mechanics and aeronautics, automatic control,

manufacturing, robotics, quality management, plant layout and process simulation. Good

mechanical engineering is built on a strong foundation of theory, reinforced by an

amalgam of experience and innovation.

Today's mechanical engineer is heavily involved in the management of people

and resources as well as the development and use of new materials and technologies,

especially computer-aided engineering. A rapidly growing field for mechanical engineers

is environmental control, comprising the development of machines and processes that

will produce fewer pollutants, as well as the development of new equipment and

techniques to reduce or remove existing pollution. Mechanical Engineers are committed

to the use of technology to improve the quality of life for society as a whole.

2. AUTOMOBILE TRANSMISSION SYSTEMS - DESIGN

Introduction

Stress and Strain

All machine parts are subjected to forces, which arise due to one or more of the

following:

Self weight, External forces, Energy transmission, Frictional resistance, Inertia of

parts and change of temperature.

Stress can be described as a measurement of intensity of force. As all engineers

know, if this intensity increases beyond a limit known as yield, the component's material

will undergo a permanent change in shape or may even be subjected a to dramatic failure.When forces act on a body, resisting forces are set-up within the body. These

forces per unit area are called Stresses. It is essential to determine the values of internal

stresses set-up so as to ensure an adequate factor of safety. Stresses due to tensile force,

compressive force, shear, bending moment and thermal effects are discussed here.


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Tensile Stress

When a body is subjected to two equal and opposite axial pulling forces, F-F as

shown in fig. , the stress induced at any section A-A of the body is known as tensile stress

and the corresponding strain, the tensile strain.

t

Compressive StressWhen a body is subjected to two equal and opposite axial pushing forces, F-F as

shown in fig. , the stress induced at any section A-A of the body is known as compressive

stress and the corresponding strain, the compressive strain.

t

Shear Stress

When a body is subjected to two equal and opposite forces, F-F acting

tangentially across the resisting section as a result of which of the body tends to shear off

at the section; the stress induced is known as shear stress and the corresponding strain,

the shear strain.

F F

F F

F F

F F


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Thermal StressChanges in temperature will produce the thermal effects on materials. Some of these

thermal effects include thermal stress, strain, and deformation. The first effect we will

consider is thermal deformation. Thermal deformation simply means that as the "thermal"

energy (and temperature) of a material increases, so does the vibration of its

atoms/molecules; and this increased vibration results in what can be considered a

stretching of the molecular bonds - which causes the material to expand. Of course, if the

thermal energy (and temperature) of a material decreases, the material will shrink or

contract. For a long rod the main thermal deformation occurs along the length of the rod,

and is given by:

where, (alpha) is the linear coefficient of expansion for the material, and is the

fractional change in length per degree change in temperature.

Some values of the linear coefficient of expansion are:

Steel = 12 x 10-6/oC = 6.5 x 10-6/oF;

Brass = 20 x 10-6

/oC = 11 x 10

-6/oF;

Aluminum = 23 x 10-6

/oC = 13 x 10

-6/oF.

The term is the temperature change the material experiences, which represents

(Tf - To), the final temperature minus the original temperature. If the change in

temperature is positive we have thermal expansion, and if negative, thermal contraction.

The term 'L' represents the initial length of the rod.

StressStrain DiagramVery useful information concerning the behavior of material and its usefulness for

engineering applications can be obtained by making tensile test and plotting a curve

showing the variation of stress with respect to strain. Tensile test is one of the simplest

and basic tests and determines values of number of parameters concerned with

mechanical properties of materials like strength, ductility and toughness.

F

F

F

Q = FF

F


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The specimen used in tensile test can be circular, square or rectangular cross section. The

standard gauge length is given by:

A65.5

where, A is the cross-sectional area of the specimen.

= 5 d for circular cross section.

In tensile test, the specimen is subjected to axial tensile force which is gradually

increased and corresponding deformation is measured. Initially the gauge length is

marked on the specimen and initial dimensions d and are measured before starting the

test. The specimen is then mounted on the machine and gripped in the jaws. It is then

subjected to axial tensile force which is increased by suitable increments. After each

increment, the amount by which the gauge length increases. The procedure of

measuring the tensile force and corresponding deformation is continued till fractureoccurs and the specimen is broken into two pieces. The tensile force divided by the

original cross-sectional area of the specimen gives stress, while the deformation divided

by gauge length gives the strain in the specimen.


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Factor of Safety

Factor of safety is defined as the ratio of maximum stress to working stress.

Working stress is defined as safe stress which the machine part is subjected to. It is

usually lower that the maximum stress at which failure of the material takes place. For

ductile materials, Factor of safety is defined as the ratio of Yield point stress to working

stress. For brittle materials Factor of safety is defined as the ratio of ultimate stress to

working stress.

Selection of factor of safety depends on:

1. Material type

2. Mode of manufacture

3. Type of stress

4. Working or Service conditions

5. Shape of the part

6. Assumptions made in the design

ELEMENTS OF TRANSMISSION

Front Engine Rear Wheel Drive Vehicle


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Power train of front engine rear wheel drive passenger car:

CLUTCH

LocationIt lies between the engine and the gear box.

Need of the Clutch

- To disconnect the engine from the remaining part of the power transmission

system.

- To permit gradual taking up of the load

- To prevent jerky motion of the car in starting

- To facilitate smooth shifting of gears

Components of Clutch

- Engine flywheel

- Clutch plate

- Pressure plate

- Cover plate


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Parts of a single Plate Clutch

Operation:

Engine flywheel and pressure plate through cover plate drive clutch plate by

friction during engaged position. When the clutch is disengaged by clutch pedal, pressure

plate is moved away from clutch plate, thus contact between flywheel and clutch plate is

lost. Therefore, clutch shaft which is splined to clutch plate stops or its speed decreases.


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Single Plate Clutch

Design criteria:

- Clutch is designed to transmit the engine torque without slip

- Friction surface to have reasonable coefficient of friction

- Friction material to absorb the heat generated

- To have reasonable thermal conductivity to dissipate heat

- The force required by the clutch to separate the drive should not be excessive

- Friction material to have adequate surface area to absorb and transfer the heat

- Radial width ( r2r1 ) is designed to transmit the torque

Clutch Manufacturing

Pressure plate is made up of cast iron material. The surfaces are accurately machined

and pressed against the driven plate. The pressure plate is made with milling process.

Milling Process

Milling is a cutting process that uses a multi-edge cutting tool to remove material while

traveling along various axes with respect to the workpiece, able to generate complex

shapes and profiles. Milling is a process where a work part is shaped and sized by feeding

material past a rotating multiple tooth cutter that removes material during each pass.

Material may be feed vertically or horizontally. The machined surface may be flat,

angular, or curved. The


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shaped in nearly any fashion. Milling is a versatile process that allows large amounts of

material to be removed quickly.

By milling operation a large variaty of flat surfaces-horizontal, vertical or inclined, are

performed. Generaly, milling machines are destinated for

1. Facing

2. Profiling

3. Pocketing

4. Slot cutting

5. Hole machining

6. 3-D surface machining

At all types of milling machines, the cutting tool has to have o rotation motion, that is

cutting motion. The rotation axe of the tool could be horizontal or vertical, dependoing of

machine tool version. The feeding motion is achieved either by part or tool, or both,

usualy on three perpendicular directions. In this respect a large variety of milling machine

were developed.

Conventional Milling Machine are generally classified with

Horizontal milling machine

Vertical milling machine


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Horizontal milling machine architecture

3D view of Horizontal milling machine

Milling Operations


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Face Milling:

Process where the cutter is mounted having an axis of rotation perpendicular to

the workpiece surface.

-- used to create flat surfaces

-- leaves cutting marks on the machined surface

End Milling:

Process where the cutter usually rotates on an axis perpendicular to the

workpiece, although it can be tilted.

-- used to create various profiles in a part.

-- may have tapered or ball nose tools to produce tapered or rounded features.


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Vertical Milling machine architecture

The work piece which is to be machined is clamped on the table and the cutting

tool is held on the spindle. The suitable feed and speed is chosen to perform the

operation. T- Slots are provided on the top of the table to hold the work piece. Clutch

plate is clamped on the table by any one of the work holding device from clamp, bolts

and nuts, etc. To get the perfect smooth surface the correct speed and feed is to be

selected. To remove the heat which produced during machining is to be removed by

applying a suitable coolant.


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GEAR BOX (Manual Transmission)

Need:

- To move the vehicle from rest

- To change the speed of the vehicle

- To move the vehicle in reverse direction

Fundamentals of Gear Operation

Power flow in pair of gears

For a single pair of gear wheels (Refer Diagram A)

Gear ratio = No. of teeth in driven gear / No. of teeth in driving gear (TB / TA)

For multi pairs (Compound gears) (Refer Diagram B ),

Gear ratio = product of number of teeth in driven gears = (TB * TD / TA * TC)

Product of number of teeth in driving gears

Diagram C refers to power flow in reverse gear using idler gear (I).


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Components of a 4-Speed Constant Mesh Gear Box

Operation & Construction

The pairs AB, CD, EF, GH are always in mesh. The gears C, E, G are rotating on

bearings, without transmitting power to main shaft.

The dog clutch or hub and main shaft are splined to each other, ie, they rotate as a

single unit.

The lay shaft (or) Counter-shaft has integral gears (B, D, F, and H) with it. i.e) the

speed of the lay shaft is the speed of all these gears. (B, D, F, H).

Main shaft is connected to propeller shaft through universal joint.


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Power Flow in each Gear

First Gear: A - BHGHUBSHAFT

Second Gear: ABFEHUBSHAFT

Third Gear: A - BDCHUBSHAFT

Fourth or Top Gear: AHUBSHAFT

Note: The total number of teeth in each pair is same. ie, TA+TB = TC+ TD

SIMPLE PROBLEMS (Design of Gear Box)

(1) Calculate the number of teeth in each gear wheel, for a 4Speed gear box, if

the gear ratios are 1:1, 1.38:1, 2.24: 1, 3.8:1, approximately. Assume counter

shaft speed is half that of the engine speed and the smallest gear is not to have

less than 15 teeth.

Solution:

TA = TH = 15 (Assumption)

TB/TA = 2 = NA/NB

TB = 30, TA+TB = TG+ TH = 45, Therefore, TG = 30

First Gear:

A - BHGHUBSHAFT

Exact Gear ratio = TB * TG / TA * TH = 30 * 30 / 15 *15 = 4

Second Gear:

A - BFEHUBSHAFT

Second Gear ratio = 2.24 = TB * TE / TA * TF = 2 * TE / TF

TE / TF = 1.12

TA+TB = TE+ TF = 45, TF = 21.22 = 22, Therefore TE = 23

Exact Gear ratio = TB * TE / TA * TF = 30 * 23 / 15 *22 = 2.09

Third Gear:A - BDCHUBSHAFT

Third Gear ratio = 1.38 = TB * TC / TA * TD = 2 * TC / TD

TC / TD = 0.69

TA+TB = TC+ TD = 45, TD = 26.62 = 27, Therefore TC = 18

Exact Gear ratio = TB * TC / TA * TD = 30 * 18 / 15 *27 = 1.33


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EXERCISE PROBLEMS:

(1)Evolve a design for spur gears to be used in an ordinary gear box that give the

following speed ratios:

1.0, 1.43, 2.29, 3.91

The smallest pinion in the system is to have a minimum of 15 teeth.

Answer: (TA = 15, TB = 30, TC = 15, TD = 30, TE = 21, TF = 24,

TG = 26, TH = 19)

(2)Gear ratios for a small passenger car are

1st

gear : 4.2: 1

2nd

gear : 2.56: 1

3rd

gear : 1.52: 1

Top gear : 1: 1

The smallest pinion in the gear train must have at least 15 teeth. Speed of the

engine shaft = 1.52 * speed of lay shaft. Calculate number of teeth in each gear wheel

and actual gear ratios on the basis of the above result.

GEAR BOX

It is common experience that a high torque is required at the driving wheels when

a vehicle is starting from rest, climbing a hill or accelerating. Due to the variable nature

of resistance because of load and gradient changes, it is imperative that the engine power

should be available over a wide range of road speeds.

For this purpose the transmission or gear set is provided to permit the engine

crankshaft to revolve at a relatively high speed while the wheels turn at slower speeds.

The gear set is enclosed in a metal box called GEAR BOX.


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The gear box is fitted between the clutch and the rear axle and helps the road wheels to

get the power of the engine in varying ratios. The sliding mesh type gearbox is the

simplest type of gearbox.

Gearbox is of streamlined design, rugged in construction, made of graded cast

iron. It is completely oil-tight, dust proof and capable of being installed in the open

without a separate cover. The faces and bores are accurately bored and machined on

latest precision machines to ensure perfect alignment and interchangeability.

Gearbox consists of the following main elements:

1. Gear box outer case

2. Input power clutch assembly gears

3. Constant mesh gears

4. Splined main shaft

5. Gear lever

Manufacturing process of Gear Box outer Case: Casting Process

METAL CASTING PROCESS

The following block diagram shows the outline of production steps in sand casting

process.

1. Patterns

A pattern is a model or a replica of the object to be manufactured.

2. Types of Pattern

There are many types of mould patterns available. Few types of widely used

patterns are listed below:

1) Single solid pattern or single piece pattern

Mould

Sand

Mold Melting of

Metal

Pouring

Into Mold casting

Cleaning and FinishingInspection

Pattern


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2) Split pattern

3) Match plate pattern

4) Loose piece pattern

5) Skeleton pattern

6) Sweep pattern

7) Gated pattern

8) Cope and Drag pattern

3. Pattern Allowances

To compensate the Shrinkage during solidification and for better surface finish,

easy removal of pattern from the mold cavity.

1. Shrinkage allowance

2. Finishing allowance or Machining allowance

3. Draft allowance or Taper allowance

4. Distortion allowance or Camber allowance

5. Shaking allowance or Rapping allowance

4. Moulding Sand

Mould sand is the medium in which the cavity is made for the casting.

The main ingredients of Mould Sand:

1. Silica or River Sand

2. Clay

3. Water

Properties of mould sand:

1. Refractoriness 5. Strength

2. Permeability 6. Cohesiveness

3. Adhesiveness 7. Collapsibility

4. Flowability

5. Types of Moulding1. Green sand Moulding: Green sand is a mixture of silica, clay moisture (6-8%)

and additives.

2. Dry sand Moulding

Additive


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The additive includes binders and special ingredients to get some specific

properties.

Mould sand mixing device

The mould sand is needs to be mixed well before using it for preparing the mould.

A special mechanical mixing device is used called Sand Muller.

6. Tools Required

1. Mould Boxes

i) Cope Box

ii) Drag Box

2. Bottom board

3. Riddle

4. Rammer

5. Runner and Riser pins

6. Trowel

7. Lifter

8. Mallet

9. Shovel

10.Strike-off bar

11.Vent wire

12.Draw spike

13.Slick

14.Gate cutter


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7. MOULDING PROCEDURE

The following procedure can be used for making Gear box. The required gear box

pattern is to be prepared first, then using the following procedure it can be produced. The

following steps explain the casting procedure with split pattern as an example:

1. Select the required pattern for making gear box. One half of the pattern is placed

on the moulding board. The moulding box (drag) is placed with the dowel pins

down position as shown in the following figure.

2. Apply facing sand over the pattern. Molding sand is filled in the molding box up

the pattern is fully covered by the moulding sand. Then, the pattern is to be

pressed firmly around the surfaces of the pattern with fingers.

3. The drag box is completely filled with sand up to the top and ram it by hand

rammers. Then the excess sand is leveled by a strike off bar as shown in the

following figure.


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4. Then make many, small vent holes on the top of the mould as shown in the figure.

5. Now title the drag box upside down position as shows in the following figure.

6. Then sprinkle the dry parting sand such a way that the pattern and top sand

surface have been completely covered.

7. Then place cope box over the drag box correctly using the dowel pins available on

the side of the mould boxes.

8. Then, place another half of the split pattern over the first half in correct position

using the locator pins available in the split pattern itself as shown in the figure.


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9. Place the Sprue pin on the side of the pattern and Riser pin on the top of the

pattern as shown in the following figure.

10.Fill the cope box with moulding sand and ram the sand firmly using the same

procedure which is followed in drag box and made few vent holes on the top

surface of the mould as shown in the following figure.

11.Remove the sprue and riser pins carefully ad then lift the cope box then, place it

on the surface table with upside down position.

12.Carefully remove the split patterns available on the box boxes using draw spike

immediately after moistening the edges of the pattern.

13.Then, a small passage known as gate is cut in order to connect the sprue basin

and the mold cavity.

14.The cope is placed over the drag carefully again to get the two halves of the mold

together as shown in the following figure.


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15.Now the mold is ready for pouring the hot molten metal.

8. Casting Process for Gear Box production

After preparing the gear box mould cavity, the molten metal (Grade Cast Iron)

will be poured through the pouring basin. It flows through the sprue hole, sprue basin,

runner and gate and fills the entire cavity and raise up through the riser hole. Then the hot

metal available in the molding cavity is allowed to cool.

Finally the gear box case is removed from the sand casting mould. Then it may

require certain finishing and secondary machining operation depends upon the functional

requirements.

PROPELLER SHAFT

- Propeller shaft connects gear box to the final drive gears of the vehicle

through universal joint.

- A universal joint allows the drive to the transmitted through a variable angle.


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- A tubular section propeller shaft is normally used because of its low weight,

torsional strength.

Design of propeller shaft

- Since propeller shafts of road vehicles are sufficiently long and operate in

general at high speed, whirling may occur at certain critical speed. This

produces bending stress in the material.

- Critical speed of the P.S. varies directly as the diameter of the shaft and

inversely as the square of the length.

- Therefore diameters are selected as large as possible and lengths as short as

possible.

Propeller shafts are so designed that the critical speed is about 60% higher than

the engine speed at maximum power.

Propeller shaft - Manufacturing

Propeller shaft is a driving shaft that connects the gear box to the differential. It

consists mainly three parts

a. Shaft This to withstand mainly torsional loads. It is made of tubular cross

section. Solid shafts are also used.

b. Universal Joints- One or two joints are used based depends upon the type of rear

axle drive. The universal joints account for the up and down movements of the

rear axle when the vehicle is running

c. Slip Joint or Telescopic joint Depending upon the type of drive, one slip joint

may be there in shaft. It serves to adjust the length of the propeller shaft when

demanded by the rear axle movements.


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Propeller shafts are normally made by extrusion process under metal forming process. In

this the metals are deformed to the required shape by means of plastic deformation.

Plastic Deformation

As with other metallurgical practices, differences between hot and cold working

are not easy to define. When metal is hot worked, the forces for deformation are less and

the mechanical properties are relatively unchanged. When a metal is cold worked,

greater forces are required and the strength of the metal is increased. In hot working the

thickness of the material is changed substantially, but in some cold working operations,

such as the finish rolling of sheet metal, the thickness remains approximately the same. In

the manufacture of metal components, the basic alternatives available for the production

of a designed shape include casting, machining, welding, and deformation process. Hotworking is a deformation process. Metal deformation exploits and interesting fact of

metals: their ability to flow plastically in the solid state without accompanying

deterioration of properties. Moreover, in forcing the metal into a desired shape there is

little or no waste of material.

Hot working is the plastic deformation of metals above their recrystallization

temperature, which varies with different materials. Hot working does not necessarily

imply high absolute temperature. For example, lead and tin are hot worked at room

temperature. Recrystallization temperatures of common metals are given as;

Recrystallization Temperature of Metals

Metal F (C)

Aluminium 300 (150)

Copper 390 (200)

Gold 390 (200)

Iron 840 (450)

Lead Below room temperature

Magnesium 300 (150)

Nickel 1100 (590)

Silver 390 (200)

Tin Below room temperature


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Zinc At room temperature

Although hot working causes plastic deformation above the recrystallization temperature,

it does not produce strain hardening. Also, the hot worked metal does not possess a

greater elastic limit or become stronger, and the metal usually experiences a decrease in

yield strength; that is, a point where additional strain occurs without any increase in stress

load on the material. Ductility, which is the ability of material to be deformed plastically

without fracture, is impaired. Thus, it is possible to alter the shape of the metals

drastically with moderated forces by hot working and without causing fracture.

The recrystallization temperature of a metal determines whether or not hot or cold

working is being accomplished. For steel, recrystallization starts around 950 to 1300F

(500 to 700C), although most hot working of steel is at temperatures considerably

above this range. Various alloying effects cause variations. There is no tendency for

hardening by mechanical work until the lower limit of the recrystalline temperature range

is reached. Some metals, such as lead and tin, have a low recrystalline range and can be

hot worked at room temperature. Most commercial metals, however, require heating.

Alloy composition of these metals influences the proper working temperature range. The

typical result raises the recrystalline range temperature; prior cold working also increases

this range.During hot working operations the metal is in a plastic state and is formed readily

by pressure. In addition hot working has the following advantages:

Porosity in the metal is largely eliminated. Most ingots contain many small

blowholes. These are pressed together and eliminated.

Impurities in the form of inclusion are broken up and distributed throughout the

metal.

Course are columnar grains are refined. Since this hot work is in the recrystalline

temperature range, it should be continued until the low limit is reached to provide

a fine grains structure.

Physical properties are generally improved owing principally to grain refinement.

Ductility and resistance to impact are improved, strength is increased, and greater


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homogeneity is developed in the metal. The greatest strength of rolled steel exists

in the direction of metal flow.

The amount of energy necessary to change the shape of the steel in the plastic

state is fare less than that required when the steel is cold.

Hot working processes present a few disadvantages that cannot be ignored.

Because of the high temperature of the metal, there is rapid oxidation or scaling of

the surface with accompanying poor surface finish. As a result of scaling, close

tolerances are not practical. Hot working equipment and maintenance costs are

high, but the process is economical if compared to working metals at low

temperatures and the objective of the operation is similar.

The term hot finished refers to steel bars, plates, or structural shapes that are

purchased in the as rolled condition from the hot working operation. Some descaling is

done but, otherwise, the steel is ready for bridges, ships, railroad, cars, and other

applications where does dimensional tolerances are not required. The material has good

weldability and machinability because the carbon content is less than 0.25% for these

products.

Extrusion:

In extrusion there is no hammer blow but instead the metal is slowly squeezed by a

punch through a die. Since squeezing action is required, press forging machines, such as

mechanical forging press or hydraulic press is used. The squeezing actions of a tooth

paste tube is a good example to illustrate the concept of extrusion. In this case the

material is squeezed out under pressure through openings called die. In the case of tooth

paste or cream tubes the mouth acts as the die.


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Figure 1 Extrusion Process

The figure 2 illustrates the different types of extrusion. The concept in all extrusions is

that, the punch slides inside a cylinder. When the punch presses the metal, the hot metal

is forced out through the opening. The shape and size of the extruded part depends upon

the shape and size of the die. Depending on how the metal flows out, the different types

of extrusion are classified as follows.

Figure 2 Different Types of Extrusion Methods

Depending on the shape of the die, different cross sections can be obtained as shown in

figure 3.


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Figure 3. Different types of cross sections

Advantages of extrusion:

The extruded part has a very dense structure.

Process is cheaper.

Complicated sections that are impossible to produce by other methods can be

produced easily.

Very thin sections can be sections can be produced easily.

Surface finish is good.

Dimensional accuracy is good.

Used for mass production of uniform cross section.

Seamless tubes can be produced ( i.e. tubes which do not have joints along its

length)

Very fast production.

Limitations:

Equipment is complicated.

Initial investment needed for the press is high.

Universal joints

Universal joints are used to make a flexible connection between two rigid shafts

at an angle with each other. They permit the transmission of power not only at an

angle, but also while this angle is being varied constantly.

In motor vehicles they are used not only to permit power to be transmitted from

the horizontal transmission main shaft to the propeller shaft which is normally at an


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angle with the horizontal because the rear axle is usually lower than the transmission

main shaft, but also while the flexing of the springs caused by the road irregularities

is constantly changing this angle. Without such a flexible device the transmission of

power under these conditions would be impossible.

Final Drive

Need:

To turn the power flow at a right angle from propeller shaft to the rear

axle.

To provide mechanical advantage (to increase torque) from the

propeller shaft to the rear axle.

Rear Axle Ratio: (Final drive ratio)

Rear Axle ratio (a) =pinionbevelonteethNo.of

lcrown wheeonteethNo.of


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Overall Gear RatioOverall gear ratio (G) = Gear ratio (in Gear box) * rear axle ratio

G = g x a

Linear Speed of Wheels (v):

V = Angular speed of wheels * Circumference of wheels

V = N w * 2r

Problem:

(1) A 4 teeth drive pinion is driven by a propeller shaft at 2500 rpm and meshes

with a crown wheel on the rear axle shafts. The crown wheel has 21 teeth.

Calculate the speed of the vehicle in km/h if the diameter of the road wheels is

0.7m.

Solution:

Rear axle ratio (a) = 21/4 = 5.25

Angular speed of road wheel =ratioaxlerear

speedshaftpropeller

= 2500 / 5.25 = 476 rpm

Linear speed of wheels = (476 x x 0.7 x 60) / 1000

= 62.83 km/h.


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(2) A vehicle has a third gear ratio of 1.5 to 1 and a rear axle ratio of 4.5 to 1.

Calculate

(a)The overall gear ratio and

(b)The number of revolution made by the crown wheel per minute if the

engine speed is 2700 rpm.

Solution:

a. Overall gear ratio (G) = g x a = 1.5 x4.5 = 6.75: 1

b. Speed of the crown wheel =G

speedEngine = 2700/ 6.75 = 400 rpm

Exercise Problem:

(1)At an engine speed of 2250 rpm, a torque of 50 Nm is applied to the gearbox. If

the gearbox and final drive ratios are 3.4 : 1 and 5 : 1 respectively, and the vehicle

is traveling in a straight line, Calculate,

(a)The speed of each road wheel and

(b)The torque applied to each road wheel if the efficiency is 100%

Ans: (a) 150 rpm (b) 425 Nm

(2)In a certain axle, the final drive ratio is 6.5 : 1. When the pinion is turned by a

torque of 200 Nm, it is found that the torque produced at the crown wheel is 1170

Nm. Calculate the torque ratio and the percentage efficiency of the axle.

Ans: 5.85 : 1, 90%

Final Drive

Generally the final drive consists of a bevel pinion and a crown wheel or

alternatively worm and worm wheel arrangement.

Three types of bevel gears are used for the final drive gearing:

1. Straight bevel gearsThese contain the straight teeth. They are simplest and cheapest for all types. In

this type at one instant only one pair of teeth of pinion and the crown wheel will

be in contact. An uneven transmission of motion will take place here. As a result

these gears are noisy and suffer from high wear.

2. Spiral bevel gears


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The spiral bevel gears have curved teeth which result in greater contact of the

teeth. Because of which gears are silent running and stronger than the straight

bevel gear.

3. Hypoid Gears

These types of gears are widely used for final drive these days. In these gears,

the basic surface on which the teeth are cut is hyperboloid, which is a solid

obtained by rotating a hyperbola about an offset axis. Such gears are employed

to connect shafts at right angles to each other, but not lying in the same plane.

Both the pinion and the crown wheel are usually made from nickel-chrome alloy

steel, machined by any one of the gear cutting process and carburised after which they are

case hardened by quenching in oil.

Worm and wheel type of final drive is particularly useful in heavier vehicles

where the final reduction is greater than about 6. This gives a quiet, efficient and very

strong drive. Further, larger gear reductions are possible with worm and wheel drive in

single reduction as compared to the bevel pinion type where double reduction has to be

employed. Worm is usually made of nickel steel and is case hardened, whereas phosphor

bronze is used for the worm wheel.

Differential


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When a car turns around a corner, the distance traveled by the out side wheels is

greater than that traveled by the inside wheels. If the wheels are mounted on the dead

axles so that they turn independently of each other, like the front wheels of an ordinary

passenger vehicle, they will turn at different speeds to compensate for the difference in

travel. But, if the wheels are driven positively by the engine, a device is necessary to

permit them to revolve at different speeds without interfering with the propulsion of the

car. To accomplish this purpose a system of Gears called the Differential is provided.


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The above figure shows diagrammatically a simple bevel gear differential. The

Differential Pinion G is mounted on short axle or stud F, which is carried by the

differential frame or case E. The Case is driven by the final gear drive gears in this

instance gears C and B. The differential pinion G meshes with the side of Gears H and

H1, which drive the rear wheels through the axles K and K1.When the final drive ring

Gear C turns in the direction shown, the differential case E turns with it, carrying the Stud

F and Pinion G in the same way as indicated in the connection with fig. Any difference

in the rotation of rear wheel is compensated by the rotation of the differential pinion G on

the Stud F while revolving bodily about the X-Y axis. If the differential Pinion G rotates,

it must roll on one of the differential side gears H or H1, and the amount of motion in

rolling on the one side gear is transmitted to the other as an additional turning and driving

effort. Any retarded motion of one wheel results in accelerated motion of the other. The

rotation of the engine is thus transmitted to the rear wheels in the proportion to the

distance each wheel travels.

In figure only one differential pinion is shown, and the differential case, is merely

a frame bolted to the ring gear. In the actual differentials a number of differential pinions,

usually two are employed and usually the differential case partially encloses the

differential gears.


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Note:

Speed of the outer wheel + Speed of the inner wheel = 2 * Speed of the

crown wheel.

i.e., Reduction in speed of the inner wheel = increase in speed of outer wheel.

Problem:

(1) The steering set of a vehicle provides a turning circle radius of 6.6 m with a

wheel track (distance between left & right wheels) width of 1.2 m. The effective

road wheel-rolling diameter is 0.72 m. Calculate the number of revolutions

made by the inner and outer wheels for one turning circle.

Solution:

Mean turning radius (Rm) = 6.6 m

Outer wheel turning radius (Ro) = 6.6 + (1.2/ 2) = 7.2 m

Inner wheel turning radius (Ri) = 6.6 - (1.2/ 2) = 6.0 m

Rolling circumference of road wheel = x D = 0.72 m

Distance traveled by outer wheel for one complete turning circle = 2Ro=14.4 m

Distance traveled by inner wheel for one complete turning circle = 2Ri=12 m

Therefore revolutions completed by outer wheels =

D

o

R2= 20 revolutions

Revolutions completed by inner wheels =D

i

R2= 16.6 revolutions

Differential Lock out

The Objection to the Bevel gear differential is that, whichever wheel offers the

less resistance is turned faster, causing a loss of traction. If one wheel gets in the mud or

loose sand, the wheel on the solid ground will not be driven while other spins around dueto Differential action. For this reason some of truck differentials are provided with

devices to lock out the differential to provide better traction under difficult driving

conditions. In addition several designs of the differential have been developed that will

not permit differential action unless both wheels have traction.


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Exercise Problem:

1. A Six cylinder 4-s cycle engine develops a brake power of 44.67 kW. If the final

drive ratio is 5.2:1 and the transmission efficiency in top gear is 90%, determine

the power at the road wheels when top gear is engaged.

If this vehicle is negotiating a road bend, and the inside road wheels are making

230 rpm, Calculate the rpm of the outer wheels and the torque and power at both

outer and inner wheels.

DIFFERENTIAL

Differential contains two sun gears mesh with the two or four planet pinions. Axle

half shafts are splined to each of these sun gears. The crown wheel is free to rotate on the

half shaft. The main components of the differential are bevel gears. The bevel gears are

manufactured by different machining processes.

The both final drive and the differential are mainly contains different types of

gears only.

Manufacturing of Gears

Gear cutting is a highly complex and specialised art and that is why most of the gear

machines are single purpose machines. The following are the most commonly used

methods of manufacturing gears.

1. Casting: Gears can be cast in sand moulds. Sand casting is particularly used for

making heavy gears of cast iron and steel. Gears made by this process have poor

accuracy. These are mostly used for slow speed drives. This is not efficient for power

transmission. This gear may be machined for a good finish or left as cast for rough

machinery.

2. Hot rolling: Gears are made by forcing a master gear into a hot blank and the two are

then rolled together until the teeth of the master have penetrated for enough to form a

complete gear. The teeth are then machined. This method is little used as present, but

has possibilities for future.

3. Stamping: Stamped gears are made from sheet metals. Materials up to 3mm thickness

are practical for this process. These gears may be shaved after stamping to improve the

accuracy and finish.


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4. Powder metallurgy: In this process, a master gear of hard material is rolled against a

heated gear blank, thereby forming the teeth on the hot blank. Bakelite and other

plastic materials are the commonly used materials for manufacture of gears by this

method.

5. Extruding: In this process the brass and aluminium bar is extruded through the die

having the shape of the desired tooth element and thus the material can finally be

extruded to obtain gear form on its surfaces, and the extruded gear bar is then hack-

sawed.

6. Coining: Gears are coined from blanks in a hydraulic press or forging hammer. Gears

manufactured by this process require a light machining or may be used as such.

7. Machining: Gears are machined from the blanks, usually by a roughing and a

finishing operation. The various methods used for machining are described below.

(i) Milling: in the milling machine the cutter is mounted on the spindle and rotates

while the work piece is mounted on the table and reciprocated under the cutter.

Once the cutter finishes the tooth profile, the work piece is indexed to the next

position, and again the tooth profile is finished and so on. Using this process spur,

helical, bevel and worm gears can be manufactured.

(ii)Broaching: In this process, full form finished gears are produced in one pass by

a circular broach having inward facing teeth. The broaching tool consists of a

series of full form finishing rings at the end of a series of generating ring. All the

rings are keyed and assembled in octagon shaped broach holder. This is mainly

used in mass production and no separate finishing operation is required.

(iii)Gear Planning: In gear planning process, the cutter consists of true involute rack

which reciprocates across the face of the blank and the blank rotates in the correct

relationship to the longitudinal movement of the cutter as if both roll together as a

rack and pinion. This is used for producing external spur and helical gears.


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(iv)Gear Hobbing: in this process the gears are generated by a rotating cutter called

hob. This process is a continuous indexing process in which both the cutting tool

and work piece rotate in a constant speed while the hob is being fed into work.

Bevel Gear Generators:

Since the teeth of bevel gears constantly change in form from the large to the small

end, it is impossible to form the bevel teeth but these have to be generated. There are two

common types of bevel gear generators.

1. Straight Bevel Gear Generatorwhich cuts Straight teeth

2. Spiral Bevel Gear Generatorwhich cuts spiral teeth.

Gear Finishing: even though the gears are satisfactorily manufactured by the gear

cutting processes, some additional finishing operations may be required which depends

on the application in which the gears are used. All the mechanical finishing operations

are commonly used for finishing gears which are listed below.

1. Gear Shaving: it is cold working process. The rolling gear is in contact and under

pressure with three hardened burnishing gears. This process is ideal for

automotive gear box gears after hobbing and before hardening.

2. Gear Grinding: Heat treated gears can be finished either by grinding or by

lapping. This process is obsolete one. But when the high accuracy associated with

profile grinding is required, it is the only process to be used.

After the finishing operation the gears are to be tested. In the testing process the factors

such as concentricity, size, noise, tooth bearing, spacing etc. are to be considered.


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Axle Shaft:

- Axle shafts are splined to the side gears in differential

- They are subjected to bending stress and torsional stress

- It is designed to withstand severe torsional stresses arising during power

transmission

- The radius of the solid cylindrical axle shaft depends on torque transmitted,

weight of vehicle supported by one wheel, wheel radius, coefficient of friction

between tyre and road, safe shear stress of the material selected.

AUTOMOBILE REAR AXLE

Rear axle is the last element of the power transmission chain. Power generated in the

engine passes on to the gear box through a clutch. From the gear box it goes to the

propeller shaft through universal joints and from the propeller shaft it goes to the rear

axle to be ultimately delivered to the road wheels. One kind of automobile axle is shown

in the following picture.

Manufacturing Process

The automobile rear (or) front axle is manufactured through forging process.

Forging is the operation where the metal is heated and then a force (impact or squeeze

type) is applied to manipulate the metal in such a way that the required final shape is

obtained.

Forging enhances the mechanical properties of metals and improves the grain

flow, which in turn increases the strength and toughness of the forged components such

as automobile axle.

Forging temperature

For forging, the metal piece is heated to a proper temperate to attain plastic

properties before deformation which is essential for satisfactory forging. The following

table shows the forging temperature ranges for various metals and alloys.


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S.No. Metal / Alloy

Forging Temperature ino

C

Starting Finishing

1. Mild steel 1300 800

2. Wrought iron 1275 900

3. Medium carbon steel 1250 750

4. High Carbon steel 1150 825

5. Copper, brass and Bronze 950 600

6. Aluminium and magnesium alloys 500 350

Types of forging process

1. Smith forging (Open Die Forging): The process of reducing a metal billet

between open dies to obtain the required shape are called smith forging. In this

process Pneumatic hammers are used.

a) Hand forging: It is used to produce small numbers of light forged components.

b) Power forging: Power press is used here to apply force on the heated base material

and it is used to produce large number of components in medium (or) large size.

The sketch of the pneumatic hammer is shown in the following figure.


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2. Impression - Die Forging: The process of reducing a metal billet between closed

impression dies to obtain the required shape is called impression die forging. It is

used to make more complex shaped products with greater accuracy.

a) Drop forging: The drop hammer is used to apply more impact force on the base

metals. The ram of the drop hammer is raised to a certain height and then it is

allowed to drop freely under its own weight.

b) Press forgingThe metal is shaped not by means of a series of blows as in drop

forging, but by means of continuous squeezing action. The hydraulic press (OR)

mechanical press may used for applying the required pressure on the metals.

The sketch of the hydraulic press is shown in the following figure.Usually the

power forging and press forging techniques are used for making automobile

front (or) rear axle.


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Relationship between engine speed and vehicle speed

N / V = 2.65 * G / r

Where,

N = Engine Speed in RPM

V= Vehicle speed in km/h

G = Overall gear ratio (g * a = reduction in gear box * reduction in final drive)

r = wheel radius in m

PART - B

ENERGY

Definition: Energy is the ability to do work.

Energy is a property or characteristic of matter that makes things happen, or, in the case

of stored or potential energy, has the "potential" to make things happen.

Energy has a number of different forms, all of which measure the ability of an object or

system to do work on another object or system.

In other words, there are different waysthat an object or a system can possess energy.

LAW OF CONSERVATION OF ENERGY

The law of conservation of energy states that the total amount ofenergy in any isolatedsystem remains constant but cannot be recreated, although it may change forms, e.g.

friction turns kinetic energy into thermal energy. In thermodynamics, the first law of

thermodynamics is a statement of the conservation of energy for thermodynamic systems,

and is the more encompassing version of the conservation of energy. In short, the law of

conservation of energy states that energy can not be created or destroyed; it can only be

changed from one form to another.

CONSERVATION OF ENERGY

Conservation of energy is not saving energy. The law of conservation of energy says that

energy is neither created nor destroyed. When we use energy, it does not disappear. We

change it from one form of energy into another.
http://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Thermodynamicshttp://en.wikipedia.org/wiki/Thermodynamicshttp://en.wikipedia.org/wiki/Kinetic_energyhttp://en.wikipedia.org/wiki/Energy


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A car engine burns gasoline, converting the chemical energy in gasoline into mechanical

energy. Solar cells change radiant energy into electrical energy. Energy changes form,

but the total amount of energy in the universe stays the same. Scientists at the Department

of Energy think they have discovered a mysterious new form of energy called "dark

energy" that is actually causing the universe to grow.

We use all these energy sources to generate the electricity we need for our homes,

businesses, schools, and factories. Electricity "energizes" our computers, lights,

refrigerators, washing machines, and air conditioners, to name only a few uses.

We use energy to run our cars and trucks. Both the gasoline used in our cars, and the

diesel fuel used in our trucks are made from oil. The propane that fuels our outdoor grills

and makes hot air balloons soar is made from oil and natural gas.

The Different Basic Forms of Energy

KINETIC ENERGY

Kinetic energy is motion of waves, electrons, atoms, molecules, substances, and objects.

Radiant Energy is electromagnetic energy that travels in transverse waves. Radiant

energy includes visible light, x-rays, gamma rays and radio waves. Light is one type of

radiant energy. Solar energy is an example of radiant energy.

Thermal Energy, or heat, is the internal energy in substances the vibration and movement

of the atoms and molecules within substances. Geothermal energy is an example of

thermal energy.

POTENTIAL ENERGY

Potential energy is stored energy and the energy of position gravitational energy. There

are several forms of potential energy

Stored Mechanical Energy is energy stored in objects by the application of a force.

Compressed springs and stretched rubber bands are examples of stored mechanical

energy.

The classification of Energy:

CONVENTIONAL (Non-Renewable) NON-CONVENTIONAL (Renewable)

Oil(Petroleum) Solar
http://www.eia.doe.gov/kids/energyfacts/uses/consumption.htmlhttp://www.eia.doe.gov/kids/energyfacts/uses/consumption.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/electricity.htmlhttp://www.eia.doe.gov/kids/energyfacts/uses/transportation.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/gasoline.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/diesel.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/propane.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/propane.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/diesel.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/gasoline.htmlhttp://www.eia.doe.gov/kids/energyfacts/uses/transportation.htmlhttp://www.eia.doe.gov/kids/energyfacts/sources/electricity.htmlhttp://www.eia.doe.gov/kids/energyfacts/uses/consumption.htmlhttp://www.eia.doe.gov/kids/energyfacts/uses/consumption.htmlhttp://www.eia.doe.gov/kids/energyfacts/uses/consumption.html


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Natural Gas Wind

Coal Geothermal

Uranium (Nuclear) Biomass

Hydro

Ocean (Tidal Energy)

CONVENTIONAL

Fossil Fuels -Conventional Energy sources

Fossil fuels are used for a variety of domestic and industrial purposes. These fuels

contain high percentages of carbon and generate huge amount of energy when heated.

These non-renewable sources of energy are formed as deposits within the inner layers of

earth. The remains of animals and vegetations that died millions of years ago formed the

reserves of fossil fuels in different parts of the world. Fossil fuels are mostly found in

three basic types namely natural gas, coal, and petroleum.

Advantages:

Depending on fuel, good availability

Simple combustion process can directly heat or generate electricity

Inexpensive

Easily distributed Disadvantages

Probable contributor to global warming

Questionable availability of some fuels...major price swings based on politics of

oil regions

Cause of acid rain

Coal

Coal has been the most common source of energy.

Modern steam boilers burn coal in any of its forms as a primary fuel. Trees and plants

failing into water decayed and produced peat bogs. Gigantic geological upheavals buried

these bogs under layers of silt. Soil pressure, heat and movement of the earths curst

distilled off some the bogs gaseous matter to form brown coal, or lignite different from;

peat lignite, bituminous and anthracite.


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The largest power plant is located on the west bank at Hardeo river near korba in Bilaspur

district of Madhya Pradesh. Other power plants in India are located in Tamil Nadu,

Karnataka,Maharashtra. Thermal Power Station, a 4 X 110 MW plant located in Uttar

Pradesh.

Oil: Almost 40% of the energy needs of the world are fed by oil.

Refining petroleum or crude oil produces our fuel oils. India is not particularly rich in

petroleum reserves. The potential oil bearing areas are located in Assam, Tripura,

Manipur, West Bengal, Ganga valley, Punjab, Himachal Pradesh, Kutch, eastern and

western coastal area (in Tamil Nadu, Andhra Pradesh and Kerala). Andaman and

Nicobar Islands,Lakshadweep,and in the continental shelves adjoining these areas.

Diesel power plants in India are installed in isolated places and the total installed capacity

is estimated as 0.35 million kW i.e. Less than 2% of the total installed capacity in the

country. No addition to this is expected in near future.

GAS:

Gas is incompletely utilized at present and huge quantities are burnt off in the oil

production process because of the non-availability of ready market. The reason may be

the high transportation cost of the gas. To transport gas is costlier than transporting oil.

Large reserves are estimated to be located in inaccessible areas.

Gaseous fuels can be classified as:

(1)Gases of fixed composition such as acetylete, ethylene, methane etc.,

(2)Composite industrial gases such as producer gas, coke oven gas, water gas, blast

furnace gas etc.,

Thermal Power

Current installed base of Thermal Power is 92,216.54 MW which comes to 64.6% of

total installed base.Current installed base of Coal Based Thermal Power is 76,298.88

MW which comes to 53.3% of total installed base. Current installed base of Gas Based

Thermal Power is 14,716.01 MW which comes to 10.5% of total installed base. Current

installed base of Oil Based Thermal Power is 1,201.75 MW which comes to 0.9% of total

installed base.
http://en.wikipedia.org/wiki/Fossil_fuel_power_planthttp://en.wikipedia.org/wiki/Fossil_fuel_power_plant


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Nuclear Power: According to modern theories of atomic structure, matter consists at

minute particles known as atoms. These atoms represent enormous concentration of

binding energy. Controlled fission of heavier unstable atoms such as U235

, Th232

and

artificial element Pu230

, liberate large amount of heat energy. This enormous release of

energy from a relatively small mass of nuclear fuels makes this source of energy of great

importance. The energy released by the complete fission of one kg of U236

, is equal to

the heat energy obtained by burning 4500 tones of high grade coal or 2200 tones of oil.

The heat produced b nuclear fission of the atoms of fissionable material is utilized in

special heat exchangers for the production of steam which is then used to drive turbo

generators as in the conventional power plants.

Kaiga NPCIL Karnataka, Kakrapar NPCIL Gujarat, Kalpakkam NPCIL Tamil

Nadu,Narora NPCIL Uttar Pradesh, Rawatbhata NPCIL Rajasthan, Taapur NPCIL

Maharastra.Currently, seventeen nuclear power reactors produce 4,120.00 MW (Some

under construction).

Non-Conventional

Solar Energy:

The sun has produced energy for billions of years. Solar energy is the suns rays (solar

radiation) that reach the earth.

Solar energy can be converted into other forms of energy, such as heat and electricity.

Solar energy can be converted to thermal (or heat) energy and used to:

Heat waterfor use in homes, buildings, or swimming pools.

Heat spacesinside greenhouses, homes, and other buildings.

Solar energy can be converted to electricity in two ways:

Photovoltaic (PV devices) or solar cells change sunlight directly into

electricity. PV systems are often used in remote locations that are not connected

to the electric grid. They are also used to power watches, calculators, and lighted

road signs.

Solar Power Plants - indirectly generate electricity when the heat from solar

thermal collectors is used to heat a fluid which produces steam that is used to

power generator. Out of the 15 known solar electric generating units operating in

the United States at the end of 2006, 10 of these are in California and 5 in


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Arizona. No statistics are being collected on solar plants that produce less than 1

megawatt of electricity, so there may be smaller solar plants in a number of other

states.

Applications of Solar Energy:

Solar Water Heating, Space heating, Space cooling, Solar Energy: Thermal Electric

Conversion, Solar Energy: Photovoltaic electric Conversion, Solar distillation, Solar

pumping, Agriculture and Industrial process heat, Solar Furnace, Solar Cooking, Solar

production of Hydrogen, Solar Green house.

The major disadvantages of solar energy are:

The amount of sunlight that arrives at the earth's surface is not constant. It

depends on location, time of day, time of year, and weather conditions.

Because the sun doesn't deliver that much energy to any one place at any one

time, a large surface area is required to collect the energy at a useful rate.

Wind Energy:

Energy extracted from the wind is initially energy in the form of rotary, translational, or

oscillatory mechanical motion. This mechanical motion can be used to pump fluids or can

be converted to Electricity.

Wind energy which is an indirect of source solar energy conversion can be utilized to run

wind mill, which in turn drives the generator to produce electricity.

Energy of wind can be economically used for the generation of electrical energy. Winds

are caused from tow main factors:

1. Heating and cooling of the atmosphere which generates convection currents.

Heating is caused by the absorption of solar energy on the earths surface and

tin the atmosphere.

2. The rotation of the earth with respect to atmosphere, and its motion around the

sun.

The potential of wind energy as a source of a power is large. The energy available in the

wind over the earth surface is estimated to be 1.6 X 107

Mega Watts. Which is of the

same order magnitude has present energy consumption on the earth.


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Applications:

Applications of some what more powerful turbines, up to about 50kW, are for operating

irrigation pumps, offshore oil drilling platforms. Aero generators in the intermediate

power range, roughly 100 to 250 kW, can supply electricity to isolated populations (e.g.

on Island), to small Industries.

In larger wind mills the electric power ranges from 2000 to 5000 kW or 2 to 5 megawatts.

Windmills are located in Tamil Nadu , Karnataka, Rajasthan. Gujarat, Madhya Pradesh.

Tidal Energy:

The periodic rise and fall of the water level of sea is called tide. These tides can be used

to produce electrical power which is known as tidal power. When the water is above the

mean sea level, it is called flood tide. When the level is below the mean sea level it is

called ebb tide.

A tidal basin is formed which gets separated from the sea, by dam. The

difference in water level is obtained between the basin and sea. The constructed basin is

filled during high tide and emptied during low tide passing through turbine respectively.

By using reversible water turbines, turbines can be run continuously, both during high

tide and low tide. The turbine is coupled to generator, potential energy of the water

stored in the basin as well as energy during high tide, is used to drive the turbine, which

is coupled to generator, generating electricity.

Tidal power plants have been constructed in Western part of India.

Geothermal Energy:

The word geothermal comes from the Greek words geo (earth) and therme (heat).

So, geothermal energy is heat from within the earth. Geothermalenergy is obtained from

the internal heat of the planet and can be used to generate steam to run a steam turbine.

This in turn generates electricity, which is a very useful form of energy. Geothermal

energy is a renewable energy source because the water is replenished by rainfall and the

heat is continuously produced inside the earth.

NHPC to set up pilot geothermal power plant in Chhattisgarh. Indian has 400

medium to high enthalpy geothermal springs, clustered in seven provinces shown in


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Figure 1. The most promising provinces are i) The Himalaya, ii) Sohana, iii)

Cambay, iv) Son-Narmada-Tapi (SONATA) and v) the Godavari. With the recent

volcanic eruption, the Barren Island, a part of the Andaman-Nicobar chain of islands, is

added to the above list. Most of them are liquid dominated systems with one or two

having both liquid and gas dominated systems.

Biomass:

Biomass is organic material made from plants and animals. Biomass contains

stored energy from the sun. Plants absorb the sun's energy in a process called

photosynthesis. The chemical energy in plants gets passed on to animals and people that

eat them. Biomass is a renewable energy source because we can always grow more trees

and crops, and waste will always exist. Some examples of biomass fuels are wood, crops,

manure, and some garbage.

When burned, the chemical energy in biomass is released as heat. If you have a fireplace,

the wood you burn in it is a biomass fuel. Wood waste or garbage can is burned to

produce steam for making electricity, or to provide heat to industries and homes.

Biomass can be converted in to biogas as fuel by means of conversion technologies.

Biomass Conversion Technologies

Thermochemical Conversion, gasification and Liquefaction, Biochemical Conversion

Fermentation, Hydrogenation.

Renewable Power

Current installed base of Renewable Power is 12194.57 MW which comes to 7.7% of

total installed base.

Power production status of non-conventional energy in India

---------------------------------------------------------------------------------------------

Renewable Power Potential Achieved

---------------------------------------------------------------------------------------------

Wind Power 20,000 MW 1,000 MW

Small Hydro Power 10,000 MW 172 MW

Biomass 20,000 MW 141 MW

Solar photovoltaic Power 20 MW/sq.km 810 KW


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Packaged Diesel Power Plant

Diesel electric plants in the range of 2 to 50 MW capacities are used as central stations

for small supply authorities and works and they are universally adapted to supplement

hydroelectric or thermal power stations where standby generating plants are essential for

starting from cold or under emergency conditions

INTERNAL COMBUSTION ENGINES

Definition of Engine:

An engine is a device which transforms one form of energy into another form.

Definition of Heat Engine

Heat engine is a device which transforms the chemical energy of a fuel in to the

thermal energy and utilizes this thermal energy to perform useful work.

Heat engines can be broadly classified into two categories:

(i) Internal Combustion Engines (IC Engines)

(ii) External Combustion Engines (EC Engines)

Engine Components

Cylinder:

It is a cylindrical vessel or space in which the piston makes a reciprocating

motion. The varying volume created in the cylinder during the operation of the engine is


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filled with the working fluid and subjected to different thermodynamic process. The

cylinder is supported in the cylinder block.

Piston:

It is a cylindrical component fitted into the cylinder forming the moving boundary

of the combustion system. It fits perfectly in to the cylinder providing a gas-tight space

with the piston rings and the lubricant. It forms the first link in transmitting the gas

forces to the output shaft.

Combustion Chamber:

The space enclosed in the upper part of the cylinder, by the cylinder head and the

piston top during the combustion process, is called the combustion chamber. The

combustion of fuel and the consequent release of thermal energy results in the building

up of pressure in this part of the cylinder.

Inlet Manifold:

The pipe which connects the intake system to the inlet valve of the engine and

through which air or air-fuel mixture is drawn in to the cylinder is called the inlet

manifold.

Exhaust Manifold:The pipe which connects the exhaust system to the exhaust valve of the engine

and through which the products of combustion escape into the atmosphere is called the

exhaust manifold.

Inlet and Exhaust Valves:

Valves are commonly mushroom shaped poppet type. They are provided either

on the cylinder head or on the side of the cylinder for regulating the charge coming into

the cylinder (inlet valve) and for discharging the products of combustion (exhaust valve)

from the cylinder.

Spark Plug:

It is a component to initiate the combustion process in Spark Ignition (SI) engines

and is usually located on the cylinder head.


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Connecting Rod:

It connects the piston and the crankshaft and transmits the gas forces the piston to

the crankshaft.

Crankshaft:

It converts the reciprocating motion of the piston into useful rotary motion of the

output shaft. In the crankshaft of a single cylinder engine there is a pair of crank arms

and balance weights. The balance weights are provided for static and dynamic balancing

of the rotating system. The crankshaft is enclosed in a crankcase.

Piston Rings:

Piston rings, fitted into the slots around the piston, provide a tight seal between

the piston and the cylinder wall thus preventing leakage of combustion gases.

Camshaft:

The camshaft and its associated parts control the opening and closing of the two

valves. The associated parts are push rods, rocker arms, valve springs and tappets. This

shaft also provides the drive to the ignition system. The camshaft is driven by the

crankshaft through timing gears.

Cams:

These are made as integral parts of the camshaft and are designed in such a way to

open the valves at the correct timing and to keep them open for the necessary duration.

Fly Wheel:

It is aninertia mass in the form of a wheel is attached to the output shaft of engine

and this wheel is called the flywheel.

Engine Nomenclature

Cylinder Bore (d):

The nominal inner diameter of the working cylinder is called the cylinder bore

and is designated by the letterdand is expressed in millimeter (mm).

Piston Area (A):

The area of a circle of diameter equal to the cylinder bore is called the piston area

and is designated by the letterA and is usually expressed in square centimeter (cm2)


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Stroke (L):

The nominal distance through which a working piston moves between two

successive reversals of its direction of motion is called the stroke and is designated by the

letterL and expressed is usually in millimeter (mm).

Dead Centre:

The position of the working piston and the moving parts which are mechanically

connected to it, at the moment when the direction of the piston motion is reversed at

either end of the stroke is called the dead centre. There are two dead centres in the

engine as indicated,

(i) Top Dead Centre (ii) Bottom Dead Centre

(i) Top Dead Centre (TDC):

It is the dead centre when the piston is farthest from the crankshaft. It is

designated as TDC. It is also called the Inner Dead Centre (IDC).

(ii) Bottom Dead Centre (BDC):

It is the dead centre when the piston is nearest to the crankshaft. It is designated

asBDC. It is also called the Outer Dead Centre (ODC)

Displacement or Swept Volume (Vs):

The nominal volume swept by the working piston when traveling from one dead

centre to the other is called the displacement volume. It is expressed in terms of cubic

centimeter.

Clearance Volume (Vc):

The nominal volume of the combustion chamber above the piston when it is at the

top dead centre is the clearance volume. It is designated as VC and expressed in cubic

centimeter (cc).

Compression Ratio (r) :

It is the ratio of the total cylinder volume when the piston is at the bottom dead

centre, VT, to the clearance volume, VC. It is designated by the letter r.


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FOUR STROKE CYCLE PETROL ENGINE

Petrol engine is also known as Spark Ignition (S.I.) engine. It requires four

strokes of the piston to complete one cycle of operation in the engine cylinder. It is

known as Otto Cycle.

1. Suction Stroke

During suction stroke, the inlet valve (I) opens and air and fuel (petrol) mixture is

sucked into the cylinder. The piston moves downward from top dead centre (TDC) till it

reaches bottom dead centre (BDC). During suction stroke exhaust valve (E) is closed.

2. Compression Stroke

During this stroke, both the inlet and exhaust valves are closed. The air-fuel mixture

is compressed as the piston moves upwards from BDC to TDC. As a result ofcompression, pressure and temperature of the charge are increased.

Shortly before the piston reaches TDC, the charge is ignited by means of a spark

plug. It suddenly increases the pressure and temperature of the products of combustion,

but the volume practically remains constant.

3. Expansion or Working Stroke

During this stroke, both the valves remain closed. Due to the rise in pressure, piston

is pushed down with a great force. The hot burnt gases expand pushing the piston from

TDC to BDC. It is also called working stroke as work is done by the expansion of hot

gases.


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4. Exhaust Stroke

During suction stroke, the exhaust valve opens, as piston moves from BDC to TDC.

This movement of the piston pushes out the hot gases from the cylinder. The exhaust

basic mechanical tvs

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