industrial development of an ox-drawn prototype …mate.tue.nl/mate/pdfs/11879.pdfmay 2010...

Industrial development of an ox-drawn prototype Conservation Farming planter

M.J. Naber BSc

May 2010

CST.2010.028

Industrial development of an ox‐drawn

prototype Conservation Farming planter

Master Traineeship

M.J. Naber BSc (0571509)

CST report number: CST.2010.028

Supervisors:

prof.dr.ir. M. Steinbuch (The Netherlands)

ir. P. Stevens (Zambia) Eindhoven, 17 May 2010

Industrial development of an ox‐drawn prototype Conservation Farming Planter 2

Table of contents Traineeship

1. Abstract page 3

2. Preface page 4

3. Personal motivation for traineeship in Africa page 5

4. Situation in Zambia page 6

5. Research institute GART page 8

6. The principles of Conservation Farming page 9

7. A Conservation Farming planter page 10

8. Creating a furrow and seed dropping page 12

9. Fertilizer and seed metering page 14

9.1 Fertilizer metering page 14

9.2 Seed metering page 18

10. Driving metering systems and soil cover page 24

11. Assembly page 26

11.1 Planter unit page 27

11.2 Handles page 29

11.3 Depthwheel page 30

11.4 Ripper page 31

11.5 Total design page 32

12. Extra design page 33

13. Non‐technical aspects page 36

14. Conclusions page 37

15. Recommendations page 38

16. References page 39

17. Appendices page 40


1. Abstract

A prototype planter is made by GART, because of the demand of small scale farmers for a CF ox‐drawn

planter. Its main tasks are ripping, placing seed and fertilizer and cover them with soil. This report

outlines the improvements on this prototype to make it more robust, cheaper, simpler, available locally

and let it comply with the demands of farmers. With a partially new manufactured prototype the

changes have had short tests and show that they are an improvement.

An extra design is added to the report, which even more reduces the amount of parts used and

improves its robustness. Manufacturing this design has to be more precise than the new design.


2. Preface

Small‐scale farmers in Zambia need solutions for all the work they have to do by hand. These have to be

simple machines to keep costs low. Although a simple machine cannot create large steps forward, they

are a small step in changing the poor economic situation in Zambia. With 64 percent of its population

below the poverty line things have to change.

A planter which suits the Conservation Farming principles, an agricultural method, and suits the

demands of the farmer is not yet available. The planter should rip, place seed and fertilizer and cover

them with soil. To stimulate these principles and to give farmers a higher productivity the Golden Valley

Agricultural Research Trust made a prototype ox‐drawn planter. Its test results and the reaction of

farmers were positive. Still the prototype needs a lot of improvements to the design and it is necessary

that industry gets involved.

With a traineeship is attempted to contribute to the development by creating a new design. This report

will outline the changes in the design of the first prototype planter. This is done per task by first

explaining the prototype, the requirements and the problems and secondly showing the solutions via

new designs and prototypes. Next to this an extra design is mentioned on which larger changes have

been applied.

But before the technical details are discussed, the importance of developments in Zambia is explained in

chapters about Zambia, Golden Valley Agricultural Research Trust, Conservation Farming and a personal

motivation.


3. Personal motivation for traineeship in Africa

The department Mechanical engineering of the Technical University of Eindhoven stimulates students to

go abroad during their masters’ traineeship [1]. Normally the faculty uses its vast variety of contacts

with industry and universities around the world.

A traineeship can give a student insight in a working environment and the profession as a mechanical

engineer. By going abroad it is possible to be more challenged than in the safe environment of Holland.

A traineeship in a third world country is not a usual choice. And it is more difficult to arrange because of

the limited amount of contacts the faculty has in these regions.

The choice for a third world country was the result of a personal desire to contribute to a community

which is in more need than western countries. In more wealthy environments an institute or a company

has the ability to gather manpower or knowledge by the use of money. In the more poor conditions this

isn’t possible and a “free” student is an ideal solution.

Major parts of Africa are struggling with their development and are faced with a lot of poverty. This lack

of money limits technical developments and most of the time only small adjustments can be made to

the current situation. The major industry is farming and inhere there is a large potential for growth.

Were this potential lies will be outlined in the next chapter. This potential can give a student an easy

place to start a traineeship and can help the environment a lot.

With this starting point in mind an assignment is found at GART (Golden Valley Agricultural Research

Trust) via the contacts of the University of Wageningen. Chapter 5 will give more insight in this

organization and its goals.


4. Situation in Zambia

The country Zambia lies in southern Africa and is landlocked between Angola, Congo, Malawi,

Mozambique, Namibia, Tanzania and Zimbabwe. With around 12,6 million inhabitant and surface of

about 750 km2 it does not have a dense population. Figure 4.1 shows a map of the country with its

surrounding countries.

Fig 4.1: Map of Zambia with surrounding countries

Zambia was a colony of Great Britain till 1964 and was considered as a middle income country at the

moment of separation. Wealth was mainly provided by the copper mines in Copperbelt region. After the

United States and Russia it was the largest supplier of copper at that moment. Because of the collapse of

the copper prizes in 1975 and a failing government the country came in decline and is now considered

as one of the poorest countries of Africa [2].

Since 1991 the country has had five multiparty elections and it has at this moment a stable political

situation. Because of this the Dutch Ministry of Foreign Affairs gives Zambia the lowest possible risk

factor for traveling in this country. [3].

With the use of foreign aid (2004/2005) Zambia is finally fulfilling its economical potential. The aid

mainly focuses on limited incomes from other resources than copper (e.g. agricultural), corruption,

infrastructure and HIV/AIDS. The necessity of this focus can be seen when a closer look is taken at the

figures of Zambia’s population. The average life expectance of a born child is 38 years and this is the

second lowest of the world. Of the 12.6 million citizens, 1 million have HIV/AIDS and this courses

around 60 thousand deaths every year. On top of this comes the fact that 64 percent of the population

is living below the poverty line and 51 percent is considered in extreme poverty [2].


Of the working class 85 percent is active in agriculture, but they provide a relative small contribution to

the gross domestic product, 19 percent. Poverty is a dominant factor in this sector and causes that most

of the yield is used for own consumption instead of trade [4]. Institutions are founded with foreign aid,

to improve the situation and thereby gain more profit from the work force and the available land (58

percent of the countries surface). One of these is GART (Golden Valley Agricultural Research Trust) and

according to the World Bank this is “currently one of the prominent agricultural research trusts in

Zambia”. The following chapter focuses on the goals and programs of GART [5].

With the described aid and improvements in education and communication the population is gaining

opportunities to improve their own situation and the government. Independent newspapers like “The

Post” play a dominant role, but it will take long before significant changes are achieved.


5. Research institute GART

The Golden Valley Agricultural Research Trust (GART) is self‐sustaining and autonomous Public Private Partnership Initiative which is created in 1993 by the Government of the Republic of Zambia in partnership with the Zambia National Farmers Union. GARTs main focus is to contribute to the optimization of the production, commerce and trade of crops, milk, chicken and goats for small‐, medium‐ and large‐scale farmers. In this focus there are two core programs:

1. Research and development in Conservation Farming (CF). 2. Research and Development of Smallholder Livestock Systems

In the CF program, which is explained in the next chapter, is a demand for proper CF equipment. GART has a research station in Magoye for the development and testing of these. Here it has the availability of a simple workshop and test plots. Farmers slowly adopt new methods in farming with training, developed equipment, fielddays and on‐farm testing. Thereby contributing in the struggle against poverty, hunger and helping the national economy [6].


6. The principles of Conservation Farming

Conservation Farming (CF) aims to create sustainable use of the soil to produce stable yields, hereby

reducing costs and labor. History can tell that intense use of land can lead to erosion of the soil,

degradation and decline in soil fertility through loss of organic matter and soil structure [7]. To prevent

this, CF tries to create sustainable use by mimicking natural processes in the soil to restore the natural

aggregated soil structure and improve the organic matter content. This is done in three steps: soil cover,

minimal disturbance and crop rotation.

Soil cover is a layer of natural residues. This layer is created during harvest by not removing the

leftovers. The cover stimulates natural processes in the soil and increases the organic matter content

sustainably.

Minimal disturbance aims to reduce the amount of human intervention. Mechanical tillage can disturb

the natural processes and CF reduces this for example with zero‐tillage systems.

With crop rotation the activities in the soil are constantly changing. This suppresses the growth of non‐

beneficial substance like diseases.

The techniques CF uses are zero‐tillage systems, fertilizers, water management, herbicides, etc.

These techniques are all linked together. This can be seen in the example of water management during

planting. When the soil is tilled to get the seeds in the ground this disturbance tends to mix the drier

surface layers into the seed zone. Next to this the disruption will decrease the bulk density of the

seedbed. The thereby created larger surface will result in high evaporative losses [8]. A planter which

has less tillage will reduce these effects and increase the harvest.


7. A Conservation Farming planter

The previous chapter explained the basic principles of CF. A farmer needs proper equipment to use

these in practice. For planting and spreading fertilizer correct equipment is not available for small‐scale

farmers. Conventional equipment disturbs the soil too much.

The method for planting, done by small scale farmers, is currently creating a furrow with a hand plow or

oxen‐driven plow and on another moment, when weather conditions are good, planting by hand.

Farmers are currently more and more using rippers instead of plows, because of CF. One of these is the

Magoye ripper (figure 7.1) These rippers disturb the soil less, but still a farmer needs to plant by hand.

He can only plant with the right weather conditions and the same applies for plowing. Therefore he

needs to wait twice for proper weather and in the intermediate period the soil condition decreases. This

causes a low productivity of land and labor.

Figure 7.1: Magoye ripper

To solve this, a combination of a planter and a ripper is required. It should be ox driven to decrease

human labour, thereby using the available recourses a typical small scale farmer has.

Keeping the design of the planter as simple and as functionally possible ensures that;

It can available locally if it can be manufactured in a simple workshop with off‐the‐shelf

materials.

The manufacturing costs are kept to a minimum to attract interest from manufacturers.

It is robust, reliable, easy to maintain and easy to use.

The required tasks the planter has to execute are;

Ripping the soil to create a furrow.

Placing the seed and fertilizer at the required intermediate distance or density.

Cover the seeds with soil.


In line with these requirements a prototype is made by GART in 2007. This was done in a rudimentary

workshop using parts of old farming machinery. In several tests was shown that the accuracy of planting

came close to that of planting by hand. On top of that was the positive reaction of the test group

farmers. For adaptation by a large group of non‐schooled farmers this is critical. Via mouth‐to‐mouth

advertising the prototype planter was borrowed by neighboring farmers without urge of GART. [9]

Next to all the positive results the tests also show multiple points for improvements to the design.

Several parts and the overall configuration have problems and they limit better results. Next to the

problems it is necessary that dimensions become standard instead of coincidences.

Per task the following chapters will discuss the corresponding parts. Each chapter will describe first the

current prototype, the requirements and the problems, secondly the suggested improvements are

discussed and at the end, if possible, a reflection of the results of the new prototype.


8. Creating a furrow and seed dropping

To create a seedbed for placing seeds and fertilizer a ripper opens a furrow. Figure 8.1 shows a photo

and two views of the current ripper.

Figure 8.1: Photo and views of ripper

The tine opens the seedbed. It is connected to the foot via a pin which slides into a cylinder; friction will keep it in place. During planting this part will wear and to reduce the number of replacements it is made out of quenched and heat treated iron. The wings are used for expansion of the seedbed. They are attached to the foot with a bolt. To keep a

wing in place it is clamed between the tine and an extension on the foot.

The seed and fertilizer are dropped via tubes. First the fertilizer and secondly the seed. They are placed

in the furrow created by the tine.

The ripper is a well‐tried part which is common in similar configurations of other machines. Because of

the simple attachment of the tine it requires a small amount of operations during manufacturing.

Because of these advantages the configuration of the wings and tine are kept the same. In the new

design the main focus is on the angle of the tine relative to the soil.


A correct choice of the angle will convert the pulling force of the oxen in a correct balance between the

vertical and horizontal forces. The vertical force will keep the tine into the soil and the horizontal force is

used to spilt the soil. The angle depends on multiple factors like soil condition and type of furrow; it has

been thoroughly examined in the past.

To reduce material costs the dimensions are altered. The tine is shorter, 7 cm, and the wings have got

standard measurements.

Currently the seeds and fertilizer are dropped after each other. In here is the possibility that the

fertilizer comes in direct contact with the seed. Via this contact the fertilizer can kill a germinating seed.

To reduce this risk the placing of the tubes is altered. Instead of ending in steel pipes the tubes are

clamped in the wings, one on the left and one on the right. The seed or fertilizer will drop into the gap

created by the wing. This can be seen in figure 8.2.

Figure 8.2: Seed and fertilizer placed next to each other

The tubes are mainly placed behind the foot to reduce friction forces; they only spread close to the

wings. The angle of the wings will ensure that the end of the tubes face backwards and thereby will not

scoop up soil. (figure 8.3)

Figure 8.3: New ripper with separately the tine, foot and wings


9. Fertilizer and Seed metering

To get the seeds and fertilizer into the tubes which end at the ripper, two rotating mechanisms are used.

The mechanisms are not similar because of differences in demands. Therefore this chapter contains a

paragraph about the fertilizer metering mechanism and a second about the seed metering mechanism.

9.1 Fertilizer metering

Fertilizer, figure 9.1.1, does not have to be handled grain by grain, but the target is to spread a certain

amount evenly across the land. Fertilizer is not cheap and therefore control over the amount which is

spread is important. 200 L/ha is a standard which most farmers use.

The second demand is to use plastics. Metals corrode when they get in contact with fertilizer. Other

types of materials will be too expensive or are not easy available.

The current design was, instead of what the second demand would suggest, made out of steel. The main

reason for this was the lack of ideas for a simple solution.

Figure 9.1.1: Fertilizer


The current design, figures 9.1.2 and 9.1.3, has a basket which contains the fertilizer. The bottom of the

basket has an opening with a sliding cover. A disk, which meters the fertile, is placed in the opening and

the rest of the opening is closed by the cover. By changing the position of the cover and replacing the

disk with another one, a farmer can change the amount of fertilizer dropped into the seedbed.

Figure 9.1.2 Side and front view of current fertilizer meteringmechanism

Figure 9.1.3: Photos of fertilizer meteringmechanism

The used metering disk is taken out of another planter. Via rotation the disk picks up fertilizer with its

cups and drops it into the tube. With another disk, and thereby changing the opening on the bottom of

the basket, a different amount of fertilizer can be spread over the land.

The new design requires some changes to be able to make the metering mechanism out of plastic.

Herein the design is mainly limited by the available materials. There is hardly any plastic industry in

Zambia and production is mainly done in the capital, Lusaka.

An extra demand is not to use extra parts. The current prototype requires different disks for changing

the amount of fertilizer which is spread. These extra parts will get lost and limit the flexibility of a farmer

to change his setting.


The new design which complies to the demands is show in figure 9.1.4.

Figure 9.1.4: New fertilizer metering, partially open

The metering disk, figure 9.1.5, will rotate and thereby the cups will transport the fertilizer from the

inlet of the casing, figure 9.1.6, to the outlet. The size of the opening of the inlet can be changed via

rotation of the volume setter, figure 9.1.7. An external hopper is used to carry all the fertilizer and it is

connected via a tube to the inlet.

It can be seen that the new design consists mainly out of tubes and flat plates. These are plastic sewer

pipes and plastic plates which can easily be found. The volume setter, and the casing are a sewer pipe

inside a fitting and they create a tight coupling. The pipe of the volume setter is cut under an angle to be

able to control the size of the opening. The metering disk can be made from a solid rod where material

is taken off to create cups.

Figure 9.1.5: Metering disk Figure 9.1.6. Casing Figure 9.1.7: Volume setter


With the whole volume of the metering cups the mechanism can spread around 250 L/ha. This is well

over the standard 200 L/ha, but it gives a farmer the ability to adept to the condition of his land.

Between the outer radius of the metering disk and the inside radius of the volume setter is a spacing,

figure 9.1.8. This is made after tests with the new prototype, figure 9.1.9. The fertilizer grains will get

stuck between the cups and volume setter if the spacing is too small, thereby blocking the rotation of

the disk. Crushing of the fertilizer with a large force is the only method to keep the mechanism rotating.

The theoretical open connection between the inlet and outlet showed in practice no problem. With a

not to large gap and a standstill of the metering disk the fertile will be kept inside.

Figure 9.1.8: Gap between disk and setter

Figure 9.1.9: Photos of new prototype

The steel side covers and the aluminium metering disk used in the new prototype will eventually be

made out of plastic, but for convenience this isn’t done in the prototype.

Spacing


9.2 Seed metering

With the placing of seeds, figure 9.2.1, it is important that the spacing between the seeds is correct and

constant. The difference in growth between correct spacing and bad spacing can be seen in figure 9.2.2.

Plants that are too close to each other will grow less and large gaps will let too much land unused.

Next to this it is important for a metering system to handle the seeds not too brutal. A broken seed has a

negative effect on its germination.

Figure 9.2.1: Mais seed

Figure 9.2.2: First Photo shows bad spacing the second is correct spacing

The metering system of seeds also has to be compatible for multiple types of seeds. Maize seed is

mostly used in Zambia, but herein are also differences in types


The current design uses a vertical disk with extending cups, figure 9.2.3. Via rotation of the disk it will

pick a seed out of the hopper. The cup has an opening on the backside of the disk and the seed will drop

though this opening when it passes a slot in the casing the hopper. This system is intuitive and allows

everyone to understand what is happening. A second advantage is the limited amount of parts.

Figure 9.2.3: Current prototype

The design also has a couple of disadvantages

1. The disk is connected to the driveshaft via a small tube and a pin. To work properly it is

important that the disk is placed tight against the hopper. Misplacement of the holes for the pin

or a not perfect right‐angled tube will translate or skew the disk relative to the hopper.

Therefore disks will fit only one the planter, the one which they are made for.

2. On multiple places seeds get between the disk and the hopper. Thereby crushing the seed.

3. The disk came from another planter and is handmade, figure 9.2.4. A small piece of tube is

welded onto a flat disk. The size and the angle of the tube are important and are currently

guessed. Manufacturing this disk will require much labor and precision, and a lot of tests have to

be done to be sure which type of cup is correct. All of this makes one disk expensive.

Figure 9.2.4: Cup on disk


4. A limited amount of seed can be carried, because of the disk placement inside the hopper. The

disk has to be able to pick seeds, but when the seeds drop through the opening at the back the

cups shouldn’t be able to directly pick up another one and also drop this. Therefore the seeds

have to be higher than the lowest point of the disk and lower the opening at the back.

To solve these issues and to keep costs as low as possible the remaining of this paragraph shows for

each problem a solution. In the new design the basis principle of a vertical disk is kept, because a change

in direction would require expensive parts, like gears. Chapter 12 shows a more drastically changed

design, where the vertical disk is skipped.

To align the disk tight and parallel to the hopper the attachment to the driveshaft is spitted into two

parts. One for driving the rotation and one for the aligning. The result is shown in figure 9.2.5.

Figure 9.2.5: Rotating and pressing seed disk

Driving the disk is done by the left pin which slide freely into the slot of the disk. A spring will press the

plate onto the back of the hopper and aligns it. The other side of the spring is kept in place by the right

pin. Over the driving pin slides an attachment with a slot which ensures that the spring will press the

disk instead of the driving pin. Because of the combination of a slot and a spring the plate can have

another thickness and welding does not have to be done.


The second problem, the crushing of seeds, is hereby partially solved, but also two other things are

changed. First the hopper gets another design, less angles, and it becomes a separate unit, figure 9.2.6.

Secondly the rotation speed is halved. De driving mechanism which is discussed in chapter 10 has got a

2:1 ratio. The lower speed will reduce the friction on the seeds.

Figure 9.2.6: Seed disk in box, with and without hopper

A design without cups, third problem, was not found in techniques used by western farmers. Their

systems have a high accuracy but are also expensive and require good maintenance, making them

useless for small‐scale farmers, Figure 9.2.7.

Figure 9.2.7: Meteringmechanism of a modern western planter


Therefore the idea of cups is simplified into a disk with angled holes, figure 9.2.8. Drilling holes is much

easier than welding a small piece of tube with the right angle. The correct dimensions of the holes can

be determined with less effort. The angle of the holes is in line with the principle of scoping up a seed

and dropping it at the back.

Figure 9.2.8: Disk with angled holes

A piece of foam is pressed to the disk, figure 9.2.9. When a hole picks two seeds instead of one. The

second will stick out of the hole and the foam will push it back into the hopper. Secondly the foam

presses onto the seed inside the hole when it slides over the hole in the hopper, thereby providing an

extra stimulus to drop into the tube.

Figure 9.2.9: Foam pressed on disk; and foam after test

The foam also provides a solution to the fourth problem. A test shows however, that because of the

friction, the foam wears to quick and setting the right compression of the foam requires a high accuracy.

A test without foam shows that the meteringmechanism works fine, but it still requires a solution for the

fourth problem.


The problem is solved by shrinking the size of the opening of the separate hopper. The hopper which is

shown in the left half of figure 9.2.6 has only a small vertical opening. This opening connects the seeds in

the hopper with the lower part of the disk. Because of a small thickness of the box, in which the disk is

placed, seeds will not get as high as the hole at the back because of friction (see figure 9.2.10).

Figure 9.2.10: Opening in hopper

A simple tests with the new prototype confirmed that the new design works. Because of lack of time

extensive tests could not be performed. These have to be done to determine the exact dimensions for

the angled holes. It can easily be seen in the short test that the solutions for the other problems work.

Appendix 16.1 shows a number of pictures of the manufactured prototype.

Opening from

hopper to the box

carrying the disk

Opening at the back

Thickness box


10. Driving metering systems and soil cover

To drive the two metering disks a wheel is used. This wheel is connected via a chain to the disks and can

move freely up and down. This is necessary; otherwise it will disturb the height of the ripper. Slippage of

the wheel has to be as low as possible, because it affects the spacing of the seeds.

The current follow wheels are shown in figure 10.1. Between the two wheels the sprocket for the chain

is placed. The sprocket is welded to a tube which can rotate freely over a rod. The wheels are bolted to

the tube to pass on the rotation. The chain is tensioned by sliding the rod up and down a slot.

Two bended flatbars provide the suspension.

Figure 10.1: Current follow wheel

This system has two main problems. The first problem is crop residue getting stuck, figure 10.2. Crop

residues are leftover from the previous harvest. Farther away from the furrow increases the change of

crop residue getting stuck. In the used configuration protection of chain is hard to provide. Next to

getting stuck, crop residue also causes the wheels to slip.

Figure 10.2: Crop residue blocking the chain


The second problem is wear of the suspension. Because of the roughness of the terrain the two wheels

will move up and down independently of each other, thereby they will rotate the suspension bars. These

bars will wear at their connection points and also the driveshaft of the metering disks will wear, because

it is close to the connection points (see next chapter).

These problems can be solved by replacing the two wheels by one, figure 10.3. This wheel will be placed

directly in the furrow. In here the sand is loose and there is less crop residue. The pins on the wheel can

penetrate the loose soil easily and slip will be reduced. The sprocket is placed on the outside of one of

the suspension bars. This bar can directly be used to create a cover for the sprocket to protect it.

The seeds and fertilizer are dropped just next to the furrow, chapter 8. The wheel with its pins will close

the opening created by the tine and by its weight the wheel will compress the soil a bit, thereby

improving germination.

Figure 10.3: New design with one follow wheel

The rotation of the wheel is passed on to the sprocket through a rod which can freely rotate inside two

tubes. These tubes are connected via bolts to the suspension bars and provide the tensioning of the

chain, see figure 10.4.

Figure 10.4 Tubes with bolts provide the tensioning of chain


11. Assembly

In the previous three chapters the main components of the planter were described. Next to these there

are a couple of other components. All the components are coupled to a main beam, further mentioned

as the planterbeam (picture 11.1).

Figure 11.1: Planterbeam

The planterbeam is composed out of two coupled C beams. Between the beams the components can be

placed via bolts and nuts of by welds. These components are:

‐ Planter unit;

‐ Handles;

‐ Depthwheel;

‐ Ripper.

In the following paragraphs the components are described.


11.1 Planter unit

The following parts have to be connected to create one part which is the called the planter unit. This

unit is as a whole connected to the planterbeam.

‐ Driveshaft

‐ Suspension follow wheel

‐ Sprocket

‐ Fertilizer meteringmechanism

‐ Seed meteringmechanism

In this unit it is important that the driveshaft is disturbed as little as possible. Secondly it is required that

replacing parts (or the whole planter unit) should be easy. The third requirement is that the placing of

the unit is as close as possible to ripper to shorten the traveling distance of seeds.

The current prototype, figure 11.1.1, has two pins connected to the planter beam. Each pin has a ring

through which the driveshaft rotates. The driveshaft creates an indirect coupling of the two pins. A

meteringmechanism and a suspension bar for the follow wheel are also mounted on each ring.

The two hoppers are connected to each other via connections bars to create extra firmness.

Figure 11.1.1: Current prototype planterunit


It can be seen from figure 11.1.1 that the parts are not aligned. The pins can move because of play and

this skews the driveshaft. This will also skew the meteringdisks and they will wear rapidly. The

suspension bars can slide easily of their ring, thereby dropping the tension on the chain and creating

extra delay during planting. Robustness against drops and bumps of the planter is low.

In the new design, figure 11.1.2 the parts are connected via a rigid box, planterbox. Via four bolts the

box is connected with the planterbeam. The box is hanged underneath the planterbeam to reduce the

distance to the ripper. The hopper of the fertilizer is placed on top of the planterbeam to reduce forces

on the panterbox.

The new place of the sprocket in the follow wheel requires a different place of one of the metering

mechanisms. The fertizer meteringmechanism, cyan colored, is placed inside the box. Because of the

width of the mechanism, the suspensionbars will not slide of their carrying ring. The seed metering is

done on the right side of the box, green colored.

Figure 11.1.2: New design planterunit


The carrying rings for the suspension bars have a larger inner diameter than the diameter of the

driveshaft. This ensures that any forces form the follow wheel goes to the planterbox instead of going

the driveshaft. See figure 11.1.3.

Figure 11.1.3: Carrying of suspension bars

On the inside of this ring a bearing can be placed. But these come with a prize and a precise placing of

two small tubes is probably good enough. A photo of the new prototype can be found in appendix 16.2.

11.2 Handles

The handles of current prototype and the new design are almost the same and are shown in figure

11.2.1. The handles are made with a bended flatbar. In the current design they are welded too the

planterbeam, but to remove them more easily the new design uses bolts. This attachment uses the

same holes as the ripperbeam, see paragraph 11.4. To have grip during work the handgrips are made

with a flattened tube with holes.

Figure 11.2.1: Handles current prototype and new design

Carrying ring


11.3 Depthwheel

The depthwheel is used to control the height of the ripper. The original prototype and new design are

shown in figure 11.3.1. Because it does not have any other function is kept as simple as possible.

Figure 11.3.1 Depthwheel

On the planterbeam a small block is welded next to which the heightbar of the depthwheel can slide.

This block prevents the depthwheel from rotating. On block the yoke is welded. This is the attachment

point for the chain to the oxen. The attachment height can be changed depending on the length of the

chain and the height of the oxen.

On the other end of the heightbar a wheel is attached. This is done via a fixed rod and an intermediate

tube. The wheel can rotate freely over the intermediate tube. This protects the wheel from getting

clamped when a farmer tightens the bolt to hard. See figure 11.3.2.

Although planting is done relatively close to the soil surface, the depthwheel can control heights up to

30 cm. This is done, because without the planter unit the remaining can be used as a ripper. Herein

deeper heights are sometimes required.

Figure 11.3.2: Wheel with intermediate tube

Welded block

Yoke

Intermediate tube

Heightbar


11.4 Ripper

The functional part of the ripper is described in chapter 8. The attachment of the ripper needs to be

strong since the forces at the tine create a moment via the ripperbeam to the bolts. On the prototype

shown in figure 11.4.1 a pull rod can be attached to decrease the forces on the bolts. Since in the shown

configuration the forces aren’t too high and an extra pull rod will create other problems the new design

is kept the same. Especially from an aesthetic point of view the bulky appearing is not an option.

Figure 11.4.1: Current prototype and sketch of connection via friction blocks

The attachment to the planter beam is changed to reduce the number of large holes. Instead of two

friction blocks on each side of the ripperbeam, one block is welded to the ripperbeam. This is shown in

figure 11.4.2

Figure 11.4.2: New connection ripperbeam


11.5 Total design

Figure 11.5.1 shows the total assembly of the new design

Figure 11.5.1: Total assembly


12. Extra design

The combination of a follow wheel with suspension, a chain and a hanging planterbox does not fully

comply with the demand to use as less parts as possible. The shifting of the rotation can be skipped if

the metering mechanisms are directly coupled to the follow wheel. This also shortens the traveling

distance of seed to the furrow [10].

A combination of the seed meteringmechanism of seed and the follow wheel is shown in figure 12.1.

Figure 12.1: Overview extra design

The mechanism works with a rotating wheel, figure 12.2 and a stationary cover, figure 12.3. The wheel

has an extra cylinder with holes, the metering ring. These holes can pick up a seed. The cylinder rotates

inside another cylinder which is part of the stationary cover. This cover has 2 holes, one on the side for

the inlet of seed and one on the cylinder for the outlet of seed.

Figure 12.2 Wheel with metering ring Figure 12.3: Stationary cover

The rotation of the metering ring will cause the holes to pass the outlet hole in the cover. At that

moment the seed can drop into the outlet tube. The hole in the cover is significantly larger than the

holes in the metering ring. This ensures that a seed gets enough chance to drop, instead of being

crushed.

Inlet

Outlet

Metering ring


A separator, figure 12.4, is used to prevent multiple seeds being dropped at the same moment. The

separator covers a small region inside the metering ring. A seed inside a hole can pass the separator but

others will be kept outside. A rubber strip is used to prevent crushing. The rubber strip can be made out

of an old inner tube of a car.

Figure 12.4 Separator

The rubber is placed a little bit further than the bottom of the metering ring. At the lowest point of the

metering ring the holes will move almost horizontally. This allows the holes to be similar to the more

used holes of some western metering systems. These systems have a horizontal placed disk with straight

holes. Implementation of the right dimensions for the holes can be done without extensive testing.

Figure 12.5: Open assembly

The wheel is placed close to the ripper and has a rigid connection to the planterbeam. This will ensure

that the pins will penetrate the loose soil and the close arrangement to the ripper will prevent

disturbances in the height of ripping.

This design has some other advantages:

‐ Tight placing of the cover will protect the system from sand.

‐ Only the wheel has to be changed for a different type of seed.

‐ The metering system for the fertilizer (chapter 9.1)can be placed on the other side of the wheel

‐ The hoppers for the seed and fertilizer can be placed on top of the planterbeam and are connected

with tubes

Rubber strip


Pictures of the manufactured prototype can be found in appendix 16.3. Figure 12.6 shows how the total

assembly would look like.

Because of lack of time the system could not be tested extensively. A short test showed that the

mechanism works, but lacks precision. The cover was not made with enough care and fitted therefore

not precise enough onto the metering ring. Welds on the inside of the metering ring caused problems

with the separator. The rubber was sometimes not able to close the gap enough. These two problems

caused multiple seeds to pass and drop too easily and some got stuck. Improvements on the

manufacturing of the prototype will solve these problems.

Figure 12.6: Fixed wheel connected via tubes with hoppers


13. Non‐technical aspects

A number of aspects of the traineeship are discussed in this report but some non‐technical not. These

are relevant for the work done in Zambia and are therefore mentioned in this chapter.

Interest of manufactures and their capabilities.

One of the largest challenges is the step from a design to a manufactured product. To contribute to this

step a local manufacturer is contacted. Saro is one of the larger companies in Zambia and they primarily

trade in agricultural machines. These are mainly imported products, but to reduce costs some are made

in Zambia. Saro has a relative good workshop with skilled staff.

A presentation and conversation aroused their interest and led to an agreement of making a prototype

in their workshop. The focus in the conversation was on design aspects and possibilities of making

everything in Zambia. No problems were found. This combined work on a prototype by a company and

GART will hopefully result in a planter available in shops.

Availability of materials.

Manufacturing a planter is not the whole story. It is also necessary that parts are easily available and

reparations do not require difficult procedures. To determine the availability without a thorough market

research the parts for the new prototype were bought in the local shops.

This resulted in small changes in the design, but eventually all was found quite easily. Steel is available

everywhere as long as the dimensions are not too extreme. Plastic tubing and plates are also available

but can only be processed with rudimentary methods. More is possible in the capital but this is too far

for a remote farmer.

Design drawings in Autocad

Most of the drawings are made with AutoCAD 2009. Normally other programs are used to make

technical drawings, but these were not available. To allow the drawings to be processed further it was

necessary to use Autocad and to learn how to use the program.

To stimulate the use of the drawings and Autocad, explanation in the use of Autocad was done multiple

times.


14. Conclusions

The mentioned designs comply with the required tasks. The soil is ripped; seeds are dropped at a

constant rate; fertilizer is spread evenly across the land and the follow wheel drives the disks and closes

the furrow.

Both the new and extra design can be made with materials available in Zambia. A remote farmer with a

simple workshop has the equipment to perform reparation.

The number of parts has increased in the new design, but the need for precise manufacturing is lowered

at a couple of critical points, seed metering disk and planterunit. The fertilizer metering mechanism can

be made with plastic and a farmer can set his own quantity per hectare without extra parts. The

accuracy of seed picking and dropping increased, although dimensions of holes still have to be tested

thoroughly. These benefits weigh so much that they compensate the extra parts and make the new

design an improvement. The found manufacturer agreed on making a full prototype in their workshop.

The extra design drastically decreased the number of parts. The downside is that production of the

seedmetering mechanism requires a higher accuracy. This is for a manufacturer with proper equipment

not a problem, but a simple workshop needs extra time for precise reparations. With proper tests the

feasibility of this design can be determined.

The new design has increased the ease of use. Soil cover disturbs less the follow wheel and the amount

of slippage is reduced; Tension on the chain is easier kept and its protection against wear is increased;

the fertilizer distribution can be set without extra parts and More seed can be carried during planting.

The improvements in the ease of use of the extra design are similar at most points. By placing the wheel

closer to the ripper even less soil cover can disturb the wheel. The removal of the chain also removes

some problems.

The new design is more resistant for crashes and drops, because of the arrangement in combination

with the planterbox. This will increase the lifespan of the planter and decreases the amount of

reparations. The extra design is even more robust because of the fixed wheel.


15. Recommendations

Parts have been made for the new design but for proper testing it is required to have a full new

prototype planter. Because of the collaboration with Saro this can be done at their workshop and for

further steps it is important to keep them involved during tests.

The new fertilizer meteringmechanism needs to be calibrated. This is preferably done when the planter

is stationary and the wheel is turned by hand. The amount of fertilizer dropper per rotation can be used

to determining how much per hectare is dropped. By doing this at the different settings the figures can

be indicated on the side.

For the seed meteringmechanism it is required to do tests with multiple types of disks to determine the

best dimensions for the angled holes. First this has to be done stationary and secondly in the field to

tests the effects of a rough terrain.

The extra design has to be manufactured more precise and has to be compared with the results of the

new design. At equal accuracy this design is more preferred because of reduction of the amount of

parts.


References

[1] Tue, “Master in buitenland”,http://w3.tue.nl/nl/diensten/cec/studievoorlichting/

masteropleidingen/mechanical_engineering/studieopbouw/#c128679, seen on 13‐04‐2010,

in Dutch.

[2] CIA, “World factbook”, https://www.cia.gov/library/publications/the‐world‐

factbook/geos/za.html, seen on 13‐04‐2010.

[3] Dutch Ministry of Foreign Affairs, “Reizen en landen, Zambia”, http://www.minbuza.nl/nl/

Reizen_en_Landen/Landenoverzicht/Z/Zambia , seen on 13‐04‐2010, in Dutch.

[4] IFAD (UN), “Rural Poverty Portal”, http://www.ruralpovertyportal.org/web/guest/

country/home/tags/zambia, seen on 13‐04‐2010.

[5] World Bank, “Zambia, Country Brief”, http://web.worldbank.org/WBSITE/EXTERNAL/

COUNTRIES/AFRICAEXT/ZAMBIAEXTN/0,,menuPK:375684~pagePK:141132~piPK:141107~theSite

PK:375589,00.html, seen on 13‐04‐2010.

[6] Golden Valley Agricultural Research Trust, “Profile” report, www.gartzambia.org , Lusaka 2008 [7] L.R. Brown, “Introduction” for “No‐till farming systems”, edited by: T. Goddard, M. A. Zoebisch, Y. Gan, W. Ellis, A. Watson and S. Sombatpanit, published by “The world Association of Soil and Water Conservation”, 2008. [8] J. R. Murray, J. N. Tullberg and B. B. Basnet, “Planters and their Components”, The University of Queensland, Canberra, 2006. [9] A. Chomba and P. Stevens, “Development and Testing of the New Concervation Farming

Planter”, GART Yearbook, 2008

[10] Digital communication with dr.ir. P.C.J.N. Rosielle, TU/e, 04‐03‐2010.


16. Appendices

16.1 Seed metering

Figure 16.1.1: Spring and pin combination

Figure 16.1.2: Disk with cups (can be changed by a disk with holes) pressed against the back of the box with the

spring.


Figure 16.1.3: Small box for seed disk, hole at the back is shown

Figure 16.1.4: Disk with angled holes and slot for pin


16.2 Planter unit

Figure 16.2.1: Driveshaft in planter box, seed metering mechanism is welded to the box. Pipe will be connected to

the inlet of fertilizer mechanism


16.3 Extra design

Figure 16.3.1: Cover with separator

Figure 16.3.2: Metering ring without wheel inside cover, showing a hole of the ring passing the hole in the

cover.

industrial development of an ox-drawn prototype …mate.tue.nl/mate/pdfs/11879.pdfmay 2010...

Documents