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DISK-CHAIN-DIKER CONSIDERATIONS
FOR SEEDBED PREPARATION
Harold T. Wiedemann
chain rotates and the blades leave a broadcast pattern of
diamond-shaped basins 4 inches deep. There are about
18,000 basins per acre {fig. 2). Pulling the chain diker behind a disk chain achieves tillage, land smoothing, and
basin formation in a single pass, and greatly improves the
operation of the disk chain. The chain diker will traverse
any size brush debris the disk chain can traverse. Diking
increased grass stand densities threefold compared to
nondiked treatments the first year when May/June rainfall was 37 percent below normal; however, in years with
25 and 27 percent above-normal rainfall there was no difference in densities between treatments, all were excellent (yr 2 = 1.48 plants!ft2; yr 3 = 2.56 plantsffi2; 25 inches/
yr average rainfall). In a 48 percent lower rainfall zone
{13 incheslyr), diking increased grass stands by 50 percent,
average stand 0.38 plants/ft2• Diking appears to have the
best potential when rainfall is limited.
Chain diking has been evaluated for runoff reduction in
a 3-year wheat production system near Vernon (25 inches/
yr rainfall). Diking followed planting; all other operations
were conventional. Slope averaged 0.3 percent in the fine
sandy loam soil and runoff measurements were recorded
from September through May. Diking reduced runoff by
46 percent over the 3-year period compared to the nondiked treatment. The reduction was 21 percent, 72 percent and 45 percent and rainfall was 23.4, 15.8 and 25.8
inches/crop season, respectively.
Further information on the chain diker is discussed by
Wiedemann and Smallacombe {1989). Construction of the
chain diker is in collaboration with its inventor, Bruce
Smallacombe, Capella Sales and Engineering, Capella,
Queensland, Australia.
ABSTRACT
Equipment to prepare seedbeds on shrub-littered rangeland has been under development by the Texas Agricultural Experiment Station for several years. The disk-chaindiker is a combination of the disk chain and chain diker
implements; the combination device shows promise for
rangeland seeding. The disk-chain-diker is composed
of several components, each of which influences its performance. Drawbar pull as influenced by operating mass,
disk blade size, chain size, chain angle, roller configuration, and diking chain attachment is discussed.
BACKGROUND
Equipment to prepare seedbeds on debris-littered rangeland has been under development by the Texas Agricultural Experiment Station for several years. The disk
chain and chain diker are two significant advancements
that have been combined to form the "disk-chain-diker"
implement {fig. 1). This unique tool shows promise for
rangeland seeding <Wiedemann and Smallacombe 1989).
The disk chain was developed first, and its purpose
was to till land littered with logs and brush debris. Disk
blades were welded to alternate links of a large anchor
chain and swivels were attached to each end of the chain.
When the chain was pulled diagonally, disking action was
achieved as it rotated {fig. 1). Early engineering studies
on disk chains evaluated pulling characteristics, operating mass, and other engineering indices {Wiedemann and
Cross 1982, 1985, 1987). In seeding studies at six locations, grass densities were increased 35 and 92 percent
over seedbeds prepared by nonmodified {smooth) chains in
loamy sand and clay loam, respectively, in a 20- to 25-inch
annual rainfall zone {Wiedemann 1982). We found the
disk chain to be well suited for use on extensive acreages
of debris-littered rangeland. It can easily be pulled over
shrubs like tarbush {Flourensia cemua DC.), creo~otebush
(Larrea tridentata DC.), sagebrush (Artemisia filifolia
Torr.), sand shinnery oak (Quercus havardii Rydb.), and
small mesquite (Prosopis glandulosa Torr. var. glandulosa) on undisturbed rangeland; however, it was originally
designed to traverse stumps and logs on rootplowed land.
The chain diker was developed by an Australian inventor to reduce runoff from wheat (Triticum aestivum L.)
fields. This tool uses specially shaped blades welded to
a large anchor chain. As it is pulled over tilled land, the
BASIC UNIT
The disk-chain-diker is a combination of several compo- ·
nents, each of which influences its performance. A basicsize unit will be described that has functioned well over a
broad range of conditions. Tests with this basic unit will
be discussed, and then component variation will be referenced to the performance of the basic unit. The basic diskchain-diker is a 20-disk-blade unit using 2.5-inch diameter anchor chain with 28-inch diameter disk blades welded
to alternate links for tilling; a 20-inch diameter flexing
roller for a center brace (35 feet wide); and a 3-inch diameter anchor chain with specially shaped blades welded to
each link for diking {basin formation), see figure 1.
DRAWBAR PULL
Paper presented at the Symposium on Ecology, Management, and Restoration of Intermountian Annual Rangelands, Boise, ID, May 18-22, 1992.
Harold T. Wiedemann is Professor of Agricultural Engineering, Texas
A&M University Agricultural Research Center, P.O. Box 1658, Vernon, TX
76385.
Drawbar pulling requirements are significantly influenced by operating mass {weight) while soil type has little
314
100
!Basic Unit!
...
90
~c.
80
Cl)
Cl)
/
/
f
0
:::z::
~
i'
~
3
70
v
60
/
50
v
/
40
2.0
1.5
2.5
3.0
3.5
Speed (mph)
Figure 1-Disk-chain-diker implement under development by the Texas Agricultural Experiment
Station for enhanced seedbed preparation on
debris-littered rangeland. The combination of
the disk chain (front portion of implement) and
chain diker (rear portion) provides tillage, land
smoothing, and basin formation in a single pass.
Figure 3-Drawbar horsepower requirements
to pull the "basic-unir disk-chain-diker at various speeds. Horsepower values are based on a
20-blade unit and a regression equation with an
r 2 = 0.94.
Cl)
5.0
550
'0
as
Draft
m
... 4.5
500
±19
~
... 4.0
!c.
3.5
,/
~
~ 3.0
...
.!
~
c
/
2.5
v
/
/
400
...I»
350
Ql
300
/
200
150
I
2.0
0
.,
=
...
CD
250 ID
,. - 0.94
1.5
i
450 0"
Power
2.0
0
2.5
3.0
iD
c.
-CD
c;:
3.5
Speed (mph)
Figure 2-Basins are formed as the anchor
chain with specially shaped blades rotates.
Figure 4-Per-blade drawbar power and
draft requirements of the basic disk-chaindiker for various speeds (Wiedemann and
Cross 1990).
influence. The heavier the unit the more powe r is required
for pulling, and the deeper the disk blades penetrate the
soil. Pulling tests with the basic unit were conducted in a
well-tilled, clay loam soil. Average draft force was 515lb/
blade± 19lb when pulled at 2-, 2.5- or 3-mileslhour (mph).
It follows that the 20-blade unit would require 10,300 lb
of drawbar pull. Horsepower, which combines pull and
speed inputs, is significantly increased a s speed is increased (fig. 3). It requires 81.3 drawbar horsepower to
operate the basic unit at 3 mph. A 140-engine-horsepower
crawler tractor with direct drive can pull a 20-blade unit
easily at 2 mph, but it is a full load at 3 mph. A 200engine-horsepower crawler tractor is best for 3 mph operation over a broad range of slopes. Number of blades
to be pulled must be matched to the drawbar pulling capacity of the tractor. Addit ional tractor information is available from Wiedemann and Cross (1990). Power
requirements for units other than 20 blades can be determined from data in figure 4.
315
Table 1-s2ecifications of disk chains that have been tested
Disk
chalnslze1
Chain link
Diameter Pitch
- - - - -Inches - - - -
17/ex 24
17/ex 28
2'/2X 24
21hx28
3x24
3x28
17/e
17/e
2 112
2'12
3
3
Weight
Disk blade
Diameter x thick weight
Roller
length
pln/pln2
Blade
spacing
Lb
Inches
Lb
Ft
Inches
21
21
49
49
86
86
24x 1/4
28x 3/a
24X1/4
28 x3/e
24X'/4
28 x3/e
32
55
32
55
32
55
27.8
27.8
35.4
35.4
41.5
41.5
15
15
20
20
24
24
7.5
7.5
10
10
12
12
Disk chain
Length
O~eratlng'
Mass/blade
1-gang
Width
Lb
- - - - - - -Ft - - - - - 13.1
13.1
17.5
17.5
21.0
21.0
25.8
25.8
33.4
33.4
39.6
39.6
74
97
130
154
204
228
'Size Is chain diameter x blade diameter (inches).
Roller, 20-lnch OD diameter pipe with 1/4·1nch wall thickness, pin to pin length.
'Triangular system with 30 degrees between roller and line formed by disk-chain. Width equals 87 percent of length of two gangs plus 361nches of attachment
hal'dware. Mass/blade equals weight of two links plus one disk blade. Each gang has 21 chain links and 10 disk blades.
2
50
OPERATING MASS
Operating mass is influenced by both anchor chain and
disk blade weight and is expressed in lblblade. Operating
lblblade is calculated as the weight of two chain links and
one disk blade {blades welded to alternate links). Anchor
chain size largely determines the operating mass, which
influences performance. Sizes and weights of six disk
chains that have been tested are listed in table 1. Sizes
and weights of other anchor chains suitable for use are
listed in table 2. An addition of lib of operating mass per
blade will increase the draft requirement by 1.9lb. This
relationship is illustrated in figure 5 for operating masses
between 74 and 228lblblade. The basic unit weighed 154
lhlblade. A 3-inch chain with 28-inch disk blades would
weigh 228 lblblade.
(mm)
2
21/a
2'14
23/a
2'12
25/e
23/4
27/a
3
(51)
(54)
(58)
(60)
(64)
(67)
(70)
(73)
(76)
.5
20
!
v
/
10
0
(.) -10
IL
.
v
G)
'-20 .
J~~
-
v
-50
~0
II II
50
v
/
II II
75
/
II II
100
/
/"
II II
125
v
Ill I
150
I Ill
175
Ill I
200
II II
225
250
Operating Mass (lblblade}
Link
Pitch
- - - - -Inches- - - - 12.0
12.75
13.5
14.25
15.0
15.75
16.5
17.25
18.0
30
Q
Figure 5-Change in required drawbar draft
for various changes in operating mass/blade
of the disk chain referenced to the "baslc-unir
154 lblblade. Regression data adapted from
Wiedemann and Cross (1987).
Table 2-8tud-link anchor chain specifications'
Inches
Q
c
Disk blades 24, 28, 30, and 32 inches in diameter have
been evaluated. Performance of the 30- and 32-inch disk
blades was unsatisfactory because blades did not remain
in a vertical position all the time. The blades "flopped" as
Length
40
G)
DISK BLADE SIZE
Chain diameter
c
1!
8.0
8.5
9.0
9.5
10.0
10.5
11.0
11.5
12.0
Weight
Links/shot
(90ft)
Lb
Number
25
30
36
42
49
57
66
75
86
133
125
119
113
107
103
97
93
89
the chain was pulled, and this increased wear in the chain
links (Wiedemann and Cross 1982, 1987). The preferred
blade diameter is 28 inches because it weighs more, blade
thickness is greater, and it traverses debris better than
the smaller blade. If the chain diker is not used and a
lighter roller is utilized, then the 24-inch blade is a better
choice.
CHAIN SIZE
Chain size selection is influenced by soil condition. The
harder the soil (resistance to penetration), the more mass
per blade is needed to achieve satisfactory disking action
(soil cutting). Tests were conducted in three different soil
conditions to predict depth of disking. A soil cone penetrometer meeting ASAE Standards was used to characterize
'Actual weights and lengths may vary slightly.
316
30
the penetration resistance of soils and establish a cone
index (CI) rating. Site one was a clay loam soil that had
been rootplowed (12 to 14 inches deep) and disked (8 inches
deep). The CI was 164 psi. A similar value would be expected in an undisturbed deep sand. A CI of 351 psi was
measured in a dry (near wilting point), clay loam soil on
a 15-year-old rootplowed site. At a third site, a CI of
1,238 psi was measured in an undisturbed, very dry (below wilting point), fine sandy loam soil. Chain sizes of 2,
2.5, and 3 inches and two disk blade sizes were tested covering an operating mass range of 74 to 228 lb/blade. Further information on this study is covered by Wiedemann
and Cross (1987).
The 2-inch chain has given adequate performance in
disturbed soil when conditions were favorable (adequate
moisture, loamy soils, little turf, and minimal brush debris). The 2.5-inch chain, however, can perform satisfactorily over a much broader range of adverse conditions
than the 2-inch chain, and draft is about one-third less
than the 3-inch chain. Adequate disking action with minimum draft is desirable. The 2.5-inch chain size has given
the best performance in disturbed (rootplowed) and some
undisturbed soils (soils with less than 300 psi Cl). Disking
depth was 3 to 4 inches. This chain size has also functioned well in shinnery-infested deep sand. The relationship
of disking depth to operating mass/blade is shown in figure 6. The three soil conditions cover a wide range of soil
strength. If both the mass (Min lblblade) and cone index
CCI in psi) are known, the depth of cut (±0.5 inches) can
be predicted by the formula Y = 2.25 + 0.01M - 0.002CI.
.
-a
5.0
~
4.0
.c
t!
Q
c
:i2
Q
•
3.0
~
Cl· 164
2.0
Cl· 351
1.0
0
25
.5
CD
20
/
Q
15
~
()
CD
Q
/v
10
-ECD
5
:.
0
e
.
/
-5
/
v
/
I
25
30
35
I
I
40
45
50
J
55
Chain Angle {degrees)
Figure 7-change in required drawbar draft for
various chain angles referenced to the standard
30-degree angle. Regression data adapted from
Wiedemann and Cross (1985).
In soil with a Cl over 300 psi, the 3-inch chain is necessary for satisfactory performance. At the site with a CI
of 1,238 psi, two passes with the 3-inch chain were required for satisfactory tilling. If the disk chain is to be
used mostly in undisturbed soil, the 3-inch chain is favored. It must be kept in mind that rangeland needing
renovation most probably will be dry and hard.
CHAIN ANGLE
~
0
Q
;
6.0
CD
.5
!
..
v v
-
~
75
~
~
--- ---- ----
1--
Cl· 11238
I
50
~
100
I
v v
~
I
125
150
---
~
175
~
I
200
Disking action also can be influenced by changing
the chain angle. Chain angle is the angle between the
roller and the line formed by the disk chain (fig. 1). An
angle of 30 degrees was determined to be the optimum by
Wiedemann and Cross (1985). Aggressiveness ofdisking
action can be increased by increasing the chain angle, but
pulling requirements will be significantly increased as
shown in figure 7. Increasing the disk's aggressiveness
destroys more surface vegetation because of increased soil
disturbance. The chain angle may be changed by changing the width of the roller or length of the disk chain.
Chain angle also influences the effective width between
blades as noted in table 3.
~-"""
I
~
~
I
225
I
250
Operating Mass {lb/blade)
ROLLER
Figure 6-Depth of disking for various operating
masseS/blade in three different soil conditions
described by an ASAE Soil Cone Index. Cl164
psi is a tilled soil; a deep sand would be similar.
Cl 351 psi is an average, undisturbed, clay loam
rangeland. Cl1,238 psi is very-dry, very-hard,
fine sandy loam rangeland. Regression data
are from Wiedemann and Cross (1987).
The roller serves as a brace to hold the two disk chains
at the selected chain angle (fig. 1). It is made from 20-inch
outside diameter (O.D.) pipe with a 0.25-inch wall thickness. A flexing center joint is crucial for proper operation
on uneven soil surfaces. Design of the flexing joint allows
vertical movement only. The ridged bar that must be
317
Table 3-Disk-chaln blade spacing
Chain size
Chain angle
Inches
Degrees
2.0
2.0
2.0
2.5
2.5
2.5
3.0
30
3.0
40
50
3.0
40
50
30
30
50
30
after a short drying period. When excessive amounts
of timber are present, the site must first be raked or
chained and burned before the disk-chain-diker can
be used successfully.
Inches between blades1
Actual
Operating
16
16
16
20
20
20
24
24
24
BRUSH DEBRIS CONSIDERATIONS
13.9
12.3
10.2
17.4
15.4
12.8
20.9
18.5
15.4
Determining when brush debris is excessive is, to a
large degree, a practical judgment based on experience.
The following explanation may help in making that decision. First to be discussed is standing mesquite regrowth
that is to be rootplowed. On sites where mesquite regrowth is less than 8 ft tall and stem diameters are less
than 3 inches (at the base), tree density makes little difference in the unit's operation. Moderate stands of trees
8 to 12 ft tall with stem diameters averaging 4 inches or
less will usually not be difficult to traverse. However,
dense stands will need to be chained following rootplowing to break up the limbs so the disk-chain-diker can operate without difficulty. Dense stands are difficult to walk
through. Moderate stands of 12 to 18 ft tall trees with
6-inch stem diameters will need to be chained following
rootplowing to break up limbs. Dense stands of these size
trees may require two-way chaining to break up the limbs
sufficiently. Stands with trees over 20 ft tall or stem
diameters more than 8 inches will need to be raked or
chained and burned before plowing. Rootplowed stumps
or stumps partially lodged in the soil have not been a
problem.
'At 30 degrees operating Is 87 percent of actual, at 40 degrees operating
is 77 percent of actual, at 50 degrees operating is 64 percent of actual.
pin-attached between the flexing joint and the front attachment plate is necessary for proper operation of the
disk chain. Cleats on the roller prevent "pipe-skidding,"
which can stall forward motion and damage the roller.
Tests with a 12-inch diameter pipe were unsatisfactory
when operating width was over 20 ft. The roller accounts
for 11.6 percent of the required draft. A major increase
in the roller size and weight would increase the draft
requirement.
DIKING CHAIN
STANDING BRUSH CONSIDERATIONS
A 3-inch chain was selected over smaller chains for
the diking unit because of better blade penetration into
the soil on rough, uneven, debris-laden surfaces. The diking chain accounted for 2,065 lb of draft. This equates to
103 lblblade or 20 percent of the required drawbar pull
for the basic unit. Action of the disk chain was greatly
improved when the chain diker was added to the system.
Soil cutting was equal across the entire operating width
because blade flopping was virtually eliminated. Increased soil cutting was reflected by the draft force of7,411lb
for the disk chain without the diker unit attached compared to a force of 8,254 lb for the disk chain when the
chain diker was attached.
In standing brush, the disk-chain-diker has not had
difficulty traversing shrubs less than 8 ft tall that break
easily or are shallow rooted. In tests conducted in tarbush (average height 3 ft) and shinnery (height <2 ft) the
implement either severed or uprooted the plants. In shinnary mottes, the basic unit (2.5-inch chain) traversed
trees 8 to 10 ft tall (trunk diameter 4 inches), but little
disking was accomplished. In standing mesquite, the
heavier implement (3-inch chain) has traversed trees up
to 18ft tall when top growth had been sprayed; however,
when stems were alive trees taller than 10 ft occasionally
tangled in the disk chain. Mesquite less than 8 ft tall has
not been a problem to traverse. Tall trees in moderate-todense stands may require two passes with the disk-chaindiker for satisfactory tilling.
GENERAL APPLICATION
Prototypes of the basic unit have given satisfactory performance over a broad range of conditions on selected test
sites. Soil type, condition, moisture content, percent slope,
and surface roughness can all influence performance.
However, brush debris can be a liiniting factor. The unit
was designed to traverse brush debris, but not excessive
amounts of timber. In field tests it has traversed 16-inch
diameter logs 6 ft in length and 24- by 36-inch stumps on
rootplowed land. Problems develop when several logs or
irregular-shaped logs lodge in the unit or when excessive debris prevents the blades from penetrating the soil.
Standard smooth chaining ahead of disk-chain-diking
can be helpful in some situations to break up brush debris. Brush debris (following rootplowing) breaks up better
CONSTRUCTION PLANS
Construction plans were drawn to convey concepts and
are offered as a guide for fabrication (see fig. 8). Dimensions were based on the selected components of the basic
unit. Dimensions for units having other than 20 disk
blades or different chain sizes are listed in tables within
the set of engineering drawings.
The complete set of plans is available from the Texas
Agricultural Experiment Station, P.O. Box 1658, Vernon,
TX 76384. Request Center Technical Report TR-2, "DiskChain-Diker Construction Plans." The Experiment Station offers the construction plans as a public service and
318
<20.5 Lll«S/ SU:£>
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20 BLADE DOUBLE ROLLER UNIT
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DIKER UNIT>
••<SOME PARTS ARE PROTECTED UNDER PATENT'S>••
<SEE SHEET 14>
._.,::•="'-=-=-;::__----1
TEXAS A&H UNIVERSITY
AGRICULTURAL RESEARCH
~AND EXTENSION CENTER
~
AT CHn.LitiJYHI:-1/ERIOI
,AD-'IIIDIDin,...
mu:DISK -CHAIN-DIKER
IMPLEMENT
Figure 8-Pian view of dlsk-chain-diker.
does not assume responsibility for construction, manufacturing, or use of this device. Some components are covered by patents.
Wiedemann, H. T.; Cross, B. T. 1982. Draft of disk-chains
for rangeland seedbed preparation. Transactions of the
ASAE. 25(1): 74-86.
Wiedemann, H. T.; Cross, B. T. 1985. Influence of pulling
configuration on draft of disk-chains. Transactions of
the ASAE. 28(1): 79-82.
Wiedemann, H. T.; Cross, B. T. 1987. Influence of operating mass on disk-chain performance. Transactions of
the ASAE. 30(6): 1637-1640.
Wiedemann, H. T.; Cross, B. T. 1990. Innovative devices
for rangeland seeding. Paper 90-1564. St. Joseph, MI:
ASAE.12 p.
Wiedemann, H. T.; Cross, B. T. 1990. Disk-chain-diker
implement selection and construction. Ctr. Tech. Rep.
90-1. Vernon, TX: Texas A&M University, Agricultural
Research and Extension Center. 19 p.
Wiedemann, H. T.; Smallacombe, B. A. 1989. Chain dikera new tool to reduce runoff. Agricultural Engineering.
70(5): 12-15.
ACKNOWLEDGMENTS
I am grateful for the technical assistance provided by
B. T. Cross and G. G. Schulz in design, construction, and
testing of the disk-chain-diker implement. To Sam Stone
I am especially indebted for his skillful drawing of the
plans. Appreciation is expressed to Bruce Smallacombe
for his advice and trips to the United States to cooperate
on this project.
REFERENCES
Wiedemann, H. T. 1982. New developments in mechanical
brush control: Proceedings 1982 international ranchers
roundup. Uvalde, TX: Texas A&M University, Agricultural Research and Extension Center: 181-189.
319