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This is to certify that the

thesis entitled

Field Evaluation of Hydraulic Torque Assisted Disk Implement

l
I

presented by

Omer Ozel

has been accepted towards fulﬁllment
of the requirements for

M.S. degree in Agricultural Engineering

' Ens/ﬂow,

Major professor

Date December 16, 1997

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FIELD EVALUATION OF HYDRAULIC TORQUE ASSISTED DISK IMPLEMENT
By

Omer Ozel

A THESIS
Submitted to
Michigan State University
in partial fulﬁllment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Agricultural Engineering

1997

ABSTRACT

FIELD EVALUATION OF HYDRAULIC TORQUE ASSISTED DISK
IMPLEMENT

By

Omer Ozel

The performance and power requirements of the hydraulically driven soil-
engaging disk are discussed. Draﬁ, hydraulic rotary, and total powers consumed were
measured at various system pressure settings and ground speeds by a microcomputer
based data acquisition system.

The power disk was quantitatively compared powered vs. non-powered. The
results show that applying supplemental hydraulic torque to the disk up to the breakaway
torque has caused a draﬁ reduction by up to 15 % when the torque approached the
breakaway torque of 358 N-m (3168 lb-in). However, a signiﬁcant reduction on total

power requirement was not observed in the ﬁeld tests.

Dedicated to my beloved family, Asuman, Kevser, and Yusuf.

iii

ACKNOWLEDGMENTS

In the name of Allah, God, the most beneﬁcent and merciful. He has blessed us
with the capacity to learn and appreciate His creation. He is the all-knowledgeable. All
praises be to Him ﬁrst.

I would like to express my sincere appreciation to all those people who provided
encouragement and assistance throughout my graduate program. Special thanks go to the
following individuals and institutions:

Dr. Daniel E. Guyer, my major professor, for his guidance and encouragement
throughout my study. He has always kept his door open to me and provided me with his
invaluable ideas on my project.

Dr. Gary R. Van Be, a member of my guidance committee, for his innovative
suggestions on hydraulics and being very responsive for all my questions and requests
about my project during the implementation of the system.

Dr. Darryl D. Warncke, a member of my guidance committee, providing me with
helpful comments on the soil tillage aspect of my research project.

The technical personnel in the research workshop, Richard Wolthuis and Richard
Ledebuhr, for their efforts in building the machine and modifying its components when

needed. I beneﬁted much from their experiences on workshop mechanics.

iv

My honorable nation and The Republic of Turkey through Gaziosmanpasa
University, for giving me the opportunity to study in the USA in the hope for improving
the academic education and the agriculture in my beautiful country.

Finally my parents, my family and my friends for their supports, encouragement

and conﬁdence in this challenging part of my life.

TABLE OF CONTENTS

LIST OF TABLES ........................................................................................................ ix
LIST OF FIGURES ........................................................................................................ x
CHAPTER 1
INTRODUCTION ............................................................................................................ 1
1.1 Background ................................................................................................................. 1
1.2 Objectives ................................................................................................................... 2
CHAPTER 2
LITERATURE REVIEW ................................................................................................. 4
2.1 Principles of Disk Implement Design ......................................................................... 4
2.2 Power Disks ............................................................................................................... 7
2.3 Instrumentation ......................................................................................................... 11
CHAPTER 3
EQUIPMENT ................................................................................................................ 14
3.1 Power Disk and Hydraulic System Components ...................................................... 14
3.2 Tractor ....................................................................................................................... 20
3.3 Instrumentation—Data Acquisition System ............................................................... 21
3.3.1 Transducers (Sensors) ..................................................................................... 23
3.3.1.1 Pressure Sensors for Measurement of Pressure Drop .......................... 23
3.3.1.2 Draﬁ Measurement ............................................................................. 25
3.3.1.3 Disk Speed Measurement ................................................................... 28

vi

3.3.1.4 Ground Speed Measurement ................................................................ 29

3.3.2 Signal Conditioning Modules .......................................................................... 30
3.3.3 Data Acquisition (Computer Interface) Hardware .......................................... 31
3.3.4 Data Acquisition Software for Analysis and Monitoring ................................ 33
3.3.5 Personal Computer (PC) .................................................................................. 35
CHAPTER 4
FIELD PROCEDURES .................................................................................................. 37
4.1 Test Field and Soil Properties ................................................................................... 37
4.2 Method of Data Collection in the ﬁeld ..................................................................... 39
4.2.1 Repetitions ....................................................................................................... 39
4.2.2 Varying Ground Speed .................................................................................... 39
4.2.3 Varying Pressure Relief Valve Settings ........................................................... 39
4.2.4 Data Acquisition and Sampling Frequency ..................................................... 40
4.2.5 Data Storage ..................................................................................................... 41
CHAPTER 5
RESULTS AND DISCUSSION ..................................................................................... 42
5.1 Power Disk ................................................................................................................ 44
5.2 Data Acquisition System and Sensors ...................................................................... 45
5.3 Main Concepts for Evaluation of Hydraulic Torque Assisted Disk ......................... 46
5.3.1 Draft Ratio versus Hydraulic Torque Assist .................................................... 47
5.3.2 Ratio of Disk Speed-Ground Speed versus Torque ......................................... 53
5.3.3 Speciﬁc Power Requirements of the Disk Implement ..................................... 55

vii

CHAPTER 6

CONCLUSIONS ............................................................................................................. 57
CHAPTER 7

RECOMMENDATIONS FOR FUTURE RESEARCH ................................................. 59
APPENDIX A: Powered Disk Implement Performance Equations ............................... 60
APPENDIX B: Speciﬁcations of Sensors ....................................................................... 63
APPENDD( C: Results from Statistical Analysis .......................................................... 65
APPENDIX D: Sample Conditioned Raw Voltage Data Graphs ................................... 78
BIBLIOGRAPHY ........................................................................................................... 81

viii

LIST OF TABLES

Table 3.3.1 Calibration Response Equations and Coefﬁcients of Determination ..... 24
Table 4.1.1 Soil Properties of Test Field for Power Disk Study ................................ 38

Table 5.3.1.1 Power Requirements (kW) for Different Ground Speeds at Relief Valve
Setting of 8274 kPa (1200 psi) ................................................................ 52

ix

LIST OF FIGURES

Figure 3.1.1 Hydraulic Torque Assisted Disk Implement ........................................ 15
Figure 3.1.2 The Power Disk in Operation .............................................................. 15
Figure 3.1.3 Hydraulic Circuit Diagram for Power Disk ......................................... 17
Figure 3.3.1 Elements of a PC-Based Data Acquisition System .............................. 21
Figure 3.3.1.2.1 Wheatstone Bridge Circuit for Strain Gages ....................................... 27
Figure 5.3.1.1 Draft Ratio versus Torque .................................................................... 49
Figure 5.3.1.2 Best-Fit Line of Draft Ratio versus Torque ......................................... 50
Figure 5.3.2.1 Ratio of Disk Speed-Ground Speed versus Torque ............................. 54

1.1

 

Chapter 1

INTRODUCTION

Background

As primary or secondary tillage equipment, disk implements are commonly used
all over the world. Such implements require a sizable amount of draﬂ power. As
the energy costs increase day by day, the efficient use or design of this type of
machine plays a more important role on reducing fuel costs.

A power-driven disk could be an alternative solution to reduce the draft
power. Various mechanically driven systems have been developed for better
performance and power efﬁciency. By recent advances in the development of
hydraulic power and control components, designers have had alternative
opportunities for power transmission and control. One implementation of these
technological developments might be hydraulic remote control and power of the
active disk blade for power efﬁciency and safety reasons. Power can be
transmitted to the disk by hydraulic hoses, instead of traditional power takeoff
shafts. This type of control and power of machines could make signiﬁcant
contributions to farm power research and agricultural machinery safety.

On the other hand, to a farmer in a developing country, the primary source
of power, a tractor, is most likely to have less than 10 kW of power and pertinent
equipment are usually small category if available. Due to the depressed

agricultural economy, it is not possible for such farmers to buy a large tractor or

1.2

any big Speciﬁc equipment for only one purpose. They usually resort to using
the same implement for various farming activities, such as using a disk plow
to harvest root crops, after minor modiﬁcations to meet speciﬁc operating
conditions.

Previously there have been some studies on implementation and
improvement of disk blades for the above purpose. Gupta, et al. (1993,1994)
developed two prototype potato harvesters having mechanically driven disk
blades. One of them was a one-row disk blade powered by a two-wheel walking
type (single axle) tractor of 6 kW (8 Hp). The other was also a one-row disk blade
with an additional separator and a single axle tractor of 8.6 kW (11.5 Hp) power.

The main idea behind Gupta's approach was to develop a cost-effective,
easy to use potato harvester, which does not require great power or labor. As a
result of huge population movements from rural to suburb areas in developing
countries in last few decades, the need for agricultural workers increased and
labor shortages occurred. Consequently, labor cost has increased and labor has
been troublesome. The mechanization of agricultural production with smaller
tractors, therefore, has been inevitable for farmers of small size.

Objectives

Three speciﬁc objectives of this study were:

1. To develop a hydraulic power driven soil-engaging disk system in order to
reduce draft and power requirements as a ﬁinction of the supplemental

torque to a disk at varying ground speeds.

To develop a personal computer (PC) based data acquisition system to
record soil-engaging disk implement performance for evaluation.

To measure the draft forces acting on the disk and compare the energy
requirements of a disk blade as a tillage implement under powered and

non-powered conditions.

2.1

Chapter 2

LITERATURE REVIEW

Principles of Disk Implement Design

There have been a number of studies on disk implements in order to determine the
essential and optimum design parameters, such as disk angle, tilt angle, and other
geometric properties of disks, and the effect of each parameter on power
requirement of disk implements while changing other variables like ground speed,
working depth and soil type of the test ﬁeld. The vast amount of information and
research regarding these parameters and their effects provides a very good
resource for engineers and workers of disk implements to improve future designs.

A review of the literature on fundamentals of design of disk implements is
necessary to fully understand the operation of the disk implement. It was also
helpful in the selection of rational working ranges of the variables involved with
this study. Keeping the previous knowledge in mind, the number of variables for
this research were decreased to observe the main effect of the new design.

Clyde (1939) is one of the earliest workers who had reported soil forces
acting on disks. He observed the effect of disk angle, vertical angle, disk diameter
and moisture content of the soil and provided the guidelines for the design of disk
implements and proper hitching procedures. He gave an understanding of how
and where the soil forces act on disks. The observations were carried out by a

basic data acquisition system due to the technology available at that time.

Gordon (1941) made signiﬁcant contributions to the design of disk
implements by working on a single blade disk plow under laboratory conditions.
Two ﬁrmly packed different soils in soil bins were used for the test runs. The disk
was placed in a framework through which the reaction of the soil on the disk was
imparted to six hydraulic cells. The hydraulic cell pressures were recorded and
through these records the soil reactions on the disk were resolved into three
directional components; draft (horizontal force), vertical reaction force upward
and downward, and side force. He noted that the largest variation in soil reactions
on the disk were due to the soil types and soil properties. Other important ﬁndings
of this study can be summarized brieﬂy:

0 Minimum draft was observed at a disk angle of 45 degrees. Increasing
values of this angle caused steep increases in draft.
0 Doubling the forward speed from 4 km/h (2.5 mph) to 8 km/h (5 mph) in

sandy loam soil increased the draft by % 67.

0 As the disk concavity increased, the draﬁ and upward thrust of the soil
increased.

0 Increases in disk angle settings had an effect of improving soil penetration
and reducing the upward thrust.

Harrison and Reed (1962) studied the forces on tillage equipment at
different depths and speeds in the ﬁeld and determined the power requirement for
different working conditions. These data are useful in selecting and using tillage

equipment in connection with different sizes of tractors.

In a study by Gill et a1. (1980), the effect of geometric parameters on disk
forces was investigated. They studied on three disk shapes and three sizes. The
results of the work conﬁrmed that optimum harrow design and operating
conditions are inﬂuenced by disk blade geometry. Both the conical and Spherical
II (a compound spherical disk with two distinct radii of curvature) had lower
forces than did the more commonly used Spherical I disks. Increases in draft
caused by increases in forward speed are essentially linear.

McCreery and Nichols (1956) also studied the geometry of disks and soil
relationships. They reported that the convex side of the disk had created a greater
soil compaction at small disk angles. Some concepts on disk implements were
explained in detail. The back surface of a disk is named the bearing area of the
disk which resists against penetration. For a lower draft and better penetration, the
bearing area of a disk must be minimized. On the other hand, the concave side of
a disk is known to be the pressure area which overcomes the soil. The application
of pressure against the soil causes the soil to rupture and pulverize.

Both the bearing and pressure areas depend on disk diameter, tillage depth
and disk angle. It is possible to reduce the bearing area by choosing smaller
diameters, or decreasing the working depth or increasing the disk angle.

Related to this issue, Gill et a1. (1981) reported the inﬂuence of disk
curvature on soil penetration. Their conclusion was that increases in the radius of
curvature while selecting the proper disk angle and mass had a signiﬁcant effect

on penetration. They found that reducing the force acting on the back surface of a

2.2

disk by increasing the radius of curvature or increasing the disk angle in a range
of 11.5 degrees to 20 degrees, or both at the same time, caused a reduction in the
draﬁ and vertical forces.

Improving disk penetration is an important point for developing lighter
disk plows that might penetrate to the desired depths without adding weights. The
lighter tillers are of particular interest from the standpoint of the development of
powered disk tillers, improvement of ﬁrel economy, reduction in soil compaction
and control of depth.

Taylor (1967) also reported a study on ﬁeld measurement of forces and
moments on Wheatland plow disks and summarized that the performance of a
plow would be radically affected by the disk angle—furrow width relationship, the
selected tilt angle and the speed at which it operated.

Power Disks

Soehne (1963) studied the work quality of both conventional and powered
disk plows. His observations indicated that the powered disk caused more soil
pulverization where the conventional plow caused large clods in the ﬁeld. While
mentioning the advantage of the single pass of the powered disk, he warned of
possible destruction of soil structure by rigorous action of it. In terms of power
requirements, he reported that:

0 Increasing the disk peripheral velocity versus ground speed with a ratio of

1.3-1 .5 reduced the drawbar pull by 30% and increased total power

requirement by 120%.

o Doubling the disk speed double reduced the draft to half, however, then
the total power requirement increased to 170%.

0 AS the disk speed increases, the side and vertical forces become larger.

0 When compared to the free rolling disk, the high power requirement, the
relatively low reduction in draft, the difﬁculties involved in design and
high costs, the development of the power disk could not be justiﬁed.
Abernathy (1976) also reached the same conclusion after the laboratory

tests on a self-powered disk. He reported that using powered disks could reduce
draft by 20%, but the total power requirement was three to six times greater than
that of free rolling disks.

Tembo (1986) studied a power take-off (PTO) driven disk tiller for
performance evaluation. He conducted ﬁeld tests to determine the drawbar power,
PTO power and total power requirements of the disk tiller. When 90% of total
power was transferred through the PTO shaft and 10% of total power was
obtained through the traction to the implement, a 30% savings in energy
utilization was achieved at a peripheral disk velocity to ground speed (pdv/ gs)
ratio of 2.5. He also reported that no energy savings were observed at higher
peripheral disk velocities as total speciﬁc power increased with increases in
peripheral disk velocity.

The use of hydraulic power in agricultural machinery instead of

mechanical power transmission has been studied by few researchers to compare

the power transmission efﬁciency and safety of mechanical and hydraulic
systems.

In this respect, Young (1975) carried out ﬁeld tests to evaluate the
performance of a hydraulic powered disk implement. DynaTil was a tandem disk
harrow designed for only investigating the future of powering disks. The reason
was that the on-the-go adjustability of gang speed and gang angle would provide
farmers with greater control by allowing them to vary the degree of tillage to ﬁt
ﬁeld conditions. Today, this issue is very important in terms of precision farming.
As GPS (global positioning system) on machinery becomes more prevalent in
agriculture, the automation and integration of such tillage equipment will be
inevitable.

Input power was provided from the tractor 1000 rpm PTO drive shaft
into two hydraulic pumps placed on the DynaTil. The pumps were variable
displacement and pressure compensated with capabilities of 151.4 l/min (4ngm)
each at 13790 kPa (2000 psi). Flow from the pumps was directed to ﬂow dividers
which divided and directed the hydraulic ﬂuid to four hydraulic motors, one on
each disk gang. The peripheral disk speed was the main test variable and was set
by a ﬂow controller located at the tractor cab. The gang angle was controlled from
the tractor hydraulic system connected to a hydraulic cylinder in the gang angling
mechanism.

The subjective evaluation of ﬁeld performance showed more cutting and

mixing of mulch with the soil, more soil pulverization, more control of degree of

10

residue incorporation and soil pulverization by adjustments of gang angle and
gang speed, the ability to work in heavy mulch residues at high gang angles. Field
comparisons were also made of the DynaTil Operating powered vs. non-powered.
The difference between the powered and non-powered was very evident during
the spring of 1975 testwork where the powered machine did a much better job of
tearing apart sod. In one of the test ﬁelds he found that the horsepower
requirements of the DynaTil powered were less than non-powered implements. In
others, the DynaTil powered required less horsepower up to a certain forward
speed. Another area of interest was the tractor slippage. Operating powered
reduced the slippage 7% in one test ﬁeld and 4% in another.

Shearer, et a1. (1993) developed an open circuit, ﬂuid power drive for the
purpose of providing an alternative method for transmitting and controlling power
by replacing the mechanical PTO drive of a large baler. They reported hydraulic
drive design considerations related to this application and ﬁeld trial data. Their
investigation concluded that a hydraulically driven system could provide the
required power up to 25 kW (34 Hp) to the baler with safety, protect the
machinery against overloads and easily reverse the baler mechanisms when
plugging occurs. They also mentioned that there were some inefﬁciencies in the
hydraulic circuit sufﬁcient to require an additional oil cooler to maintain a

reasonable reservoir temperature.

2.3

11

Instrumentation

Measurements of the average draft required by the tillage equipment and
other pertinent parameters are necessary in research in order to determine the
equipment efficiency and loading, and develop more efﬁcient machinery. The
exact and simultaneous determination and the record of measurements related to
a study can be achieved by only using a well adapted instrumentation.

The data acquisition systems utilized in soil-engaging implement research
are usually designed to measure average draft, forward speed, disk speed, slip,
engine speed, fuel consumption, working depth, etc.

Most of the instrumentation that early researchers used was mechanical
and only able to monitor the variables of operation coarsely. Later some
photographic means to get simultaneous readings of the pressure gauges and pen
recordings were implemented for draft measurements. Clyde (1936,1939)
developed and used such techniques in his tillage meter method using a hydraulic
dynamometer for force determination.

For the last few decades, microcomputers have been used in agricultural
machinery for the acquisition and processing of the tractor-equipment
performance data. Numerous tractor monitoring and data acquisition systems have
been developed and reported during the 1980 and early 19903.

Carter (1981) developed an instrumentation system for a subsoil tool to

measure average draft by implementing strain gages.

12

Grevis et al. (1983) developed a low-cost, versatile microcomputer based
data acquisition system for tractor performance variables. The system measured
drawbar pull and power, ground speed, wheel slip, fuel ﬂow and engine speed and
provided for printing these variables as well as recording on magnetic tape.

Tembo (1986) reported the use of an Apple IIe microcomputer and a 16
channel 12-bit A113 A/D converter for the collection and analysis of data in ﬁeld.
The parameters measured included horizontal and vertical force components for
draft power calculation, PTO speed and torque, ground speed by a radar speed
sensor, right side front and rear wheel speeds for slip determination. The same PC
and A/D converter was used in other research done by Mah (1990) and Mungai
(1991) with some modiﬁcations depending on the variables needed.

Watts et al. (1989) reported a mobile instrumentation and data processing
system for testing cultivation equipment. The tractor three-point linkage and
drawbar forces, PTO speed and torque, forward speed, wheel slip, fuel ﬂow and
depth of work were measured and then the data from the pertinent transducers
were passed via a telemetry link to a location where they were recorded and
processed by an on—board computer driven by specially written programs.

A portable instrumentation system developed by Thomson et al. (1989)
was used to measure draft and speed when using either pull type or three point
hitch mounted tillage implements. They measured horizontal and vertical draft,
true ground speed and drive wheel speed. A compact and portable datalogger was

utilized for data collection. It also provided strain gage load cells with 5 Vdc

13

excitation voltage. Later the data collected was transferred to a microcomputer via
a magnetic cassette tape for ﬁirther processing.

Graham et al. (1990) reported an acquisition system mounted on a tractor,
which was designed to measure drawbar pull, true ground speed, and wheel
slippage while pulling farm implements. Maj or components of the system
consisted of a datalogger, a hydraulic drawbar dynamometer, and a radar-based
ground speed sensor.

Lackas et al. (1991) developed a portable data acquisition system using a
laptop computer for monitoring the performance of pull-type soil-engaging
implements during ﬁeld operation. They measured the horizontal and vertical
forces exerted by the implement and ground speed. A computer program written
in BASIC was used to open communications between the laptop and the A/D
(Analog to Digital) unit, to send commands to initiate data transfer, collection and

analyze the data.

3.1

Chapter 3

EQUIPMENT

Power Disk and Hydraulic System Components:

The disk used in this study was a 660mm (26") in diameter, 6.4 mm (0.25") thick,
5 87 mm (23.125") in spherical radius, 102mm (4") concavity. The rotating disk
mounted on a frame was attached to the tractor 3-point hitch in the normal
manner.

It was designed and built as a single unit powered disk after modifying a
disk plow with two disk blades. The scraper on the original disk was removed.
The disk and tilt angles were kept the same. Tilt angle was not adjustable on the
original plow. The disk angle and the tilt angle were measured to be 45 and 15
degrees, respectively. The disk was placed to the center line of the old frame with
its original shank. The rear furrow wheel was removed for better determination of
the hydraulic power effect on draft by avoiding its interference with the vertical
and side forces acting on the disk equipment.

Depth of working was controlled by lowering or raising the whole frame
by means of the tractor hydraulic system in position control mode. Also to give
better depth control, a support wheel running on the unplowed land was mounted
to the mid-left of the machine frame.

The power disk with the hydraulic system components is shown in Figure

3.1.1. Figure 3.1.2 shows ﬁeld operation of the disk.

14

., .
ii at“

. 2“ .-

\

 

Figure 3.1.2 The Power Disk in Operation

16

The disk was powered and controlled by the hydraulic system shown in
Figure 3.1.3. The ﬂow control valve (4) and ﬂowmeter (6) are the optional
devices used in preliminary tests.

The operation and design criteria of the hydraulic torque assisted system
can be explained as follows:

The desired soil displacement operation for a constant speed in powered
disk equipment is based on hydraulic torque or pressure applied to the disk. The
amount of torque available can be controlled by setting the relief valve.

When the pressure or torque requirement of the disk caused by soil
resistance is less than the relief valve setting, the disk will be supplemented
hydraulically to the required amount. While there is minimal soil resistance
against the disk rotation in operation, system pressure will never reach the high
relief valve settings thus providing the desired soil displacement and disk design
speed.

With the relief valve set at low pressures, the torque to be applied will be
limited up to the relief valve settings. If a resistance higher than-the valve setting
is seen, increasing pressure will be relieved by ﬂow through the relief valve back
to the reservoir.

The disk speed depends on system ﬂow rate. Flow rate can be maintained
at the desired level by providing sufﬁcient system pressure to overcome the soil

resistance. During the calibration of the disk speed sensor, ﬂow rate was regulated

17

 

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18

by tractor engine speed so as to increase PTO pump speed and by the ﬂow control
valve located at a point before the motor in the pressure line.

To set the relief valve to a certain maximum pressure for ﬁeld
experiments, the ﬂow control valve to the motor and the solenoid valve were both
shut off while the PTO pump was supplying ﬂow, then system pressure was
checked by the pressure gage while turning the pressure setting screw on the relief
valve. When the desired pressure setting was attained, the ﬂow control valve was
opened completely and the solenoid valve was opened or closed based on
operation mode selection and the test run was started.

Four maximum pressure settings of 2758, 4137, 6205, and 8274 kPa
(400, 600, 900, 1200 psi) were selected to observe the effect of supplemental
torque on potential draft reduction. The relief valve was set approximately
according to glycerin ﬁlled pressure gage readings assuming that they indicate
true values.

The detailed information about the hydraulic system components shown in
Figure 3.1.3 is given below.

Pump (2)

In the early stages of the research, the tractor’s own hydraulic pump was used to
power the disk. In preliminary ﬁeld tests, it was observed that the disk hydraulic
system was interrupted by the tractor’s hydraulic system while controlling the
working depth. Also the tractor hydraulics were not sufﬁcient enough to provide

large powers. Therefore, a Prince HC-PTO Pump (Model: HC-PTO-2A ) was

19

selected as the primary power source, independent from the tractor’s hydraulic
system.

It was a hydraulic gear pump, speciﬁcally designed for PTO drive
operation at 540 rpm (design rpm) on agricultural tractors. It provides a ﬂow rate
of 43.2 1pm (11.4 gpm) and an input power of 13.5 kW(18.l Hp) at design rpm.
These numbers are based on an operating pressure of 13790 kPa (2000 psi). The

required shaft type is 35 mm (1.375") in diameter, 6 tooth. (ASAE 8203.13

 

MAR94)

Suction and return line sizes were 25.4 mm (1") and 12.7 mm (0.5"),
respectively. A 100 mesh suction strainer and a 10 micron return line ﬁlter were
placed in the hydraulic circuit for both proper ﬂow and ﬁltering. Though the
minimum recommended reservoir size for the pump was 57 l (15 gal)

a IO-gallon size reservoir with 19 l (5 gal) of oil was implemented.

A 280 mm (11") long torque arm and 3.56 kN (800 lb) minimum working
strength chain were used as torque arm kit as described in the manual. The chain
was ﬁxed to the tractor chassis with two bolts perpendicular to the torque arm.
Disk Drive Motor (5)

To drive the disk, a low speed-high torque Ross brand hydraulic wheel motor
having a displacement of 327.8 cm3 (20 in3 ) was attached directly to the back of
the disk with a custom ﬂange and tang drive. And a custom made coupling was

used to couple the motor’s shaft to the disk shaft. The support wheel was adjusted

3.2

20
to such a level that the motor could not touch the ground surface in the ﬁeld when

in operation.

Relief Valve (2)

A pilot Operated relief valve by Sun Hydraulics was used to regulate maximum
system pressure and limit pressure in the system. A leakproof screw adjusts relief
settings between 690 and 20684 kPa (100 and 3000 psi). Care was taken not to
overload the hydraulic system beyond 13789 kPa (2000 psi) because the pump
used required a relief valve set at or below rated pressure of 15513 kPa (2250
psi). The relief valve was designed for ﬂow rates of up to 94.6 1pm (25 gpm).
Solenoid Valve (8)

A Parker brand (Model: DSO91ND012LP) cartridge style solenoid valve with a
base (Parker model: BO9-2-6P) allowing for individual piping of the valve was
selected for the hydraulic circuit. This valve was used to pressurize or
depressurize the system, for powered and non-powered cases. It is a normally
open DC solenoid valve. When the valve is energized, there would be no ﬂow
through the valve to the return line and all ﬂow would run through the motor up to
the preset system pressure.

Tractor

The towing tractor used for the power disk was a 1982 Ford model 7610. The
maximum net power and maximum PTO power of the tractor are 72.3kW

(97 Hp) and 64.2 kW (86 Hp), respectively. The transmission system offered a
variety of speeds to meet most working requirements. All speed categories were

attained easily by selecting the matching gear for a certain engine speed based on

3.3

21

4-wheel drive. The rear and front tire sizes were 18.4-34.6 and 13.6-24,
respectively.
Instrumentation-Data Acquisition System

Each component of a PC-based data acquisition system is essential for
obtaining proper results. Basically, every PC based data acquisition system
consists of the elements listed below and illustrated in Figure 3.3.1.

1. Transducers (Sensors)

2. Signal Conditioning Modules

3. Data Acquisition Hardware

4. Data Acquisition Software or Driver

5. The Personal Computer

 

Figure 3.3.1 Elements of a PC-Based Data Acquisition System

22

The instrumentation system used in this study included an IBM
compatible PC, a data acquisition board with 8 channels connected to one of the
PC’s buses, a Signal conditioner chassis with various modules and power supply,
two separate individual signal conditioning modules for the pressure sensors,
various transducers, a DC to AC voltage converter to energize the PC and signal
conditioner, an accessory battery, and different size cables and wires. All of these
components, except the sensors, were placed inside the tractor cab, paying
attention not to disturb the tractor driver during operation.

The instrumentation system was reassembled ﬁrst in the Fall of 1996 after
Mungai (1991) and ﬁnalized in the Summer 1997 following some modiﬁcations
to the disk Speed sensor. The same signal conditioner, rear wheel speed sensor
and strain gages were utilized and tested in other studies in conjunction with
Tembo (1986) and Mah (1990). Since the earlier strain gage circuits were
designed to measure horizontal and vertical components of draft and moments,
the strain gage covers were removed to ﬁnd out which ones measured the
horizontal draft component.

After the inspection of the circuits, the bridges intended for the
measurement of horizontal force components were also veriﬁed during the
calibration of sensors. The front wheel speed sensor used before was removed and

mounted to the back of the disk as the disk speed sensor.

23

The instrumentation system will be described in two sections, sensors and
data acquisition hardware. Calibration of the sensors will also be explained under
sensors.

3.3.1 Transducers (Sensors)
Main parameters needed for the performance evaluation of the power disk were
hydraulic pressure drop, draft, ground speed and disk speed. Therefore, strain
gages, pressure, and speed sensors were used to quantify these variables. Each
transducer sensed the related physical phenomena and produced electrical signals
that the data acquisition hardware could accept. The electrical signals produced
were inherently proportional to the physical parameter monitored. Draft forces,
speeds of the disk and rear wheel, and in and out pressures were converted into
analog signals that an A/D converter can measure. Then, the calibration response
equations were developed by performing linear regression procedure. The
resulting calibration equations and coefﬁcients of determination for the sensors
are shown in Table 3.3.1.

Each of the transducers will be described as follows.

3.3.1.1 Pressure Sensors for Measurement of Hydraulic Pressure Drop
The hydraulic system used two pressure-to-voltage transducers for measuring
both the pressure line pressure and return line pressure to determine the pressure
drop across the disk motor. The transducers (3 and 9) are located in the hydraulic

system as shown in Figure 3.1.3.

24

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25

In terms of calibration of these two sensors, Since both had already been
calibrated and used before in other studies in the Agricultural Engineering
laboratory, the calibration equations obtained previously were accepted as they
were. The calibration equations for the pressure transducers are given in Table
3.3.1 and speciﬁcations of the transducers are presented in Appendix B. As
mentioned previously, two glycerin ﬁlled pressure gages were also added to the
system so that it would be possible to set the relief valve to any desired pressure
and directly monitor the operation.

3.3.1.2 Draft Measurement
Determination of draft is the most important part for the evaluation of the power
disk as well as of other soil-engaging implements. Draft components are deﬁned
to be horizontal forces acting on two lower links and the top link. Draft power for
a certain case was then calculated by multiplying the forward speed by draft.
Measurement of vertical forces on lower links was neglected in this study.

The strain gages were utilized to quantify the above draft force
components on the three point links. The application of strain gages was
performed and described by Tembo (1986) as follows:

The lower link ends which were custom made hitching members bolted to
the original lower links were machined to uniform thickness and width at the
hitch points to facilitate the application of strain gages. Strain gages were
cemented on the machined surfaces. The top link was cleaned at mid-position and

strain gages were placed to respond to compressive and tensile forces only.

Certainly a great care was taken while installing these transducers to eliminate
possible damages and to maximize sensitivity, direction and location of gages.

Four strain gages (Micro Measurement, EA-XX-125PC-350) with 350
Ohm resistance established the Wheatstone bridge circuit for each of the draft
components measured. The Wheatstone bridge and its connection to the signal
conditioner module are illustrated in Figure 3.3.1.2. l. Excitation voltage was 10
volts and provided by the signal conditioner power supply. The special protective
coating system was preserved to avoid physical damages and water penetration.
The low level signals from the strain gages were transmitted to the M1060 signal
conditioning module through a ﬁve-conductor shielded cable.

Since the true and exact determination of draft depends on the true
calibration of strain gages, great care must be taken during the calibration.
The calibration of strain gages was carried out twice, one in the Fall of 1996 and
the other in the Summer of 1997. The latter was considered the ﬁnal calibration
and the data taken were used to develop the regression equations for force
determination. However, the data collected in both calibrations were very close to
each other. A detailed description of calibration process is given as follows:

During calibrations, known longitudinal forces were applied on each link
on which strain gages were placed. Tembo (1986) reported that the maximum
allowable tensile load on each of the links was found to be 20 kN (4500 lbs),
which had been determined from the geometry and material properties of the

machined lower links. Considering this ﬁnding and expecting maximum working

27

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28

force of 17.8 kN (4000 lbs), lower links were loaded up to 17.8 kN (4000 lbs) in
tension with 2.22 kN (500 lbs) increments. The top link was loaded up to 13.3 kN
(3000 lbs) in tension with the above increments The force was applied by
retracting a double acting hydraulic cylinder with a load capacity of 45 kN (10116
lbs). A hydraulic tensiometer (by John Chatillon & Sons) with a maximum load of
44.5 kN(10000 lbs) was used to measure the applied force. It was connected in
line, between the link and the hydraulic loading unit.

For each loading or known force, the data were taken and saved
immediately by means of the data acquisition system. Later, a standard regression
analysis of the data was carried out to obtain a linear regression equation that
predicts the output response voltage at each loading. The calibration equations
developed are presented in Table 3.3. 1.

After all transducers had been determined to be linear in their response,

strain gage response under compressive loading was assumed to be as linear as in

tensile loading.
3.3.1.3 Disk Speed Measurement
The sensor was to be capable of withstanding exposure to oil, dust and rough
handling because of its location. Therefore, a magnetic pickup sensor (inductive
proximity switch) manufactured by Wabash Inc. was selected and used to
measure the instantaneous rotational speed of the disk.
A custom-made sprocket having 30 teeth was implemented to generate

frequency output proportional to the disk speed. The frequency signals produced

29

were sent to the frequency to voltage (FN) converter module of the signal
conditioner. The reason for conversion was that the software driver of the data
acquisition board, which was a built-in function created by a driver setup program
inside an Excel spreadsheet, could only handle analog signals.

A number of disk speeds were set either by regulating the engine speed so
as to increase pump ﬂow or by metering the ﬂow control valve to the hydraulic
disk motor. When a certain disk speed was set and veriﬁed by tachometer, the
data acquisition system was initiated to sample the sensor. The sensor was
sampled for each speed setting and the data collected were recorded for the
regression analysis of the sensor output. Then, a calibration response equation
was developed as shown in Table 3.3. 1.

3.3.1.4 Ground Speed Measurement
To measure the rear wheel speed as a base for ground speed determination, a
cylindrical magnetic pickup (Wabash Inc.) was mounted on a bracket and
positioned near the periphery of the sprocket. The sprocket mounted on the axle
hub just inside the right rear wheel. A 1.3mm (0.05") gap was left between the
pickup and sprocket teeth surfaces. As the wheel turned, the passing of the
sprocket teeth and gaps past the magnetic pickup generated an alternating signal
with a frequency proportional to the wheel speed.

The frequency signal produced was sent to the signal conditioner and

processed by the M1080 Frequency to Voltage (FN) module, and the analog

3.3.2

30

voltage obtained was supplied to the related channel of the A/D converter located
in the PC bay.

Signal Conditioning Modules

The electrical signals generated by the transducers must be converted into a form
that the data acquisition board can accept. Ampliﬁcation is the most common
signal conditioning process. Low-level strain gage or pressure transducer signals
should be ampliﬁed to increase the measurement resolution. For the best
resolution. the signal should be ampliﬁed so that the maximum voltage swing
equals the maximum input range of the A/D converter.

In addition, by placing the ampliﬁer close to the transducer, interference
from noise picked up on the lines between the transducer and the computer is
minimized. This minimization occurs because the signal has already been
ampliﬁed before it travels across the lines to the computer. However, in mobile
applications like in this research, signal conditioners need to be kept in tractor
cabs due to harsh working conditions.

Two different signal conditioning modules were used for analog signal
ampliﬁcations. Since the pressure transducers had come with their pre-established
signal conditioning modules, only three modules of the 24-channel signal
conditioner were used for strain gage signal ampliﬁcations. Signal conditioning
modules also produced excitation for strain gages and pressure transducers, which

require external signal sources.

31

3.3.3 Data Acquisition (Computer Interface) Hardware
A data acquisition or computer interface system is a device that allows the user to
feed data from the real world to a computer. In this research, a PC—based data
acquisition system was used to monitor and record the signals produced by the
sensors. The data acquisition system utilized had only 8 channel inputs. There
were 7 sensors used on the power disk system to monitor the required variables
mentioned earlier. The signal from each sensor was sent to one of the 8 channels
of the A/D converter after signal conditioning or frequency to analog converting
processes.

The A/D converter was a plug-in computer data acquisition card, the
PIE-137 system (by P. 1. Engineering Inc., Williamston, Michigan). It was
installed directly on one of the PC’s serial buses within the computer case.
Advantages of such cards are speed and cost because they are connected directly
to the bus, and they do not need extra packaging and external power.

It uses a 12-bit converter with a maximum conversion rate of 66 000
conversions per second. It features 8 channel analog inputs with software
selectable ranges between i0.2 V and i200 V, and on-board timing.

The plug-in card is designed for the IBM compatible PCS and has a
terminal board (a panel named Smart-bay) that attaches it, and that is where all
the connections for sensors are made. The Smart-bay panel wired to the plug-in
card allows easy access to all 8 channels of input. Each Smart-bay has an onboard

microprocessor with its own RAM to handle data acquisition and control

functions and RISC processors with two F IFOs to handle the communication to
the computer. These processors are used to eliminate the time conﬂicts and to
handle high speed data transfer easily. The standard system connection panel is
also a P. 1. Engineering product with 8 standard 6 wire R111 (modular telephone
style) sockets.

Each socket has :

One Analog line (+)

One Analog Return line(-)

One Control and Power Ground line (fused ground)
One diode protected and current limited Power line
One Digital Input line (IN)

One Digital Control line (OUT)

ow+wwr

The PIE-137 system is supplied with driver software that works under
Windows. providing the user with the options needed for basic applications. The
details of the software will be explained in Section 3.3.4.

The sampling rate was selected at 25 Hz (samples per second) after
considering the test run lengths and data accumulation during each run. This
selection was in a range that most tillage research had been done. This rate was
also considered to be enough for the representation of the ﬁeld work because the
ﬁeld conditions and other measured variables do not change rapidly within the
selected working ranges.

The theoretical resolution of a A/D converter is equal to the size of the
Least Signiﬁcant Bit (LSB) of the converter. This is the smallest quantity of

voltage that the A/D converter can detect. It is determined by dividing the full

3.3.4

scale range by 2 raised to the power which equals the number of bits in the A/D

converter.

The full scale ranges used in this study were :6 V (12 V) for strain gages
and speed sensors, and ilO V (20 V) for the pressure transducers. These ranges
were chosen in order to match the input signal's range to the board's signal range
to take best advantage of the resolution available to accurately measure the signal.
The theoretical resolutions with the 1.2-bit converter used were 2.93 mV and
4.88 mV for the i6 V and :10 V ranges. respectively. These resolutions were
considered to be offering very accurate digital representation of the analog signals
interested. Information lost in the conversions was also considered negligible for
this type of research.

Data Acquisition Software for Analysis and Monitoring

Software is one of the PC-based data acquisition elements that must be examined
closely. Because plug-in data acquisition boards do not have displays, the
software is the only interface the user has to the system. The software is the
component that controls the system. The software integrates the transducers,
signal conditioning, and data acquisition hardware into a complete, functional

data acquisition system. Therefore, before developing a data acquisition system,

the software must be evaluated completely.

34

The driver software provided by the data acquisition board manufacturer
(P. 1. Engineering) included:

0 Simple functions under Visual Basic for Windows with example programs
for the user’s needs,

a Simple functions as add-ins to the Excel through the Menu bar,

0 A voltmeter displaying the analog input of the selected channel,

0 A multi channel monitoring utility displaying results after scanning all
channels.

From these options, the Multipoint Voltage add-in function in the Excel
environment was selected for the 7 channel data acquisition in the ﬁeld. Using
Excel for multipoint measurements, up to 8 channels with selectable ranges is
very convenient and easy for further analysis of data. During data acquisition, the
data is imported directly ﬁom the data acquisition hardware to an Excel
spreadsheet through special communication software that links the data
acquisition card with Excel. No programming skills are required for the control of
data acquisition system when the Multipoint Voltage add-in function in Excel is
used. This function is enough for every application unless a digital input is
measured. If there are any frequency or digital inputs to measure, these signals
must be converted to analog signals by means of a signal conditioning module
then directed to the computer interface sockets.

Alternatively, some simple functions provided by the manufacturer for

any control program which might be developed under Visual Basic would be used

3.3.5

35

to control the data acquisition process. For such custom applications, users have
to write their own software in standard programming languages. The
programming language that is used must be able to write to and read data from the
data acquisition board plugged into the computer.

Data acquisition software provided removed the low-level hardware
programming details and gave the user high-level function calls that could be used
with conventional programming languages.

Personal Computer (PC)

The data acquisition computer was an IBM compatible, 486-DX2/66-MHz
computer with a user-ﬁiendly Windows3.1 interface. Microsoft Ofﬁce’s Excel,
Visual Basic and the data acquisition board driver were already set up and ready
to use for a complete data collection and analysis.

The A/D system was a 12-bit system as described in detail in Section
3.3.3. The same computer was used during the calibration of the sensors. The
power source for the PC was a 12 Vdc-120Vac, 60Hz, 500 Watt voltage converter
(V enner Corp., Ohio, Model: 20-500).

Generally, the processing capabilities of the PCs have increased to a level
at which they have plenty of computational power for most data acquisition and
analysis applications. The PC microprocessor used was also capable of processing
data fast enough to respond to the real-world signals.

While working with a PC based data acquisition system, the limiting

factor for collecting large amounts of data is often the hard disk. Therefore, it was

36

ensured that there was sufﬁcient free disk space to hold the data before

performing any acquisition.

4.1

Chapter 4

FIELD PROCEDURES

Test Field and Soil Properties

The tests were conducted on a Michigan State University farm, in the ﬁeld
adjacent to the Clinical Center. All data from tests were taken on the same day,
July 28,1997. The soil on the test site was Metea loarny-sand. The ﬁeld was
nearly level and fallow with clover cover. A few lines of compaction were
observed in the ﬁeld probably caused during ﬁeld operations.

Measurement of soil cone index (index of soil strength) was carried out
after considering the ASAE Standard 83132. A nonstandard penetrometer
(manufactured by Soil Instruments, Chicago) was used based on complete depth-
penetration relationship, and measurements were made to a depth of 127 mm (5")
in the test area of the ﬁeld. The default rod length of the penetrometer was a
limiting factor on the penetrations. A depth of 127 mm (5") was considered
sufﬁcient enough to represent the soil property. The diameter and base area of the
penetrometer were 9.2 mm (0.362") and 67 mm2 (0.1 inz), respectively. Forty
cone index measurements were taken randomly across the ﬁeld to determine the
average cone index value of the soil.

Soil samples were also collected for the determination of soil moisture
content on the test day. Twenty samples were taken randomly to a depth of 203
mm (8") and immediately put into sealed plastic containers to avoid any moisture

loss. The soil moisture samples were weighed before drying. They were dried in

37

38

an oven at 105 °C for 24 hours and the moisture content was determined after
measuring each dried soil sample weight.
The average values, standard deviations, maximum values, and minimum

values of both cone index and moisture content are presented in Table 4.1.1.

Table 4.1.1 Soil Properties of Test Field for Power Disk Study

 

Soil Property [Average Std. Dev. Maximum Minimum

 

 

 

 

 

 

 

 

Cone Index (kPa) 4920 1410 7580 2410
Moisture Content
(%’ dry base) 10.4 1.2 12.3 8.2

 

There are several consequences of both the variability and the method of
the above measurements. First, the cone index and the soil moisture content were
assumed to be the average value representing the whole ﬁeld. Second, the
maximum value of force during penetration of the instrument was recorded
regardless of whether that maximum value was reached at the top, middle, or
bottom of the 127 mm (5") stroke.

In addition to the 7 variables monitored by the data acquisition system, the
average tillage width and depth of the randomly selected furrows were measured
and determined to be 438 m (17.25") and 197 mm (7.75"), respectively. They
were approximately ﬁxed all over the ﬁeld because the depth of working was
controlled by the support wheel running on the unplowed ground and the disk

angle was kept the same during the test runs.

4.2

4.2.1

4.2.2

4.2.3

39

Method of Data Collection in the Field

This section describes the procedures used in the ﬁeld to collect data.

Repetitions

Each test run required approximately 120 seconds to complete the data set. Three

repetitions of each variation under power or unpower conditions were recorded.
The tractor driver initiated the data collection once a steady-state was

reached at the start of each run. Another individual switched the solenoid valve on

and off for 20 second periods to simulate power-unpower conditions. During the

data acquisition, the process was also monitored by the tractor driver for any

possible errors that might occur.

Varying Ground Speeds

To observe the effect of different forward speeds, three different speeds were

used. The ground speeds under test were approximately 0.5, 1.0, and 1.5 m/sec

(1.12, 2.24, and 3.36 mph). The respective gears were Lowl, Low2, and Low3.

The selected speeds were established based on 4-wheel drive at 2100 rpm tractor

engine speed.

Varying Pressure Relief Valve Settings

Four different relief valve pressure settings, 2758, 4137, 6205, and 8274 kPa

(400, 600, 900 and 1200 psi), were accommodated by adjusting the hexagonal

screw and verifying them by looking at the pressure gages. Once a pressure level

was set up, it was kept constant for different ground speeds.

40

4.2.4 Data Acquisition and Sampling Frequency
As mentioned in detail earlier, a program provided by the data acquisition card
manufacturer, which is an add-ins function inside Excel, was directly used in the
data acquisition. With this version of Excel, it was possible to store 16384 rows of
data for each run. Considering sampling rate (frequency) of the system, it was a
very good data storage environment as well as a proper place for signal
processing.

The program, Multi-Point Voltage function under Excel, was activated
by selecting this function under the Signal + Control menu. Then, the channels
for the sensors and their bipolar voltage ranges were selected appropriately as
well as the data acquisition frequency and the required time for sampling.

As soon as the system was ready for data collection, the test run was
started. When steady-state was reached after a buffer zone, the Enter key was
depressed to run the whole data acquisition system. The screen was updated by
selected periods for checking the system operation by a cell in the upper left
corner of spreadsheet updating the data quantity.

A sampling frequency of 25 Hz was selected because it was sufﬁcient for
tillage data collection and proper for storing data. This frequency provided good
resolution of data points per distance traveled in the ﬁeld, especially at slow

speeds.

41

4.2.5 Data Storage
After each test run in the ﬁeld, the data collected was immediately stored in
individual Excel ﬁles on the hard drive of the PC along with the information
related to the settings of variables and the ﬁeld conditions. The data ﬁles were
also copied on ﬂoppy disks for any unexpected failure of the hard disk drive and
for ﬁirther analysis of the data in higher technology computers in the ofﬁce

(off-line).

Chapter 5

RESULTS AND DISCUSSION

A power (hydraulic assisted) disk implement with a single disk was
designed and fabricated in order to conduct experimental studies in the ﬁeld.

A PC based data acquisition system having sensors was implemented to measure
and record the pertinent variables instantaneously. The inﬂuence of hydraulic
torque assist to the disk on draft requirements was determined from the data
obtained.

Experiments to determine the effects of this new approach were carried
out in an MSU farm ﬁeld whose properties are presented in Chapter 4. Data
speciﬁc to the given conditions, settings and situation were obtained and later
statistically analyzed for a proper presentation of the research results.

There are some special considerations related to the results of ﬁeld
experiments. These have to be summarized before reporting and interpreting the

research results.

1. From the review of literature, it is understood that there are various settings or
mechanical design factors affecting draft requirements, such as angle settings
of disks, disk dimensions, and the geometry of the tractor-implement
attachment. The dimension and angle settings of the disk were considered to

be in the optimum range. These geometric settings were kept the same during

42

43

the experiments so that it could be possible to highlight only the effect of
powering the disk and to eliminate the effect of other factors as much as
possible.

. To be able to apply more hydraulic torque and to observe the effect of it on
draft requirements in a broader range, the maximum possible working depth
and cutting width were set based on the geometry of the disk and the attached
disk motor. Therefore, this application might not be an actual practice
performed by farmers.

. Since the lower links and top link between the tractor and the implement were
approximately in parallel with each other and the ground surface while
traveling, all strain gage measurements were considered to be due to pure
longitudinal forces. The cross sensitivity of the vertical forces on the
longitudinal forces was neglected. The calibration response equations of the
horizontal forces did not include the vertical axis response voltages (cross
sensitivity).

. The forward speed of the tractor was measured only by means of the speed
sensor-sprocket system placed on the right rear wheel. Slip was assumed to be
negligible for this tractor-disk implement match because of the ratio of
available power by tractor and the draft power required by the disk.

. System ﬂow rate used in hydraulic power calculations was determined based

on the motor displacement and disk speed measured by the speed sensor.

5.1

44

6. In terms of soil condition, the average ﬁeld cone index was found to be
relatively high and it varied a lot even in a very short distance over the ﬁeld.
Power Disk
The powered disk implement was designed only to test some concepts regarding
hydraulic power applications on agricultural machines. It was intended that a
basic disk implement would be fabricated only for experiments in the ﬁeld and
then the possibility of applying this technique on other disk equipment would be
sought if signiﬁcant improvements were achieved. Because of conflicts and
doubts about the justiﬁcation of powered disks from the previous studies on
powering disk implements, this concept had to be veriﬁed whether the powered
system works and it is practical.

Some shortcomings regarding only the hydraulic components and body of
the machine were observed during preliminary experiments in the ﬁeld and later
they were modiﬁed step by step for more reliable performance, as mentioned
previously.

The hydraulic pressure relief valve was very helpful while regulating
system pressure and provided the desired pressure settings. It was capable of
adjusting system pressure up to 20680 kPa (3000 psi) with 690 kPa (100 psi)
increments. However, the maximum system pressure required in the ﬁeld was

determined to be around 6900 kPa (1000 psi).

5.2

45

The solenoid valve was activated manually by an on-off switch for certain
periods of time. The line on which the solenoid valve was placed was used to
bypass ﬂow so that the disk could be set to nonpowered. This method was an easy
way of controlling or directing ﬂuid ﬂow to obtain the power and non-powered
modes.

No leakage or contamination was observed from the hydraulic system
components under very harsh and dirty ﬁeld conditions. It can be stated that it is
technically feasible to apply hydraulic power and control techniques on soil-
engaging agricultural implements with safety.

Data Acquisition System and Sensors

Accuracy in measurements is very important in any research since every ﬁnding
or conclusion depends on the data obtained by the data acquisition system. Each
variable must be measured with acceptable accuracy and reliability. Therefore, the
sensors used in this study, except the two pressure transducers, were subjected to
certain calibration procedures under laboratory conditions and their accuracy was
determined. For the pressure transducers, the previous calibration response
equations determined by the Agricultural Engineering Department were used.

One of the proximity sensors used to determine the disk speed
malfunctioned. After a long inspection of connections to that sensor considering
the other potential noise sources, it was detected that the sensor was producing
weak signals. This problem was eliminated after replacing that sensor by another

sensor producing stronger signals.

5.3

46

The calibration response equations developed and the coefﬁcient of
determination (r2) values of the measured parameters are listed in Table 3.3.1. The
measured load exhibited excellent agreement with the applied load for each
sensor. The coefﬁcient of determination (r2) approached 1.000 for all calibration
equations.

All sensors were essentially found to be linear in their responses to known
applied loads under laboratory conditions. The hysteresis effect on the strain
gages while loading and unloading was found insigniﬁcant for all three strain
gage bridges on the links.

The PC with the data acquisition card in the tractor cab was able to
monitor and record the conditioned analog voltages generated by sensors. While
performing each test run, the data being collected was monitored for any possible
failure. Despite the harsh and dusty environment in the ﬁeld, neither the PC with
data acquisition board nor the signal conditioner failed during operation.

The data acquisition system developed can be considered a portable
system because it can be easily moved to other tractors. As the microcomputer
technology improves quickly, new and affordable laptop computers will become
available in the market. The use of laptops will soon replace the cumbersome PCs
with monitors and the required power converters.

Main Concepts for Evaluation of Hydraulic Torque Assisted Disk
The detailed evaluation of main concepts are based on average values of

measured variables. The complete statistical analysis of data sets for each run are

5.3.1

47

shown in Appendix C. Equations for the calculation of parameters, such as disk
speed, draft power, hydraulic rotary power, are listed in Appendix A. Two sample
graphs prepared from the conditioned raw voltage data are shown as in Appendix
D.

The main concepts analyzed are 1) Draft Ratio versus Hydraulic Torque
Assist, 2) Ratio of Disk Speed-Ground Speed versus Torque, 3) Speciﬁc Power
Requirements of the Disk Implement.

Draft Ratio versus Hydraulic Torque Assist

The most important objective of this research was to determine the real effect of
powering the disk implement on draft requirements. All energy saving related
studies regarding soil-engaging implements were concerned about reducing the
draft. For this purpose, most workers tried to implement rotary power by
mechanical means or to apply vibration to the active working blade. The previous
papers reported conﬂicting results regarding the draft reduction when disks were
powered.

In this study, a hydraulic power transmission technique that provides the
required supplemental hydraulic torque was studied. The amount of torque
available to the disk was set as a variable and limited by the relief valve at low
pressure settings. In previous experiments reviewed in Chapter 2, the speed of
disks were controlled by means of gear reduction units for a constant disk speed.
Therefore, the disks were rotating at a preﬁxed RPM and the torque to be applied

was dependent on the soil resistance against the machine during forward motion.

48

In this research the PTO pump provided ﬂow depending on the preset
engine speed. The relief valve was on standby and it was bypassing overﬂow
when needed by reducing excessive system pressure down to the preset pressure
settings. Meanwhile, there was some loss in the disk speed because the bypassed
ﬂow rate reduced the ﬂow rate passing through the motor. Therefore, there was
always ﬂuctuations on the disk motor speed at low relief valve settings.

When the relief valve was set to 8274 kPa (1200 psi), the system pressure
on average never reached that value. All ﬂow was passing through the disk motor
providing quite constant disk speed. Such high pressure relief valve setting is the
design working setting for maintaining constant disk speed and avoiding the
inefﬁciency due to relieved ﬂow rate through the relief valve.

Each test run included both powered and non-powered working conditions
for comparison of the two operation modes. The hydraulic system was alternately
powered and unpowered every 20 seconds for 3 replications. The experimental
data was collected for 3 different ground speeds at 4 various pressure relief valve
settings and the draft ratios were obtained after the draft calculations. The term of
draft ratio is deﬁned as the draft measured in powered mode divided by the draft
measured in non-powered mode. The draft ratios indicated how much draft power
reduction was achieved for the selected variable settings.

The acquired data sets showing the relationship between the draft ratio and
hydraulic torque occurring for the three forward speeds are presented in Figure

5.3.1.1.

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Ideally when no hydraulic torque is applied to the disk motor, the draft
ratios of powered and non-powered modes must be 1 or unity. This means that no
pressure drop occurs and the disk is free rolling in either case. As the torque
(pressure drop) being applied increases, the draft ratio is expected to change
somewhat. Figure 5.3.1.2 illustrates that there is certainly draft reduction with
increasing pressure drop. The maximum draft reduction attained in this research
was around 15 % and it occurred at the maximum torque or pressure drop. The
maximum draft reduction of 15 % is based upon the best ﬁt line shown in Figure
5.3.1.2.

The regression line in Figure 5.3.1.2 has a very poor coefﬁcient of
determination ( r2 ) of 0.18 with scattered data sets of ratios. The scattered data,
pointing to a poor relationship, can be explained by the changes in soil resistance
during operation. This is because other variables which might affect the ratios,
such as ground speed, working depth and width, were determined to be quite
constant for all test runs. A more reliable regression line to predict the draft
reduction versus hydraulic torque or rotary power could have been established in
a test ﬁeld with more uniform soil properties or in more controlled soil bins under
laboratory conditions.

It can be summarized that powering a single disk implement slightly
reduces the required draft power but it also often increases the total power
required due to supplemental rotary power to the disk. For example, Table 5.3.1.1

shows the total power requirements of powered and non-powered modes for

 

52

Table 5.3.1.1 Power Requirements (kW) for Different Ground Speeds at Relief Valve

Setting of 8274 kPa (1200 psi)

 

 

 

 

 

 

 

 

 

Operation Power Ground Speed
Mode Component 0.5 m/sec 1 mlsec 1.5 m/sec
Draft 3.62 9.00 13.76
3
i
g. Rotary 0.07 0.08 0.08
E
Total 3.69 9.08 13.84
Draft 3.73 7.66 10.42
B
i‘.’
g Rotary 1.22 1.92 2.21
62
Total 4.95 9.58 12.63

 

 

 

 

 

 

 

5.3.2

53

different ground speeds at the pressure valve setting of 8274 kPa (1200 psi). Total
power requirements for 0.5 m/sec (1.12 mph) and 1 m/sec (2.24 mph) increased
when the disk was powered. For the ground speed of 1.5 m/sec (3.36 mph), the

total power required decreased, but when the relief valve was set to 900 psi at the

 

same ground speed, the total requirement increased. Therefore, as a soil working
implement it is impossible to justify powering the disk implement studied in terms

of energy savings. If the powered disk is considered to be a potential root crop

 

harvester for the farmers of developing countries, it might perform the required
function providing the desired operating speeds and the rotary power.

Ratio of Disk Speed-Ground Speed versus Torque

Change in the ratio of disk peripheral speed and ground speed (Vd/Vg) against the
supplemental hydraulic torque applied was another important concept under test.
The resulting data for three different ground speeds when the disk was powered
are presented in Figure 5.3.2.1, where each data point represents the average of
three replications.

The maximum torque occurring during all test runs was found in the
neighborhood of 360 N-m (3200 lb-in). The effect of lower torque values on
Speed ratio might be proportioned to that of the maximum torque applied so that it
can be general rule applicable to hydraulically driven disks.

Figure 5.3.2.1 Shows that there is almost a linear relationship between
Speed ratio and supplemental torque applied. Non-powered data sets indicated a

speed ratio of approximately 1 for all forward speeds. Therefore, it is expected

54

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5.3.3

55

that all speed ratios for different ground speeds converge at 1 when no
supplemental torque is applied. In Figure 5.3.2.1, all speed ratios converge at a
value of 1.15 when a torque of 100 N-m (888 lb-in) is applied and increase up to
the values of 1.54 and 2.04 depending on the forward speeds at the torque values
of 3 16 N-m (2792 lb-in) and 358 N-m (3168 lb-in), respectively. The speed ratios
increased linearly for each ground speed depending on the torque applied. At low
relief valve settings, load inertia or soil resistance made it impossible to accelerate
to full disk speed, so part of the pump output bypassed over the relief valve.
Therefore, there had always been power losses at the relief valve settings of 275 8,
4137 and 6205 kPa (400, 600, 900 psi).
Speciﬁc Power Requirements of the Disk Implement
The performance of disk implements is usually measured in terms of draft,
speciﬁc draft, power requirements, and depth. In order to provide some practical
data for those who are interested in disk implement design, the power
requirements of the powered disk used were calculated and discussed below.

Speciﬁc draft power for tillage equipment is deﬁned as the power required
to manipulate the soil per unit area at a given ground Speed. Total speciﬁc power
for a powered equipment includes both speciﬁc draft power and speciﬁc rotary
power required to displace the soil per unit area. These are the important criteria
while comparing different powered disks.

The draft power, rotary power and total power requirements of the disk

used in this study are tabulated for different forward speeds and system pressure

56

settings in Appendix C. Using these tables, speciﬁc power requirements of the
disk implement for each case can be found by dividing the resultant power values
by the average cross section of the furrows, which was determined to be
approximately 716 cm2 (111 inz). This provides a means to compare or estimate
the power requirements of such disk implements under different working
conditions.

The forward speed is the most inﬂuential factor on draft requirements. The
tabulated data indicate that as the forward speed increases, the total speciﬁc

power requirement also increases.

Chapter 6

CONCLUSIONS

The following conclusions were drawn from the results of the research:

1.

Disk implement draft as a function of supplemental hydraulic torque changing with
the pressure drop across the hydraulic motor can be determined by a PC based data
acquisition system.

There is a slight relationship between the ratio of power and non-power drafts

and the torque applied. The ratios of powered and non-powered drafts were related
statistically to the torque required to rotate the disk blade by using the regression
analysis in Excel. 75% of the draft ratio data points are observed less than 1, that is,
the draft forces become smaller when the disk system is powered. Once the
supplemental torque increased to the breakaway torque value, the maximum draft
power reduction was achieved by about 15 percent based on the best ﬁt line of
regression. However, the supplemental hydraulic power requirements often cancelled
the savings of draft reduction.

The PC based data acquisition system performed the data collection and storing
procedures without any loss or damage despite the harsh and dirty environment. An
effective method of measuring rotational speed of the disk was developed using a
proximity switch and a custom-made sprocket placed around the disk ﬂange at the

back. This might provide a basis for a better understanding of soil handling by disks.

57

 

58

4. The results also show that there is a strong inﬂuence of soil variability on the draft
data as mentioned in previous studies. Therefore, the test of such disk implements for
performance evaluation must be conducted in laboratory soil bins for more reliable
results.

5. The nature of the ratio of disk peripheral speed and forward speed, for a powered

disk was determined as a function of hydraulic torque in various forward speeds. This

parameter was observed to be about 1 when the disk was free rolling without

supplemental hydraulic torque.

Chapter 7

RECOMMENDATIONS FOR FUTURE RESEARCH

. Since the results from the study are not encouraging in terms of savings in energy
utilization, the application of vibration techniques together with powering disks might
be investigated for much more potential reduction in draft with rational savings.

A more reliable comparison method of the disk implement powered and non-
powered can be achieved when the disk is powered and non-powered for shorter time
intervals. For example, 5 or 10 second interval instead of 20 seconds for each mode
can be conducted in order to reduce the inﬂuence of soil variation on implement draft.
. Photographic means to record the work done by the equipment can be implemented
for the subjective evaluation of the degree of pulverization and soil displacement.
Using these visual records along with the numerical data can provide more reliable
interpretation of the machine performance.

. The inﬂuence of the powered disk implement on soil compaction can be determined
for a complete evaluation of the powered system.
. To be able to set more uniform soil conditions by selecting the most appropriate test

routes, cone index measurements can be made in the test site before test day.

59

APPENDICES

APPENDIX A

APPENDIX A

POWERED DISK IMPLEMENT PERFORMANCE EQUATIONS

This appendix presents the performance equations used in calculations and the
pertinent dimensions of the powered disk and tractor right rear wheel. All calculations
were performed in Excel. The raw voltage data were converted to actual values of the
related variables based on the calibration equations developed. Then, statistical analysis

of the data was performed and printed in tabular form as shown in Appendix C.

60

61

PERFORMANCE EQUATIONS NOMENCLATURE

Right Link Horizontal Force

Left Link Horizontal Force

Top Link Horizontal Force

Net Draft Force

Disk Diameter

Ground Speed

Peripheral Disk Speed
3.141592654

Peripheral Disk Speed to Ground Speed
Pressure In to Hydraulic Motor
Pressure Out from Hydraulic Motor

Pressure Drop across Hydraulic Motor

1. IMPLEMENT DRAFT REQUIREMENT (N):

DRAFT (kN) =R(i)+L(i)+T(i)

= I:Net

2. DRAFT POWER (kW):

DRAFT POWER (kW) = FM vgr

=(kN*m/s)

62

. HYDRAULIC ROTARY POWER (kW):

ROTARY POWER (kW) = [(PIn - Po...) * Q] / 60000
= (AP * Q) / 60000

= (kPa * l/min) / 60000

. TOTAL POWER (kW):

TOTAL POWER (kW) = DRAFT POWER + ROTARY POWER

= (kW)
. POWERED DISK:
DISK DIAMETER = 660mm
DISK PERIPHERAL SPEED (m/s) = [RPM * (1r * D)] / (60*1000)

= (rpm*1t*mm) / (60* 1000)

APPENDIX B

APPENDIX B

SPECIFICATIONS OF SENSORS

Appendix 8.] : Strain Gages for Determination of Draft Forces

Sensor Origin : Micro Measurements (MM) Inc., (EA-XX-125PC-3 50)

Speciﬁcation : Four arm 350 0 full bridge assembly, bonded onto the
right and leﬁ sides of the lower drawbar links, and at the
mid-point of the top link.

Excitation Voltage : 10 volts-dc

Calibration Range for Static Loading:

Right Link Force : 0 to 17.8 kN (4000 1b) with increments of 2.2 kN (500 1b)
Leﬁ Link Force : 0 to 17.8 kN (4000 lb) with increments of 2.2 kN (500 lb)
Top Link Force : 0 to 13.3 kN (3000 lb) with increments of 2.2 kN (500 lb)

Appendix B.2: Strain Gage Amplifier (Signal Conditioner)

Origin : Data Capture Technology Inc.
Speciﬁcations
Input Conﬁguration : High Gain Differential
Input Impedance : 1 MO Differential
Il‘lput Mode : Resistive bridge in 1, 2 or 4 arm connection with internal

bridge completion.
IIlput Range : Up to 500 mV

NOise : Less than 5 uV r.m.s. at maximum gain

63

64

Drift : Less than 2 pV at maximum gain

Bandwidth : DC — 10 kHz
20 — 5000 in switched steps with interpolate control
Voltage Output : Up to i 2 Vdc

Voltage Output Impedance: 0.5 Q

Appendix B. 3 : Pressure Transducers for Determination of Pressure Drop

: Basingstoke, England

Origin
Series 2000, Transinstruments
Model : 2000 G G H30 02 AlOA H04
Range : 20680 kPa (3000 psi)
Output : O -10 Vdc
Excitation Voltage : 12.5 - 30 Vdc
3 Cables to transducers : Power(+), Ground (-), Analog Signal (volt)

Appendix B. 4 : Speed Sensors for Determination of Disk and Ground Speeds
Origin : Wabash Inc.
Model : 60-0198"G", Magnetic Pickup (cylindrical pole piece, 2.5

inches reach

Speciﬁcation : 14 VP-.. at 30 inches /sec, 1.3 mm (0.05") air gap
Kernko (Japan) RPM Speed Indicator with special adapters was used as tachometer while

calibrating the disk and ground speed sensors. The indicator had a range of 100 - 1000

er- For slower tractor rear wheel speeds, a stopwatch was used.

APPENDIX C

APPENDIX C

RESULTS FROM STATISTICAL ANALYSIS

Excel was used for the statistical analysis of the data collected. First, raw voltage
values of each variable were converted to actual values. Second, the pertinent
conversions required for SI units were performed. Third, the data were statistically
analyzed. Last, the results of the statistical analysis were arranged and presented in

tabular form on the following pages.

The tractor engine speed for all tests was set to be 2100 rpm. The disk implement
was operated in the position control of the tractor hydraulic system.

The headline at each table lists: Test Number, Tractor Gear Selected, Mode

(Powered, Non-powered), Relief Valve Pressure Setting.

65

 

Test l-N, Lowl, Non-Powered, NA

66

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

  

 

 

 

  

 

 

 

 

l1 1.0 AVG MAX MIN ST DEVI
||Top Compression (kN) 8303.01 14038.96 4059.02 1791.72"
[[Right Draft (kN) 10934.11 16389.22 6360.79 1814.96]
ﬂLeft Draft (kN) 4583.38 8658.93 1203.40 1331.45“
[Ground Speed (m/sec) 0.58 0.65 0.52 003"
“Disk Speed (m/sec) 0.57 1.96 0.39 0.21"
“Pressure Drop (kPa) 669.97 806.68 537.79 40.29"
IFlowrate (l/min) 5.41 18.59 3.72 1.97||
||Net Draft (kN) 7214.48 11612.31 2895.00 1452.76)
ﬂVngr 0.98 3.32 0.73 0.36“
"Draft power (kW) 4.20 6.97 1.64 0.88“
||Rotary power (kW) 0.06 0.21 0.04 0.02||
“Total power (kW) 4.26 7.04 1.69 0.87||
Test l-P, Lowl , Powered, 2758 kPa (400 psi)
m-P AVG MAX MIN ST DEW
[33p Compression (kN) 7153.89 12332.43 3043.75 1578.04)
[Bight Draft (kN) 10319.61 16861.15 6183.82 1781.90]
[511 Draft (kN) 3691.15 7470.37 203.92 1274.13]
[ground Speed (m/sec) 0.58 0.65 0.52 003]
Disk Speed (m/sec) 0.61 0.98 0.48 0.061
Pressure Drop (kPa) 2582.79 3061.25 2223.54 149.95!
Flowrate (l/min) 5.83 9.24 4.59 0.59|
Net Draft (kN) 6856.87 11269.92 2927.13 1626.83)
ngr 1.05 1.61 0.88 0W
Draft power (kW) 4.00 6.85 1.63 0.98“
Rotary power (kW) 0.25 0.40 0.18 0.03]
otal power (kW) 4.25 7.13 1.87 0.98

 

 

 

 

 

 

 

67

Test 2-N, Lowl , Non-Powered, NA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  

 

 

 

  

 

 

 

  

 

 

|12-U AVG MAx MIN ST DEV ]|
[Top Compression (kN) 7264.07 12526.85 3735.00 1700.68[|
[Right Draft (kN) 8897.20 14000.10 4827.03 1745.73||
[Left Draft (kN) 2967.40 7119.20 -39.19 1393.47“
Fround Speed (m/sec) 0.54 0.62 0.47 003"
[Disk Speed (m/sec) 0.56 0.83 0.41 0.07
[Pressure Drop (kPa) 609.04 754.97 496.42 39.82
[Flowrate (l/min) 5.26 7.87 3.88 0.67
[Net Draft (kN) 4600.52 8748.03 729.81 1538.36
[Vngr 1.04 1.61 0.80 0.12
[Draft power (kW) 2.46 4.76 0.39 0.82
[Rotary power (kW) 0.05 0.08 0.04 0.01
[Total power (kW) 2.52 4.82 0.46 0.82
Test 2-P, Lowl, Powered, 4137kPa (600 psi)
ILZ-P AVG MAX MIN ST DEV
mm Compression (kN) 7073.46 15162.24 3259.76 1623.67
"ﬂight Draft (kN) 8751.68 16595.69 5682.40 1756.81
[Left Draft (kN) 2653.26 7497.38 -39.19 1093.44
Ground Speed (m/sec) 0.54 0.63 0.46 0.03"
Disk Speed (m/sec) 0.71 0.87 0.59 0.04[
Pressure Drop (kPa) 3841.69 4550.50 3092.27 293.67I
Flowrate (l/min) 6.76 8.20 5.63 0.39[
Net Draft (kN) 4331.48 9141.06 1503.49 1397.94[
ngr 1.33 1.57 1.16 0.06[
Draft power (kW) 2.33 5.35 0.80 0.77]
Rotary power (kW) 0.43 0.58 0.34 0.04[
Total power (kW) 2.76 5.88 1.21 0.77“

 

 

 

 

 

 

68

Test 3-N, Low 1, Non-Powered, NA

 

Test 3-P, Lowl, Powered, 6205 kPa (900 psi)

 

Test 4-N, Lowl , Non-Powered, NA

69

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ﬁ4-U AVG MAX MIN ST DEV]
[Top Compression (kN) 8378.15 12397.24 5527.93 may
[Right Draft (kN) 10805.65 14649.00 8101.02 971.68[
[Left Draft (kN) 4197.96 6930.11 2256.90 795.12[
[Ground Speed (m/sec) 0.55 0.63 0.47 0.03[
[Disk Speed (m/sec) 0.61 0.83 0.48 0.05“
[Pressure Drop (kPa) 691.35 837.71 558.47 50.15[
[FIowrate (llmin) 5.74 7.87 4.51 0.49]
[Net Draft (kN) 6625.46 9596.10 3794.64 941 .93[
[Vngr 1.11 1.51 0.94 0.07[
[Draft power (kW) 3.62 5.47 2.08 0.55[
[Rotary power (kW) 0.07 0.10 0.05 0.01“
[Total power (kW) 3.69 5.53 2.16 0.55[
Test 4-P, Lowl, Powered, 8274 kPa (1200 psi)

|14-P AVG MAx MIN ST DEV ||
ITop Compression (kN) 6807.38 18402.48 602.77 2281 .12"
[Right Draft (kN) 10230.57 19486.24 2939.33 2208.22“
Eeft Draft (kN) 3390.33 11171.12 -1903.08 1606.29“
[Ground Speed (m/sec) 0.55 0.61 0.48 0.03“
Eisk Speed (m/sec) 1.03 2.96 0.68 0.31“
Pressure Drop (kPa) 7517.52 9080.32 5894.97 573.63“
[Flowrate (l/min) 9.75 28.06 6.42 2.95“
[Net Draft (kN) 6813.52 12254.89 207.08 1690.7ql
[Vde 1.89 5.77 1.28 0.57“
|Draft power (kW) 3.73 6.64 0.10 0.95“
[Rotary power (kW) 1.22 4.02 0.74 0.38“
[Total power (kW) 4.95 9.33 2.02 0.92"

 

 

 

 

 

70

Test 5-N, Low 2, Non-Powered, NA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[21-u AVG MAX MIN ST DEV [
[Top Compression (kN) 8774.87 17257.60 192.34 2236.26[
[Right Draft (kN) 12232.96 21255.97 2319.92 2606.83[|
ﬂeft Draft (kN) 5276.68 12008.52 -1281.78 1588.06[
[Ground Speed (m/sec) 1.13 1.21 1.07 0.03[
[Disk Speed (m/sec) 1.04 1.53 0.86 0.09[
[Pressure Drop (kPa) 515.14 682.58 372.31 49.57]
[Flowrate (l/min) 9.84 14.52 8.12 0.87]
Wt Draft (kN) 8734.76 16627.06 845.80 2043.54]
[Vngr 0.92 1.39 0.80 0.08]
|[Draft power (kW) 9.86 18.24 0.94 2.30!
[Rotary power (kW) 0.08 0.14 0.06 0.01[
[TotaI power (kW) 9.94 18.33 1.07 2.30]
Test 5-P, Low 2, Powered, 2758 kPa (400 psi)

[21-P AVG MAX MIN ST DEVI
[Top Compression (kN) 9174.80 20778.66 2417.30 2293.32I
[Right Draft (kN) 13224.86 22376.79 6213.32 2836.80]
[Left Draft (kN) 5560.98 13089.03 284.96 1526.71]
||Ground Speed (m/sec) 1.12 1.19 1.04 0.03|
[Disk Speed (m/sec) 1.19 2.02 0.91 Oﬂ
|Pressure Drop (kPa) 2478.09 2937.14 2120.12 154.37|
[FIowrate (Vmin) 11.30 19.13 8.66 1.54]
[Net Draft (kN) 9611.04 16866.78 4108.64 2194.@
|Vngr 1.07 1.81 0.84 0.14|
[Draft power (kW) 10.76 18.79 4.72 2.4g
@tary power (kW) 0.47 0.83 0.33 0.07[
[Total power (kW) 11.22 19.19 5.11 2.4g

 

 

 

 

 

71

Test 6-N, Low 2, Non-Powered, NA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[22-U AVG MAX MIN ST DEVI
[Top Compression (kN) 9046.34 16458.34 5095.90 1735.23
[Right Draft (kN) 11095.15 17775.51 6360.79 2009.8ﬂ
Heft Draft (kN) 4185.61 9172.18 1041.32 1209.47]
[Ground Speed (m/sec) 1.08 1.17 1.00 0.03]
[Disk Speed (m/sec) 1.05 1.22 0.88 0.06[
[Pressure Drop (kPa) 429.09 703.26 289.58 56.24]
[Flowrate (Vmin) 9.96 11.53 8.33 0.56]
[Net Draft (kN) 6234.41 10489.35 1379.08 1609.75]
[Vngr 0.97 1.11 0.84 0.05]
[Draft power (kW) 6.73 11.55 1.56 1.72]
[Rotary power (kW) 0.07 0.11 0.05 0.01[
[Total power (kW) 6.80 11.62 1.64 1.72]
Test 6-P, Low 2, Powered, 4137 kPa (600 psi)

[22-P AVG MAX MIN ST DEV |
[Top Compression (kN) 7823.04 13066.89 3864.61 1587.9g
[Right Draft (kN) 10125.29 15858.31 6567.26 1688.46]
[Left Draft (kN) 3387.61 7254.27 420.02 1245.g[
[Ground Speed (m/sec) 1.07 1.16 1.01 DIM
[Disk Speed (m/sec) 1.34 1.51 1.12 0%
[Pressure Drop (kPa) 3708.10 4333.32 2999.19 299.89]
[Elowrate (Ilmin) 12.74 14.35 10.57 0.64]
[N_et Draft (kN) 5689.86 9731.66 1832.38 1464.07]
[Vngr 1.25 1.40 1.07 0.03[
[Draft power (kW) 6.10 10.80 1.92 1.58]
[Rotary power (kW) 0.79 1.01 0.60 0.07[
[rotaI power (kW) 6.89 11.60 2.63 1.57]

 

 

 

 

 

Test 7-N, Low2, Non-Powered, NA

72

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[23-0 AVG MAX MIN ST DEV [
[Top Compression (kN) 8256.24 18056.86 2395.70 2153.27[
[Right Draft (kN) 10833.70 17451.06 2791.85 2299.08]
[Left Draft (kN) 4360.96 15790.32 -66.21 1654.57]
[Ground Speed (mlsec) 1.08 1.17 0.99 0.03[
[Disk Speed (mlsec) 1.13 2.41 0.91 0.17]
|Eressure Drop (kPa) 470.24 713.60 330.95 45.75[
[@wrate (l/min) 10.73 22.87 8.66 1.65[
Bet Draft (kN) 6938.43 14417.64 329.94 1979.96l]
[Vngr 1.05 2.20 0.86 0.16

Eraft power (kW) 7.47 15.76 0.37 2.14

@tary power (kW) 0.08 0.27 0.06 0.02

[Total power (kW) 7.56 16.03 0.53 2.14

Test 7-P, Low 2, Powered, 6205 kPa (900 psi)

[23-P AVG MAx MIN ST DEV |
[Top Compression (kN) 7456.98 14362.98 3713.40 1650.1ﬂ
Bight Draft (kN) 11048.99 18807.85 7363.64 1858.70]
[L_eft Draft (kN) 3953.95 9631.39 474.05 1433.8ﬂ
Eround Speed (mlsec) 1.08 1.16 1.01 0.03[
@sk Speed (mlsec) 1.59 1.91 1.36 0.12[
[Pressure Drop (kPa) 5638.73 6918.83 4374.69 454.99[
ﬂawrate (l/min) 15.03 18.09 12.86 1.14]
[N_et Draft (kN) 7545.96 13829.81 3717.69 1834.73[
[Vngr 1.47 1.76 1.27 0.11[
[Draft power (kW) 8.15 15.05 3.97 2.1%
Eptary power (kW) 1.41 1.90 1.11 0.1g[
[Batal power (kW) 9.56 16.38 5.38 1.93]

 

 

 

 

 

73

Test 8-N, Low 2, Non-Powered, NA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[24-U AVG MAX MIN ST DEV]
[Top Compression (kN) 9793.54 17127.99 5398.32 1858.57]
@ht Draft (kN) 12809.70 22022.85 7806.07 2223.53
[Left Draft (kN) 5573.34 10198.66 2337.93 1256.40]
[Ground Speed (mlsec) 1.05 1.14 0.97 0CD]
[Disk Speed (mlsec) 1.08 1.28 0.88 0.05]
[Pressure Drop (kPa) 491.65 703.26 72.39 64.24]
[Flowrate (Ilmin) 10.24 12.11 8.33 0.50]
INet Draft (kN) 8589.50 15341.74 3768.59 1664.4ﬁ
[Vngr 1.03 1.19 0.88 0.04[
Raft power (kW) 9.00 15.92 3.94 1.75]
@tary power (kW) 0.08 0.12 0.01 OW]
[Total power (kW) 9.08 16.00 4.04 1.74]
Test 8-P, Low 2, Powered, 8274 kPa (1200 psi)

]24-P AVG MAX MIN ST DEV

[Top Compression (kN) 7328.64 13974.15 3778.20 1841.41

]R_ight Draft (kN) 10719.12 18276.93 6213.32 2128.52
Eeft Draft (kN) 3999.78 8280.75 690.15 1456.31

[g'ound Speed (mlsec) 1.04 1.13 0.96 0.03

@isk Speed (mlsec) 1.70 2.08 1.39 0.15
Eressure Drop (kPa) 7148.09 9080.32 5584.71 530.05]
[ﬂiwrate (Ilmin) 16.10 19.75 13.15 1.43[
Mt Draft (kN) 7390.26 14508.97 2590.64 1902.00[
[V_ngr 1.64 2.01 1.37 0.14[
praft power (kW) 7.66 14.87 2.52 1.9g]
]R_otary power (kW) 1.92 2.53 1.36 0.21]
[Total power (kW) 9.58 16.67 4.57 1.88[

 

 

 

 

 

74

Test 9-N, Low 3, Non-Powered, NA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[31-0 AVG MAX MIN ST DEﬂ
[Top Compression (kN) 9029.69 15378.26 3065.35 1460.2ﬂ
Bight Draft (kN) 11436.94 18040.97 5770.88 1525.95]
Eeft Draft (kN) 5330.01 9280.23 1149.37 1021.40]
Fround Speed (mlsec) 1.60 1.68 1.51 0.03

[Disk Speed (mlsec) 1.50 1.76 1.27 0.11

[Pressure Drop (kPa) 366.48 537.79 206.84 58.71

[Flowrate (l/min) 14.21 16.72 12.03 1.04

[Net Draft (kN) 7737.27 13156.91 3050.26 1245.21

[Vngr 0.93 1.09 0.81 0.07

[Draft power (kW) 12.41 20.64 4.72 2.00[
[Rotary power (kW) 0.09 0.12 0.05 0.01[
[Total power (kW) 12.50 20.72 4.81 2.00]
Test 9-P, Low 3, Powered, 2758 kPa (400 psi)

]31-P AVG MAX MIN ST DEV]
[Top Compression (kN) 8705.45 19849.79 84.33 1940.62]
ﬁght Draft (kN) 11520.75 20754.54 3912.68 2084.77]
[Left Draft (kN) 5175.36 16357.58 -822.56 1424ﬂ
Eround Speed (mlsec) 1.60 1.68 1.53 0.03]
[Disk Speed (mlsec) 1.71 2.11 1.54 org
[Pressure Drop (kPa) 2430.46 3050.90 2078.75 183.67]
[Flowrate (Ilmin) 16.19 20.04 14.56 0.7g
[Net Draft (kN) 7990.66 17262.34 3005.78 1767.03]
[degr 1.07 1.31 0.97 0.03[
[Draft power (kW) 12.81 28.26 4.87 2.8_8[
[Rotary power (kW) 0.66 0.90 0.53 0.0g
[Total power (kW) 13.47 28.84 5.45 2.87]

 

 

 

 

 

75

Test 10-N, Low3, Non-Powered, NA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[32-u AVG MAX MIN ST DEV]
[Top Compression (kN) 10138.47 17948.85 3432.58 1898T5[
[Right Draft (kN) 13348.03 21314.96 7422.63 2056.9ﬂ
Eeft Draft (kN) 5359.00 11036.06 1122.36 1219ﬁ]
[ground Speed (mlsec) 1.54 1.65 1.44 0.03[
[Disk Speed (mlsec) 1.52 1.75 1.33 0.07[
[Pressure Drop (kPa) 284.13 455.05 155.13 46.18]
Elowrate (Ilmin) 14.38 16.55 12.65 0.70]
met Draft (kN) 8568.56 13055.33 4466.80 1536.01]
[Yngr 0.98 1.09 0.90 0.04[
[gram power (kW) 13.21 19.87 6.90 2.3q
[Rotary power (kW) 0.07 0.11 0.04 0.01]
[Total power (kW) 13.28 19.94 6.97 2.39]
Test 10-P, Low 3, Powered, 4137 kPa (600 psi)

ﬁz-P AVG MAX MIN ST DEV]
[Top Compression (kN) 8211.86 16436.74 4210.23 1678.28]
[Right Draft (kN) 11540.88 19279.77 7304.64 1816.50]
Eeft Draft (kN) 4285.49 9631.39 474.05 1274.44]
@und Speed (mlsec) 1.54 1.63 1.46 0.03[
@sk Speed (mlsec) 1.82 2.19 1.58 0.12[
Pressure Drop (kPa) 3601.60 4354.00 2906.12 305.44]
[Flowrate (Ilmin) 17.27 20.79 14.93 1.13
ﬂat Draft (kN) 7614.50 11861.34 3494.05 1534.34
[Ingr 1.18 1.43 1.05 0.07
@Eft power (kW) 11.76 18.86 5.32 2.37
Eatery power (kW) 1.04 1.38 0.75 0.11
[rotaI power (kW) 12.79 20.09 6.36 2.36

 

 

 

 

 

76

Test 1 1-N, Low 3, Non-Powered, NA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[33-u AVG MAX MIN ST DEV]
[Top Compression (kN) 9696.01 19568.97 5225.51 1984.11]
[Right Draft (kN) 13145.88 26447.15 8130.52 25671—5]
[.eft Draft (kN) 5214.78 10928.01 1500.54 1437.02]
Eround Speed (mlsec) 1.56 1.65 1.42 0.03
pisk Speed (mlsec) 1.56 1.77 1.29 0.08]
Eressure Drop (kPa) 312.25 506.76 175.81 54.73]
Elowrate (Vmin) 14.77 16.80 12.19 0.76]
Mt Draft (kN) 8664.65 18532.32 3390.62 2127M
[Vngr 1.00 1.17 0.84 0.75]
[gait power (kW) 13.49 29.00 5.31 3.33
[Eatery power (kW) 0.08 0.13 0.05 0.01[
mataI power (kW) 13.57 29.07 5.37 3.38]
Test ll-P, Low 3, Powered, 6205 kPa (900 psi)

[33-P AVG MAX MIN ST DEV]
[rop Compression (kN) 8175.55 15140.64 3432.58 1891E|
ﬁght Draft (kN) 11913.80 18365.42 7127.67 2046.23
[Left Draft (kN) 4322.82 9820.48 366.00 1495.85]
[gound Speed (mlsec) 1.55 1.70 1.42 0.04[
[D_isk Speed (mlsec) 2.06 2.40 1.78 0.13]
Eessure Drop (kPa) 5412.33 6701.65 3805.87 444.62]
[ﬂowrate (Ilmin) 19.56 22.70 16.89 1.27]
Bet Draft (kN) 8061.07 13642.27 3694.39 1889.15]
[)2ng 1.33 1.53 1.18 0.08]
Baft power (kM 12.53 21.29 5.72 2.99
Eatary power (kW) 1.76 2.33 1.30 0.18]
[Total power (kW) 14.30 22.85 7.24 2.93]

 

 

 

 

 

Test 12-N, Low 3, Non-Powered,

77

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[34-U AVG MAX MIN ST DEV [
[l'op Compression (kN) 10078.00 21599.52 2892.54 1736.94[
[Right Draft (kN) 13334.25 22966.70 4296.12 1864.13]
Left Draft (kN) 5609.06 14385.65 -687.50 1348.16]
Bound Speed (mlsec) 1.55 1.63 1.46 0.03]
Eisk Speed (mlsec) 1.54 1.69 1.35 0.06[
Eressure Drop (kPa) 333.11 599.84 103.42 58.58]
ﬂiwrate (Ilmin) 14.61 16.01 12.82 0.59]
[Net Draft (kN) 8865.31 14983.14 716.08 1701M]
[Vngr 0.99 1.08 0.90 0.03
[Draft power (kW) 13.76 23.19 1.09 2.63]
[ﬂatary power (kW) 0.08 0.15 0.02 0.01[
[Bital power (kW) 13.84 23.30 1.20 2.63]
Test 12-P, Low3, Powered, 8274 kPa (1200 psi)

[3_4-P AVG MAX MIN ST DEV

[rop Compression (kN) 6761.06 20260.22 1812.46 1824.35
ﬁght Draft (kN) 10196.14 27803.94 5475.93 1720.97
[Left Draft (kN) 3313.75 11873.46 -930.62 1448.62
[gound Speed (mlsec) 1.54 1.66 1.46 0.03[
[Disk Speed (mlsec) 2.20 2.86 1.94 0.14[
Eressure Drop (kPa) 6349.30 8842.45 4581.53 635.32]
Eowrate (Ilmin) 20.88 27.11 18.38 1.37]
[N_et Draft (kN) 6748.82 17391.22 2013.86 1605.78[
[Vngr 1.43 1.84 1.31 0.1g]
[D_raft power (kW) 10.42 27.80 3.24 2g]
[Rotary power (kW) 2.21 3.59 1.57 0.23]
[Total power (kW) 12.63 30.53 5.38 2.53

 

 

 

 

 

APPENDIX D

APPENDIX D

SAMPLE CONDITIONED RAW VOLTAGE DATA GRAPHS

The printouts Show the raw voltage data of the pertinent parameters measured. These
analog voltage values were converted to the actual data by using the calibration

equations developed earlier.

In the printouts :

Channel 1 Top Link Force
Channel 2 Right Link Force
Channel 3 Left Link Force
Channel 4 Ground Speed
Channel 5 Disk Speed
Channel 6 Pressure In

Channel 7 Pressure Out

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BIBLIOGRAPHY

BIBLIOGRAPHY

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1021.

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ASAE Standards, 41St Ed. 1994. $313.2. Soil Cone Penetrometer. St. Joseph, MI: ASAE.

Carter, Lyle M. 1981. Instrumentation for Measuring Average Draft. Transactions of the
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Clyde, A. W. 1939. Improvement of Disk Tools. Agricultural Engineering 20(6): 215-
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Gill, W. R., Reaves, C. A., and Bailey, A. C. 1980. The Effect of Geometric Parameters
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Gill, W. R., Reaves, C. A., and Bailey, A. C. 1981. The Inﬂuence of Harrow Disk
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Gupta C. P. and Bohra C. P. 1993. Field Evaluation of Vibrating Powered Disk Potato
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Harrison, H. P. and Reed, W. B. 1962. An Analysis of Draft, Depth and Speed of Tillage
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Lackas, G. M., Grisso, R. D., Yasin, M. and Bashford, L. L. 1991. Portable Data
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Shearer, S. A., Dong, F ., Jones, P. T., Swetnam, L. D. 1993. Fluid-Power Drive for
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Tembo, Solomon 1986. Performance Evaluation of the Power Disk- A PTO Driven Disk
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