HAND IN HAND report

DESIGN AND FABRICATION OF A
MECHANICAL WINDROW TURNER
A PROJECT REPORT
Submitted in partial fulfillment of the
Requirement for the award of the
Degree of
BACHELOR OF TECHNOLOGY
In
MECHANICAL ENGINEERING
By
GAUTAM MERWAN BALAGOPALA
10BME1045
S. SUROTHAM
10BME1086
THULASIRAM REDDY P.
10BME1106
VARUN MOORTHY
10BME1110
Under the Guidance of
Prof. C.P. Karthikeyan
SCHOOL OF MECHANICAL AND BUILDING SCIENCES
VIT University CHENNAI
(Tamil Nadu) 600127
(MAY 2014)

SCHOOL OF MECHANICAL AND BUILDING SCIENCES
CERTIFICATE
This is to certify that the project work titled “Design And Fabrication Of
A Mechanical Windrow Turner” that is being submitted by “Gautam
Merwan Balagopala (10BME1045), S. Surotham (10BME1086),
Thulasiram Reddy P. (10BME1106), Varun Moorthy (10BME1110)” is
in partial fulfillment of the requirement for the award of Bachelor of
Technology in Mechanical Engineering, is a record of bonafide work
done under my guidance. The contents of this project work, in full or in
parts, have neither been taken from any other source nor have been
submitted to any other Institute or University for award of any degree or
diploma and the same is certified.
Thesis submission date:
Guide Program Chair
Internal Examiner External Examiner

THIS PROJECT IS DEDICATED TO
THE NGO “HAND IN HAND” AND ITS CAUSE OF
PROMOTING SOLID WASTE MANAGEMENT
FOR A GREEN INDIA

i
ACKNOWLEDGEMENTS
The project has been an enriching experience for the four of us and we would like to
thank the people who have been pivotal in providing us with such an experience. Our
sincere gratitude to our project guide, Dr. C.P. Karthikeyan, whose inputs and support
have been crucial in guiding our efforts in the right direction throughout the entire
project’s progress from brainstorming to implementation. We thank Mr. Jalasayanan
(HIH) for proposing this project idea to us and for introducing us to the challenge of
finding an innovative and green solution for small scale solid waste management. We
would also like to extend our gratitude to all of the volunteers of HIH for helping us on
site at the HIH projects and for their kind cooperation in answering our doubts with
regard to the pragmatic aspects of our project. The University and the staff have been
very kind in providing us with the equipment and expertise necessary for the completion
of this project and we are very grateful for this valuable opportunity to do something
significant before becoming professionals.
(Gautam Merwan Balagopala)
Reg. No. 10BME1045
(S. Surotham)
Reg. No. 10BME1086
(Thulasiram Reddy P.)
Reg. No. 10BME1106
(Varun Moorthy)
Reg. No. 10BME1110

ii
ABSTRACT
The objectives of the work undertaken are to design a fully mechanical model
of a windrow turner to suit the capacity of windrow composting operations of HIH as
per requirements laid out by their officials. The requirements given are to turn a
windrow of approximate dimensions 1.5ft height, 3ft width. and 15ft length with a
machine which is powered manually by a pushing or pulling force with a suitable
transmission ratio from the wheels of the machine to the turning shaft. The transmission
system from the wheels to the shaft has to be designed without using a chain drive as it
would require much maintenance and is not properly suited for such a dirt-involving
operation. The size and weight of the transmission system are important factors of the
design since the entire machine has to be mobilized entirely by manual pushing or
pulling forces. This is because of wanting to adhere to HIH’s “green” philosophy. The
hardware prototype was tested against a heap of fine sand with properties comparative
to an equivalent heap of compost and design modifications were made based on the
observations from testing.

iii
TABLE OF CONTENTS
LIST OF TABLES v
LIST OF FIGURES vi
LIST OF ABBREVIATIONS viii
LIST OF GRAPHS ix
1 INTRODUCTION 1
1.1 Motivation 1
1.2 Scope 1
2 BACKGROUND THEORY 3
2.1 Windrow Composting 3
2.2 Market Survey 3
3 DESIGN 4
3.1 Study of Windrows 4
3.2 study of commercial Windrow Turners 5
3.3 Theoretical calculations 7
3.3.1 Power input 7
3.3.2 Shaft load 9
3.3.3 Heap load 10
3.4 Design of mechanisms 12
3.5 Design of transmission system 12
3.6 Design of Blade Shaft 14
3.7 Design of Frame 16
4 FABRICATION AND ASSEMBLY 19
4.1 Fabrication of blade shaft 19
4.2 Fabrication of shaft-end flanges 20
4.3 Fitting of driver pulleys 20
4.4 Plummer block mounts 21
4.5 Assembly on frame 22
5 ANALYSIS AND TESTING 23
5.1 Analysis 23
5.1.1 Blade shaft 23
5.1.2 Flange shaft 24

iv
5.2 Testing and observations 25
5.2.1 First test 25
5.2.2 Second test 26
5.2.3 Third test 27
6 CONCLUSIONS 29
REFERENCES 30
BIO DATA 31

v
LIST OF TABLES
SL.NO NAME PAGE.NO
1
sizes and power variations of various windrows for
MENART windrow turners 5
2 Data from table 1 converted to standard units 5
3 possible combination of mechanisms 12
4
Hit and trial mass optimization data for blade
shaft 15

vi
LIST OF FIGURES
SL.NO DESCRIPTION PAGE.NO
1 Commercial Windrow Turner and windrow 3
2 studying the compost material 4
3 Analyzing a windrow at HIH biogas plant,
Mamallapuram
4
4 Dimensions of windrow to be operated upon 5
5 Schematic of a cross-belt pulley drive 7
6 push cart wheel with measured outer diameter 8
7 Schematic of blade shaft rotating through the heap
(side view)
11
8 Flow chart of transmitted torque from source to
blade shaft
11
9 Schematic of a cross-belt pulley drive 13
10 RP CAD Model and Finished Prototype 14
11 Two-dimensional representation of shaft with
respect to heap
14
12 Revised CAD Model of shaft and finished shaft 15
13 Two-dimensional representation of revised shaft
with respect to heap
15
14 Initial design of frame; Custom made Chassis 16
15 depiction of common push cart 17
16 Finalized design; CAD model of the machine
developed using the common push cart frame
18
17 Drawing of blades with notched profile 19
18 Gas welding of blades to shaft 20
19 Flange fitting with shaft 20
20 Shaft-end Flange 20
21 Pulley press-fitted
with MS sleeve
20
22 Fine Internal
Threads on sleeve
20
23 fine threads on wheel hub 21
24 Pulley fastened onto the wheel hub 21
25 Plummer block mounts 21
26 Deformation analysis of shaft in ANSYS 23

vii
27 Equivalent stress analysis of shaft in ANSYS 24
28 Simulated result; plot of factor of safety for flange
shaft
24
29 simulated result; plot of factor of safety for the
shaft portion of the flange shaft
25
30 First test setup 25
31 Schematic of straight belt drive 26
32 Straight belt drive testing 26
33 Test setup 3 27

viii
LIST OF ABBREVIATIONS
SL.NO ABBREVIATION EXPANSION
1 HIH Hand-In-Hand
2 NGO Non-Government Organization
3 MS Mild Steel

ix
LIST OF GRAPHS
SL.NO DESCRIPTION PAGE.NO
1 Variation of height Vs power on commercial
windrows
6
2 Variation of Cross Section Vs Power on commercial
windrows
6
3 Variation of Section Vs Power on commercial
windrows
7

1
CHAPTER 1
INTRODUCTION
1.1 MOTIVATION - Two major factors have influenced the decision of the final
year project. The project had to be contributive towards the environment and towards
society as well. With these motives in mind, brainstorming began for problems
concerning the environment which could be tackled by the group. An NGO, Hand In
Hand (HIH), based in Chennai whose mission is to maximize solid waste management
attracted the attention of the group. HIH has 16 projects taking care of the waste of
various town and panchayat level administrations across Chennai and a few in other
parts of Tamilnadu as well. HIH tries to reduce the amount of waste reaching the
landfills by reusing as much of it as possible through various processes like biogas
generation, composting, recycling, etc. After seeing a few of their projects and talking
with officials of HIH, the group was able to identify a few opportunities for contribution
concerning solid waste management among the various projects. The idea of design and
fabrication of a fully mechanical model of a turning machine for the windrow
composting process was proposed by one of the NGO officials, Mr. Jalasayanan. It was
a proposal for creating a “green” model of a machine for a particular process of
composting and it also had the most direct social impact among the other ideas which
made it well suited for the group’s motives of doing a project which is contributive
towards the environment and the society.
1.2 SCOPE - Upon successful completion of the design and fabrication of such a
small-scale and manually powered windrow turner, not only would it help HIH
undertake windrow composting operations with greater ease and efficiency but also it
would be seen as an attractive implement for such small-scale windrow composting
operations taken up by government bodies in rural areas as well as other private
institutions in the cities as well. Thus, the call for such a machine extends much beyond
just that of one NGO and has a potential to attract the attention of government bodies
as well. They would be able to undertake composting operations more efficiently and
within a reasonably cheap budget as well when compared to the cost of commercial
windrow turners available in the market. Although not a commercial market, providing
a useful tool for this niche market can be seen as a start to the means of an easier and

2
cheaper composting process and in turn encourage a consumer market of Earth-
conscious individuals who could start practicing such windrow composting even on
their own terraces perhaps. It would be easy, cheap, and suitably hygienic considering
one has to simply push or pull the machine across a row of organic waste. More and
more waste could be efficiently recycled. Encouraging solid waste management
activities i.e. converting waste to useful forms of energy at the smaller and smallest
levels is a strong undertone of this project.

3
CHAPTER 2
BACKGROUND THEORY
2.1 WINDROW COMPOSTING - Windrow composting is a process of
composting organic waste by piling organic matter or biodegradable waste in long rows,
called windrows. These rows are generally turned periodically to improve porosity and
oxygen content, mix in or remove moisture and redistribute cooler and hotter portions
of the pile. It is a commonly used farm scale method of composting for large volume
compost production from windrows which are 4ft or higher and as much as 12ft wide.
It is also carried out just as efficiently in smaller volumes and that’s what HIH is trying
to implement with the waste from particular panchayat towns. Since the volume of
waste generated by such small towns is not nearly as high as that of a farm, they cannot
use the huge windrow turners commonly available in the market. These are both too
expensive and unreasonably oversized for HIH’s operations or any government solid
waste management projects as well. They require a much smaller machine for turning
their windrows and require it to be fully mechanical as per the NGO’s “green”
philosophy as well. This is the group’s contribution towards HIH through this project.
2.1 MARKET SURVEY – In order to get a better idea about how to go about the
design, a study of commercially available windrow turners was taken up along with a
market survey to better determine the kind of materials and services available locally
at our disposal. Successive site visits to the HIH projects in Mamallapuram and St.
Thomas Mount Cantonment were taken up to better understand the essence of windrow
composting and the ambience involved for the operation and maintenance of the
windrow turner to be designed by the group. Interaction with the volunteers of HIH
gave much insight towards the development of the preliminary design.
Figure 1: Commercial Windrow Turner and windrow

4
CHAPTER 3
DESIGN
3.1 STUDY OF WINDROWS – The design process was initiated by first studying
small windrows for which the design was being
done. These heaps were available for our study at
HIH’s solid waste management plant in
Mamallapuram. The windrows were carefully
analyzed for important parameters such as mass,
density, porosity, moisture content, toughness, etc.
It was found that there is no standard density for organic compost material in the
windrows as they are a mixture of different kinds of organic waste. The heterogeneous
mixture consists of vegetable peels, egg shells, coconut shells, slurry, etc. This mixture
is first shredded by passing it through an organic shredder before being piled up into
windrows. The shredding process is important because it converts coarse material into
finer particles and enables easy mixing of the windrows. It essentially reduces the
toughness of the organic material which in turn reduces the effort required to carry out
the mixing. Each and every windrow will have varying densities depending on the
porosity and the amount of moisture absorbed by the heap. Thus, more specific
information on the density and the porosity of the material of the windrows was
required to proceed with the design.
Upon critically discussing with the HIH officials, significant information was extracted
regarding the characteristics of the heap as far as our design requirements were
concerned. Instead of using actual organic compost, the officials approved that the
Figure 2: studying the compost material
Figure 3: Analyzing a windrow at HIH biogas plant, Mamallapuram

5
behavior of dry sand with certain given properties is analogous to the behavior of
organic compost, i.e. Sand could be used to design and test the machine. Dry sand has
a density of 1700 Kg/m3
and
when moist it has a density of
1920 Kg/m3 [1]
.
HIH’s required heap
dimensions were 3ft width, 1.5
ft height and 15 feet length.
3.2 STUDY OF COMMERCIAL WINDROW TURNERS – Having obtained
a fair idea about the characteristics of the matter to be turned (dry sand), the next step
was to study existing commercial windrow turners. Companies like Menart and
Aerosmith are experts in manufacturing large-scale windrow turners. The technical
details of such machines were borrowed to draw a scaled-down analogy for the
specifications of our own machine [2]
.
height(m)
height
(ft)
section (m) section(ft)
cross
Section(sq.m)
cross
section
(sq.ft)
Power
(HP)
1.4 4.592 1.5 4.92 0.5 5.3792
1.5 4.92 1.8 5.904 1 10.7584
1.6 5.248 2 6.56 1.5 16.1376
1.7 5.576 3.3 10.824 2.7 29.04768 80
1.8 5.904 4.3 14.104 4.5 48.4128 100
1.9 6.232 4.8 15.744 5.5 59.1712 125
2 6.56 5.3 17.384 6.6 71.00544 140
Figure 4: Dimensions of windrow to be operated upon
Table 2: sizes and power variations of various windrows for MENART windrow turners
Table 2: Data from table 1 converted to standard units

6
Based on the figures in the above table, various graphs were drawn and the trend lines
were extrapolated to help estimate the power requirement for our scaled-down machine.
0
20
40
60
80
100
120
140
160
0 1 2 3 4 5 6 7
Power(HP)
Height (ft)
Height Vs Power
0
20
40
60
80
100
120
140
160
0 10 20 30 40 50 60 70 80
Power(HP)
Cross Section (sq.ft)
Cross Section Vs Power
Graph 1: for a height of 1.5 ft the power is around 2 HP
Graph 2: for a cross section of 2.25 ft the power is around 20 HP

7
Observing the extrapolated results from the above graphs, it can be seen that
there is a lot of deviation arising between the results for the scaled-down required power
based on various parameters of the heap. Thus, the extrapolations were seen to be
inconclusive and unreliable as a reference for determining the scaled-down input
power. So, theoretical method have been adopted in calculating the input power which
will be discussed in the next section.
3.3THEORETICAL CALCULATIONS –
3.3.1 Power input - Since the Machine is mechanically operated, the input power comes
from the pushing action of the operators. It has been deducted that an average human
can produce a power output in the range of 100 to 120 W [3]
.
0
20
40
60
80
100
120
140
160
0 2 4 6 8 10 12 14 16 18 20
Power(HP)
Section (ft)
Section Vs Power
Graph 3: for a section of 3 ft the power is around 17 HP
Figure 5: Schematic of a cross-belt pulley drive

8
Power output by an Average Human (Ptotal) = 120 W
Total no.of. humans = 2
Diameter of the wheel (dwheel) = 406.4 mm
Distance travelled by one rotation of the wheel (Srotation) = 3.14xdwheel
= 3.14x406.4x10-3
= 1.276 m
Chosen time for the wheel to cover Srotation m (trotation) = 3.5 s
Selected speed of the cart
(speed at which the cart is to be pushed) Vcart = 0.3645 m/s
R.P.M of the wheel (Nwheel) = Vcart x 60/(3.14xdwheel)
= 0.36x60/(1.276)
= 17.14 R.P.M
The torque produced on the wheels by the pushing action is calculated as follows.
Torque produced (Ttotal) = Ptotal x 60(2x3.14xNwheel)
= 120 x 2 x 60/(2x3.14x17.14)
= 133.75 Nm
Total weight of the cart = 27 Kg
Acceleration required acart – Srotation = u trotation +0.5acart t2
rotation
1276.096 = 0 + 0.5xacart x 3.52
Acart = 0.208m/s2
Figure 6: push cart wheel with measured outer diameter

9
Force required to push the cart (Fcart) = 27xacart
= 27x0.208
= 5.635 N
Power required to push the cart through a distance
Srotation metres in trotation seconds (Pcart ) = Fcart x Vcart
= 5.625 x 0.364
= 2.05 W
Power available to drive the blade shaft (Pshaft) = Ptotal - Pcart
=240 – 2.05
= 237.94 W
Torque available from this power (Tdriver) = Pshaft x 60/(2x3.14xNwheel)
= Pshaft x 60/(2x3.14x17.14)
= 132.61 Nm
This is the torque available that can be used to drive the blade shaft.
3.3.2 Shaft Load - Since the shaft is a rotating element, certain resistance has to be
overcome and this resistance is called mass moment of Inertia. The torque available
from the wheels, after transmission reduction, must be great enough to do two jobs:
one, Overcome the mass moment of inertia and two, overcome the resistance caused
by the heap.
Total mass of the shaft (Mshaft) = 6.66 Kg
Mass of cylinder (Mcylinder) = 3.54 Kg
Mass of one Blade (Mblade) = 0.176 Kg/blade
No.of blades = 18
Outer Radius of cylinder (rcylinder out) = 50.8 mm
Inner radius of cylinder (rcylinder in) = 44.8 mm

10
Mass Moment of inertia of Cylinder (Icylinder) = (½)Mcylinder x (rout
2
- rin
2
)
= 3.8x(50.8 – 44.80) 2
x10-6
/2
= 0.0010152 Kgm2
Distance of blade center of gravity
from cylinder axis (rblade) = 107.1 mm
Mass Moment of inertia of one blade (Iblade) = Mblader2
blade
= 2.018792 kgm2
Total mass moment of inertia (Itotal) = Icylinder + 16xIblade
= (4.9 + 16x57.72)x10-3
= 36.3392 kgm2
Selected transmission ratio (rtrnsmission) = 1:4
Ndriven = 4xNwheel
= 417.4
= 68.57 R.P.M
Angular velocity of driven pully (wdriven) = 7.177 rad/s
Angular Acceleration of the Driven pully (αdriven) = 2.050 rad/s2
Torque required to rotate the shaft from rest (Tshaft) = Itotal x αdriven
= 0.0765 Nm
3.3.3 Heap Load - The heap load is calculated in analogy to completely lifting a
particular volume of heap having a certain mass through a distance which is equal to
the tip to tip distance of the blade shaft. Though this is not the exact case, scope for
margin of safety is allowed.
Density of heap material = 1600 Kg/m3
Volume of heap through which the
shaft rotates at any point of time (Vheap) = 457.2x914.4x138x10-9
/2
= 0.0288m3
Mass of the volume Vheap (Mheap) = 0.0209x1600
= 33.44 Kg

11
It is considered that at any point of time the blade shaft is in effective contact with the
heap for a distance of 100 mm in the direction parallel to the heap.
The torque required to rotate the shaft through
the heap (Theap) = 33.44x10x138x10-3
= 32.77 Nm
Total torque required at driven pully (Trequired driven) = Theap + Tshaft
= 32.85 Nm
Torque available at the Driven pulley
after reduction (T available driven) = Tdriver/2
= 33.15Nm
Tavailable driven > Trequired driven
Figure 7: Schematic of blade shaft rotating through the heap (side view)
Figure 8: Flow chart of transmitted torque from source to blade shaft

12
3.4 DESIGN MECHANISMS – The basic principle is that when the machine is
moved over the heap, the windrow should be mixed underneath. So, the machine should
essentially consist of the following parts:
1) A frame
2) Wheels
3) Transmission System
4) Blade Shaft
With these parts, different combinations of mechanisms were developed. They are
depicted in the following table.
DEPENDENT INDEPENDENT
1-man transmission system motor/engine
2-men transmission system pedalling
3-men transmission system hand cranking
Dependent or independent refers to the connection between the wheels and the blade
shaft. The rotation of the blade shaft can be either dependent or independent of the
rotation of the wheels. If the system is dependent then there has to be a transmission
system to transfer the power from the wheel to the blade shaft. Independent systems
can have separate operators for pushing the cart and rotating the shaft. Upon proposing
these combinations to HIH, they selected the 2-men dependent system as they wanted
to promote green technology by avoiding electricity and fossil fuels.
3.5 DESIGN OF TRANSMISSION SYSTEM – A 2-men dependent system
requires a transmission system so that when two operators are pushing the cart, the
power from the two is effectively transferred to the blade shaft. The following
conventional systems are available:
1) Belt Drive
2) Chain Drive
3) Gear drive
Table 3: possible combination of mechanisms

13
After carefully considering, belt drive has been chosen to develop the transmission
system owing to the following factors:
1) Belt drives are the simplest of the three and involves lesser moving parts. Since
the design is a low powered application, belt drive is just enough to handle the
load.
2) Chain drives involve more moving parts and need to be lubricated and HIH
recommends minimal maintenance. Also, there will a lot of dirt and fine
particles suspended in the surrounding space while mixing the heap and this dirt
might settle on the sprockets that could lead to jamming of the drive.
3) Gear drives are not cost effective. They cannot be used in systems where there
is a longer center distance involved as idler gears need to be installed to cover
the entire distance. Also, the same dirt jamming problem may arise.
Figure 3 Cross belt drive diagram
The direction of rotation of the wheel and the direction of rotation of shaft are to be
opposite to each other. This is a must because only in this arrangement the windrow
process proceeds efficiently i.e. proper mixing of the heap happens. Accordingly, A-
type pulleys were selected based on the torque requirements, the center distance was
selected (9 x ds)[4]
and the belt length for cross belt drive is calculated by,
[4]
Where,

14
dL = 8 in
dS = 2 in
C = 9 x 2 x 25.4 = 456 mm
LC = 53 in
3.6 DESIGN OF BLADE SHAFT – Simultaneously, rapid prototyping of the shaft
was undertaken in the college itself. Since it was only the chassis that was asked to be
revised, the shaft design became finalized and in order to test its effectiveness in
transporting material from the outside edges to the inside to maintain the heap shape, it
was deemed necessary to go for rapid prototyping of a scaled down model of the shaft.
Figure 10: RP CAD Model and Finished Prototype
The observations from the rapid prototype testing led us to believe that there was too
much vertical drop in between the blades of the shaft and that material would get
dropped in these gaps instead of getting fully mixed.
Figure 11: Two-dimensional representation of shaft with respect to heap

15
The design of the shaft was then re-iterated to have more blades and less vertical drop
between the successive blade edges. A second rapid prototype was not taken up due to
economic constraints.
Figure 12: Revised CAD Model of shaft and finished shaft
Figure 13: Two-dimensional representation of revised shaft with respect to heap
The weight of the shaft plays an important role is effective power transmission. The
power required to rotate the shaft should be as minimum as possible. So, the number
of blades and the type of shaft have been optimized from the following trials:
shaft
diameter
(inch)
material blade
thickness
(mm)
blade
width
(mm)
total weight
(Kg)
shaft type
4" AISI 1010 2 50 64.946 solid
4" AISI 1010 2 50 3.629 hollow(1mm)
4" AISI 1010 2 50 6.067 hollow(2mm)
4" AISI 1010 2 50 8.45 hollow(3mm)
2" AISI 1010 2 50 17.505 solid
2" AISI 1010 2 50 2.785 hollow(1mm)
2" AISI 1010 2 50 3.967 hollow(2mm)
Table 4: Hit and trial mass optimization data for blade shaft

16
Finally, a hollow shaft of 4 inch outer diameter has been chosen to be the optimal
design based on strength, stress and required size conditions
3.7 DESIGN OF FRAME –
Based on the initial market survey and study of commercial windrow turners, a rough
design concept was modelled in SolidWorks. As the blade shaft was the main
component affecting the quality of operation, the chassis was completely redesigned
according to the market survey conducted. Based on our understanding of the
problem, a steering system was incorporated and a highly unique chassis design was
made which could not use standard parts but used much less material by avoiding
unnecessary appendages for achieving light weight design. Other commonly available
parts like bicycle forks and wheels were also used in order to achieve a very cheap
design.
The frame part of the machine was custom designed to easily accommodate the center
distance of the driver and the driven pulleys. This design was then presented as a
proposal to the concerned NGO officials. Upon review and discussion with their
Figure 14: Initial design of frame; Custom made Chassis

17
officials, certain suggestions were made and constraints were laid upon the design
wherein the total design had to be re-iterated to meet these specifications.
1) The main concern of the NGO
was that instead of designing a
totally new chassis for the
machine, an actual and
commonly available
‘pushcart’ had to be used as
the base chassis. Accordingly
changes had to be
incorporated into the design and subsequent calculations and analysis were done.
2) A search for procuring used ‘pushcarts’ for the fabrication was unsuccessful and it
was decided to purchase and use the necessary parts for making a new pushcart,
The concept being unchanged: Recycling a used push cart. But Instead of actually
using a used push cart, a new push cart would play the same role in defining the
solution and is solely used for the purpose of proper demonstration.
3) The basic under frames of the pushcart (C-bends) were purchased in order to keep
the base chassis as that of a typical pushcart. The rest of the parts (Wheels) of the
pushcart were left out for later purchase to cater more specifically to the needs of
our design. Thus, certain parts (lateral Rods) which would have otherwise had no
role in our design were left out. This allowed us to keep to the constraint of using a
normal pushcart while at the same time giving us the flexibility to change out a few
parts for ones more suitable for our design; for example using smaller 16” wheels
instead of standard 26” wheels.
Taking all of these constraints and suggestions into account, a fresh design was made
based on the purchased standard parts like the c-bends. The aim of the second design
was to achieve as much standardization as possible in at least the parts and components
used even if it were slightly more costly. Standardization meant easier purchase and
maintenance for the NGO as well. The second design was then presented to the officials
of the NGO and the project progressed forward only after their approval of the same.

18
This was a very important part of the project as the end user of our unique product was
going to be the NGO and it was essential that those client requirements be met on par
with their expectations.
Figure 16: Finalized design; CAD model of the machine developed using the common push cart frame

19
CHAPTER 4
FABRICATION AND ASSEMBLY
The main stages of fabrication are:
1) Fabrication of Blade Shaft
2) Fabrication of Shaft-End Flanges
3) Fitting of Driver Pulleys
4) Plummer Block Mounts
5) Assembly of Frame
4.1 FABRICATION OF BLADE SHAFT – The blade shaft proved to be the
largest and most critical part of the fabrication phase. An MS pipe and MS sheet metal
pieces were purchased according to dimensions laid out in the final design. According
to the design, a certain profile had to be cut into one side of the blade sheets so that they
could sit perfectly on the MS pipe for welding. Necessary notching was done in the MS
sheet metal pieces by means of gas cutting and subsequent grinding.
Figure 47: Drawing of blades with notched profile
These notched blades were then positioned onto the MS pipe shaft in a specific spiral
orientation as per the final design. This step required a lot of time in order to get the
maximum precision possible in maintaining the perfect spiral shape of the blades being
welded onto the shaft. The blades were carefully tacked into place with a simple metal
arc welding electrode. They were then tweaked after tacking into the appropriate
angular orientations and positions and then the blades were completely welded into
position with a gas welding torch. Gas welding was decided upon as the most suitable
option for this operation as it would have minimal heat exposure to the blades since
they are of very little thickness (2mm) and at the same time ensure the strength of the

20
welded joints would be sufficiently strong. The welding was performed on both sides
of the blades for ensuring maximum strength of the blade-shaft joints as they would be
bearing most of the load from the resistance of the heap being turned.
Figure 18: Gas welding of blades to shaft Figure 19: Flange fitting with shaft
4.2 FABRICATION OF SHAFT-END FLANGES – Flanges were included in
the design in order to connect the blade shaft to the chassis through the smaller pulley.
A standard flange of 1.5inch
internal diameter was purchased
and welded to each end of the
blade shaft. The complementary
flange for connection to the chassis
and small pulley was fabricated by
using a flange blank. A hole was
drilled in its center and a smaller
diameter billet of 20mm diameter was welded into it so that the pulley and chassis
mounting Plummer block could be fitted onto it.
4.3 FITTING OF DRIVER PULLEYS – One of the more thought
Figure 20: Shaft-end Flange
Figure 21: Pulley press-fitted
with MS sleeve
Figure 22: Fine Internal
Threads on sleeve

21
requiring phases of the fabrication was that of fitting the bigger 8 inch driving pulley to
the hub of the wheel so that they could rotate together to drive the belt around the
smaller pulley and rotate the shaft. For that, it was thought to make use of the threading
which was provided on one side of the wheel hub.
It is a fine thread that is provided there and its complementary fine thread had to be
made in the inside of the bigger pulley. This proved to be a problem though as the pulley
is of cast iron material and was not suitable for machining such a fine thread in it. This
problem was overcome by boring a larger hole in the pulley and press fitting an MS
sleeve into the hole and machining the fine threading into the sleeve instead. This let
the pulley be freely screwed on and off of the hub of the wheel. To ensure that the
pulley doesn’t unscrew itself during operation, a lateral hole was drilled into the pulley
and a bolt was placed in it to restrict motion between the pulley and the Mild Steel
sleeve with the threading. Zip tags were also tied between the wheel spokes and the
pulley spokes to restrict relative motion between the pulley and the wheel.
4.4 PLUMMER BLOCK MOUNTS – The center distance between both pulleys
was determined during the design of the
transmission system to be 9xds. This
distance was appropriately located and
marked on the chassis where the Plummer
block holding the smaller pulley was to be
mounted. A pair of MS plates of
dimensions 50x100x6mm were welded to
the c-bends at the appropriate locations and
Figure 23: fine threads on wheel hub Figure 24: Pulley fastened onto the wheel hub
Figure 25: Plummer block mounts

22
bolt holes were drilled in them for fixing the Plummer block to them. After the Plummer
block was fixed to the chassis, the connecting flange with the 20mm billet could be
assembled to the blade shaft and put in place. The location of the smaller pulley on that
billet (lateral position) was then determined visually so that both pulleys be in the same
plane. A small hole was drilled in the side of the pulley similar to what was done on the
bigger pulley and a bolt was screwed into it against the billet to keep the pulley’s lateral
position fixed on the billet.
4.5 ASSEMBLY OF FRAME – A typical push cart contains 4 c-bends. They are
assembled in two sets, one on each side. Two bends hold two wheels, one at each end
of the set. Holes are provided on the c-bends where the hub screws of the wheels can
sit. Based on the positioning of the bigger pulley screwed onto the wheel hub of the
rear wheels, the appropriate spacing between the pair of c-bends was determined.
Adequately sized spacers were fabricated from small MS billets and placed on the hub
screws to maintain equal spacing between the pair of c-bends at the front and back. All
the four c-bends needed to be fixed rigidly in their respective lateral positions. A
support structure of lateral and longitudinal constraints was made using wooden beams
which were all bolted together to fix the c-bends in place from the top. A simple
plywood sheet was bolted on top of the wooden support structure to act as a top covering
for the entire machine. Two handles, one on each side of the machine, were made using
MS pipes and welded to the c-bends to Sheet metal pieces were cut to appropriate sizes
and attached underneath the wooden frame and between the two pairs of c-bends to
form a tunnel shape in the direction of the machine’s motion above the blade shaft. This
helps keep the turning operation confined to the space underneath the tunnel and also
provides a shape for good air flow through the material as it is being turned.

23
CHAPTER 5
ANALYSIS AND TESTING
5.1 ANALYSIS
There are two major components which are subjected to significant stresses:
1) Blade shaft
2) Flange shaft
5.1.1 Blade shaft - The blades are welded to the shaft. This means that there will be
enormous cantilever effects especially on the tips of the blades at the bent portion.
Twisting moment arises throughout the shaft. The entire shaft rotates through the heap
and undergoes continuous but gradual loading. So the setup is as follows:
i) Motion constraint: displacement is constrained on of the surfaces of the
bent portion of each blade since the bent profile is responsible for scooping
the sand and undergoes stress in lifting the sand throughout the heap. So,
displacement in X,Y and Z directions are constrained on the bent portion
of the blade.
ii) Loading: The shaft is rotated by the torque provided from the wheels and
this torque is applied on the flanges of the shaft. So, the transmitted torque,
33.15 Nm is applied as twisting moment on both the flanges.
The setup is then meshed and solved.
Figure 26: Deformation analysis of shaft in ANSYS

24
It can be observed that the maximum deformation of 0.00456 mm occurs near
the flanges.
Figure 27: Equivalent stress analysis of shaft in ANSYS
It is observed that the maximum stress of 6.0877 MPa occurs near the flanges.
5.1.2 Flange shaft - The same amount of torque is transferred to the blade shaft
through the flange shaft from the wheels. Here, the stress lies on the bolt holes
because they are the points of stress raisers as they are discontinuities in the disc.
i) The constraint is applied on the bolt holes.
ii) The torque of 33.15 Nm is applied on the free end of the shaft.
Figure 28: Simulated result; plot of factor of safety for flange shaft

25
5.2 TESTING AND OBSERVATIONS – Testing of the machine gave way to
many necessary changes and even some very important design modifications. As was
discussed earlier, it was approved by the officials to use dry sand as an analogous
material for actual compost in both the design and testing of the machine. An ideal
testing heap was decided to be made in a suitable outdoor ambience with sample
dimensions of height 1.5ft, width 3ft and length about 4ft.
5.2.1 First Test - The first model of the
machine had a cross belt drive with an
A53 size belt. The transmission ratio
was 1:4 since the pulleys were of 2inch
and 8inch diameters. The actual heap
size varied slightly in dimension than
the ideal heap defined earlier due to
minor human difficulties in forming the
heap perfectly. The heap was actually a
bit wider and more voluminous than the predefined ideal heap and the testing was
conducted by pushing the machine through it at different speeds. It was observed that
Figure 29: simulated result; plot of factor of safety for the shaft portion of the flange shaft
Figure 30: First test setup

26
the shaft rotation was inhibited immediately upon contact of the blades with the heap
regardless of the speed of pushing. There was basically zero penetration and upon
further forced rotation of the driving wheels, either wheel skidding or belt slipping was
observed. The inferences made from the testing was that the resistance provided by the
heap of dry sand was much greater than the theoretically calculated resistance and that
the torque was not being sufficiently transferred to the shaft for such a resistance. The
direction of the blade shaft rotation being opposite to the direction of motion of the
shaft was also observed to be an important reason for the unexpectedly high resistance
being faced by the machine.
5.2.2 Second Test – Based on the inferences from the first test, possible design
parameters which could be modified were listed out and whatever changes could be
made immediately and without incurring any extra expense were first done before the
second testing.
Since the direction of the shaft rotation being opposite to shaft motion against the heap
seemed to be a main problem in the previous setup, the shaft rotation was reversed by
making the
cross belt
drive into a
straight belt
drive with the
same A53
size belt. The
size and
shape of the
heap were
Figure 31: Schematic of straight belt drive
Figure 32: Straight belt drive testing

27
also reduced to match that of the ideal test heap better and testing was conducted by
pushing the machine through the heap at various speeds again. A great deal of slack
was observed in the belt drive but nevertheless the shaft was able to rotate freely
through the heap even at low speed without any hindrance. There was no belt slippage
and the mixing ability of the shaft was just ok but not great. The major inference from
this test was that the belt needed to be of a smaller size so as to avoid so much slack
and have a good tight tension. The reversal of the direction of rotation of the shaft by
using a straight belt drive seemed to be very effective in easing the motion of the blades
through the heap. The torque transferring ability of the transmission system no longer
seemed to be a problem if the slack could be adjusted.
5.2.3 Third Test – It was decided that the transmission system be kept as a straight drive
belt system itself and by revising the calculations of the transmission system design for
a straight belt drive, instead of cross belt drive as it was earlier, a belt of size A52 was
decided to be used.
The belt length for straight drives is given by,
[4]
Upon substituting the values of dL, dS and C, the belt length was determined to be
52.106 in.
The test heap was also made very carefully to match the size and shape of the ideal test
heap and testing was conducted by pushing the machine through the heap at various
speeds. The motion of the blades and shaft through the heap was very smooth and a fair
level of mixing of the heap was observed although still not perfect. A more ideal mixing
scenario would have been possible with the cross belt drive setup but the torque in that
case was observed to be insufficient so it was ruled out as a possibility after the second
test itself. It was also observed however that the general shape of the heap was greatly
distorted after pushing the machine through the heap. This was seen to be attributed to
the size of the shaft pushing through the heap. It was designed by keeping in mind the
design of commercial windrow turners but happened to be too large for the particular
sort of testing setup with much lower shaft rotation speed and torque compared to the

28
commercial machines. With higher speeds, the contact of the shaft with the heap is
greatly reduced and the contact with the blades is much more so better mixing and less
distortion are observed in commercial machines. In our machine though, since the rpm
is significantly lower, the shaft is in contact with the heap more than the blades and
hence the distortion seems to be arising. A totally different kind of shaft design would
have to be proposed for such lower speed operation and that could be achieved with
more dedicated research in the area. But otherwise, the testing proved to be successful
as there was a fair mixing of the contents of the heap.
Figure 33: test setup 3

29
CHAPTER 6
CONCLUSIONS
The prototype of a small scale fully mechanical windrow turner was designed and
successfully fabricated. Upon its testing, inferences were drawn based on which scope
for further optimization of the design were identified.
1) It was observed that the torque transmission had minor deviations from the actual
theoretical deduction. The rotating direction of the shaft proved to develop too much
resistance while rotating through the heap due to which the rotation direction had to be
reversed. Further research can be carried out on improving the transmission system
which can deliver torque more properly to overcome the resistance that arose in the first
orientation.
2) The current shaft and blade profile were developed from commercially existing large
scale machines. It was observed that for such low speed mechanically operated
machines, the central cylindrical portion of the shaft was distorting the shape of the
heap. Further research on the shaft and blade profiles of such small scale mechanical
models of windrow turners could prove useful for better designs.

30
REFERENCES
(1) http://www.rfcafe.com
(2) MENART SP Turners catalog.
http://www.menart.eu
(3) Density of common building materials – RF cafe
http://hypertextbook.com
(4) V. B. Bhandari, 2012, Design Of Machine Elements Third Edition, Belt
Drives pp 499-540

31
Personal Information
Name Gautam Merwan Balagopala
Reg. No. 10BME1045
Date of Birth 02/11/1991
Age 22 years
Education B.Tech Mechanical
College VIT University, Chennai
Contact details
Address S/o Meher Isaa Balagopala
8/S1, Vesta Selva,
5th
Street, Sarathy Nagar,
Velachery, Chennai
Pin: 600042
Contact no. +91-9884064451
E-mail ID gbalagopala@gmail.com

32
Name S. Surotham
Reg. No. 10BME1086
Age 22 years
Contact details
Address S/o C S Suresh
New No:10 , Old No: 15
Kesava Perumal Sannidhi Street
Mylapore, Chennai
Pin: 600004
Contact no. +91-9551077475
E-mail ID suro_srsh@live.com

33
Name Thulasiram Reddy Padala
Regn No. 10BME1106
Age 21 years
Contact details
Address S/o Venkata Reddy Padala
Do.no.129, rukmini Nagar,
1st
Street, Maduravoyal,
Chennai
Pin: 600095
Contact no. +91-8939081388
E-mail ID Thulsiramptr@yahoo.co.in

34
Name Varun Moorthy
Regn No. 10BME1110
Age 22 years
Contact details
Address S/o C V Sundaramoorthy
48/10 Syndicate Bank Officers Qts,
Nandini Layout
Bangalore
Pin: 560096
Contact no. +91-9626949100
E-mail ID Varunmoorthy.92@gmail.com

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