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CHAPTER 1

INTRODUCTION

1.1 INTRODUCTION TO WIND MILLS

Wind mills or wind turbines are devices that extract power from the wind and produce

mechanical or electrical power. The term wind turbineis often reserved for machines that use

rotors as wind energy collectors. Wind turbines are classified as horizontal-axis (HAWTs) or

vertical-axis turbines (VAWTs). Nearly all wind turbines manufactured today are horizontal-

axis. Vertical-axis machines have been plagued with blade fatigueproblems. In addition, the

rotors on VAWTs are typically lower than those of HAWTs. The latter positioning presents a

disadvantage because the velocity of the wind decreases near the ground. Most HAWTs have

two or three blades. The blades can be oriented upwind or downwind of the tower.

1.1.1 WORKING OF WIND MILL

Wind turbines produce electricity by using the natural power of the wind to drive a generator.

The wind is a clean and sustainable fuel source, it does not create emissions and it will never run

out as it is constantly replenished by energy from the sun. In many ways, wind turbines are the

natural evolution of traditional windmills, but now typically have three blades, which rotate

around a horizontal hub at the top of a steel tower. Most wind turbines start generating electricity

at wind speeds of around 3-4 meters per second (m/s), (8 miles per hour); generate maximum

„rated‟ power at around 15 m/s (30mph); and shut down to prevent storm damage at 25 m/s or

above (50mph). Generating electricity from the wind is simple: Wind passes over the blades

exerting a turning force. The rotating blades turn a shaft inside the nacelle, which goesinto a

gearbox. The gearbox increases the rotation speed for the generator, which uses magnetic fields

to convert the rotational energy into electrical energy.

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Figure 1.1 cross section view of a windmill

1.1.2 YAW DRIVE

The yaw drive is an important component of wind mills. To ensure the wind turbine is producing

the maximal amount of electric energy at all times, the yaw drive is used to keep the rotor facing

into the wind as the wind direction changes.

Figure 1.2 working of yaw drive

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1.1.3 ACTIVE YAW SYSTEMS

The active yaw systems are equipped with some sort of torque producing device able to rotate

the nacelle of the wind turbine against the stationary tower based on automatic signals from wind

direction sensors or manual actuation (control system override). The active yaw systems are

considered to be the state of the art for all the modern medium and large sized wind turbines,

with a few exceptions proving the rule (e.g. Vergnet). The various components of the modern

active yaw systems vary depending on the design characteristics but all the active yaw systems

include a means of rotatable connection between nacelle and tower (yaw bearing), a means of

active variation of the rotor orientation (i.e. yaw drive), a means of restricting the rotation of the

nacelle (yaw brake) and a control system which processes the signals from wind direction

sensors (e.g. wind vanes) and gives the proper commands to the actuating mechanisms.

The most common types of active yaw systems are:

Roller yaw bearing - Electric yaw drive - Brake:

The nacelle is mounted on a roller bearing and the azimuth rotation is achieved via a

plurality of powerful electric drives. A hydraulic or electric brake fixes the position of

the nacelle when the re-orientation is completed in order to avoid wear and high fatigue

loads on wind turbine components due to backlash. Systems of this kind are used by most of

the wind turbine manufacturers and are considered to be reliable and effective but also quite

bulky and expensive.

Roller yaw bearing - Hydraulic yaw drive:

The nacelle is mounted on a roller bearing and the azimuth rotation is achieved via a

plurality of powerful hydraulic motors or ratcheting hydraulic cylinders. The benefit of the

yaw system with hydraulic drives has to do with the inherent benefits of the hydraulic

systems such as the high power-to-weight ratio and high reliability. On the downside

however the hydraulic systems are always troubled by leakages of hydraulic fluid and

clogging of their high pressure hydraulic valves.

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Gliding yaw bearing - Electric yaw drive:

The nacelle is mounted on a friction based gliding bearing and the azimuth rotation is

achieved via a plurality of powerful electric drives. The need for a yaw brake is eliminated

and depending on the size of the yaw system (i.e. size of the wind turbine) the gliding

bearing concept can lead to significant cost savings.

Gliding yaw bearing - Hydraulic yaw drive:

The nacelle is mounted on a friction based gliding bearing and the azimuth rotation is achieved

via a plurality of powerful hydraulic motors or ratcheting hydraulic cylinders. This system

combines the characteristics of the aforementioned gliding bearing and hydraulic motor systems.

1.1.4 PASSIVE YAW SYSTEMS

The passive yaw systems utilize the wind force in order to adjust the orientation of the wind

turbine rotor into the wind. In their simplest form these system comprise a simple roller

bearing connection between the tower and the nacelle and a tail fin mounted on the nacelle and

designed in such a way that it turns the wind turbine rotor into the wind by exerting a

"corrective" torque to the nacelle. Therefore the power of the wind is responsible for the rotor

rotation and the nacelle orientation. Alternatively in case of downwind turbines the tail fin is not

necessary since the rotor itself is able to yaw the nacelle into the wind. In the event of skew

winds the "wind pressure" on the swept area causes a yawing moment around the tower axis (z-

axis) which orients the rotor.

The tail fin (or wind vane) is commonly used for small wind turbines since it offers a low cost

and reliable solution. It is however unable to cope with the high moments required to yaw the

nacelle of a large wind turbine. The self-orientation of the downwindturbine rotors however is a

concept able to function even for larger wind turbines. Passive yaw systems have to be designed

in a way that the nacelle does not follow the sudden changes in wind direction .

Roller Bearing (free system):

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The nacelle is mounted on a roller bearing and it is free to rotate towards any direction. The

necessary moment comes from a tail fin or the rotor (downwind wind turbines)

Roller Bearing - Brake (Semi-active system):

The nacelle is mounted on a roller bearing and it is free to rotate towards any direction, but

when the necessary orientation is achieved an active yaw brake arrests the nacelle. This

prevents the uncontrolled vibration and reduced gyroscopic and fatigue loads.

Gliding Bearing/Brake (Passive system):

The nacelle is mounted on a gliding bearing and it is free to rotate towards any direction. The

inherent friction of the gliding bearing achieves a quasi-active way of operation.

1.1.5 DISADVANTAGES OF YAW SYSTEM

1. Complex in design.

2. More expensive.

3. Maintenance and running cost is higher.

4. Tough to handle during breakdown.

To overcome this problem we fabricated a mechanism that converts bidirectional

rotary motion into unidirectional rotary motion which is to be fed to a generator for

continuous power generation. Just by using gears and chain drive using freewheel

mechanism.

CHAPTER-2

FREEWHEEL MECHANISM

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A freewheel or overrunning clutch is a device in a transmission that disengages

the driveshaft from the driver shaft when the driven shaft rotates faster than the driving shaft. It

also prevents the power Transmission in opposite direction. It is A advanced form of a Paul

&ratchet drive.

1.2.1 Paul &Ratchet Mechanism

A wheel provided with suitably shaped teeth, receiving an intermittent circular motion from an

oscillating or reciprocating member, is called a ratchet wheel.

A is the ratchet wheel, and B is an oscillating lever carrying the driving pawl, C.

A supplementary pawl at D prevents backward motion of the wheel.When arm B moves

counterclockwise, pawl C will force the wheel through a fractional part of a revolution

dependent upon the motion of B. When the arm moves back (clockwise), pawl C will slide over

the points of the teeth while the wheel remains at rest because of fixed pawl D, and will be ready

to push the wheel on its forward (counterclockwise) motion as before.

The amount of backward motion possible varies with the pitch of the teeth. This motion could be

reduced by using small teeth, and the expedient is sometimes used by placing several pawls side

by side on the same axis, the pawls being of different lengths.

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The contact surfaces of wheel and pawl should be inclined so that they will not tend to disengage

under pressure. This means that the common normal at N should pass between the pawl and the

ratchet-wheel centers. If this common normal should pass outside these limits, the pawl would be

forced out of contact under load unless held by friction. In many ratchet mechanisms the pawl is

held against the wheel during motion by the action of a spring.

1.2.2 FREEWHEEL MECHANISM

Figure 1.3 Freewheel mechanism

Aspecial form of a ratchet is the overrunning clutch. Have you ever thought about what kind of

mechanism drives the rear axle of bicycle? It is a free-wheel mechanism which is an overrunning

clutch. As the driver delivers torque to the driven member, the rollers or balls are wedged into

the tapered recesses. This is what gives the positive drive. Should the driven member attempt

todrive the driver in the directions shown, the rollers or balls become free and no torque is

transmitted.

The drive disc teeth and continue rotating, producing a characteristic clicking sound

proportionate to the speed difference of the driven gear relative to that of the (slower) driving

gear.The saw teeth of the drive disc lock with the teeth of the driven disc, making it rotate at the

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same speed. If the drive disc slows down or stops rotating, the teeth of the driven disc slip over

the axle

A more sophisticated and rugged design has spring-loaded steel rollers inside a driven cylinder.

Rotating in one direction, the rollers lock with the cylinder making it rotate in unison. Rotating

slower, or in the other direction, the steel rollers just slip inside the cylinder.

Most bicycles freewheels use an internally step-toothed drum with two or more spring-loaded,

hardened steel pawls to transmit the load. More pawls help spread the wear and give greater

reliability although; unless the device is made to tolerances not normally found in bicycle

components, simultaneous engagement of more than two pawls is rarely achieved.

CHAPTER-3

GEAR DRIVE

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A gear is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part

in order to transmit torque. Two or more gears working in tandem are called a transmission and

can produce a mechanical advantage through a gear ratio and thus may be considered a simple

machine. Geared devices can change the speed, torque, and direction of a power source. The

most common situation is for a gear to mesh with another gear, however a gear can also mesh a

non-rotating toothed part, called a rack, thereby producing translation instead of rotation.

The gears in a transmission are analogous to the wheels in a pulley. An advantage of gears is that

the teeth of a gear prevent slipping.

When two gears of unequal number of teeth are combined a mechanical advantage is produced,

with both the rotational speeds and the torques of the two gears differing in a simple relationship.

Figure 1.4 spur gear

1.3.1 Fundamental Law of Gear-Tooth Action

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The fundamental law of gear-tooth action statesthat for gears with fixed center distance the

common normal to the tooth profiles at the point of contact must always pass through a fixed

point (the pitch point) on the line of centers (to get a constant velocity ration).

In Figure 1.8considertwo mating gear teeth, in which

Tooth profile 1 drives tooth profile 2 by acting at the instantaneous contact

point K.

N1N2 is the common normal of the two profiles.

N1 is the foot of the perpendicular from O1 to N1N2

N2 is the foot of the perpendicular from O2 to N1N2.

Figure 1.5 Two gearing tooth profiles

Although the two profiles have different velocities V1 and V2 at point K, their velocities

along N1N2 are equal in both magnitude and direction. Otherwise the two tooth profiles would

separate from each other.

We have

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Or

We notice that the intersection of the tangency N1N2 and the line of center O1O2 is point P, and

Thus, the relationship between the angular velocities of the driving gear to the driven gear,

or velocity ratio, of a pair of mating teeth is

Point P is very important to the velocity ratio, and it is called the pitch point. Pitch point divides

the line between the line of centers and its position decides the velocity ratio of the two teeth.

The above expression is the fundamental law of gear-tooth action.

Constant Velocity Ratio

For a constant velocity ratio, the position of P should remain unchanged. In this case, the motion

transmission between two gears is equivalent to the motion transmission between two imagined

slip less cylinders with radius R1 and R2 or diameter D1 and D2. We can get two circles whose

centers are at O1 and O2, and through pitch point P. These two circle are termed pitch circles.

The velocity ratio is equal to the inverse ratio of the diameters of pitch circles. This is the

fundamental law of gear-tooth action.

Conjugate Profiles

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To obtain the expected velocity ratio of two tooth profiles, the normal line of their profiles must

pass through the corresponding pitch point, which is decided by the velocity ratio. The two

profiles which satisfy this requirement are called conjugate profiles. Sometimes, we simply

termed the tooth profiles which satisfy the fundamental law of gear-tooth action the conjugate

profiles.

Although many tooth shapes are possible for which a mating tooth could be designed to satisfy

the fundamental law, only two are in general use: the cycloidal and involute profiles. The

involute has important advantages -- it is easy to manufacture and the center distance between a

pair of involute gears can be varied without changing the velocity ratio. Thus close tolerances

between shaft locations are not required when using the involute profile. The most commonly

used conjugate tooth curve is the involute curve(Erdman &Sander 84).

Involute Curve

The following examples are involute spur gears. We use the word involute because the contour

of gear teeth curves inward. Gears have many terminologies, parameters and principles. One of

the important concepts is the velocity ratio, which is the ratio of the rotary velocity of the driver

gear to that of the driven gears.

Figure 1.6 Generation of the Involute Curve

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Figure 1.7 Involute curve

The curve most commonly used for gear-tooth profiles is the involute of a circle. This involute

curve is the path traced by a point on a line as the line rolls without slipping on the

circumference of a circle. It may also be defined as a path traced by the end of a string which is

originally wrapped on a circle when the string is unwrapped from the circle. The circle from

which the involute is derived is called the base circle. IN Figure 1.7, let line MN roll in the

counterclockwise direction on the circumference of a circle without slipping. When the line has

reached the position M'N', its original point of tangent A has reached the position K, having

traced the involute curve AK during the motion. As the motion continues, the point A will trace

the involute curve AKC.

Properties of Involute Curves

1. The distance BK is equal to the arc AB, because link MN rolls without slipping on the

circle.

2. For any instant, the instantaneous center of the motion of the line is its point of tangent

with the circle.

3. Note: We have not defined the term instantaneous center previously. The instantaneous

center or instant center is defined in two ways (Bradford &Guillet 43):

a. When two bodies have planar relative motion, the instant center is a point on one

body about which the other rotates at the instant considered.

b. When two bodies have planar relative motion, the instant center is the point at

which the bodies are relatively at rest at the instant considered.

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4. The normal at any point of an involute is tangent to the base circle. Because of the

property (2) of the involute curve, the motion of the point that is tracing the involute is

perpendicular to the line at any instant, and hence the curve traced will also be

perpendicular to the line at any instant.

5. There is no involute curve within the base circle.

1.3.2 Condition for Correct Meshing

Figure1.8 Two meshing gears contacting at K1 and K2

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To get a correct meshing, the distance of K1K2 on gear 1 should be the same as the distance

of K1K2 on gear 2. As K1K2 on both gears are equal to the base pitch of their gears, respectively.

Hence

Since

and

Thus

To satisfy the above equation, the pair of meshing gears must satisfy the following condition:

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CHAPTER-4

CHAIN DRIVE

A sprocket or sprocket-wheel is a profiled wheel with teeth, cogs, or even sprockets that mesh

with a chain, track or other perforated or indented material. The name 'sprocket' applies generally

to any wheel upon which are radial projections that engage a chain passing over it. It is

distinguished from a gear in that sprockets are never meshed together directly, and differs from

a pulley in that sprockets have teeth and pulleys are smooth.

Sprockets are used in bicycles, motorcycles, cars, tracked vehicles, and other machinery either to

transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion

to a track, tape etc. Perhaps the commonest form of sprocket is found in the bicycle, in which the

pedal shaft carries a large sprocket-wheel which drives a chain which in turn drives a small

sprocket on the axle of the rear wheel. Early automobiles were also largely driven by sprocket

and chain mechanism, a practice largely copied from bicycles.

Sprockets are of various designs, a maximum of efficiency being claimed for each by its

originator. Sprockets typically do not have a flange. Some sprockets used with timing belts have

flanges to keep the timing belt centered. Sprockets and chains are also used for power

transmission from one shaft to another where slippage is not admissible, sprocket chains being

used instead of belts or ropes and sprocket-wheels instead of pulleys. They can be run at high

speed and some forms of chain are so constructed as to be noiseless even at high speed.

Chain drive is a way of transmitting mechanical power from one place to another. It is often used

to convey power to the wheels of a vehicle, particularly bicycles and motorcycles. It is also used

in a wide variety of machines besides vehicles.Most often, the power is conveyed by a roller

chain, known as the drive chain or transmission chain, passing over a sprocket gear, with the

teeth of the gear meshing with the holes in the links of the chain. The gear is turned, and this

pulls the chain putting mechanical force into the system. Another type of drive chain is the

Morse chain

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Though drive chains are often simple oval loops, they can also go around corners by placing

more than two gears along the chain; gears that do not put power into the system or transmit it

out are generally known as idler-wheels. By varying the diameter of the input and output gears

with respect to each other, the gear ratio can be altered, so that, for example, the pedals of a

bicycle can spin all the way around more than once for every rotation of the gear that drives the

wheels.

Figure 1.9 A sprocket

Figure 1.10 A chain drive

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CHAPTER-5

DESIGN CALCULATION

Calculations:

Scaled down ratio = 1:20(appx) for real time application

Force given for input shaft = 50N

Diameter of the shaft = 15mm

Speed of gear = 50rpm

Running time = 10hrs/day

2.1 Gear design:

Since both the gear and pinion are made of same material we have to design only the

pinion

Material selection: caste iron

Calculation of z1 & z2:

Let module m = 2mm

Gear ratio: i = 1

No of teeth pinion z1 = 52

No of teeth in gear z2 = 52

Gear life:

N = 365*10*60*50 = 1.09 * 107

rev

Design torque:

[Mt] = Mt * k*kd

= 50*0.051*1.3 = 3.5Nm

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Calculation of Eeq, other stress:

Eeq = 2.15 * 105

Design bending stress = (1.4*0.7*352)/(2*1.5) = 115 N/mm2

Design contact stress = 26.5*55*0.585 = 852 N/mm2

Calculation of center distance:

a = 3*(40+40)/2 *= 120mm

Calculation of gear parameters:

face with b = 0.3*102 = 30.6 mm

pitchdia d = 2*52 = 104 mm

pitch line velocity v = (3.14*0.102*100)/60 = 0.533m/s

¥p = 18/102 = 0.176

Check for various stress:

Calculated Bending stress = (1+1)*65000/(0.120*0.003*0.018*0.366) =75N/mm2

Similarly Calculated Contact stress = 300 N/mm2

Here the calculated stress is less than design stress hence the design is safe and

satisfactory.

Basic dimensions of gear:

Module m= 2mm

Face width b=30.6mm

Center distance a= 102mm

Pcd d= 102mm

Tooth depth h= 6mm

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2.2 Sprocket design

Power transmitted = 15watt

Speed = 50rpm

i = 1

center distance = 120mm

Calculation of no of teeth:

For i = 1

No of teeth Z = 18

Calculation of pitch:

a = (50-30)p

p = 6mm

Here the standard pitch value = 9.525mm

Calculation of total load:

Pt = (1020*N) / v

= 1020*50*10*60/(15*9.525*100)= 200N

Pc = m*v2

=25N

Ps = 15N

Total load = 200+25+15 = 240N

Calculation of design load:

P = 240*1.567 = 374.4N

Roller stress:

Roller stress = 240*1.5625/30= 12.8N/mm2

From the table allowable value = 30N/mm2

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Calculation of F.S

F.s = 10200/374.4 = 27.6

Design Required F.S = 7.8

From above calculations the design is safe and satisfactory

Basic Dimensions of Sprocket:

From above calculations using trial and error method the materials for gear, sprocket and

shafts is selected as Mild Steel (M.S)

Materials Specifications:

Table1: material specification

S.No Name Numbers Material Dimension

1 Shaft 2 M.S Ø14mm

2 Sprocket 2 M.S Ø 60mm

3 Spur gear 2 C.I Ø 102 mm

4 Chain 1 M.S 508mm length

5 Frame 1 -- --

PCD of sprocket= 45mm

Outside dia= 60mm

Chain length= 508 mm

Pitch=9.565mm

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CHAPTER -6

DESIGN FABRICATION

Figure 3.1 2-D view of our design

3.1 Materials used

1. Shafts (2nos)

2. spur gears (2nos)

3. sprockets (2nos)

4. chain drive

5. frame and collers.

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3.2 Machining process used:

1. Gear cutting

2. Sprocket cutting

3. Turning & facing of shaft

4. Welding

3.3 DESCRIPTION OF PARTS

Shaft

The shafts are made of mild steel. They are machined to dia 14mm in lathe using facing and

turning process. The tool used for machining is high speed steel.

Spur gear

The gears are made of mild steel. They manufactured using milling machine with module

2mm. They are attached to theshaft using collar with the aid of a bolt.

Freewheel gear

It is made of mild steel. To make a freewheel gear one of the spur gear is center bored to a

dia 60mm in lathe. A freewheel sprocket whose teeth is machined and removed in lathe using

carbon tip tool is welded at the center bore using dot arc welding. It is attached to the shaft using

a collar with aid of a bolt. It resemble a freewheel drive in power transmission.

Free wheel sprocket

It is the rear wheel sprocket of bicycle made of mild steel with dia 60mm. The sprockets

are attached to shaft using collar with the aid of bolt.

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Frame

The frame is made up of cast iron plates. It consists of a flat plate over which four vertical plates

are welded using butt type arc welding which acts as a beam. The frame is used to hold the shaft

mounted with gears.

The setup is painted using oil paint to avoid rusting and corrosion. The gears and the sprockets

are lubricated using oil SAE40 for free rotation.

Figure 3.2solid works diagram 3D view

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3.4 ASSEMBLING

The machined gear is inserted into the shaft and it is attached using collar with the aid of a bolt.

Similarly the freewheel gear is also attached to the shaft using collar with the aid of a bolt. The

freewheel sprockets are also attached to shaft using collar and bolt. The two shafts are fixed into

the frame and adjust in such a way that the gears mesh each other properly. The gear assembly is

checked for proper meshing of gears. The sprockets are connected by a chain.

3.4 WORKING

Driver shaft rotates in clockwise direction

(Consider Figure 3.1 viewed from front)

When the driver shaft rotates inclock wise directionthe gear-1 rotates clock wise due to external

meshing the gear-2 rotates in counter clockwise direction as a result the driven shaft rotates in

counter clockwise direction.

Simultaneously the sprockets-3 & sprocket-4 keeps rotating in idle condition due to presence of

freewheel drive.

Thus in clockwise rotation of driver the power is transmitted through gear drive. i.e. from gear-1

to gear-2. And the driven shaft keeps rotating in counter clockwise direction

Driver shaft rotates in counter clockwise direction

Consider Figure 3.1 viewed from front)

When the driver shaft rotates in counter clock wise direction the sprocket-3 rotates counter clock

wise direction so thesprocket-4 rotates in counter clockwise direction as a result the driven shaft

rotates in counter clockwise direction.

Simultaneously the gear-1 and gear-2 keeps rotating in idle condition due to presence of

freewheel drive in gear-2.Thus in counter clockwise rotation of driver the power is transmitted

through chain drive. i.e. from sprocket-3 to sprocket-4. And the driven shaft keeps rotating in

counter clockwise direction.

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Mode of power transmission:

From driver shaft to driven shaft

When driver rotates in

clockwise rotation power is transmitted using gears during

Counter clockwise direction power is transmitted using chain drive.

Thus in both the cases the driven shaft keeps rotating in counter clockwise direction which

is required output.

3.5 ADVANTAGES

Easy design

Simple mechanisms

Power loss is very less

Proper use of available energy

Practical feasibility is high

Requires less initial cost

3.6 DISADVANTAGES

Lubrication is required for gear and sprockets

For high power applications sprockets should be replaced by gears

Noisy operation

3.7APPLICATIONS

Used in wind mills for continuous generation of power

Tidal turbines for power generation

For running pumps & mills using wind turbines

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CHAPTER-7

COST ESTIMATION

Table2: cost estimation

S.No Name Numbers Cost (Rs)

1 Shaft 2 450

2 Sprocket 2 275

3 Spur gear 2 300

4 Chain 1 50

5 Frame 1 300

6 Machining - 300

Total cost Rs 1675

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CHAPTER-8

PHOTOGRAPHS

Figure 4.1 Top view of the setup

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Figure 4.2 chain drive

Figure 4.3 gear drive

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CHAPTER-9

CONCLUSION

As per the design I have fabricated the “mechanism for converting

bidirectional motion of a shaft to unidirectional motion” a trial run was

conducted and the rotation of output shaft is found to unidirectional. During this

project I learnt about various production process.

I also studied about various fabrication methods and how to handle

various machines available in manufacturing a component.

The fabricated mechanism will be cost wise cheap also have a wide

application in windmills, tidal turbines, wave power plants and also in some

industrial machines.

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CHAPTER-10

REFERENCE

1. R.S.Khurmi J.K.Gupta “Theory of machines “ ISBN 81-219-0132-4

2. S.K.Hajra Choudhury A.K.Hajra Choudhury Nirjhar Roy “Elements of Workshop

Technology “ ISBN 82-85099-14-6

3. S.Md.Jalaludeen “Machine Design – Design of Transmission systems” ISBN 81-87721-

10-3

4. R.S.Khurmi J.K.Gupta “ A Text book of Machine Design “ S.Chand Publications

5. Robert.L.Norton “Machine Design – An Integrated approach”

6. Design Data book – PSG College of Technology

WEBSITES

1. www.google.com

2. www.Youtube.com

3. www.wikipedia.com

4. www.mekanizmalar.com

5. www.howstuffworks.com