Post on 27-Nov-2014
Design and Development of a Cutting and Lifting
Mechanism for a Lemon Grass Harvester
By
Low Kok Huan
A PROJECT REPORT SUBMITTED IN PARTIAL FULLFILMENT OF THE
REQUIREMENT FOR THE DEGREE OF BACHELOR OF ENGINEERING
(AGRICULTURAL AND BIOSYSTEMS)
FACULTY OF ENGINEERING
UNVERSITI PUTRA MALAYSIA
SERDANG, SELANGOR
MAY 2011
I
ABSTRACT
The design and development of a cutting and lifting mechanism for a lemon grass
harvester are described. The experimental unit of harvester is fully tractor mounted to
facilitate its maneuverability. However, there are several important factors affecting its
performance. The harvesting operation is automatic because the harvester experimental
unit have a pair of lagging cutter bar with horizontal wide V-shape of 150 degrees angle
to break the soil layer of 10cm depth of ridge, thus its passive force driven lifting
mechanism of lemon grass clump will act to facilitate that inclined movement of lemon
grass clump upward with tractor speed to a roller conveyor which its speed is 1.5 times
faster than that of tractor.
II
ABSTRAK
Rekabentuk dan pembangunan mekanisme pemotongan dan pengangkatan bagi sebuah
penurai serai dijelaskan. Unit eksperimen bagi penurai dipasang sepenuhnya di traktor
untuk memudahkan pergerakannya. Namun, ada beberapa faktor penting yang
mempengaruhi prestasi. Operasi tuai dijalankan secara automatik kerana unit
eksperimen bagi penuarai ini memiliki sepasang pisau pemotong dengan bentuk
melintang lebar-V dari sudut 150 darjah untuk memecahkan lapisan tanah kedalaman
10cm ridge, seterusnya mekanisme pengangkatan pasif akan mendorong rumpun serai
terangkat untuk memudahkan gerakan cenderung rumpun serai ke atas dengan kelajuan
traktor ke conveyor roller yang kelajuan adalah 1.5 kali lebih cepat daripada traktor.
III
ACKNOWLEDGEMENTS
I would like to thank my supervisor Dr Rimfiel for his interest and advices as well as En
Zainal, En Anwar, and other technicians for their technical support and assistances. I
appreciated the courage and actions supported from my precious faculty member,
Kimmy Bong, Robin Liew and fellow course mates, KBP 07/08. Thank you.
IV
TABLE OF CONTENTS
Page
ABSTRACT I
ABSTRAK II
ACKNOWLEDGEMENTS III
TABLE OF CONTENT IV
LIST OF TABLES V
LIST OF FIGURES VI
CHAPTER
1 INTRODUCTION 1
1.1 Objectives 2
2 LITERATURE REVIEW 3
2.1 Agronomy of lemon grass 3
2.2 Production areas 4
2.3 Harvesting 5
2.4 Soil requirements 6
2.5 Planting spacing 6
2.6 Other root crop harvester 8
2.7 Conceptual design of
lemon grass harvester by Hafiz 9
2.8 Cutter bar 12
3 METHODOLOGY 15
3.1 Introduction 15
3.2 Design requirements 16
3.3 Configuration option 17
3.4 Design concept 21
3.5 Blade for soil root cutting mechanism 22
3.6 Component for lifting mechanism 24
3.7 Conveyor 26
3.8 Design calculation
3.8.1 Draft force 28
3.8.2 Supporting leg 30
3.8.3 Radder bars 36
3.8.4 Roller conveyor 38
3.9 Laboratory testing 42
4 RESULTS AND DISCUSSION 43
5 CONCLUSIONS 48
REFERENCE 50
APPENDICES 53
V
LIST OF TABLES
Table Page
3.1 Description of sketches of concept design of
lemon grass harvester 18
3.2 The sketches show the variety of shape of cutting blade. 23
3.3 Length of radder bars which attached to a soil cutting blade 34
3.4 The related data of sprocket in chain
transmission system (Pitch 12.7 mm) 41
VI
LIST OF FIGURES
Figure Page
2.1 Planting spacing lemon grass. 7
2.2 Prepared lemon grass ready for marketing. 7
2.3 The width and height of a lemon grass clump. 10
2.4 Heterotypic harvester and mower blades. 13
2.5 Cutter bars. 14
3.0 Sketch of the experimental unit of lemon grass harvester 21
3.1 Soil-root cutting blade and its radder bars. 25
3.2 Opening angle of cutting blade 25
3.3 Depth of a supporting leg during operation is carried out. 31
3.4 A supporting leg in cantilever condition. 31
3.5 Shear force and bending moment diagram for cantilever beam
of a supporting leg. 32
3.6 Uniform load distribution is applied on the radder bars. 36
3.7 Shear force and bending moment diagram of radder bars system. 37
3.8 Sprocket system configuration. 38
VII
4.1 Front view of experimental unit of lemon grass harvester. 45
4.2 Right-hand side view of experimental unit of lemon grass harvester . 45
4.3 Left-hand side view of experimental unit of lemon grass harvester. 46
4.4 Back view of experimental unit of lemon grass harvester. 46
4.5 Top view of experimental unit of lemon grass harvester. 46
4.6 Connection between the frame and supporting leg. 47
4.7 Cutting blades and its radder bars. 47
4.8 Chain transmission system. 47
1
CHAPTER 1
INTRODUCTION
The Malaysian agriculture is dominated by cash crop plantation of oil palm trees
and its related technologies were advanced mostly compared to that of other crops.
However, local organic food industry especially organic herbal industry has grown up
gradually in recent years. For instance, lemon grass also known as `Serai’ in its Malay
name, it is a fragrant ever-green tropical grass with citrus lemon flavor. Lemon grasses
are used in distilling processes for producing essential oil, namely, citronella oil which
is a raw material in pharmaceutical purposes besides in domestic use for preparing
Malaysian favorite citrus spices either in form of dried and powdered, or used fresh.
With having intensive uses in daily life, wise consumers always demanded high quality
and value-added agricultural product in large volume. Unfortunately, the most critical
obstacle the organic herbal industry facing is mechanical transformation. Currently,
there is no mechanization is used in lemon grass plantation either in planting or
harvesting operation (Hafiz, 2008) except simple gardening tool.
Furthermore, limited manual lemon grass harvesting capacity caused farmers
suffered high labor cost per day (Hj Saudi bin Hj Hamid, 2008). Manual harvesting of
entire plant clump, for example, chopping and pulling out the clump from ground
require a lot great efforts and experiences. Other factor is shortage of labor in
agricultural sector due to migration to urban area.
2
Besides that, time consuming manual operation in lemon grass plantation will
affect the commodity competence, in particular, in export market. "We will work with
two French companies to market the products in France where demand for our oil
extracts has grown by leaps and bounds," said by Malacca Biotechnology Corp's Chief
Executive Officer Zam Abdul Karim. To satisfy high demands from essential oil
processing industry, mechanical harvesting surely helps farmers increase their lemon
grass harvesting production in aspect of saving harvesting time. However, there is no
suitable lemon grass lifting machine except chop, hoe, and cutter such simple
equipment.
This project aims to design and develop a cutting and uplifting mechanism of
tractor mounted lemon grass harvester with suitable root-cutting and lifting mechanisms
for small scale production.
1.1 Objectives:
The research objectives of this project were to:
1. Design and fabricate a suitable cutting blade for soil-root cutting mechanism
2. Design and fabricate a component for lifting mechanism
3. Investigate the ability of the completed cutting and lifting mechanism to respond
to rotational inputs of the PTO connection.
3
CHAPTER 2
LITERATURE REVIEW
2.1 Agronomy of lemon grass
The lemon grasses belong to the family Gramineae. Its scientific name is
Cymbopogon marginatus and etc. The genus has about 55 species. Two major types
have considerable relevance for commercial use: East Indian lemongrass, Cymbopogon
flexuosus, which is also known as Cochin or Malabar grass, and is native to India and
Sri Lanka. And West Indian lemongrass Cymbopogon citratus, which is native to
southern India, Ceylon, Indonesia, and Malaysia.
The lemon grass is a tropical perennial crop typically planted in rows. It requires
average rainfall distribution of about 2,000-2,500 mm in a year. It grows well in range
of mineral soil to peat soil and in altitude of 600-1,500 m. The ideal climate for growing
lemon grass is tropical or subtropical climate. It is grown by propagation. Propagation is
achieved by dividing the root clump. The plants grow in dense clumps up to 2 meters in
diameter and have leaves up to 1 meter long.
Hafiz (2008) presented useful information of plant’s physical dimension, root
depth, planting row and hill spacing. This information was crucial in understanding of
nature of plant and its planting considerations.
Hafiz (2008) also provided the some basic operational cost per acre about lemon
grass. Since no mechanical harvesting method is available locally, he described about
4
local harvesting procedure of lemon grass while suggesting a conceptual design of
lemon grass harvester to help increase farmer’s performance.
2.2 Production areas
Lemon grass is a herb identified for agriculture development and an important
source of income with the East Coast Economic Region (ECER) states of Pahang,
Terengganu, Kelantan and the district of Mersing, Johor. For example, BIO Daun Sdn
Bhd is farming the lemon grass on 121 ha of land in both Kelantan and Pahang. (BIO
Daun Plantation Sdn Bhd, 2008)
Internationally, lemon grass is grown through Africa, in the Democratic
Republic of the Congo (DRC), Angola, Gabon, Chad, Central African Republic,
Madagascar and Comoros Islands. Guatemala is known to be the leading exporter with
about 250 000 kg per year. China produces 80 000 to 100 000 kg per year. The United
States of America (USA) and former Union of Soviet Socialist Republic (USSR) import
approximately 70 000 kg per year each, the United Kingdom 65 000 kg, France and
Japan 35 000 kg each, and West Germany around 20 000 kg per year. (Department of
Agriculture, Forestry and Fisheries, Republic of South Africa, 2009)
5
2.3 Harvesting
The harvest can take place from 6 to 9 months after planting the slips. The grass
can then be harvested frequently during the active growing season, up to once every
month. Frequent cutting stimulates growth. The oil yield will be reduced if the plant is
allowed to grow to too large. The grass should be harvested early in the morning,
provided it is not raining and allowing heavy dew to evaporate in order to avoid colour
loss during a hot day.
The plants are harvested mechanically or by hand. Cut the grass 10-15 cm above
ground level. Avoid cutting too low as it will delay regrowth. Prevent splitting or
cutting edges by using sharp tools and machinery that make clear cut. Oil quantity is
optimal in the upper parts of the plant. Should the grass be cut too low, there will be less
oil in the leaves. In South Africa, there are up to three harvests can be obtained in the
first year and up to 5 to 10 harvests during each of the 3 to 5 succeeding years,
depending on soil moisture status, management and weather. This is because the yield
of oil is less during the first year of establishment and increase in the second year and
reaches a maximum in the third and fourth years, after which it declines. For
economical purpose, the plantation is maintained only for 6 years. (Department of
Agriculture, Forestry and Fisheries, Republic of South Africa, 2009)
In fact, Malaysian farmers adopt other farming and harvesting practices of
lemon grass. The lemon grass is usually harvested twice a year (Hafiz, 2008). For this
farming practice, farmers should harvest the grass by hand 10-15 cm above ground level
when the grass matures. Six months later, a clear cut of the grass include its root should
6
be removed by machinery and then be preparing for next planting season of lemon grass.
The objectives of this project serve for the final harvesting of the grass mechanically.
2.4 Soil requirements
Lemon grass is widely adapted to a range of soils and performs well on sandy to
clay loam soils with a PH range of 5.0 to 8.4 and good drainage. The lower the altitude
and more alkaline the soil has, the higher is the citral content of the soil. Usually, the
variety of soil with high citrates is in demand. For instance, drier and loamier soil yields
higher citral content in lemon grass. (Department of Agriculture, Forestry and Fisheries,
Republic of South Africa, 2009)
2.5 Planting spacing
Generally, a row spacing of 20 cm with a row width of 40 cm is used in, that
will give a total of 125 000 plants per ha in a high rainfall area or under irrigation.
Traditionally, the ridge is not required in plantation of lemon grass. However, a ridge of
height of 10 cm should be used for soil-root cutting operation can be carried out easily.
Also a range of row spacing of 140-200 cm should be used to accommodate the width
of a tractor. These large spacing should be utilized to plant some short term vegetables
such as eggplant, cabbage, and lettuce or intercropping with green beans as to provide
the crop with nitrogen and assist in weed control before the lemon grass matures.
7
Figure 2.1: Planting spacing lemon grass
Figure 2.2: Prepared lemon grass ready for marketing (Department of Agriculture,
Forestry and Fisheries, Republic of South Africa, 2009)
8
2.6 Other root crop harvester
Basically soil-breaking and uprooting mechanism were simultaneously applied
by almost root crop harvesters. Although agronomy of lemon grass is quite different
from other root crop, for instance, groundnut, onion, potato and other root crop types,
but these two mechanisms were needed for harvesting of lemon grass. With
modification and adaptation of each advantages of other root crop harvester over the
countries, this lemon grass harvester prototype gain benefits during its design phase.
From the literature review done by Hafiz (2008), there were many models of
peanut harvester available over many countries besides potato harvester and onion
harvester. The details about machine component and harvesting mechanisms of each
harvester have been provided in his research paper, Conceptual Development of a
Lemon Grass Harvester, 2008 p.18-25.
An improved model of groundnut harvester (1988) developed by Univesiti Putra
Malaysia (UPM) and its harvesting concept are referred intensively by this project. The
design of this model is rather machinability in nature and its functionality in harvesting
is quite good and high in efficiency.
9
2.7 Conceptual design of lemon grass harvester by Hafiz (2008)
Conceptual model of development of lemon grass harvester suggested by Hafiz
(2008) is mainly consists of leaves cutter, subsurface rotary finger reel, conveyor, and
other components.
Hafiz explained in his paper that a leaves cutting operation is carried out first
before lifting process of lemon grass. The reason for cutting the leaves is facilitate the
operation later.
Most importantly, the principle of his lifting process of subsurface rotary finger
reel is as follows: the teeth of subsurface rotary finger reel will break up the soil
structure which it is in turn automatically push clumps of lemon grass from the bottom
to the lifting system.
Hafiz also claimed that there are several important points for his system will
push and convey the clumps rather than using the root cutting method while the whole
subsurface rotary finger reel is submerged below the ground. The size (diameter, width,
and type) of subsurface rotary finger reel must be as small as possible for minimizing
the contact area between soil and subsurface rotary finger reel, thus it will reduce power
requirement. Besides that, nearly zero drawbar power requirement is needed because
the rotor tends to move the machine forward as it works.
10
With reference to his research data of parameter of a clump of lemon grass:
Parameter of lemon grass(Hafiz, 2008)
Figure 2.3: The width and height of a lemon grass clump
Average root depth = 7.2 cm
Weight = 9kg
The crop is an aromatic plant whose roots are fibrous shallow and spread into the soil,
has long leaves. The essential parts of the lemon grass are stalks and leaves. The
essential oil is extracted from fresh plant material by means of steam distillation.
There are several technical problems arisen from his design. As stated in his
paper, the coverage of maximum depth below the ground, which is 12 cm, by his
subsurface rotary finger reel since the reel is working below ground. The design depth
exceeds the average root depth of 7.2cm so that the root system of plant will be
removed. Although the teeth may be sufficiently capable to break up the soil surface,
but he did not describe the way subsurface rotary finger reel will get into the depth of
12 cm below ground especially the soil is initially firm. The case will be different if
there is either a ridge there or high moisture content of soil.
11
Secondly, the length of shaft of subsurface rotary finger reel is too long, which
is 82 cm compared to that of the required dimension that is average clump diameter of
60 cm. The reel may face more soil resistance below the ground with its excess length
of the reel is about 22 cm. The suggested tolerance range of length should less than 5cm.
Furthermore, the design torque is also too small which is 577 Nm with 375 rpm and
safety factor of 1.2 to carry out the clump pushing work. As a result, the shaft of reel
which its dimension of 4 cm may either face reduction of revolution or varying
deflection of subsurface rotary finger reel below the ground due to imbalance loading
of clump and soil clods during the soil breaking and clump lifting processes. Further
modification is required to secure the change of deflection of shaft.
The working conditions under the soil surface will also affect the performance
of transmission system of chain for subsurface rotary finger reel. Although Hafiz
suggested a modification which is add-on of sharp metal on chain thus will help break
up the soil structure while the system of reel is rotating below the ground. But the
transmission system especially the sprocket may become either rusted or defected in a
shorter period compared to that of normal use under lubrication condition.
The problem of falling apart of clump may exist after lifting process. In his
design, the subsurface rotary finger reel has four part surface and each surface has
twenty teeth. This feature may help griping the clump as well as breaking up the soil
structure. But the base structure of clump may become loosen due to partial support of
reel of 13 cm width, thus it is falling apart during the stage from subsurface rotary
finger reel to conveyor. In addition to that, the gap between reel and belt conveyor
remained undefined. If the conveyor is too close to the surface of ground, the scattered
12
soil particles may affect the efficiency of power transmission of conveyor. Also, the
ambiguous part is unclear dimensions of sprocket.
Other problems rose, which have been stated in his paper, when using a
hydraulic motor to run the reel. Besides that, there are insufficient skills and tool to
fulfill the requirements of complex construction of curved shape of subsurface rotary
finger reel holder except special machining is ordered. As a result, a lemon grass
harvester of simpler machinability should be designed as to save cost and material.
2.8 Cutter bar
Harvest loss consists of agricultural produce that is produced but not
successfully removed from the field. There are several major categories of loss: pre-
harvest loss, gathering unit loss, and machine loss. In the agricultural sector, the harvest
loss of grain, for example soybean, is severe. Poor field conditions and a poorly
adjusted combine may contribute to harvest loss of 6-8 bushels of soybeans per acre.
Harvesting losses cannot be completely eliminated, but they can be reduced to only 1-2
bushels per acre if the performance of the combine is maintained regularly.
(Cooperative Extension Service, Lowa State University, 1984). The cutter bar is the
major cause of field harvesting loss, accounting for about 80% of combine header
harvesting loss of soybean ( Quick, 1973; Dunn et al., 1973). Research results by Dunn
et al.(1973) on soybean asserted that harvesting loss were caused by the cutter bar and
about 61% of the field loss was due to shatter. Nave and Hoag(1975) investigated
13
different cutter bar and knife configurations mainly sickle and knife frequencies in a
laboratory test stand. Their results showed that knife section and guard spacing of less
than the conventional 76.2 mm would reduce plant stem acceleration and result in
shatter loss. Although physiology of lemon grass is different from that of soybean,
farmers will suffer the harvest loss in a way of crop damage and finally abandon the
crop if the cutter bar is not designed specially. Traditionally, the available literature
review are focused on vertical blade on the soil tillage or cutter bar cutting plant stem
but there a few review about horizontal cutter bar cutting soil structure and root system
especially closely related to harvesting of herb. Despite that, modified reasoning of
machine design has been applied on the harvesting of lemon grass, which may help
improve the harvesting efficiency of lemon grass. And a future research work on
efficiency of different cutter bar configuration on harvesting lemon grass is suggested to
determine the optimum performance.
The figures below display different kind of harvester cutter bar in terms of shape
and application. These cutter bars are mainly used for grain harvesting, for example,
soybean, maize, and other besides grass mowing.
Figure 2.4: Heterotypic harvester, sickle guard, and mower blades.
14
Figure 2.5: Cutter bars
Material:High quality 65Mn spring steel
Thickness: 2.00mm; 2.80mm
Surface Treatment: Only with anti-rust oil after quenching; varnish stoving; paint oil
stoving; galvanized; blueing; chromeplate, etc.
Main Application: Harvester blade (knife sections & ledger blade) are used in
harvesting machines like combine harvesters (New Holland, John Deere, Swaraj etc.),
straw reapers, mowers and hreshing machines, etc.
[Source: 1. WINDSOR agricultural implements and spare parts
2. www.grandeermachine.com
3. www.topmachinebiz.com ]
15
CHAPTER 3
METHODOLOGY
3.1 Introduction
After the initial research steps were taken, the actual mechanism design
development of each component of the harvester took place. The machine is designed to
assist farmer without consuming much time and human power during lemon grass
harvesting operation.
The process began with brainstorming process of various concepts that had potential
to form the functional requirement of each component. However, there are a lot of
constraints in designing such a machine. The machine was designed basically based on
various parameter and constraints
i) Basic parameter of a lemon grass clump(height, width, and weight)
ii) Root depth
iii) Row and hill spacing
and other important considerations.
16
3.2 Design requirements
The machine will be designed so that farmers able to afford to buy it at reasonable
price and help farmers increase their harvesting efficiency during harvesting operation.
The desired features were displayed in list below:
• Tractor mounted
• Able to break up soil layer and cut off lemon grass root
• Lifting the lemon grass clump to conveyor
• Reduce physical damages to lemongrass bunches
• Feasibility in manufacturing process and material selection
• One row harvesting
17
3.3 Configuration option
The preliminary design of cutting blade, lifting tool, and conveyor is selected
from various sources include reference from technical book, the agricultural product
catalog available in market, and brainstorming processes. However, the design of the
machine is evolving through the real construction practices as to achieve feasibility in
manufacturing process.
There are three option of initial model of the implement that have its own
characteristic and disadvantages.
Option A will use big vertical and triangular blade to cut the root and slide the
clump by its body. The principle of the operation may be sound good, but its
supporting leg may not able to support the weight of blade of solid mass and pull force
from tractor while penetrating through the soil. Second, the cost factor is a very
important consideration in designing the machine. Since this type of blade may require
special machining, thus causing unexpectedly high cost to the project budget although
the machining of blade may able to cast various shape of cutting edge efficiently.
Option B will use a horizontal square blade to cut the root and slide the clump
afterward through its finger extensions. This configuration may be able to contribute a
lighter weight compared to that of option A since the blade is responsible for cutting
function solely. The blade must have sharp and smaller cutting area to cut the root
efficiently. The assistance of its finger may also help reduce the weight but this
structure may not able to last long with its inclined angle.
18
Option C will use a long inclined V shape blade. The structure may be rigid
enough as to lift the clump and can be designed lighter so that the several supporting leg
able to support the long blade. However, the blade may convey a lot of soil mass
together with lemon grass clump during the tractor is moving.
Table 3.1: Description of sketches of concept design of lemon grass harvester
Concept A
A big vertical and triangular blade,
which its width are about 600 mm and
thickness of more than 100mm , will be
used to cut the root of lemon grass
underground and simultaneously slide the
clump up onto the conveyor while the
tractor is moving forward.
Concept B
A horizontal square blade, which its
dimensions of 600 x 30 x 10mm , will be
used to cut the root underground , then
the clump will slide onto the finger
which attached to the blade , thus drop
onto the conveyor while the tractor is
moving forward.
Concept C
A long inclined V shape blade, which its
sub ground cutting edge will cut the root.
After that, the clump will slide onto its
body and then onto the conveyor.
19
From the sketches above, the component of blade is the determining factor in these
configuration options because the blade design is affected by its shape, opening angle,
and other dimensions which are interdependent, thus affecting the lifting mechanism.
So the selection of suitable blade design should be carefully chosen as to contribute to
easy machinability in next step. The machine is desired as to cut off the root system of
the grass and then should be able to lift the clump onto a conveyor. Since the blade will
operate beneath 10cm depth the ridge, the blade is subjected to the threat of being blunt
after operating. A convenience of replaceability of the blade should be included in the
machine feature so that the efficiency of cutting has been maintained during the
operation. Also, the support leg of the blade faces the threat of distortion during the
operation. As a result, these two components should be designed properly at low cost
and have a feature of replaceability. Besides that, an lifting mechanism should be
designed so that a clump will be lifted just after the cutting mechanism. In short, a good
machine should be properly included these features.
There are three options of combining the root cutting mechanism and lifting
mechanism together. First, an option of triangular blade of 60 cm x 30 cm x 10 cm
(length x width x thickness) which requires a special machining as to able to cut off the
root and able to slide passively the clump of lemon grass through its body. This big
structure may require slightly high cost of material and machining as well as cause soil
loss during operation. Also, the fabrication of a long inclined V-shape blade also faces
the same problems besides a special connection between support leg and the blade need
to be designed so that the V-shape inclined blade is hung up as to lift the clump. The
triangular blade and incline V-shape blade expose their body to the soil as to slide the
20
clump onto the conveyor meanwhile they also cause soil resistance between the body
and the clump. The larger the exposed surface area of blade beneath the soil, the higher
the resistance the blade will face. As a result, these two option of blade should avoided
as to reduce cost, machinabilty, material usage, and soil resistance.
In relation to these reasons, the option of horizontal square blade can be arranged in
a way such that it has a V-shape opening as to minimize the soil resistance meanwhile it
will cause lesser soil loss when its radder bars slide passively the clump up. This is
because the gaps between the radder bars allow the excessive loose soil particles drop
down to ground as well as to minimize the contact area between the circular radder bars
and clump. Although the radder bars may be easily broken but a stronger strength of
material can be selected to support the mass of above 9 kg. This option is a material
saver compared to that of other two options because it need mild steel of dimension of
60 cm x 8 cm x 2 cm ( length x width x thickness) and about 10 pieces of iron bars of
length 40 cm. The choices of the conveyor can be varied according the requirements of
farm conditions. A roller conveyor will be preferred because its motion is synchronous
and running without slack.
In sum, the feasible concept is concept B.
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3.4 Design concept
The experimental unit of lemon grass harvester has five crucial parts inclusive
roller conveyor, a pair of V-shape cutting blade with radder bars, frame, wheel, and
power transmission system.
Frame functions as overall physical machine supporter; most interesting part is
that the existing support structure of gearbox and the three point hitch linkage are
incorporated inside frame structure as back bone. After the tractor, a pair of submerged
lagging cutting blade with horizontal wide V-shape of 150 degrees angle will break up
the soil layer about depth of 10 cm beneath soil surface, thus separating the root system
and soil apart. As the motion of tractor and its lemon grass harvester are running, the
combined structure of cutting blade and its radder bars is pulled actively by tractor. The
exposed root system will slide passively onto the surface of radder bars after the soil-
root cutting process. In sequences, the lemon grass clump will be lifted up by angle of
30 degrees but the gravity force acts on the clump so that the clump thus drops onto
roller conveyor nearby. However, irregular sharp metal strip are welded on the surface
of roller conveyor as to help lifting the clump onto conveyor. A sketch of the
experimental unit of the lemon grass harvester is as shown in Appendices, page 53.
22
3.5 Blade for soil root cutting mechanism
There are four sketches of different type of cutting blade have been produced
after considering the current machine requirement and agronomy of lemon grass. The
blades have been visualized and compared their advantages and disadvantages as below
according to design criteria especially its machinability.
These four types of blade connected with its radder bars which are desired to lift
the clump onto conveyor after cutting off the root of the grass. To facilitate the
feasibility of blade design, its advantages and disadvantages from each blade design
should be compared as to produce a desired cutting performance. The triangular blade is
usually used in grain harvesting because it cut the stem effectively in air by its
concentrated cutting force in centre. However, its knife head will be blunt in a shorter
time compared to that of operating in air since the blade is expected to operating in soil.
The second option is the horizontal blade which requires simple machinability , but it
faces high soil resistance when it is operating in soil. As a result, a modification should
be applied on horizontal blade as to reduce the soil resistance, thus introducing two
different opening angles of V- shape blade of 45o and 75
o which will face reduced soil
resistance when they are operating in the soil. However, the V- shape blade of angle 75o
will be selected since this design will save the material usage by its larger length
coverage as compared to that of V- shape blade of angle 45o.
In sum, a proper selection of blade should stick to the project objective and
design requirements. The feasible design of blade is design D.
23
Table 3.2: The sketches show the variety of shape of cutting blade.
Advantage Disadvantage
Design A: Horizontal triangular blade
-Concentrated cutting
force in centre
-Easy blunt knife
head.
-Not suitable in
cutting soil.
Design B: long and horizontal square
blade
- Simple machinability
-High soil resistance
Design C: V-shape blade with angle of
45o (Hassan bin Osman, 1988).
-Reduced soil resistance -Increased
machinability
Design D: V-shape blade with angle of
75o
-Reduced soil resistance
-Material saver(larger
length coverage)
-Increased
machinability
24
3.6 Component for lifting mechanism
The radder bar functions to lift the lemon grass clump passively while the clump
slide onto it.( Hassan bin Osman,1988) There are several considerations should be taken
care of when designing the dimension of radder bars as to maximize the performance of
lifting mechanism. The shape of radder bars should be cylindrical as to minimize the
contact friction between clump and surface of radder bars. Although there is a gap
between each radder bar, the clump may occupy the gap down. But, clump may not
easily fall apart since it is come in clustered mass with its fibrous root system. Second,
the speed of tractor is operating above 2km/h and the length of radder bar is designed to
be less than 400mm.
Time
ntDisplacemeVelocity =
5556.0
4.0=Time = 0.72 sec
The short reaction time is required that lemon grass slides onto conveyor after
the cutting of its root. Thus, the clump should be transferred to conveyor before
sufficient time is allowed for the clump to become fallen apart.
The angle of inclination, Ө of radder bars should equal or less to 45o as to avoid
incapability of sliding up of clump which will create a clump blockage on the radder
bars and affect the lifting mechanism of next lemon grass clump. Meanwhile its angle
of inclination should create an elevated height of more than 13 cm because this elevated
25
height will not only lift the clump but will also avoid the conveyor from suffering the
damage during the machine is working close to the ground.
The strength of radder bars is crucial in determining the ability resisting the
maximum weight of lemon grass of 9 kg as stated in Hafiz‘s report besides unknown
conveyed soil mass. Since the project aims to build a component of a cutting and lifting
mechanism of the lemon grass harvester, the mild steel should serve its purpose during
the experiment as to save project cost.
Figure 3.1: Soil-root cutting blade and its radder bars
Figure 3.2: Opening angle of cutting blade.
26
3.7 Conveyor
The machine is working close to soil surface thus may cause the machine
subject to threat of damage during its working operation. Careful dealing with various
constraints is required to fulfill the project objectives. Since the elevated height of
fingers is around 13-16 cm and the consideration of thickness of frame, there are several
options for selecting suitable conveyors: belt conveyor, chain conveyor, and roller
conveyor for conveying operation
Although belt conveyor is commonly used in industry, its slippage in
transmission may not suitable in this case for conveying the lemon grass clump during
the operation is running. This is because next clump will be cut in next minute after
previous cutting of lemon grass root. If there are blockage occurs in conveyor due to
decreased conveying efficiency, it will affect the next clump conveying and slow down
the operation.
Chain conveyor may be suitable for this experiment. Chain conveyor have the
advantage of lighter weight, low vibration effect, and synchronized motion as to ensure
smooth conveying operation, but large diameter of sprockets are required to transmit
power to support weight of clump. Besides that it may not be suitable to support the
weight of lemon grass clump especially in inclined direction while its sprockets close to
soil surface. It may require high cost of industrial chain for transporting the clump of
maximum 9 kg.
27
The application of roller conveyor has its advantages similar to that of chain
conveyor, but it has at least three separate rollers with smaller size of sprocket. It is also
costly and high maintenance as compared to that of belt type. Although the roller
conveyor also faces the threat of damage while working close to soil surface, it can be
replaceable either by parts or by whole small system. It is suggested that a small roller
conveyor can used after the lemon grass uplifting process by fingers, thus the clump
will be passed to other larger conveyor system either of roller conveyor or chain
conveyor for future research work. By comparison, the roller conveyor is selected for
serving the project objectives.
By combining the selected component, the functional requirement of cutting,
uplifting, and primary conveying mechanism of lemon grass will be fulfilled by using
Concept B with Design D: a pair of V-shape blade with angle of 75o
each and roller
conveyor system.
28
3.8 Design calculation
3.8.1 Draft force
To pull an implement at a given speed in the field, the total amount of draft,
which is the draft force required to pull a complete implement in the field , must be
known. The unit draft is the draft force required to pull some unit of the tool. Total draft
is therefore the sum of the unit draft. Total draft consists of draft force of cutting blade,
draft force required to pull the rest of component of lemon grass harvester (gearbox,
frame, and roller conveyor).
To calculate the draft force of soil cutting blade, the following factor must be
considered:
a. Width of the tool
b. Depth of cutting
c. Ground speed
d. Soil resistance
Soil resistance is based on texture, but may vary widely within a textural class
depending on characteristic such as looseness (i.e. density), moisture content, and subtle
changes in particle size distribution.
Generally, a moist sandy loam soil would have about 6.4 pounds of resistance per
square inch or 44 kPa(Technical note 21.Soil, draft, and traction; Dirt Hog’s
companion). However, shear stress of sandy loam available in Taman Pertanian
29
Universiti(TPU) is 1.22 pounds of resistance per square inch or 8.42 kPa at a soil
moisture content of 20.74 %( Boon, 2005). A dry sandy loam would have a much
greater draft, and therefore require more power to cut through the soil, than a moist
sandy soil loam. However, there is high humidity in soil of Malaysia due to its tropical
climate with shinny and rainy day contributes to different moisture content of soil
throughout the year.
Consider a 45 cm cutting blade penetrate 10 cm deep of a ridge has a 450 square
centimeter cross section area (width of tool x depth) operating at a speed of 3.2 km/hrs.
A moist sandy loam soil would have about 6.4 pounds of resistance per square inch or
44 kPa will be taken as reference in this calculation.
Data:
Width, w=45 cm= 1.47 ft
Depth, h= 10cm = 0.328 ft
Area, A= 450 cm2 = 0.482 ft
2
Speed = 3.2 km/hrs = 1.988 mph
Shear strength of moist sandy loam soil, б = 6.4 pounds of resistance per square inch
Unit draft = w x h x б (Dirt Hog’s Companion. Technical Note 21)
Unit draft of two cutting blade = 6.4 x 0.482 x2 = 6.17 lb of resistance
Draft force required to pull the rest of component of lemon grass harvester
(gearbox, frame, and roller conveyor) is estimated about 30kg or 66.138 pound and
30
maximum mass of 2 lemon grass clump of 18 kg or 39.68 pound on the harvester
during the operation.
Total draft = 6.17 + 66.138 + 39.68
= 111.98 pound
3.8.2 Supporting leg
The figure below illustrates a supporting leg of length 70cm which is connected
to a V shape blade and the frame by screw. Although the height of a lemon grass plant
may reach up to 120 cm( Hafiz, 2008), but the length of supporting leg has been
reduced to 70cm due to the constraint of PTO height of tractor. However, this
constraint will not damage the quality of lemon grass as its stalk contains high yield of
oil content than that of its leaves and the useless leaves will be discarded. Also, this
supporting leg is subject to high resistance and moment during operation when its
length is too long, thus this supporting leg should be designed as to resist the opposing
resistance. As a result, the supporting leg can be replaceable easily if there is any failure
occurs and the effective length of supporting leg has been reduced to 61cm where
measurement starts from position of screw to the blade.
31
Figure 3.3: Depth of a supporting leg during operation is carried out
Figure 3.4: A supporting leg in cantilever condition.
32
Figure 3.5: Shear force and bending moment diagram for cantilever beam of a
supporting leg
The joint is assumed to be fixed as to able to resist moment. The pattern of
resistance is estimated as triangular which influence of resistance increases with the
increasing length beneath the soil. The value of parameters is given as below:
Diameter, D = 1 in = 2.54 cm
Working length, L = 61 cm
h/3 = 10/3 cm
L-h/3 = 57.67 cm
Unit draft = w x h x б
= 1986 N
33
Moment, M = unit draft x (L-h/3)
= 114.554 kNm
Rx= 0
Ry= 1986 N
Second moment of area of supporting leg, I = 4
4rπ
; r = radius
= 2.04 x10-8
m4
Center distance = D/2
= 0.0127 m
Bending stress, б = I
Mc±
(Marshek, K. M., 1987)
= 81004.2
0127.0554.114−
±x
x
= ± 71.32 M Pa
Circular area, Ac = πr2 = 5.067 x 10
-4 m
2
Shear stress, τmax = cA
V
3
4
(Budynas, R. G, 2008)
= 410067.53
19864−xx
x
= 5.225 MPa
34
Take factor of safety =2
Yield strength, sy = 2б
=142.64 MPa
Material selection:
1018 mild steel
Ultimate tensile strength =63,800 psi = 439MPa
Yield strength =53,700psi= 370MPa
Elongation =15%
Rockwell hardness =B71
Modulus of Elasticity = 200 GPa (Eagle national steel, 2009)
Deflection at the unsupported end = EI
PL
3
3
=)1004.2()10200(3
)1061(198689
32
−
−
xxxx
xx
= 0.0368 m
Although the calculated yield value of 142.64 MPa of the supporting leg is
lower than that of 1018 mild steel, which is 370 MPa. But the supporting leg is
stretched under force without failure by the value of theoretical deflection which is 3.68
cm when it is assumed operating under the soil. The longer the length the cantilever
35
beam, the larger the deflection it is. Since the length of supporting leg is constrained by
the height of lemon grass and position of power takeoff of tractor, the length of 61 cm is
the minimum requirement. From the calculations, the length of supporting leg which is
61 cm is going to be distorted and need to be replaced after operations. To reduce the
deflection, a stronger material of higher modulus of elasticity and larger diameter
should be used as the supporting leg by assumed its length and the load distribution is as
indicated as above.
36
3.8.3 Radder bars
Consider a cutting blade having 6 radder bars of diameter, D of 1cm each and its
distance from centre to centre of the radder bars is 5cm. The inclined angle of 30o of
radder bars was taken as to lift the grass up. As a result, there are a total number of
radder bars of 12 for a pair of cutting blade and the maximum estimated height of
radder bar from soil surface, h is 25.45 cm which is the lifted elevation for the position
of roller conveyor installation. The design of radder bar help lifting the grass up from
the ground and avoid the roller conveyor suffering the damage during the operation
where is closer to the ground. The table below showing the lengths of radder bar which
installed on the other edge of the cutting blade opposite to that of sharp cutting blade.
Table 3.3: Length of radder bars which attached to a soil cutting blade
Radder bars Length (cm)
A 36
B 37
C 39
D 40
E 41
F 43
Figure 3.6: Uniform load distribution is applied on the radder bars.
37
Figure 3.7: Shear force and bending moment diagram of radder bars system.
Assume the length of longest radder bar is 43 cm
Rx = 0 N
Ry = 63.3 N
Moment, M is 13.6095 Nm at the end of support
Since the maximum moment will be shared by at least 10 radder bars if in case
of smaller diameter of clump. The moment is increasing as the length of radder bar is
increasing. By considering the longest length of radder bar, average moment of each
radder bar is 1.36 Nm at the end of support. Despite of that, the whole radder bar system
should be able to resist this bending moment in a short reaction time of 0.72 second
when the clump is sliding on the surface of radder bars.
38
3.8.4 Roller conveyor
Figure 3.8: Sprocket system configuration
The sprocket system configuration above illustrates the position of roller
conveyor and its related components. The system is a part of lifting mechanism of
lemon grass with its power source from power take-off (PTO) of tractor. First, the PTO
shaft of a tractor will transmit the power to gearbox, and then the speed reducer gearbox
will reduce the rotational speed. However, the sprocket system is designed to increase
39
the rotational speed thereby increase the forward speed of roller conveyor. As a results,
the following steps was carried out to determine the suitable dimension of the sprocket
A, B, and C as to increase the forward speed of roller which is 1.5 times faster than that
of the tractor of assumed operating forward speed 3.2 km/h. This forward speed of
roller conveyor is required to transfer the clump of the grass faster to the next stage of
conveying mechanism before any blockage occur during the lifting mechanism.
From the data available:
Power take-off (PTO) speed = 540 rpm with engine at 2199 rpm.
Speed ratio of reducer gearbox = 2:1
Speed ratio = Ng
NPTO
Speed of shaft after reducer gearbox, Ng=2
540= 270 rpm
Since sprocket C is on the same shaft as above,
>>speed of sprocket C, NC = 270 rpm
The sprockets are keyed on the shaft to transmit the power except sprocket C is splined
on the shaft to receive 270 rpm from reducer gearbox.
Tractor is assumed operating optimum on the speed of 3.2 km/h = 8/9 ms-1 when the
harvesting operation of lemon grass is running.
Given that diameter of roller, D= 2 inch = 5.08cm
40
The factor 1.5x was taken into account as shown in the following calculations.
Conveyor speed = 1.5 x (8/9) ms-1 = 4/3 ms-1
For simplicity, assume the entire sprocket A system is of the same dimension on the
shaft of roller conveyor. Since the sprocket A system is located closer to edge of
conveyor, so smaller size of sprocket of 57.07 mm pitch diameter is selected as to
minimize the contact between lemon grass clump and sprocket A.
V= r Ѡ
= r ( 60
2 Nπ
)
4/3= (2
1008.5 2−x
)(60
2 Nπ)
>> Speed of sprocket A system, NA = 501.28 rpm
Speed of sprocket B is similar to that sprocket 1 since they are on the same shaft.
NB = 501.28 rpm
Because there constraint of longer shaft which sprocket C is splined onto, one of the
shaft of system sprocket is designed to be 125 cm long where sprocket B is keyed as to
match sprocket B and sprocket C in line to power transmission.
Diameter sprocket C of 137.64mm is selected.
BN
cN =
C
B
D
D
41
28.501
270 =
64.137
BD
DB= 74.13 mm
As a result, a sprocket of closer diameter of 73.14 mm is selected.
B
C
N
N =
C
B
D
D
BN
270 =
64.137
14.73
NB= 508.1 rpm
The steps above are recalculated as get a new speed of sprocket B which is 508.1 rpm.
V= r Ѡ
= r (60
2 Nπ)
V= (2
1008.5 2−x
)(60
)1.508(2π) = 1.35 m/s
Then, the forward speed of conveyor, V is 1.35 m/s
After detailed calculations, the table below summaries all the related dimension of
sprockets will be used in the roller conveyor system.
Table 3.4: The related data of sprocket in chain transmission system (Pitch 12.7 mm)
Sprocket Pitch diameter,
D( mm)
Number of teeth Revolution(rpm)
1 57.07 14 508.1
2 73.14 18 508.1
3 137.64 34 270
42
3.9 Laboratory testing
The machine was tested in the laboratory to identify its weakness and find any
improvement to correct its problems after its fabrication of machine. The aim of
laboratory testing is ensure the machine achieves the project objectives. However, there
is no field test was carried out due to technical problems. The laboratory testing
includes testing on chain transmission, visual inspections of machine and position of
blade after installation as well as measurement of mismatched gaps due to construction
errors. As a result, a field testing should be carried out after the problems have been
tackled first in next project.
43
CHAPTER 4
RESULTS AND DISCUSSION
The experimental unit of lemon grass harvester have been inspected after it
assembly. Since there are limited time constraint, initial laboratory testing can be done
up to this stage.
Result of laboratory inspection/testing as below:
1. The blades are screwed well in position after modification. However, there are
some alignments of supporting leg when it was screwed onto frame due to
clearance inside the cylinder. Although like this, the supporting leg able pulls
the blade beneath the ridge when mounted to tractor but also support the
gearbox when the harvester detached from three points hitch linkage. One point
to be emphasized here is there in no lemon grass planted in laboratory ridge and
the ridge is artificially soft.
2. The length of radder bar has been underestimated due to a gap distance of 5cm
because construction error in forming the angle of radder bars and extra height
of wheel. Some bridging metal of 2 x 2 cm have been welded on surface of
roller conveyors as to griping the root of clump from the end of radder bars.
Although there are about 3 cm of uncovered gap between radder bars and roller
conveyor, the bottom of cross section of clump is 60cm, which is larger than the
gap, should be pass onto conveyor with assistance of bridging metals. The
44
bridging metal of 2 x 2cm is a very thin metal of about thickness of 0.4cm and
its material is mild steel of 200GPa.
3. The slack of chain tension affects efficiency of the chain drive transmission
during the conveying mechanism, thus the forward speed of roller conveyed
have been reduced. A suggestion of installation of tensioner should be adopted
as to avoid the reduction of forward speed of conveyor. The proper adjustment
of the speed of tractor and the rods of all conveyors beyond the cutting blade
and its fingers are covered with rubber or plastic to reduce damage of crop and
efficiency of transmission system in the primary conveying operation.
( Kepner,R.A.,1972)
4. The third shaft of roller conveyor is too long where there is a one unsupported-
end cantilever of 25cm from bearing and a sprocket of pitch diameter 73.14mm
in its end. This design of third shaft of roller conveyor is unavoidable because
there is no modification being allowed on the length of transmission shaft of
gear box. The deflection of third shaft of the conveyor is visible.
5. The roller wheel is improperly selected to be installed in this experimental unit
of lemon grass harvester. The main reason for this error is insufficient
experience in selecting suitable wheel for agricultural uses. A agricultural tire of
proper size should be selected as to support the weight of machine and to reduce
pressure on surface of ground during operation especially in a soft or muddy
farm land.
6. Wrong selection of hollow square mild steel as part of frame which cause the
screwed area are dented by pressure of screw.
45
Figure 4.1: Front view of experimental unit of lemon grass harvester
Figure 4.2: Right-hand side view of experimental unit of lemon grass harvester
46
Figure 4.3: Left-hand side view of experimental unit of lemon grass harvester
Figure 4.4: Back view of experimental unit of lemon grass harvester
Figure 4.5 Top view of experimental unit of lemon grass harvester
47
Figure 4.6: Connection between the frame and supporting leg
Figure 4.7: Cutting blades and its radder bars
Figure 4.8: Chain transmission system
48
CHAPTER 5
CONCLUSIONS
This report includes two main phases: the planning of machine design and
hardware fabrication.
The first phase, the planning of machine design involves defining project scope
and brainstorming for preparing a new machine design of components of cutting and
lifting mechanism of a lemon grass harvester which its purpose serves for small scale
production. There are demonstrations of many basic mechanical principle and ideas in
designing the functionality of the machine which consists of three main parts: lifting
mechanism, root cutting mechanism, and chain power transmission. These three parts
are all written into a header file, so that the related theoretical calculations able to
display the logical technical information about the machine. The design of lifting
mechanism is most interesting, since there are many obstacles such as simultaneous
motion of soil breaking up and lifting mechanism as well as meeting the set up and hold
times. The interaction of several simple mechanical parts which are a pair of wide V
shape cutting blades, radder bars, and roller conveyor are making up the critical part of
the machine. The wide V-shape cutting blades break up the soil and accommodate the
lemon grass clump instantly while reducing the soil friction resistance. Since all the
components of the machine are in continuous motion, the clump will immediately be
conveyed to roller conveyor by inclined radder bars as a gap bridging.
49
The second phase, hardware fabrication involves implementing and revising the
plan. The project requires proper considerations of material cost and physical
construction of the work packages of the machine besides good coordination in
arranging the material, machines, tools, time, and manual labor. The processes, in
general, include geometry matching and joining of multiple parts to make an assembled
machine. The work packages are carried out as a sequence of operation, which are
accomplished by a combination of machines, tools, power, and manual labor.
In sum, the project objectives were completed and the weaknesses of this
experimental unit of lemon grass were identified as in chapter 4.
There are a number of future extensions that may be done on this project. They
are as follow:
A. Design of chain conveyor extension and its storage bin
B. Design a cover for chain drive transmission
C. Redesign a new stronger frame and suitable chain drive transmission system for
supporting roller conveyor and chain conveyor.
D. Select suitable agricultural tires and design its power transmission system.
E. Suggesting a new planting spacing of lemon grass for a better harvesting
performance.
50
REFERENCE
1. BIO Daun Plantation Sdn Bhd, (7 october 2008)
http://www.mfa.org.my/?franchise-news:bio-daun-offers-lemongrass-
franchise-opportunities:20K098F515,
2. Boon N.E.; Yahya A.; Kheiralla A.F.; Wee B.S.; Gew S.K. ( 2005)
A Tractor–mounted, Automated Soil Penetrometer-shearometer Unit for
Mapping Soil Mechanics Properties. Universiti Putra Malaysia.
3. Budynas, R. G.; Nisbett, J. K., (2008) Shigley’s Mechanical Engineering
Design , Eigth Edition, McGraw-Hill.
4. Dirt Hog’s Companion. Technical Note 21.Soil, Draft, and Traction. (5/3/2011)
www.soil.ncsu.edu/upen_furrow/Documents/DHK/soi,%20Draft,%20and%20Tr
action.pdf
5. Dunn, W.R., Nave, W.R and Butler,B.J. (1973)
Combine header component losses in soybean. Trans ASAE16(6): 1032-1035
6. Essential oil crops: production guidelines for lemon grass
http://www.daff.gov.za/docs/Brochures/EssOilsLemongrass.pdf
Department of Agriculture, Forestry and Fisheries, Republic of South Africa,
2009
7. Hafiz bin Hazir(2008). Conceptual Development of A Lemon Grass Harvester,
final year student project, Universiti Putra Malaysia.
51
8. Hassan bin Osman(1988). Pembangunan Jentuai Kacang Tanah, final year
student project, Universiti Putra Malaysia
9. Hj Sauadi bin Hj Hamid (30/10/10; 22:29)
http://jasabumiagrofarm.blogspot.com/2008_10_01_archive.html
10. Eagle national steel(2009)
http://www.eaglesteel.com/download/techdocs/Carbon_Steel_Grades.pdf
11. http://www.grandeermachine.com/search.html?g=398449 (3/3/2011)
12. http://www.topmachinebiz.com/product/484405/Harvester-Blade.htm
(3/3/2011)
13. Kepner, R.A.; Bainer R.; Barger E.L. (1972), Principles of Farm Machinery,
Second Edition, The Avi Publishing Company,Inc.
14. Marshek, K. M., (1987) ,Design of Machine and Structural Parts, John Wiley&
Sons, New York,.
15. Nave,W.R. and Hoag, D.L. 1975.
Relationship of sickle guard spacing and sickle frequency to soybean shatter loss.
Trans ASAE 18(4): 630-632,637
16. Profitable soybean harvesting, 1984
http://extension.agron.iastate.edu/soybean/documents/PM573.pdf
Cooperative extension service, Lowa State Univesity. ( 14/5/11)
52
17. Quick,G.R. (1973). Laboratory Analysis of the combine header. Trans ASAE
16(1): 5-12
18. Shigley, J. E.; Mischke, C. R., (2001)
Mechanical Engineering Design, Sixth Edition, McGraw-Hill.
19. WINDSOR agricultural implements and spare parts. (3/3/2011)
http://www.discplough.com/blades.html
24. Zam Abdul Karim , Malacca Biotechnology Corp (19 Aug 2010)
http://www.daganghalal.com/HalalNews/HalalNewsDtl.aspx?id=1554
(31/10/10; 2:11)
53
APPENDICES
Figure A.1: Sketch of the experimental unit of lemon grass harvester.