Basic Mechanical Engineering Lab Manual

VIDYA PRATISHTHAN’S
COLLEGE OF ENGINEERING, BARAMATI
DEPARTMENT OF MECHANICAL ENGINEERING
LABORATORY MANUAL
SUBJECT: BASIC MECHANICAL ENGINEERING
[SUBJECT CODE: 102013]
CLASS: F.E.
YEAR: 2011-12
APPROVED BY:
H.o.D. [Mech] PRINCIPAL
Prof. P. R. Chitragar Dr. S. B. Deosarkar
VALIDITY UP TO: ACADEMIC YEAR 2012 – 2013
LABORATORY IN-CHARGE: PROF. SACHIN. M. BHOSLE

VIDYA PRATISHTHAN’S
COLLEGE OF ENGINEERING, BARAMATI
DEPARTMENT OF MECHANICAL ENGINEERING
List of Experiments
YEAR: 20010-11 SUBJECT: Basic Mechanical Engineering
1. Assembly and working of 4-bar, 6- bar, 8-bar planar mechanisms.
2. Finding relation between input angle and output angle for various link lengths.
3. Demonstration of operations of centre Lathe
4. Demonstration of operations on drilling machine
5. Demonstration of Two stroke and four stroke engine
6. Study of Package type boilers
7. Study of domestic refrigerator & window air conditioner.
8. Study of power transmitting elements: couplings, gears & bearings.
9. Study Joule’s Porous plug experiment
10. Joule’s paddle wheel experiment
11. Experimental verification of effect of insulating material on heat transfer.
Prof. Sachin M. Bhosle
[Lab-Incharge]

BASIC MECHANICAL ENGINEERING – LABORATORY MANUAL
DEPARTMENT OF MECHANICAL ENGINEERING - VPCOE
EXPERIMENT NO. 1
TITLE: ASSEMBLY AND WORKING OF 4-BAR, 6-BAR, 8-BAR PLANAR
MECHANISMS
Aim: - To study of Assembly and working of 4-bar, 6-bar and 8-bar planar
mechanism.
Theory: - Kinematic links: A resistant body or group of resistant bodies with
rigid connections preventing their relative movement is known as link. A link may
be defined as a member or a combination of members of a mechanism,
connecting other members and having motion relative to them. Thus a link may
consist of one or more resistant bodies. A slider crank mechanism consist of
four links; Frame and guides, crank connecting rod and slider. However, the
frame may consist of bearings for the crank shaft. The crank link may have
crankshaft and flywheel also, forming one link having no relative motion of
these.
Links can be classified into Binary, ternary, quaternary etc. depending upon
its ends on which revolute or turning can be placed.
Fig. 1
Kinematic pair:
A kinematic pair or simply a pair is a joint of two links having relative
motion between them. In slider-crank mechanism, link 2 rotates relative to link

1 and constitutes a revolute or turning pair. Link 4 (slider) reciprocates relative
to link 1 and is a sliding pair.
Type of kinematic pair:
Kinematic pairs can be classified according to
 Nature of contact
 Nature of relative motion
Kinematic pair according to nature of contact
a) Lower pair: A pair of links having surface or area contact between
the members is known as a lower pair. The contact surfaces of the two
links are similar.
Example: Nut turning on a screw, shaft rotating in a bearing, all pairs of a
slider-crank mechanism, universal joint etc.
b) Higher pair: When a pair has appoint or line contact between the
links, it is known as higher pair. The contact surfaces of the two links are
dissimilar.
Example: wheel rolling on a surface, cam and follower pair, tooth gears,
balls and roller bearings, etc.
Kinematic pairs according Nature of relative motion
a) Sliding pair: If two links have a sliding motion relative to each
other, they form a sliding pair.
A rectangular rod in a prism is a sliding pair.
b) Turning pair: when one link has a turning or revolving motion relative
to each other, they constitute a turning pair or revolving pair.
In slider-crank mechanism, all pairs except the slider and guide pair are turning
pairs. A circular shaft revolving inside a bearing is a turning pair.
c) Rolling pair: when the links of a pair have a rolling motion relative to
each other, they form a rolling pair, e.g. a rolling wheel on a flat surface,
ball and roller bearing, the ball and the shaft constitute one rolling pair
whereas the ball and the bearing is the second rolling pair.
d) Screw pair: If two mating links have turning as well as sliding
motion between them, they form a screw pair. This is achieved by cutting
matching threads on the two links.
The lead screw and the nut of a lathe is a screw pair.
e) Spherical pair: when one link in the form of a sphere turns inside a
fixed link, it is spherical pair.
The ball and socket joint is a spherical pair.
Kinematic Chain:

A kinematic chain is an assembly of links in which the relative motions of the
links is possible and the motion of each relative to the others is definite.
In case, the motion of a link results in indefinite motions of other links, it is
a non-kinematic chain.
Mechanism:
If one of the links of a kinematic chain is fixed to the ground and if motions of
each link results in definite motions of the others, the linkage is known as
mechanism.
To obtain constrained or definite motions of some of the links of the
mechanism, it is necessary to know how many inputs are needed. In some links
and are said to have one degree of freedom. In other mechanism, two inputs
may be necessary to get a constrained motions of the another links and are said
to have two degrees of freedom and so on.
Four bar mechanism:
A four bar mechanism is the most fundamental of the lane kinematic
linkages. It is much preferred mechanical device for the mechanization and
control of motion due to its simplicity and versatility. Basically it consists of
four rigid links which are connected in the form of a quadrilateral by four pin
joints.
A link that make complete revolutions is the crank, the link opposite to the
fixed link is the coupler and the fourth link a lever or rocker if oscillates or an
another crank, if rotates.
A four bar mechanism has the following characteristics based on the lengths of
its link.
1. It is impossible to have a four bar mechanism if length of the one of the
links is greater than the sum of the other three.
2. If the sum of the lengths of the largest and the shortest links is less than
the sum of the other two links, the linkage is known as class-I, four- bar
mechanism.
Fig.2

If the links of the four bar mechanism obtained above, are fixed, different
mechanisms are obtained known as Inversion
a. Shortest link is fixed
If the shortest link is fixed, the adjacent link b and d makes complete
revolutions. The mechanism thus obtained is known as crank- crank or double
crank or rotary- rotary mechanism.
b. Link adjacent to the shortest link is fixed;
If any of the link adjacent to the shortest link is fixed, the shortest link makes
complete revolution and acts as a crank, and the link opposite to the crank is
oscillates. The mechanism is known as a crank-rocker or crank-lever mechanism
or a rotary-oscillating converter.
c. link opposite to shortest link is fixed:
If the shortest link a is made coupler and the link opposite to it, i.e. c, is fixed,
the other two links b and d would oscillate. The mechanism is known as a rocker-
rocker or double rocker or double lever mechanism or oscillating-oscillating
mechanism.
3. When the sum of the lengths of the shortest and largest links is more
than the sum of the lengths of the other two links known as class-II, four bar
mechanism. In such mechanism, fixing any of the links always results in a
rocker- rocker mechanism. In other words, the mechanism and its inversions
give the same type of motion i.e. double-rocker mechanism.
4. Parallel-crank four-bar linkage: If in a four-bar linkage, two opposite links
are parallel and equal in length, then any of the links can be made fixed. The
four links form a parallelogram in all the positions of the cranks, provided the
crank rotates in the same sense.
The use of such a mechanism is made in the coupled wheels of locomotive in
which the rotary motion of one wheel is transmitted to the other wheel. For
kinematic analysis, link d is treated as fixed and the relative motions of the
other links are found. However, in fact, d has a translator motion parallel to the
trails.
6-bar planar mechanism:
In case of four-bar chain does not provide the required performance of an
application, one of the two single-degree of freedom six bar chain with seven
turning or revolute pairs is considered. There are two types of six-bar chains.
1. Watt chain: In watt chain the ternary links are adjacent for Watt six-
bar chain

Fig. 3 Watt-I & Watt-II mechanisms
2. Stephenson chain: In Stephenson chain ternary links separated by binary
links refer fig. for Stephenson-I six-bar mechanism, For Stephenson-II six-bar
mechanism and For Stephenson-III six-bar mechanism. It may be noted that in
both these types of mechanism some triangular shaped links are truly ternary
links while other are known as triangular to indicate the possible path of tracer
points on floating links.
Fig. Stephenson -I, II &I II mechanisms
Conclusion: -
References:

EXPERIMENT NO. 2
TITLE: POWER TRANSMITTING ELEMENTS
Aim: - Study of Power transmitting element.
Theory :- (**refer Dr. Kodgire’s Material Science and Metallurgy)
Type of Fracture :- (**refer Dr. Kodgire’s Material Science and Metallurgy)
Shaft coupling:
Shaft couplings are used to join two or more pieces of the shaft.
Types of shaft coupling:
Shaft couplings are divided into two groups as follows
1) Rigid coupling
It is used to connect two shafts which are perfectly aligned. Following are
the type of rigid coupling
a) Sleeve or muff coupling
b) Clamp or split muff or compression coupling and
c) Flange coupling
2) Flexible coupling
It is used to connect two shafts which are having both lateral and
angular misalignment. Following are the type of rigid coupling
a) Bushed pin type coupling
b) Universal coupling
c) Oldham coupling
Sleeve or muff coupling:
It is the simplest type of rigid coupling made of cast iron. It consists of a
hollow cylinder whose inner diameter is same as that of shaft. It is fitted over
the ends of the two shafts by means of a gib head key as shown in fig. the
power is transmitted from one shaft to the other shaft by means of sleeve.
Fig. 1
Clamp or split muff or compression coupling:

In this case, the muff of sleeve is made into two halves and is bolted
together as shown in fig. The shaft ends are made to abut each other and a
single key is fitted directly in the keyways of both the shafts. One-half of the
muffs are fixed from below and the other half is placed from above. Both the
halves are held together by means of mild steel studs or bolts and nuts. The
number of bolts may be two, four or six. The nuts are recessed into the bodies
of the muff castings. This coupling may be used for heavy and moderate speeds.
The advantage of this coupling is that the position of the shafts need not be
changed for assembling and disassembling of the coupling.
Flange coupling:
A flange coupling usually applies to a coupling having two separates
cast iron flanges. Each flange is mounted on the shaft end and keyed to it. The
faces are turned up at right angle to the shaft. One of the flanges has a
projected portion and the other flange has a corresponding recess. This helps
to bring the shafts into line and to maintain alignment. The two flanges are
coupled together by means of bolts and nuts. The flange coupling is adapted to
heavy loads and hence it is used on large shafting.
Fig. 2
Flexible coupling:
A flexible coupling is used so as to permit an axial misalignment of the shaft
without undue absorption of the power which the shafts are transmitting.
Following are the type of different types of flexible couplings
1. Bushed pin flexible coupling:
A Bushed pin flexible coupling is a modification of the rigid type of flange
coupling. The coupling bolts are known as pins. The rubber or leather bushes are
used over the pins. The two halves of the coupling are dissimilar n construction.

A clearance of 5mm is left between the faces of the two halves of the coupling.
There is no rigid connection between them and the drive takes place through
the medium of the compressible rubber or leather bushes.
Fig. 3
a. Oldham coupling
It is used to join two shafts which have lateral mis-alignment. it consist of two
flanges With slots and a central floating part with two tongues at right angles
as shown in fig. the central floating part is held by means of a pin passing
through the flanges and the floating part. The tongue fits into the slot of
flange and allows for ‘to and fro’ relative motion of the shafts, while another
tongue fits into the slot of another flange and allows for vertical relative
motion of the parts. The resultant of these two components of motion will
accommodate lateral misalignment of the shafts as they rotate.
Fig. 4

3. Universal or hook’s coupling
A universal or hook’s coupling is used to connect two shafts whose axes
intersect at a small angle. The inclination of the shafts may be constant, but in
actual practice, it varies when the motion is transmitted from one shaft to
another. The main application of the universal coupling is found in transmission
from gear box to the differential or back axle of the automobiles. In such a
case, we use two Hook’s coupling, one at each end of the propeller shaft,
connecting the gear box at one end and the differential on the other end. A
hook’s coupling is also used for transmission of power to different spindles of
multiple drilling machines.
Fig. 5
Gears
Gears are used to transmit motion from one shaft to another or between a
shaft and a slide. This is accomplishing by successively engaging teeth.
Gears use no intermediate link or connector and transmit the motion by
direct. In this method, the surfaces of two bodies make a tangential contact.
The two bodies have either a rolling or a sliding motion along the tangent at the
point of contact.
Classification of gears
Gears can be classified according to the relative positions of their shaft axes
as follows:
1. Parallel shafts
Regard less of the manner of contact, uniform rotary motion between two
parallel shafts is equivalent to the rolling of two cylinders, assuming no slipping.
Depending upon the teeth of the equivalent cylinder that is straight or helical,
following are the main types of gears to join parallel shafts.

Spur Gears
They are straight teeth parallel to the axis and thus, are not subjected to axial
thrust due to tooth load. At 6he time of engagement of two gears, the contact
extends across the entire width on a line parallel to the axis of rotation. This
results in sudden application of the load, high impact stresses and excessive
noise at high speeds. Further, if the gears have external teeth on the outer
surface of the cylinder, the shafts rotate in the opposite direction. In an
internal spur gear, the teeth are formed on the inner surface of an annulus ring.
An internal gear can mesh with an external pinion (smaller gear) only and the
two shafts rotate in the same direction as shown in the fig
.
Fig. 5
Spur Rack And pinion
Spur Rack is a special case of spur gear where it is made of infinite diameter so
that the pitch surface is plane. The spur rack and pinion combination converts
rotary motion into translatory motion, or vice versa. It is used in a lathe in
which the rack transmits motion to the saddle.
Helical or helical spur gears
In helical gears the teeth are curved, each being in helical in shape. Two mating
gears have the same helix angle, but have teeth of opposite hands. At the
beginning of engagement contact occurs only at the point of leading edge of the
curved teeth, as the gears rotate, the contact extends along a diagonal line
across the teeth. Thus, load application is gradual which results in low impact

stresses and reduction in noise. Therefore, the helical gears can be used at
higher velocities than the spur gear and have greater load carrying capacity.
Helical gears have the disadvantage of having in thrust as there is a force
component along the gear axis. The bearings and the assemblies mounting the
helical gears must be able to withstand thrust loads.
Fig. 6
2. Intersecting shafts
Kinematically, the motion between two intersecting shafts is equivalent to the
rolling of two cones, assuming no slipping.
When teeth formed on the cones are straight, the gears are known as straight
bevel and when inclined, they are known as spiral or helical gear.
Straight bevel gear
The teeth are straight, radial to the point of intersection of the shaft axis and
vary in cross section through out their length. Usually, they are used to connect
shafts at right angles to each other are known as mitre gears, at the beginning
of engagement , straight bevel gear make the line contact similar to spur gear.
They can also be internal bevel gears analogous to internal spur gears.

Fig. 7
Spiral bevel gear:
When the teeth of a bevel gear are inclined at an angle to the face of the
bevel, they are known as spiral bevel or helical bevels. They are smoother in
action and quieter than straight tooth bevels as there is gradual load application
and low impact stresses. Of course, there exists an axial thrusts calling for
stronger bearings and supporting assemblies these are used for the drive to the
differential of an automobile.
Fig. 8
Bearing
A bearing is the machine element which supports another machine element(
known as journal). It permits a relative motion between the contact surfaces of
the members, while carrying the load. Due to the relative motion between the
contact surfaces, a certain amount of power is wasted in overcoming the
frictional resistant and if the rubbing surfaces are in contact, there will be
rapid wear. In order to reduce frictional resistance and wear and in some cases
to away the heat generated, a layer of fluid known as lubricant may be provided.
The lubricant used to separate the journal and bearing is usually a mineral oil
refined from petroleum, but vegetable oils, silicon oils, greases etc may be used.
Classification of bearings
Though the bearing may be classified n many ways, yet the following are
important from the subject point of view.
1. Depending upon the direction of load to be supported;
The bearing under this group are classified as:
a) Radial bearing:

The load acts perpendicular to the direction of motion of the moving element as
shown in following figure.
Fig. 9
b) Thrust bearing:
If load acts along the axis of rotation of the shaft, then the bearing which
supports such shaft is called as thrust bearing.
Fig. 10
2. Depending upon the nature of contact
a) Sliding contact bearing:
Sliding takes place along the surfaces of contact between the moving element
and the fixed element. They are also known as plain bearing. The sliding contact
bearing are also known as journal bearing. They have surface contact with
moving element.
b) Rolling contact bearing;
Rolling motion takes place along the surfaces of contact between the parts.
Steel balls or rollers are interposed between the moving and fixed elements,
which offer rolling friction. They are also known as antifriction bearings. They
have point or line contact with moving element.

Fig. 11

EXPERIMENT NO. 1
TITLE: VERIFICATION OF EFFECT OF INSULATING MATERIAL ON
HEAT TRANSFER
Aim: - Experimental Verification of effect of insulating material on heat
transfer.
Apparatus: Metal rod apparatus, Electric heater, Cu rod, Thermocouples
Theory: - Insulating materials: The material of low coefficient of thermal
conductivity are called insulating material.
The material which retards the flow of heat with responsible effectiveness is
known as insulation.
Insulation serves the following purpose
1. It prevents the heat flow from system to surrounding.
2. It prevents heat flow from surrounding to the system.
Desirable properties:
1. It is able to withstand high or low temperature
2. It should have long life and could withstand rough handling
3. It must be easy to apply.
4. It is economical
Applications:
1. boilers and steam pipes
2. Air conditioning systems
3. food prevent stores and refrigerators
4. Insulating bricks
5. preservation of liquid gases
Experimental set up:
It consists of metal rod which is insulated all over its structure with layer
of insulating material. An electric coil is fixed to one end of rod while other rod
ends in water. A number of thermocouples are fitted along the length of rod.
Thermocouples are fitted along to measure temperature of inside insulation and
water inlet and outlet.
Control panel consist of temperature indicator with selector switch. A
voltmeter and n ammeter is provided to measure voltage and current supplied to

the water heater. Dimmerstat is provided to the control voltage supply to
heater.
Procedure;
1. Switch on the main switch
2. Adjust the dimmerstat to give required heat input to the metal rod ( in
the range of 80 v to 120v).

3. Circulate sufficient amount of water through water jacket
4. Take the reading of on interval 5 min. till steady state reached.
5. Note down the temperature reading (T1 to T10)
Observation table:
Sr. no. Thermocouple Temperature
30 35 40 45 50 55 60 65 70 75 80
Precautions:
1. See the dimmerstat is at zero position before switching on the main switch
2. Operate the temperature change over switch gently.
3. Be sure that steady state is reached before taking to find readings.
Conclusion: As the rate of heat transfer decreases in insulating material, it is
verify that insulating material resist the heat flow.

EXPERIMENT NO. 4
TITLE: DEMONSTRATION OF TWO STROKE AND FOUR STROKE
ENGINE
Aim: - To study working of Two stroke and Four Stroke Engine
Theory: - Any machine which derives heat energy from the combustion of fuel
& converts part of this energy into mechanical work is known as heat engine.
Heat engines are divided into two groups
1) Internal combustion Engine
2) External combustion Engine
Internal combustion Engine External combustion Engine
1) Combustion takes place inside
cylinder
Combustion takes place outside
cylinder
2)
Fuel combustion in presence of
air takes place inside cylinder &
products of combustion acts on
piston to develop power
Heat of combustion is
transferred to working fluid
outside cylinder & then fluid is
expanded to develop power
3) Eg. Diesel & Petrol engine Eg. Steam engines & Turbines
Depending upon cycle of operations IC engines are classified as
Two Stroke Engine Four Stroke Engine
One power stroke in One rotation of
crank
One power stroke in Two rotations of
crank
So we have types of IC engines as follows
1) Four stroke SI engine
2) Four stroke CI engine
3) Two stroke SI engine
4) Two stroke CI engine
Where SI engine ═ Spark ignition = Petrol engine
CI engine = Compression ignition = Diesel engine

1] Four Stroke SI engine:
The working cycle of the engine is completed four stroke or Two revolutions of
crank & Petrol is used as fuel.
1) Suction Stroke: The piston is at the Top most position (TDC) and is ready
to move down drawing the mixture of air & fuel. The inlet valve is open &
exhaust valve is closed. As the piston moves downwards the fresh charge of air
fuel mixture enters the cylinder through the inlet valve due to suction created.
This continues until piston reaches the Bottom dead centre (BDC). At this
position the inlet value closes. This downward movement of piston is known as
suction stroke & crank rotates by 180° during this period.
2) Compression Stroke: During this stroke both valves ( inlet & exhaust ) are
closed & the piston moves upward & compresses the charge enclosed in the
cylinder. The pressure & temperature of the mixture increases continuously
during this process. As the piston reaches the TDC position, the mixture is
ignited by an electric spark.
3) Power or Expansion stroke: The increased pressure of the mixture exerts
a large force & pushes the piston down. During expansion stroke both valves
remains closed. The high pressure & temperature gases pushes piston
downwards “& gas pressure gradually decreases. Piston moves from TDC to BDC.
As work is done this is called power stroke. Exhaust valve opens as piston
reaches to BDC. Pressure falls down to atmospheric pressure.
4) Exhaust stroke: Now piston moves upward from BDC to TDC. Exhaust valve
is open & inlet valve is closed. Moving piston pushes out the burnt gases through
exhaust valve. As piston reaches TDC, again the inlet valve opens & fresh
charge is taken during next suction stroke.

The engine is known as four stroke engine because one power stroke in every
four strokes of the piston.
2] Four Stroke CI Engine:
The working cycle of the engine is completed in four stroke & diesel oil is
used as a fuel therefore it is known as four stroke diesel engine.
1) Suction Stroke: The piston is at the Top most position (TDC) and is ready
to move down drawing only air. The inlet valve is open & exhaust valve is
closed. As the piston moves downwards, the air enters the cylinder through the
inlet valve due to suction created. This continues until piston reaches the
Bottom dead centre (BDC). At this position the inlet value closes. This
downward movement of piston is known as suction stroke & crank rotates by
180° during this period.
2) Compression Stroke: During this stroke both valves (inlet & exhaust) are
closed & the piston moves upward & compresses the air enclosed in the cylinder.
The pressure & temperature increases continuously during this process. As the
piston reaches the TDC position, the mixture is ignited by an electric spark.
3) Expansion Stroke: During this inlet & exhaust valve are closed & fuel
valve opens just before beginning of third stroke. Because of temperature of
air at compression stroke, fuel is ignited & combustion takes place. High
pressure & temp. Gases pushes piston down .Exhaust valve opens as piston
reaches BDC.
4) Exhaust stroke: During this inlet & fuel valve remain closed, exhaust valve
remains open. Piston moves from BDC to TDC & pushes out burnt gases.
3] Two Stroke engine:
The working cycle of the engine is completed Two stroke or One revolutions of
crank.
1) Initially piston is at TDC & as it moves downwards to BDC, exhaust port
gets opened & burnt gases moves downwards. With further downward
movement inlet port is opened & suction takes place , air fuel mixture is
admitted in crank case. Further downward movement of piston gives
compression stroke for fresh charge & now piston is at BDC.
2) Now while moving piston from BDC to TDC upwards, the charge is
compressed again & spark plug gives spark to initiate combustion.
Combustion developes fully when piston is at TDC. Due to high pressure &
temp. Piston is pushed downward.

Conclusion:-
References:

EXPERIMENT NO. 5
TITLE: Study of Package Type Boilers
Aim: - To Study of Package Type Boilers
Theory: - A steam generator known as boiler is a closed vessel made of high quality
steel in which steam is generated by water by the application of heat. The water
receives heat from hot gases through the heating surface of boiler. The hot gases are
formed by burning fuel may be coal, oil or gas. The steam which is collected under the
water surface is taken from boiler through super heater & then suitable pipes for
driving engines or turbines. A boiler consists of not only the steam generators but also
a number of parts to help for safe & sufficient operation of system as a whole. These
parts are called mountings & accessories.
Classification of Boilers:
1) According to relative position of water & hot gases :i) Fire tube ii) Water tube
2) According to axis of shell : i) Vertical boiler ii) Horizontal boiler
3) According to method of furnace : i) Externally fired ii) Internally fired
4) According to method of water circulation : i) Natural air ii) Forced air
5) According to use : i) Stationary boiler ii) Mobile boiler
6) Boilers which are factory assembled & mounted on skids and are ready for
operation once water & steam lines are connected are known as Package Boilers.
Requirements of Good Boiler:
A good boiler must posses following qualities:
1) The boiler should be capable to generate steam at the required pressure and
quantity as quick as possible with minimum fuel consumption.
2) The initial cost, installation cost and the maintenance cost should be as low as
possible.
3) The boiler should be light in weight, and should occupy small floor area.
4) The boiler must be able to meet the fluctuating demands without fluctuations.
5) All the parts of the boiler should be easily approachable for cleaning and inspection.
6) The boiler should have minimum of joints to avoid leaks which may occur due to
expansion and contraction.
7) The boiler should be erected at site within a reasonable time and with minimum
labour.
8) The water and flue gas velocities should be high for high heat transfer rates with
minimum pressure drop through the system.

9) There should be no deposition of mud and foreign materials on the inside surface
and soot deposition on the outer surface of heat transferring parts.
10) The boiler should conform to the safety regulations as laid down the boiler act.
Fig. 1
Packaged Water Tube Boilers:
Capacity: 50 tons/hr with water cooled furnace
Advantages:
i) Minimum weight
ii) Minimum maintenance
iii) Maximum structural rigidity
iv) Maximum safety
Fuel used: Coal, wood, process waste
Fig shows Package boiler with feed pump, blower & other mountings provided. Air is
supplied by blower & combustion of air & fuel takes place. As a result, hot high
pressure gases are generated in combustion chamber & flow from front end to rear
end, through central fire tube in Ist
pass
Then the gases will flow from rear end to front end again through lower fire tube in
IInd
pass.
Now in IIIrd
pass, gases again flow from front end to rear end through upper fire
tubes& the exhausted through chimney.

EXPERIMENT NO. 6
TITLE: STUDY OF DOMESTIC REFRIGERATOR & WINDOW AIR
CONDITIONER
Aim: - Study of Power transmitting element.
Theory: - Refrigeration is defined as an art of producing and maintaining
temperature in a space below atmospheric temperature. A refrigerator is equipment
used to remove the heat continuously from space (Sink) & maintain the temperature
below atmospheric temperature and reject heat to the atmosphere (source).
Vapor Compression Refrigeration System:
In Vapor compression refrigeration system, the refrigerant used alternately undergoes
a change of phase from vapor to liquid and liquid to vapor during the cycle. The latent
heat of vaporization is utilized for absorbing the heat at low temperature from the
refrigerated space. A constant temperature can be maintained in the space.
The arrangement of the components of vapor compression refrigeration system
is shown in fig. The liquid coming out from the condenser is passed through the
throttle valve (float valve). The pressure of the refrigerant is reduced as it passes
through the throttle valve. The function of the throttle valve is to allow the liquid
refrigerant under high pressure to pass at a controlled rate into the low pressure part
of the system known as evaporator. A mixture of vapor and liquid refrigerant enters
the evaporator (refrigerator) at low pressure. The liquid refrigerant absorbs the heat
load on the refrigerator as its latent heat of evaporation is converted into vapor. The
function of the compressor is to increase the pressure of the refrigerant so that the

refrigerant vapor would be able to dissipate its latent heat to the atmosphere. The
high pressure, high temperature refrigerant vapor leaving the compressor enters into
the condenser where the latent heat of refrigerant is removed by circulating either
atmospheric air or water. The liquid refrigerant leaving the condenser again enters the
throttle valve and the cycle is repeated.
Domestic Refrigerator:
The basic components are
i) Evaporator
ii) Compressor
iii) Condenser
iv) Expansion device
The evaporator where the refrigerant (working fluid) evaporates absorbs the latent
heat of vaporization is the part of the freezer cabinet, where it is loaded. In modern
frost free refrigerators, the evaporator is located outside the cabinet, as fan
circulates air from evaporator to the freezer. Just below the freezer, there is a
chiller tray. Further below are compartments with progressive higher temperature.
The bottom most compartment means of vegetable is the cold one. The cold air being
heavier flows down from the freezer to the bottom of the refrigerator. The warm air
being lighter flows upward from vegetable box to freezer gets cooled & flows down
again. Thus natural convection current is set up which maintains a temperature gradient
between top & bottom of refrigerator. The temperature maintain in the freezer is -
15°C . The condenser is usually a wire & tube type mounted at the back of the
refrigerator. Having no fan, the refrigerator vapor is condensed with the help of
surrounding air which rises above by natural convection as it gets heated after
absorbing the latent heat of condensation from refrigerant. After condensation, the
high pressure liquid refrigerant is reduced to the low pressure of the evaporator by
passing through liquid. Refrigerant is reduced to the low pressure of the evaporator by
passing through an expansion device (throttle) valve or capillary tube and cycle is
completed.
Window Air Conditioning:
Let us consider a room to be maintained at a constant temperature of 25°C. The
air from the atmosphere drawn by a fan & is made to pass over a cooling coil of
evaporation, the surface of which is maintained at a temperature of 10°C.
After passing over the coil, the air is cooled to around 10°C before being
supplied to the room at 25°C by the fan. In the cooling coil, the refrigerant R-22 or R-
134 enters at say 5°C & evaporator absorbing the latent heat of vaporization from the
room air.
The refrigerator from the evaporator is compressed to high pressure before
entering the condenser where the atmospheric air at about say 45°C in summer is

circulating by a fan. After picking up the latent heat of condensation from the
refrigerant, the air is thrown back to the atmosphere say at 55°C. The high pressure
liquid refrigerant from the condenser is reduced to the low evaporator pressure by
passing through the expansion device (capillary tube) before entering the evaporator.
The cycle repeats itself.

BASICS OF MECHANIACAL ENGINEERING – LABORATORY MANUAL
EXPERIMENT NO 7
TITLE: DEMONSTRATION OF OPERATIONS ON CENTRE LATHE
APPARATUS: lathe machine and mild steel rod.
OBJECTIVE: To study the various operations such as turning, step turning,
facing, boring, taper turning, knurling, grooving, threading of center lathe.
THEORY: A product is made up of many components which are manufactured
by various manufacturing processes such as casting, forging, welding; machining
etc depends on the application and cost of that particular component. In the
machining process various operations comes like turning, step turning, facing,
boring, taper turning, knurling, grooving, threading. All these operations can be
done on center lathe hence center lathe is one of the importance type of
machines. In this practical we are going to study the operations which are
mentioned above.
Lathe is a machine tool which rotates the work piece on its axis to perform
various operations such as cutting, sanding, knurling, drilling or deformation with
tools that are applied to the work piece to create an object which
has symmetry about an axis of rotation. Examples of objects that can be
produced on a lathe include candlestick holders, gun barrels, sticks,
table legs, bowls, baseball bats, musical instruments (especially woodwind
instruments), crankshafts and camshafts.
Parts of lathe and their function
Bed: Almost all lathes have a horizontal beam is called as bed. It has guide ways
on it for sliding and supporting tail stock and carriage.
Head stock: At one end of the bed (almost always the left, as the operator
faces the lathe) is a headstock. It contains drive mechanism with necessary
speed change arrangement to achieve different speeds. It also has chuck which
is used to hold the job.
Tail stock: It is places opposite to headstock. It can move along guide ways. Its
main applications are to hold long jobs to avoid vibrations and excessive
deformation and for drilling axial holes in the work piece it can also hold the
tools such as drill, reamer, tap to do the operations like drilling, reaming etc.
Carriage: It is located between head stock and tail stock. It can be moved in
longitudinal direction and can be fixed at any position. Carriage has following
parts
a. Saddle: Its base portion, located across lathe bed and carries cross slide and
tool post, it can be moved longitudinally along the bed.
b. Apron: it is attached to saddle and appears as hanging on front side. It
consists of gears for motion transmission.

C: Cross slide: it is mounted on top of the saddle and acts as support to
compound rest
D: Compound rest: It is mounted on cross slide and it consists of swivel and top
slide. The tool post is mounted on top slide.
E: Tool-post: it is used to hold the tool position the tool as per the requirement
.
Fig.: Schematic Illustration of center lathe
Various Lathe operations
Turning: It is the process of removing the material from
extended surface of rotating work piece. So it is the
process by which a piece of material (wood, metal, plastic,
or stone) is rotated and a cutting tool is traversed along 2
axes of motion to produce precise diameters and depths
Fig: Turning

Step Turning: It is the process of obtaining different diameters on a work
piece along the length by adjusting depth of the tool
Fig: Step Turning
Taper Turning: It is the process of giving the angle to the work piece with the
help of compound slide.
Fig: Taper turning

Boring: It is the machining of internal cylindrical forms (generating) a) by
mounting work piece to the spindle via a chuck or faceplate b) by mounting work
piece onto the cross slide and placing cutting tool into the chuck.
Fig: Boring operation
Knurling: The cutting of a serrated pattern onto the surface of a part to use as
A hand grip using a special purpose knurling tool
Fig. Knurling Tool
Threading: It is the process of producing the helical V grooves on the surface
with the help of lead screw.
Fig: Threading Process.

Facing
It is the process of removing the material from the end surface or face of work
piece.
Fig: Facing
Grooving: It is the process of producing V shape cyclical groove on the surface,
the tool has similar V shape as required to produce on work piece
Fig. Grooving
CONCLUSION:
Hence we have studied various operations such as turning, step turning, facing,
boring, taper turning, knurling, grooving, and threading which are performed on
center lathe.
REFERENCES:
1. Elements of Workshop Technology (Vols. 1 and II) by Hajra chaudhary

EXPERIMENT NO 8
DEMONSTRATION OF OPERATIONS ON DRILLING MACHINES
APPARATUS: Drilling machine and mild steel rod.
OBJECTIVE: To study the various operations on drilling machines such as
drilling, reaming, spot facing , counter boring
THEORY: Holes in the work piece are necessary for many purposes such as
fastening the object with nuts and bolts, Screws, for fixing assembly purpose
So it is necessary to make holes in the work piece. So the Drilling is a process of
making a hole in the blank work piece, or enlarging the existing hole. The
Machine which is used foe this purpose is called as drilling machine.
It consist of spindle which is rotated by the motor and transmitting mechanism,
The spindle in turn rotates the drilling tool called as drill, as drill is press fitted
into the spindle. Drill is fed into work by feed mechanism. The work piece is
fixed on the table, as the drill fed into the work piece, the hole is created by
removing material in the form of chips. All the components are supported by
frame. Cutting fluid is commonly used to cool the drill bit, increase tool life,
increase speeds and feeds, increase the surface finish, and aid in ejecting
chips.
Fig: Drilling machine

Parts of Drilling machine and their function
Base: base is the lowest horizontal part which supports the entire structure of
drilling machine. It is made up of cast iron because cast iron absorbs vibrations.
So the vibrations transmitted to foundation get reduced
Work table: It is mounted on column which supports the work. Generally its has
two types of motions
a. It can swing about column
b. it can move up and down. This facilitates the positioning of work piece while
drilling.
Spindle: It is a hollow portion which is provided with rotary motion spindle
imparts this rotator motion to drill.
Head: It consist of drive mechanism and feed mechanism.
Operations Performed on the drilling machine
Drilling: It is the process of making a hole in blank work piece with tool known as
drill.
Fig: Drilling
Reaming: It is process of finishing and sizing of drilled hole with the help of
tool called as reamer.
Fig: Reaming

Boring: It is process of enlarging the already existing hole to meet the required
Size and finish.
Fig: Boring
Spot facing: It is the process of machining a flat circular surface around a hole
to provide a seat for a bolt head nut or washer.
Fig: Spot facing
Counter boring: It is the process of cylindrically enlarging the face of existing
hole.
Fig: counter boring

CONCLUSION:
Hence we studied various operations such as drilling, reaming, spot facing,
counter boring which are performed on Drilling machine.
REFERENCES:
1. Elements of Workshop Technology (Vols. 1 and II) by Hajra chaudhary

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