design and fabrication of reel mower cycle
DESCRIPTION
The design objective is to come up with an apparatus for cutting grass that is portable, durable, easy to operate and maintain. It also aims to design a pedal- powered Mower cycle. The pushing force required for moving the reel mower is obtained from the motion of a bi-cycle.The Mower cycle consists of three main wheels with two of the wheels at the front. Between the two front wheels a cutting mechanism is made with internal spur gear system which transfers the torque to the mower spiral mechanism. The cutting mechanism is made of a flat blade rigidly fixed to the frame behind the spiral arrangement which is configured to contact at least one reel bar of the spiral blades during the rotation of the spiral mechanism.TRANSCRIPT
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I E S COLLEGE OF ENGINEERING CHITTILAPPILLY, THRISSUR Dt., KERALA680 551, www.iesce.info
MINI PROJECT REPORT
ON
DESIGN & FABRICATION OF LAWN MOWER
CYCLE
Submitted By
ABDUL SAMAD P.R (ISAMEME002)
ABHAY VISHNU V.S (ISAMEME004)
JAFEER P.A (ISAMEME022)
KIRAN JOSEPH (ISAMEME026)
MOHAMED HUWAIS (ISAMEME034)
DEPARTMENT OF MECHANICAL ENGINEERING
APRIL 2015
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Department of Mechanical Engineering
CERTIFICATE Certified that this is a bonafide record of the Mini Project Work titled
DESIGN AND FABRICATION OF LAWN MOWER CYCLE
Done by,
ABDUL SAMAD.P.R (ISAMEME002)
ABHAY VISHNU.V.S (ISAMEME004)
JAFEER.P.A (ISAMEME022)
KIRAN JOSEPH (ISAMEME026)
MOHAMMED HUWAIS (ISAMEME034)
of pre final year B Tech Mechanical Engineering in partial fulfillment of the
requirement for the award of Bachelor of Technology Degree in Mechanical
Engineering under the University of Calicut during the year 2012-2016.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Mr. Nandan K Kuttan Dr. U. Mohammed Iqbal Asst. Professor Head of the Department
(Guide)
Submitted for the Mini Project Viva-Voce Examination held on _ _ _ _ _ _ _
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Examiner I Examiner II
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i
ACKNOWLEDGMENT
We first of all we thank almighty for his blessing showered upon us in enabling us to
complete this project on time. We thank Prof. Dr.V Jayaraman (Principal of, IES College of
Engineering) for giving us a chance to fabricate this Mini project.
We would like to thank our project guide Mr. Nandan K Kuttan, (Asst. Professor,
IESCE) for giving us apt guidance. We would also like to extend our gratitude towards
Dr. U. Mohammed Iqbal, (Head of the Department) for his invaluable support &suggestions
throughout this project. We would also like to thank our project in charge Mr. Rinto K Anto,
(Asst. Professor, IESCE) and Mr. Anil D Koola, (Asst. Professor, IESCE) for their
continuing support in this endeavour.
We would like to thank Mr. Febin V, (Lab Instructor, IESCE) for his valuable time
and suggestions for fabrication of our project. Many people, especially our classmates and
family members, who have made valuable comment suggestions on this proposal which gave
us an inspiration to improve our project. We thank all the people for their help directly &
indirectly to complete our project.
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ii
TABLE OF CONTENTS
CHAPTER NO. TITLE PAGE NO.
List of Figures iv
List of Tables v
Abstract iv
Chapter 1 INTRODUCTION 1-3
1.1 Relevance 2
1.2 History 2
1.3 Project Plan 3
Chapter 2 LITERATURE REVIEW 4-24
2.1 The basics in grass cutting 4
2.2 Types of lawn mowers 6
2.3 Reel Mower Parts 14
2.4 Factors effecting clip 15
2.5 Set-up and Adjustments 19
2.6 Sharpening 23
Chapter 3 COSTRUCTION DETAILS 25-30
3.1 Selecting Required Cycle Frame 25
3.2 Mower Frame 26
3.3 Reel 26
3.4 Bed Knife 27
3.5 Main wheel with internal gears 28
3.6 Trolley Wheels 29
3.7 Balancing Wheels 29
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iii
Chapter 4 WORKING PRINCILE 31
Chapter 5 DESIGN CALCULATIONS 32-34
5.1 Spur & pinion Gear parameters
5.2 Deign Specification
5.3 The Cutting blades Design
32
33
33
5.4 Performance test and evaluation 34
Chapter 6 RESULTS & DISCUSSIONS 35-38
6.1 Discussion 35
6.2 Applications 35
6.3 Advantages 35
6.4 Design 36
6.5 Estimate 37
Chapter 7 CONCLUSION & FUTURE SCOPE 39
7.1 Conclusion 39
7.2 Future Enhancements 39
REFERENCE 40
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iv
LIST OF FIGURES
Figure No. Name PageNo.
Figure 2.1 Mulching 4
Figure 2.2 Spreading 5
Figure 2.3 Bagging 5
Figure 2.4 Push lawn reel mower 6
Figure 2.5 A rotary mower (viewed from underneath) 9
Figure 2.6 A Cordless electric mower 10
Figure 2.7 Hover mower 11
Figure 2.8 Robotic mower 12
Figure 2.9 A tractor-pulled mower 12
Figure 2.10 Zero turn mower 13
Figure 2.11 Bed knife 14
Figure 2.12 Clip and the shear point 15
Figure 2.13 Illustration of actual grass cutting process 16
Figure 2.14 Grass cutting process showing HOC 16
Figure 2.15 Clip distance and shear points 17
Figure 2.16 Side view showing bedknife during grass cutting 18
Figure 2.17 Front view of Reel mower showing Helix angle 18
Figure 2.18 Cutting path 19
Figure 2.19 Single point reel to bedknife adjust 21
Figure 2.20 Cutting unit dulling curve 22
Figure 2.21 Sharpening of blades 23
Figure 2.22 Lapped Surfaces 24
Figure 3.1 Different Body Position 25
Figure 3.2 Mower Frame 26
Figure 3.3 Reel: Helix shaped Spiral Blades 27
Figure 3.4 Bed Knife 28
Figure 3.5 Pinion Gear & Main wheel 28
Figure 3.6 Trolley wheels for supporting mower 29
Figure 3.7 Balancing wheel and frame 29
Figure 3.8 Lawn mower cycle after construction 30
Figure 6.1 View of mower Assembly 36
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v
LIST OF TABLES
Table No.
Table 6.1
Table 6.2
Name
Cost estimation
Materials used
Page No.
37
38
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering vi IESCE, Chittilappilly
ABSTRACT
The design objective is to come up with an apparatus for cutting grass that is portable,
durable, easy to operate and maintain. It also aims to design a pedal- powered Mower cycle.
The pushing force required for moving the reel mower is obtained from the motion of a bi-
cycle.
The Mower cycle consists of three main wheels with two of the wheels at the front.
Between the two front wheels a cutting mechanism is made with internal spur gear system
which transfers the torque to the mower spiral mechanism. The cutting mechanism is made of
a flat blade rigidly fixed to the frame behind the spiral arrangement which is configured to
contact at least one reel bar of the spiral blades during the rotation of the spiral mechanism.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 1 IESCE, Chittilappilly
CHAPTER 1
INTRODUCTION
Lawn mower is an essential tool for the maintenance of yards. They vary in size, mode
of operation and power. The power source riding mowers for example are usually powered
by a gasoline engine and are ridden and steered by the operator but they are costly. So our
design objective is to come up with a Lawn mower cycle that is durable, cost efficient & easy
to operate. The Lawn mower cycle is peddle powered. The power required to push the mover
is obtained from a chain-driven cycle. This project attempts to combine a cycle and a mower.
There are primarily two types of mowers namely (i) the reel mowers, and (ii) the rotary
mowers. The reel (cylindrical) mowers seem to be better. Made of blades on a revolving
cylinder, they achieve clean cut by scissors action. As the mower moves forward, the rotating
blades come in contact with a stationary bar called the bed knife and placed parallel to the
ground. Grass is held by the shearing action of the reel blades against the bed knife. The
mower is adjusted to various cutting heights. Rotary mowers are often powered either by an
internal combustion engine or an electric motor and are generally moved manually, with the
engine only spinning the cutting blades.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 2 IESCE, Chittilappilly
1.1 RELEVANCE
The main aim of our project is to come up with a cost efficient lawn mower. A lawn
mower is a machine used for cutting grass or lawns. A lawn is any area of grass; mostly
tough grass which is neatly cut like in a private garden or a public park. Walk behind mowers
are designed to be pushed by the operator and typically run on gasoline or electricity. Modern
gas powered and electric powered lawn mowers cut grass with a single blade revolving at a
high speed parallel to the ground.
Generally, in areas like ours, the conventional methods of grass cutting involved the
use of cutlasses which never met the maximum satisfaction. More so, it is strenuous, time and
labour intensive. Therefore, there is the need to develop a low cost mower which can take
care of this operation easily. The objective of the study is to design and develop a locally
fabricated peddle powered spiral blade lawn mower affordable by common man
1.2 HISTORY
The first lawn mower was invented in 1830 by Edwin Beard Budding .He was said to
obtain the idea after watching a machine in a local cloth mill which used a cutting cylinder
mounted on a bench to trim clothes for a smooth finish after weaving. Budding realized that a
similar concept could be used to cut grass if the mechanism is mounted in a wheel frame to
enable the blades rotate close to the lawns surface. These early machines were made of cast
iron and featured a large rear roller with a cutting cylinder (reel) in the front. Cast iron gear
wheel transmitted power from the rear roller to the cutting cylinder.
In 1832, Ransoms of Ipswich (under license) began the making of Buddings mower.
This company is today the worlds largest manufacturer of lawn care equipment. By mid
1850, Thomas Green developed a mower which used chains to transmit power from the rear
roller to the cutting cylinder. It was called Silens Messor meaning silent cutter. The
machines were found comparatively lighter and quieter than the gear driven machines that
preceded them. By late 1890, motorized mowers appeared as light weight petrol engines and
small steam power units became available.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 3 IESCE, Chittilappilly
In US, Colonel Edwin George produced the first gasoline powered mower in 1919.
Electric powered mowers and rotary cutting machines emerged in the 1920s and 1930s. By
1960 the introduction of plastic components greatly reduced cost. Today, new technology has
brought new improved versions. Low emission gasoline engines with catalytic converters are
introduced to help reduce air pollution. Improved muffling devices are also incorporated to
reduce noise. Today, the recent innovation is the rotary hover mower.
1.3 PROJECT PLAN
The design objective is to come up with a mower cycle that is durable, cost efficient &
easy to operate. The mini project mainly consists of 7 Chapters. The first chapter is
introduction part where we explain the basic concepts. The second chapter is literature
review. This chapter explains the components and features of lawn mower cycle. The third
chapter is design part where we explain how we made the required machine. Then the later
chapters deals with results and discussions.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 4 IESCE, Chittilappilly
CHAPTER 2
LITERATURE REVIEW
2.1 THE BASICS IN GRASS CUTTING
Grass as most other plants grow during a certain period of the year. This can off course
differ some depending on where in the world you are. For India, the grass starts to grow in
April. From then to June the grass has its high season, which means its grows fast and
strong. During this period you can cut the grass 1-2 times a week. What you should think of
is to take it easy in the beginning of the growth period as not to stress the grass. The grass is
then entering a period of low growing rate, mostly due to the sun, drying the soil.
You should take care not to cut the grass to short if the grass looks dry (turning somewhat
yellow). A good rule is to cut about one third of the grass length at a time. The grass can be
very sensitive and can be damaged if you cut too much at one time. Then we come to the
length. Here it really depends on what kind o a lawn youre aiming for. If you want a lawn
that you can walk on you should leave at least 4cm of the grass.
There are different approaches to cutting the grass all with advantages and
disadvantages.
2.1.1 Mulching
When mulching you cut the grass in to small pieces that you leave on the ground to
work as a natural fertilizer. The negative side is that you will have to cut more often to let the
mower cut the grass correctly.
Figure 2.1 Mulching
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 5 IESCE, Chittilappilly
2.1.2 Spreading
Spreading means that the mower spread the cut grass directly on to the lawn.
Depending on the amount of cut grass you might have to rake it together. The downside is the
extra work but on the other hand you will have grass to make fresh soil to use in your garden.
If you cut the grass when its long another downside can be that the cut grass can suffocate
the living grass.
Figure 2.2 Spreading
2.1.3 Bagging
Bagging involves a container that directly collects the grass for you to later empty at a
pleasant spot. The downside is that it claims more energy from the mower or you to carry it
around until you have emptied it.
Figure 2.3 Bagging
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 6 IESCE, Chittilappilly
2.2 TYPES OF LAWN MOWERS
2.2.1 Reel (cylinder )mowers
The reel (cylindrical) mower is made of blades on a revolving cylinder, they achieve
clean cut by scissors action. As the mower moves forward, the rotating blades come in
contact with a stationary bar called the bed knife and placed parallel to the ground. Grass is
held by the shearing action of the reel blades against the bed knife. The mower is adjusted to
various cutting heights.
Of all the mowers, a properly adjusted reel mower makes the cleanest cut of the grass,
and this allows the grass to heal more quickly. The cut of a well-adjusted cylinder mower is
straight and definite, as if cut with a pair of scissors. This clean cut promotes healthier,
thicker and more resilient lawn growth that is more resistant to disease, weeds and parasites.
Lawn cut with a cylinder mower is less likely to result in yellow, white or brown
discolouration as a result of leaf shredding. While the cutting action is often likened to that of
scissors, it is not necessary for the blades of the spinning cylinder to contact the horizontal
cutting bar. If the gap between the blades is less than the thickness of the grass, a clean cut
can still be made. If more however, the grass will slip through.
Figure 2.4 Push lawn reel mower
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 7 IESCE, Chittilappilly
There are many variants of the cylinder (reel) mower. Push mowers (illustrated) have
no engine and are usually used on smaller lawn areas where access is a problem, where noise
pollution is undesirable and where air pollution is unwanted. As the mower is pushed along,
the wheels drive gears which rapidly spin the reel.
Typical cutting widths are 10 to 16 inches (410 mm). Advances in materials and
engineering have resulted in these mowers being very light and easy to operate and
manoeuvre compared with their predecessors while still giving all the cutting advantages of
large professional cylinder mowers. Their distinct environmental benefits, both in noise and
air pollution, are also strong selling points, something not lost on many international zoos,
animal sanctuaries and exclusive hotel groups. The basic push mower mechanism is also used
in gangs towed behind a tractor. The individual mowers are arranged in a "v" behind the
tractor with each mower's track slightly overlapping that of the mower in front of it. Gang
mowers are used over large areas of turf such as sports fields or parks.
A gasoline engine or electric motor can be added to a cylinder mower to power the
cylinder, the wheels, the roller, or any combination of these. A typical arrangement on
electric powered machines for residential lawns is for the motor to power the cylinder while
the operator pushes the mower along.
The electric models can be corded or cordless. On petrol machines the engine drives
both the cylinder and the rear roller. Some variants have only three blades in a reel spinning
at great speed, and these models are able to cut grass which has grown too long for ordinary
push mowers. One type of reel mower, now largely obsolete, was a powered version of the
traditional side-wheel push mower, which was used on residential lawns. An internal
combustion engine sat atop the reel housing and drove the wheels, usually through a belt. The
wheels in turn drove the reel, as in the push mower.
Greens mowers are used for the precision cutting of golf greens and have a cylinder
made up of at least eight, but normally ten, blades. The machine has a roller before and after
the cutting cylinder which smooths the freshly cut lawn and minimizes wheel marks. Due to
the weight, the engine also propels the mower. Much smaller and lighter variants of the roller
mower are sometimes used for small patches of ornamental lawns around flower beds, and
these have no engine. Riding reel mowers are also produced.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 8 IESCE, Chittilappilly
Typically, the cutting reels are ahead of the vehicle's main wheels, so that the grass can
be cut before the wheels push the grass over onto the ground. The reels are often
hydraulically powered.
The main parts of a cylinder or reel mower are:
1. Blade reel/cylinder consist of numerous (3 to 7) spiral blades that are attached to
a rotating shaft. The blades rotate, creating a scissor-like cutting motion.
2. Bed knife is the stationary cutting mechanism of a cylinder/reel mower. This is a
fixed horizontal blade that is mounted to the frame of the mower.
3. Body frame the main structural frame of the mower onto which the other parts of
the mower are mounted.
4. Wheels these help propel the mower in action. Generally, reel mowers have two
wheels.
5. Push handle the "power source" of a manually operated reel mower. This is a
sturdy T-shape handle that is connected to the frame, wheels and blade chamber.
6. Motor the power source of a reel mower that is powered by gasoline or electric.
2.2.2 Rotary mowers
A rotary mower rotates about a vertical axis with the blade spinning at high speed
relying on impact to cut the grass. This tends to result in a rougher cut and bruises and shreds
the grass leaf resulting in discolouration of the leaf ends as the shredded portion dies. This is
particularly prevalent if the blades become clogged or blunt. Most rotary mowers need to be
set a little higher than cylinder equivalents to avoid scalping and gouging of slightly uneven
lawns, although some modern rotaries are fitted with a rear roller to provide a more formal
striped cut. These machines will also tend to cut lower (13 mm) than a standard four-wheeled
rotary. The main parts of a rotary mower are:
1. Cutter deck housing this houses the blade and the drive system of the mower. It is
shaped to effectively eject the grass clippings from the mower.
2. Blade mounting and drive system the blade of a rotary mower is usually
mounted directly to the crankshaft of its engine, but it can be propelled by a hydraulic
motor.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 9 IESCE, Chittilappilly
3. Mower blade a rotary mower generally has one blade that rotates horizontally.
The blade features edges that slightly curved up to generate a continuous air flow as
the blade rotates, thus creating a sucking and tearing action.
4. Engine may be powered by gasoline or electricity.
5. Wheels rotary mowers generally feature a set of four wheels; two front wheels and
two rear wheels.
Figure 2.5 A rotary mower (viewed from underneath), with a mulching blade that rotates
around the center.
2.2.3 Gasoline mower
Most rotary push mowers are powered by internal combustion engines. Such engines
are usually four-stroke engines, used for their greater torque. (although a number of older
models used two-stroke engines), running on gasoline (petrol) or other liquid fuels. Internal
combustion engines used with lawn mowers normally have only one cylinder. Power
generally ranges from two to seven horsepower (1.5 to 6.75 kW). The engines usually have
a carburetor and require a manual pull crank to start them, although an electric starter is
offered on some models. Some mowers have a throttle control on the handlebar with which
the operator can adjust the engine speed. Other mowers have a fixed, pre-set engine speed.
Gasoline mowers have the advantages over electric mowers of greater power and
distance range. They do create pollution due to the combustion in the engine, and their
engines require periodic maintenance such as cleaning or replacement of the spark
plug and air filter, and changing the engine oil.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 10 IESCE, Chittilappilly
2.2.4 Electric mower
Electric mowers are further subdivided into corded and cordless electric models. Both
are relatively quiet, typically producing less than 75 decibels, while a gasoline lawn mower
can be as loud as 95 decibels or more.
Corded electric mowers are limited in range by their trailing power cord, which may
limit their use with lawns extending outward more than 100150 feet (3045 m) from the
nearest available power outlet. There is the additional hazard with these machines of
accidentally mowing over the power cable, which stops the mower and may put users at risk
of receiving a dangerous electric shock. Installing are sidual-current device (GFCI) on the
outlet may reduce the shock risk. Cordless electric mowers are powered by a variable number
(typically 1-4) of 12-volt rechargeable batteries. Cordless mowers have the maneuverability
of a gasoline powered mower and the environmental friendliness of a corded electric mower,
but are more expensive and come in fewer models.
Figure 2.6 A Cordless electric mower
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 11 IESCE, Chittilappilly
2.2.5 Hover mower
Hover mowers are powered rotary push lawn mowers that use an impeller above the
spinning blades to drive air downward, thereby creating an air cushion that lifts the mower
above the ground. The operator can then easily move the mower as it floats over the grass.
Hover mowers are necessarily light in order to achieve the air cushion and typically have
plastic bodies with an electric motor. The most significant disadvantage, however, is the
cumbersome usability in rough terrain or on the edges of lawns, as the lifting air-cushion is
destroyed by wide gaps between the chassis and the ground. Hover mowers are built to
operate on steep slopes, waterfronts, and high-weeded areas, so they are often used by golf
course greens keepers and commercial landscapers
Figure 2.7 Hover mower (underside view).
2.2.6 Robotic mower
A robotic mower is contained by a border wire around the lawn that defines the area to
be mowed. The robot uses this wire to locate the boundary of the area to be trimmed and in
some cases to locate a recharging dock. Robotic mowers are capable of maintaining up to 5
acres (20,000 m2) of grass. Robotic lawn mowers are increasingly sophisticated, are usually
self-docking and contain rain sensors, nearly eliminating human interaction for mowing
grass. Multiple robotic mowers can be used to mow an even larger area.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 12 IESCE, Chittilappilly
Figure 2.8 Robotic mower
2.2.7 Tractor pulled mower
These are usually in the form of an attachment to a tractor. The attachments can simply
function by the movement of the tractor similar to manual push cylinder mowers, but also
sometimes may have powered moving blades. They are commonly mounted on either the side
or the back of the tractor.
Figure 2.9 A tractor-pulled mower
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 13 IESCE, Chittilappilly
2.2.8 Zero-turn riding lawn mower
A zero-turn riding lawn mower (colloquially, a z-turn) is a standard riding lawn
mower with a turning radius that is effectively zero. Different brands and models achieve this
in different ways, but hydraulic speed control of each drive wheel is the most common
method. Both commercial duty and homeowner models exist, with varying engine power
options, size of cutting decks, fuel type (gasoline or diesel), and prices. A z-turn mower
typically drives faster and costs more than a similarly sized conventional riding mower that
has steerable front wheels.
Most current models have four wheels: two small swiveling front tires and two large
drive tires in the back. Bush Hog mowers sometimes come with a small, pivoting fifth wheel
mounted in the center behind the driver. Instead of controlling the swiveling tires to steer the
machine, the large drive tires rotate independently of each other based on the driver's input.
They may rotate in opposite directions. The mower can pivot around a point midway between
the drive wheels (the classic z-turn), or it can pivot around either one of the drive wheels if
one is stationary, or it can turn in a circle of any radius. Reversal of the direction of travel can
be accomplished by causing both wheels to rotate in reverse.
Figure 2.10 Zero turn mower
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 14 IESCE, Chittilappilly
2.3 REEL MOWER PARTS
There are three main structural members in a reel cutting unit:
1. The REEL consists of varying numbers of helix shaped blades attached to support
spiders which are mounted on a rotating shaft.
2. The BEDKNIFE is attached to the bedbar and the assembly is mounted to the main
frame in a manner that allows for paralleling and adjustment to the reel.
3. The FRAME supports the rollers, the bedbar assembly and reel with its drive
mechanism, which can be hydraulic, belt driven or ground driven. A reel mower cuts
grass with a scissors-like shearing action as the moving helix shaped blades pass over
the stationary bedknife.
Figure 2.11 Bed knife
The cutting action requires that the bed knife and reel blades be sharp, matched, and in
close relationship with each other. When properly maintained and operated, reel mowers
provide superior quality of cut. It cannot be overstated that reel mowers are precision tools. It
is essential that they be adjusted and operated with this in mind.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 15 IESCE, Chittilappilly
2.3.1 Reel Mower Clip
To understand reel cutting theory, you must understand the concept of clip and the
shear point. A shear point is any single point of contact made between the reel blade and bed
knife. Clip is the forward distance traveled between successive blade contacts at one shear
point.
Figure 2.12 Clip and the shear point
2.4 FACTORS AFFECTING CLIP
1. The diameter of the reel
2. The number of reel blades
3. The speed of the reel
4. The ground speed
By following the blade path through two clips as the machine moves forward we can
illustrate the actual process of cutting grass. The bedknife pushes grass toward the shear point
while the reel blade gathers it in front. Each blade path has one-half clip in which to cut all
the grass.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 16 IESCE, Chittilappilly
Figure 2.13 Illustration of actual grass cutting process
Note that the grass outside of the forward half clip is not easily gathered. The general
rule of thumb concerning height of cut vs. clip is that both measurements should be within
20% of each other. The best results will be obtained when height of cut is equal to or close to
the clip.
Figure 2.14 Grass cutting process showing HOC
Grass extending beyond the forward half clip, yet tall enough to be within the blade
path is less likely to be cut. Reel blades may contact the grass in this area several times prior
to the actual gathering of the grass. This is the so called fanning process.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 17 IESCE, Chittilappilly
This process is more a mechanical striking of the grass that it is of the commonly
thought effect of a blowing action.
Figure 2.15 Clip distance and shear points
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 18 IESCE, Chittilappilly
The importance of the bedknife front angle is visible from the side view. Note that
(from Figure 2.16) the proper angle allows the grass behind the bedknife front edge to be
more effectively cut.
Figure 2.16 Side view showing the bedknife during grass cutting
Figure 2.17 Front view of Reel mower showing Helix angle
Cutting path: Another term known as the cutting path is the result of the helix angle and the
forward motion of the cutting unit. The shear point moves down the bedknife as the bedknife
moves forward. The grass is physically cut at an angle to the bedknife.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 19 IESCE, Chittilappilly
Figure 2.18 Cutting path
Other factors which affect reel mowing are the grass density and the grass acclimation
or grain. Grass tends to thicken at the normal maintained height of cut. The denser the grass,
the easier it is for the bedknife and reel to gather it. Grass density and grain can often
override other factors we have discussed regarding the cutting action.
The basic requirements for good performance of reel mowers are:
1. The cutting edges on the reel blades and bedknife must be straight and sharp.
2. The bedknife must be exactly parallel with the reel.
3. The bedknife should be positioned against the reel with light contact.
2.5 SET-UP AND ADJUSTMENTS
Reel mower performance depends on proper setup and adjustment procedures. An
error of .010 inch or .25 mm, in height endtoend, or from one cutting unit to another, is
visible as a mismatch on many golf course greens. Although there are design variations in
cutting units, most require the same basic procedures. A surface plate, accurate height of cut
tools and proper instruction are essential for setting up a cutting unit.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 20 IESCE, Chittilappilly
There are many factors that can affect quality of cut, including condition of the mowing
equipment and agronomic factors. Turf conditions such as excessive thatch, sponginess or
attempting to cut off too much grass height may not always be overcome by adjusting the
machine. It is important to remember that the lower the height of cut, the more critical these
factors are.
Remember that the effective or actual height of cut depends on cutting unit weight,
cutting unit accessories and turf conditions. Effective height of cut will be different than the
bench set height of cut.
Effective height of cut is the actual height the grass has been cut. Making an accurate
height measurement on the turf is difficult due to many variables. A true base is simply not
present. If the surface is uneven, spongy or varies in density, color variations in the turf may
appear in the form of a streak. This is due to the effective height of cut being too low for the
existing turf conditions. To correct problems, start or change a cultural practice, change
cutting unit configuration or raise the bench set height of cut. The lower your height of cut,
the more predictable and smooth the turf surface must be.
To accurately maintain height of cut and performance, routinely check the following
components:
1. Reel Bearings
2. Bedknife to Reel Adjustment
3. Attitude Adjustment
4. Roller Parallelism
5. Height of Cut
2.5.1 Reel to Bedknife adjustment
Single point adjust cutting units also have an adjustment mechanism on one end of the
bedknife for adjusting the bedknife parallel to the reel. This bedknife leveling mechanism
could may be an eccentric pivot bolt on one end of the bedbar, or a capscrew / jam nut
assembly.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 21 IESCE, Chittilappilly
Figure 2.19 Single point reel to bedknife adjust
Adjust the bedknife against the reel to evenly pinch one paper thickness across the
entire width of the bedknife, then cut paper strips to check blade sharpness. Put the cutting
unit on the turf and check for light bedknife to reel contact and free reel rotation. Do a final
adjustment of bedknife to reel contact if necessary. Properly adjusting the bedknife to the reel
is one of the most effective preventive maintenance practices for reel mowers. The amount of
contact and how frequently it is checked are major factors in performance. A light contact
adjustment, if maintained, will help keep cutting edges sharp on the reel and bedknife. This
requires that the adjustment be checked frequently at a predetermined time interval. Dulled
cutting edges cannot be corrected immediately by adjustment or over tightening.
Do not wait until the quality of cut has deteriorated to check the bedknife to reel
adjustment. If the cutting edges on the reel blades and bedknife are not straight and sharp the
mowing results may not be acceptable. This is true even if all other setup procedures are
correct.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 22 IESCE, Chittilappilly
Figure 2.20 Cutting unit dulling curve
The cutting unit attitude is the angle between the bottom of the bedknife and the ground
plane under the cutting unit. As the bedknife attitude is changed, it is important to note that
the reel to bedknife shear point changes relative to the center line of the reel. This can change
the after cut appearance of the grass. The result may be better or worse depending on several
factors
The result may be better or worse depending on several factors. Bedknife attitude is
adjusted by changing the height of the front, rear, or both rollers. A height of cut change is
NOT necessarily part of a change to the bedknife attitude. A large angle is also referred to as
an aggressive bedknife attitude. A small angle (flat attitude) can have most or all of the
bedknife riding ON the turf. This can influence after cut appearance.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 23 IESCE, Chittilappilly
2.6 SHARPENING
Cutting units should be kept as sharp as possible to:
1. Promote growth of healthy grass.
2. Optimize cutting unit performance.
3. Extend the life of the mower.
4. Maximize operator mowing time.
5. Allow the tractor to run most efficiently.
6. Provide excellent finished appearance of the turf.
Reel blades, and the edge of the bedknife should be checked for damage visually & by
carefully feeling the edges. Of course, this should only be done when it is certain that the reel
cannot be started, and never slide your fingers down the edges lengthwise. Rounded edges on
the reel blades and bedknife will cause the grass blades to be pinched and torn, rather than
sheared off cleanly. When light contact is not maintained, dull edges will soon result.
Sharpening will also be required if the reel is cone shaped (tapered). All reels eventually
become tapered with use. If the reel is not adjusted or ground to a cylinder shape again, a
mismatch in the height cut between adjacent reels can result.
Figure 2.21 Sharpening of blades
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 24 IESCE, Chittilappilly
There are several methods that may be used to sharpen a cutting unit. The one that
you choose will depend upon the condition of the cutting unit. It should also make the most
sense for the anticipated use. For example, if you are about to mow greens that have been
core aerated or topdressed, you may not want to grind the reels and install new bedknives. As
the reel blades run against the bedknife a slight burr will appear at the front cutting edge
surface the full length of the bedknife. Occasionally run a file or facing grinder across the
front edge to remove this burr to extend the cutting performance of the machines,
Lapping must be done after single blade grinding. This is done to establish a land
area and to insure a perfect match between the bedknife and the reel edge. Lapping is not
intended to be a reconditioning process to correct severely nicked or rounded blades, rifling
or taper. If, after 5 minutes of lapping, the edge is not restored, it is time to grind the reel.
Figure 2.22 Lapped Surfaces
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 25 IESCE, Chittilappilly
CHAPTER 3
CONSTRUCTION DETAILS
3.1 SELECTING REQUIRED CYCLE FRAME
Different products come in different styles. One product category where this is a fact is
the bicycle category. Getting the right impression of the product as well as considering the
way it is being used is important, both when it comes to emotional aspects but also
ergonomics and user interaction.
The speed of a lawnmower is not that high so the aggressive style presented below is a
bit too much even if it is effective considering the amount of energy that you can provide
from that position. If we see to the demanded speed and wanted input power the formal style
is the one best suited for our project. An honest expression with good ergonomically &
mechanical possibilities is the position we chose to work with. Hence after necessary research
a bicycle frame which gives a formal body position was chosen.
Figure 3.1 Different Body Position
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 26 IESCE, Chittilappilly
3.2 MOWER FRAME
Figure 3.2 Mower Frame
The frame is the main structural unit of the mower onto which the other parts of the
mower are mounted. The frame is that provides a base unit that all of the components
/subsystems are mounted on. The frame supports the Trolley wheels, the bedbar assembly
and the reel with its drive mechanism. The Mower Frame is made of cast iron.
3.3 REEL
The Reel consists of varying numbers of helix shaped blades attached to support
spiders which are mounted on a rotating shaft.
The reel is made up of six smaller blades of sizes 310mm x 25mm x 2mm and is made
of steel materials. The blades are mounted on the three spiders rigidly fixed to the shaft and
are oriented at a helical angle of 12 degree to the horizontal on the circular spiders for
efficient grass cutting.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 27 IESCE, Chittilappilly
Figure 3.3 Reel: Helix shaped Spiral Blades
3.4 BED KNIFE
The Bedknife is attached to the bedbar and the assembly is mounted to the main frame
in a manner that allows for paralleling and adjustment to the reel.
The bedknife takes up almost the entire distance between the wheels on each end, and
determines the cutting width of the mower. As the movable blades on the reel pass by the bed
knife, the grass trapped between the blades and the bed knife is sheared off. The slight space
between the bed knife and the reel is adjusted by a precision screw mechanism
The bedknife is also made of steel material of size 300mm x 55mm x 2.6mm. Its edge
is grinded with a front relief angle of 30 degree to make grass cutting easy in a scissor action
with the reel. The bed-knife is fixed to the machine frame behind the reel.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 28 IESCE, Chittilappilly
Figure 3.4 Bed Knife
3.5 MAIN WHEEL WITH INTERNAL GEARS
The pinion gear transfers the power from the rotation of the main wheel to the axle and
spinning blades. Driving gear has 72 teeth & the pinion gear has 13 teeth. These gears are
mounted on the mower frame.
Figure 3.5 Pinion Gear & Main wheel
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 29 IESCE, Chittilappilly
3.6 TROLLEY WHEELS
Trolley wheel acts as a support for the mower and it also helps in the movement of
entire mower assembly. Trolley wheels are attached to mower frame by means of M.S flat
bars.
Figure 3.6 Trolley wheels for supporting mower
3.7 BALANCING WHEELS
A frame for balancing wheel is made of M.S flat bars. Rubber trolley wheel of 5.5 inch
diameter is used as balancing wheels. These wheels support mower cycle and also give an
easiness to steer the mower cycle.
Figure 3.7 Balancing wheel and frame
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 30 IESCE, Chittilappilly
Figure 3.8 Lawn mower cycle after construction
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 31 IESCE, Chittilappilly
CHAPTER 4
WORKING PRINCILE OF LAWN MOWER CYCLE
The cutting mechanism is made of a flat blade rigidly fixed to the frame behind the
spiral arrangement which is configured to contact at least one reel bar of the spiral blades
during the rotation of the spiral mechanism.
To understand reel cutting theory, we must understand the concept of clip and the shear
point. A shear point is any single point of contact made between the reel blade and bedknife.
Clip is the forward distance traveled between successive blade contacts at one shear point.
The bedknife pushes grass toward the shear point while the reel blade gathers it in
front. Each blade path has one-half clip in which to cut all the grass. The pushing force
required to move the reel mower is given by the motion of bicycle.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 32 IESCE, Chittilappilly
CHAPTER 5
DESIGN CALCULATIONS
5.1 SPUR & PINION GEAR PARAMETERS
The gear train of a reel mower consists of a driving internal spur gears fixed to each of
the front wheels internally which transmits the torque from the wheels to the reel, through the
pinions on the shaft.
Using the Gear ratio/ speed ratio relation
1
2=
T2
T1 ---------(5.1)
Where,
1 = Angular velocity of driving gear (rads/s)
2 = Angular velocity of driven gear (rads/s)
1 = Number of teeth on driving gear
2 = Number of teeth on driven gear
Gear ratio = T2
T1 =
13
72= 0.18055 ---------(5.2)
Gear ratio is 1: 5.54
Module for internal spur gear (driving gear)
Module, M = 1
1 =
180
72 = 2.5 ---------(5.3)
Where,
1 = pitch circle diameter of driving gear (m)
1 = Number of teeth on driving gear
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 33 IESCE, Chittilappilly
Module for pinion gear (driven gear)
Module, M = 2
2 =
32.5
13 = 2.5 ---------(5.4)
Where,
2 = pitch circle diameter of driven gear (m)
2 = Number of teeth on driven gear
5.2 DEIGN SPECIFICATION
The following were chosen as the design standards.
Average forward speed of the machine = 0.8m/s
Speed of rotation of the blade = 1500rpm
Number of helical blades = 6
Length of bed-knife = 300mm.
The above specifications were chosen for operational convenience (From Kepner, Principles
of farm machinery 1980).
5.3 THE CUTTING BLADES DESIGN
The cutting blades are chosen as they appear in the spiral blade lawn mower. The blades are
in two sets, the bed-knife and the reel. The reel is made up of six smaller blades of sizes
310mm x 25mm x 2mm and is made of steel materials. The blades are mounted on the three
spiders rigidly fixed to the shaft and are oriented at a helical angle i.
The helix inclination angle i for a cylinder having n partial helices is given by,
Cot i =
2r ---------(5.5)
i = 1
2r = Cot1 (
6 0.310
2 0.052) = 11.08 degree
Where,
L=Length of the cylinder (m)
r = radius of the cylinder (m)
i = helix inclination angle (degree)
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 34 IESCE, Chittilappilly
5.4 PERFORMANCE TEST AND EVALUATION
The performance of the machine was evaluated through a field test. A land
predominantly covered with grass was mapped out into a plot of area 4mx2m.
Theoretical field capacity,
FCt = Vt Wt ---------(5.6)
= 0.8 0.310 = 0 .248m2/s
Where,
Vt = Forward speed (m/s)
= Theoretical width (m)
Effective Field capacity,
FCe = A/t ---------(5.7)
= (4 2)/90 = 0.08889 m2/s
Where,
A = Actual area covered by mower cycle (m2)
t = Total time taken to cut the grass for a given area ( sec)
Field efficiency,
FCe
FCt 100 %---------(5.8)
0.08889
0.2480 100
Where,
FCe = Effective Field capacity (m2/s)
FCt = Theoretical field capacity (m2/s)
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 35 IESCE, Chittilappilly
CHAPTER 6
RESULTS AND DISCUSSIONS
A lawn mower cycle was designed, fabricated and tested. The mower is powered by the
pushing force of cycle. This grass cutting machine can be used by both rural as well as urban
dwellers. It is also affordable since the cost of production is low
6.1 DISCUSSION
The performance test of lawn mower cycle is carried out on a lawn. The Effective field
capacity (FCe), Theoretical field capacity ( FCt ) and field efficiency(%) are found out .The
effective field capacity is obtained as 0.08889 m2/s and Field efficiency (%) as 35.84 %,
with an operating time of 90 seconds (1.5 minutes) .
The theoretical field capacity (FCt) of the machine was calculated to be 0.248 m2/s
with a forward speed of 0.8m/s and the theoretical width of 0.31m. The machine was seen to
be more effective when working in a dry soil condition, because there is proper gripping of
the tyres in a dry condition of the soil.
6.2 APPLICATION
A lawn mower cycle is a machine used for cutting grass in lawns at the required height.
6.3 ADVANTAGES
1. Low Cost
2. They are less dangerous than rotary mowers.
3. Require little maintenance.
4. Are environmentally friendly.
5. Produce little noise.
6. Are easy to transport and store.
7. Don't stir up dust or emit harmful fumes.
8. Don't fill debris around the yard.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 36 IESCE, Chittilappilly
6.4 DESIGN
Figure 6.1 View of mower Assembly
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 37 IESCE, Chittilappilly
6.5 ESTIMATE
A manufacturing process concerned with conversion of raw materials into finished
products with the help of labor and other services. In order to compute the cost of each of
these factors the cost of manufacturing is subdivided into what are known as elements of cost.
Elements of cost are the primary classifications of cost according to the factors upon which
expenditure is incurred the elements of cost that constitute total cost of a product are:
i. Material cost
ii. Labor cost
iii. Other expenses
TABLE 6.1 COST ESTIMATION
Sl.No. Part Name
Size/No. Cost
1 Pinion Gear 2 nos 160
2 Main Gear Wheel 2 nos 750
3 Reel blades 1 nos 1050
4 Mower Frame 1 nos 600
5 M.S Rods 2 m length 250
6 Bicycle Parts 1 nos 500
7 M.S strips 1m length 105
8 Trolley Wheels 2 nos 70
9 Balancing Wheels 5 inch dia/ 2 nos 150
10 Nuts & Bolts a)MI2/2 nos
b) M14/6 nos
c) M18/2nos
90
11 Workman ship ----- 300
Total Rs.4025
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 38 IESCE, Chittilappilly
TABLE 6.2 MATERIALS USED
No Parts Name Materials Used Quantity
1 Pinion Gear H.S.S 2
2 Main Mower Wheel Cast iron 2
3 Reel blades Steel 6
4 Mower Frame Cast iron 1
5 Bicycle Frame G.I. Steel 1
6 Trolley Wheels Rubber 2
7 Balancing Wheels Rubber 2
8 Nuts & Bolts Mild steel 10
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 39 IESCE, Chittilappilly
CHAPTER 7
CONCLUSION AND FUTURE SCOPE
7.1 CONCLUSION
The aim of our project is to design, fabricate a lawn mower cycle. This does not have
engine and is powered by a cycle. The machine is simply powered by the pushing force of a
cycle. It is also affordable since the cost of production is low. This project helped us to
improve our practical knowledge and also to express a new idea on the work shop. However
by completing this project, we feel that our aim and objectives of the project is fulfilled.
7.2 FUTURE ENHANCEMENTS
7.2.1 Energy storage
The Lawn mower cycle can be modified to an electric hybrid lawn mower, getting its
power from a battery and by human power given by pedaling. It would increase the overall
capacity of the machine as more energy would be available.
7.2.2 Back Wheel steering
The back wheel steering can be added to this machine so that the lawn mower cycle
can be easily turned in different angles. This ensures a good control and making it possible to
turn around hard corners and small obstacles.
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Lawn Mower Cycle Mini Project
Dept. of Mechanical Engineering 40 IESCE, Chittilappilly
REFERENCES
1. Atkins, T. (2005). Optimum blade configuration for the cutting of soft solids.
2. Basil Okafor, International Journal of Engineering and Technology Volume 3 No. 10,
October, 2013 Simple Design of Self-Powered Lawn Mower
3. Fundamentals of Reel Mowers by TORO Commercial products
4. Jeremy, J. (2005). Solar charged lawnmower (28th Jan. 2010).
5. Khurmi, R.S. and Gopta, J.K. (1997). Machine Design, 11th Edition. Eurasia
Publishing House Ltd. New Delhi
6. Kepner, R.A., Bainer, R., & Boroger, E. L . (1980). Principles of farm machinery
7. Kinnander, Ola (October 25, 2012). "Rise of the Lawn-Cutting Machines".
Bloomberg Businessweek.
8. Nathan Fletcher, (2007) University Of Louisville , Design project
9. S.O. Nkakini, European International Journal of Science and Technology Vol. 3 No.
4 May, 2014 Design, fabrication and evaluation of a spiral blade lawn mower
10. Yong and Chow, S.H. (1991). Design and Construction of an Improved Domestic