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American Journal of  Smart 
Technology and Solutions (AJSTS)

Design and Development of  a Tractor-Drawn Cultivator with a Pulverizing Attachment
Husen Bona Wako1*, Adesoji Matthew Olaniyan2

Volume 3 Issue 2, Year 2024
ISSN: 2837-0295 (Online)

DOI: https://doi.org/10.54536/ajsts.v3i2.3337
https://journals.e-palli.com/home/index.php/ajsts

Article Information ABSTRACT

Received: August 02, 2024

Accepted: August 30, 2024

Published: September 03, 2024

Soil tillage is one of  the most critical processes in the agricultural production system, 
requiring the greatest energy and time of  any operation. A cultivator with pulverizing 
attachment was designed and developed to reduce secondary tillage operations to a single 
pass to ensure timeliness in seedbed preparation. It consists of  a pulverizing roller as an 
active unit and cultivator tynes as a passive unit. The implement has the following major 
components; a frame, cultivator tines, and a pulverizing roller consisting of  central and 
peripheral shafts on which discs are arranged. The cultivator tynes were fitted on the main 
frame while the pulverizing roller was attached at the rear end of  the frame with the help 
of  bearings. The pulverizing blades were welded on discs in such a way as to crush the soil 
by impact force. In this way, the force exerted by the pulverizer on the clod is distributed 
uniformly in the shaft which is used to hold the pulverizing roller. The pulverizer was 
designed to break big clods formed during tillage operation and the implement was 
attached to the tractor by three point hitch. In operation, the cultivator tynes open the 
furrow, and the roller cuts and pulverizes the soil at optimum conditions for tillage. With 
a production cost of  ETB 17,587.19, the implement is within the economic reach of  an 
average smallholder farmer in Ethiopia.

Keywords
Clods, Cultivator, Draft, 
Pulverizing Roller, Soil 
Manipulation, Tillage

1 Agricultural Machinery Engineering Department, Oromia Agricultural Research Institute, Jimma Agricultural Engineering 
  Research Center, Jimma, Ethiopia
2 Department of  Agricultural Engineering, Haramaya Institute of  Technology, Haramaya University, P. O. Box 138, Dire Dawa, Ethiopia
* Corresponding author’s e-mail: husenifnaan@gmail.com

INTRODUCTION
Tillage is the process of  mechanically manipulating soil 
to make it more conducive to crop cultivation. Soil tillage 
entails breaking the earth’s compact surface to a particular 
depth and loosening the soil mass to allow crop roots 
to penetrate and disseminate into the soil (Zhou et al., 
2020). It is the mechanical manipulation of  soil and plant 
debris to prepare a seedbed for the planting of  seeds that 
will produce grain for human use. Tillage also breaks up 
the soil, improves the release of  soil nutrients for crop 
growth, eliminates weeds, and improves water and air 
circulation in the soil (Reicosky & Allmaras, 2003).
Tillage is considered one of  the most important processes 
in agriculture, as it gives suitable conditions for root 
growth, which in turn supports the growth of  plants, as it 
reduces soil resistance, increases the ventilation process, 
and eliminates weeds (Al-Shamiry et al., 2020). Tillage 
in the traditional sense is one of  the least fuel-efficient 
procedures. According to (Digman, 2012), just 20% of  
diesel fuel energy is available at the tractor’s drawbar, but 
only 4% of  that energy is transformed into soil-breaking 
energy. 
Tillage implements works based on two working motions, 
sliding type, and rotating type. Devices like moldboard 
plows and cultivators use sliding action to cut the soil. 
By functioning in a rotational motion, disc plows, disc 
harrows, clod crushers, and rollers cut and pulverize the 
soil. Because of  the soil frictional force and the contact 
area of  the implement, sliding-type implements consume 
more drafts than rotating-type implements. A negative 
draft was produced by rotary-type implements. As a result, 

the concept of  combining sliding and rotary implements 
saves a lot of  power, time, and money (Parmar & Gupta, 
2001).
Tillage operations can be performed simultaneously 
in a single pass by a combination tillage tool mounted 
on a tractor. According to (Manian & Kathirvel, 2001), 
combined tillage is a method of  manipulating the soil by 
using two or more different tillage implements at the same 
time to reduce the number and time of  field operations. 
According to (Prem et al., 2016), combined tillage is the 
use of  two or more implements at the same time to alter 
the soil. Combined tillage, in a broad sense, refers to 
the integrated management of  resources such as time, 
energy, fuel, labor, soil, and water conservation while also 
boosting output and better utilizing natural resources. It 
also helps to maintain agricultural production.
Combined tillage implement reduced larger size clods in 
the soil, improved aeration and moisture holding capacity, 
and obtained medium uniformity of  soil and finer 
pulverization modulus. The combination tool achieved 
maximal soil loosening as evidenced by the low soil bulk 
density range of  1.15 gcm-3 as opposed to the normal 1.4 
gcm-3 encountered in conventional tools operated field. 
The use of  combined tillage for seedbed preparation can 
save 44 to 55% in cost and 50 to 55% in time (Kailappan 
et al., 2001).
(Maheshwari et al., 2005) reported that soil aggregates of  
size 12 to 14 mm in the final seedbed were acceptable for 
sowing crops. Clod formation after plowing or disking is 
a significant issue. Clods block the penetration of  seed 
drill furrow openers and prevent close contact between 



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seeds and soil. To avoid the aforementioned issues clods 
must be pulverized. Because of  the time, efficiency, and 
cost savings, combining implements and minimizing the 
number of  passes is becoming more common (Alkhafaji, 
2020). 
In Ethiopia, farmers are using the conventional tillage 
system which disturbs the soil more; increases soil 
compaction increases erosion capacity by wind and water. 
The combined tillage used was also imported from other 
countries which is too expensive. The implementation did 
not consider small-scale mechanization, affordable power, 
high land agriculture, costly, and not scale appropriately. 
The overall dimensions and weight of  the tillage tool 
were heavy, not easily dismantled, or repaired and it was 
complicated. Therefore, the objective of  this study was 
to design and develop a tractor-drawn cultivator with a 
pulverizing attachment that would be operated within 
the techno-economic status of  smallholder farmers in 
Ethiopia. 

MATERIALS AND METHODS
Determination of  Physical Properties of  Soil 
Moisture Content of  Soil
Before field activities, soil samples were taken from 0 to 20 
cm below the soil surface to determine moisture content. 
Three soil samples were randomly taken from test plots 
and the weight of  each sample was determined using an 
electronic balance. The samples were then maintained in 

a hot air oven for 24 hours at a temperature of  105°C. 
The moisture content (dry basis) was calculated using the 
formula below (Javadi & Hajiahmad, 2006).
MC = (WW-Wd)/Wd ×100                                                (1)
Where, (i) MC = Moisture content of  the soil, % db; (ii) 
WW = Weight of  wet soil, g; and  (iii) Wd = Weight of  
oven-dry soil, g.

Determination of  Bulk Density of  Soil 
The oven dry mass per unit volume of  the soil is known 
as bulk density. It was determined by taking soil samples 
from various sites throughout the field with a core 
sampler. The formula was used to compute bulk density 
(Javadi & Hajiahmad, 2006).
γd = M/V                                                                         (2)
Where, (i) γd = dry bulk density of  soil, g/cm3; (ii) M = 
oven-dry mass of  soil, g; (iii) V = volume of  the core 
sampler, cm3.

Overall Structure and Descriptions of  the Implement
A cultivator with pulverizing attachment was designed 
to reduce the number of  secondary tillage operations to 
single pass and enhance timeliness in seedbed preparation. 
As shown in Figure 1, it consists of  the following main 
components; frame with cultivator tynes, pulverizing 
attachment having pulverizing blades, disc, and three-
point linkage unit.

Figure 1: Cultivator with Pulverizing Attachment

Design of  Major Components
Components of  the cultivator with pulverizing 
attachment were designed, developed, and fabricated 
based on parameters like functional requirements, 
operational requirements, and strength. While fabricating 
the tractor-drawn cultivator with a pulverizing attachment 
the basic emphasis was the simplicity of  fabrication, the 

use of  locally available materials, the minimum cost of  
fabrication, and the ease of  assembling and dismantling 
for repair were considered. The mechanical design details 
were also given due attention so that it was given adequate 
functional rigidity for the design of  the machine. 
The implement was designed having in mind that the 
frame should have sufficient strength to hold the tines 



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and also withstand failure due to developed stresses and 
bending moment in mind that it will work on heavy soils. 
The assumptions made in the design of  a cultivator with 
pulverizing attachment were as follows (Parmar & Gupta, 
2001); (i) No draft was included for pulverizing attachment 
because it is a rotating unit; (ii) The average speed of  
operations of  the tractor in the field was kept at = 3 
Km/h; (iii) Maximum soil resistance was considered as = 
0.75 Kg/cm2; (iv) Co-efficient of  friction in unploughed 
soil was taken= 0.85; (v) A seven-tyne cultivator having a 
working depth of  30 cm was considered.

Design of  Frame
The frame members were welded together at the ends 
since a fixed-type end connection was selected for the 
frame. Euler’s theory for the crippling and buckling load 
(pcr) under various end conditions is given by the equation 
below (Khurmi & Gupta, 2005).
pcr = (π2 EI)/( Le/r)2                                                       (3)
Where, (i) E = modulus of  elasticity for the mild steel 
material (E= 210 GPa); (ii) A = cross-section area for a 
hollow rectangular shape, cm2; (iii) pcr = Euler’s critical 
load, N; (iv) Le= effective length of  the frame, cm; (v) r 
= radius of  gyration of  the cross-section; (vi) I = polar 
moment of  the cross-section.
The frame was considered as a beam at the tyne and 
hitch support portion and all components were loaded 
vertically so it is considered as a column. Assuming, σy  
= 250 MPa and comparing the critical load of  the frame 
with yield strength, whether the frame is saved or not. 
From the available data, let us determine the dimension 
of  the frame. The actual length of  the frame, L = 160 cm, 
equivalent length, Le = L=160 cm for the frame one end 
fixed and another end free.
Le/r = π ×√(E/σy ) = √((210 Gpa)/(250 Mpa)) = 91.05
The crushing stress is given by 
σcr = (π2E)/(Le/r)2 = (π2×210 Gpa)/91.052 = 250 Mpa
Le/r = 91.5, Le = 160 cm then r2 = Le/91.5
= (160 cm)/91.5 = 1.749 cm, and r2 = 3.06 cm2

Radius of  gyration  r2 =I/A = (bh3)/12hb = h2/12  
Then h2 = 12×r2 = 12 × 3.06 cm2 = 3 6.71 cm2

h=6.59 cm, say h=6 cm
The dimensions of  the frame were made from mild steel 
rectangular pipe which had h = 6 cm and thickness t = 0.4 
cm and width = 7.5 cm.
The critical load is found as:
Pcr = (π2EI)/Le

2 = (π2×210(h3b)/12)/Le
2 

= (π2×210×(603×75)/12)/1602 = 1,091.92×108  kN
Hence, critical stress
σcr = Pcr/A = Pcr/(b×h)
= (1,091.92×108 KN)/(45 cm2) = 242.65 Mpa
Comparing the critical stress wit h the yield strength of  
the material, critical stress is less than the yield strength 
of  the material (σcr ≪ σy). According to Euler’s theory 
of  buckling, for slender columns, the critical buckling 
stress is usually lower than the yield stress. Hence, the 
designed frame was saved from buckling. The frame of  
the cultivator was made from mild steel (M.S) rectangular 

pipe shape of  6 × 7.5 sizes (cm) × 0.4 cm thickness cross-
section. All components of  the cultivator were assembled 
and fitted on the frame.

Design of  Cultivator Tines
A cultivator was used to open the furrow at the desired 
depth of  operation. The tine-type cutting blade was used 
as uniform depth of  operation or plowing was required. 
A cutting unit of  tine was fitted at one end of  the share 
and the other end was attached with a frame by bolts and 
nuts for adjusting depth. The thickness, width, and length 
of  the tyne were decided on the assumption given by 
(Sharma & Mukesh, 2010).
Let, b x h = bare cross-section area, cm2

L= length of  breast of  tine
The length of  the inclined part of  the tyne generally 
ranges from 10 to 20 cm, and the radius of  curvature 
R < 12 cm. The minimum clearance length of  tine (HI) 
between the land surface and the lower edge of  the frame 
was 20 cm. The height of  the tine was calculated as the 
formula given below.
HT = amax + HI + ΔH                                                          (4) 
= 10+35+15 = 60 cm
Where, (i) amax = depth of  tool, cm; (ii)  HI = length of  
tyne, cm; (iii) ΔH = length of  tine used for fastening with 
frame, cm.
Load angle was determined by;
tanα = 10/30 = 0.33                                                         (5)
α = tan-1 (0.73) = 36.12°
Now radius of  curvature was determined as;
RC = (Ha-l1 sinα)/cosα                                                        (6)
= (20-18sin36.12)/cos36.12 = 11.62 cm 
Where, (i) l1 = length of  breast of  the share; (ii) Ha = 
height of  the first curvature point of  the tyne from the 
point of  share.
The cutting blade of  the tine was exposed first to bending 
due to soil resistance. The soil resistance, FX is horizontal 
and acts in the axis of  symmetry of  the tyne. Average 
soil resistance was obtained by the formula given below 
(Kumar et al., 2017) and Table 1.
FX= d × w × KO                                                              (7)
= 30×20×0.2 = 120×9.81 = 1,777.2 N 
Where, (i) d = Effective working depth of  tine (cm); (ii) w 
= Working width of  the tine (cm); (iii) KO = Specific soil 
resistance (kg/cm2).

Table 1: Specific Soil Resistance at a depth of  15 cm
S/N Soil Type Specific resistance, kg/cm2

1 Light 0.12
2 Medium 0.15
3 Heavy 0.20
4 Very heavy 0.25

Source: (Dubey, 2003)

The draft force exerted on the cutting blade was 
determined using the following equation;



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D = KO × n × w × d                                                      (8)
= 0.8×7×20×30 = 3,360 kgf  = 32,691.6 N
Where, (i)D = draft force, kgf; (ii) KO= soil resistance, 
kg/cm2; (iii) w = width of  tine, cm; (iv) d = depth of  tine, 
cm; (v) n = number of  tine.
Finally, the total draft required for operation and each 
draft of  the tines was calculated by,
Dt = D × FOS × g                                                          (9)
Dt = 3,360 ×1.5×9.81 = 49,442.4 N
Where, (i) Dt = total draft, N; (ii) D = draft, N; (iii) FOS = 
factor of  safety; (iv) g = force due to gravity, m/s2. 
Di = (Draft (N))/(number of  rows)                                    (10)
= 32,961.6/7 = 4,708.8 N
It was assumed that the draft force on the tine was 
determined and acting at a height of  h/3 from the 
bottom of  the tine. The distance of  the draft application 
on furrow opener tine (d) was calculated by the formula 
given below (Sharma & Mukesh, 2010).
d = h/3                                                                         (11)
= 60/3 = 20 cm
Moment arm length = (h-d) = 60-20 = 40 cm                 (12)
The maximum bending moment was determined 
according to the following formula.
Bending moment of  tyne (BM) 
= Draft × moment arm length                                                           (13)
= 4,708.8 N×40 = 188,352 N m
Therefore, the maximum bending moment of  tine was 
determined by multiplying the bending moment of  tine 
with a factor of  safety. (take,  FOS=1.5) 
Maximum bending moment
= bending moment × FOS                                            (14)
Mb = 188,352 Nm×1.5 = 282,528 Nm
Mild steel was used for the design of  tine and assuming 
bending stress, σb = 56 N/mm2. Section modules of  
each cutting blade (Z) were determined as the following 
formula.
Z = ( Mb)/σb                                                                 (15)
= (282,528 )/56=5.05 cm3

Where, (i) Mb = maximum bending moment; (ii) σb = 
bending stress; (iii) Z = section modulus of  tine; (iv) b = 
width of  mild steel.
According to (Khurmi & Gupta, 2005), the Section 
modulus of  tine of  a cultivator with pulverizing 
attachment was calculated by using the formula,
Z = 1/6  × b3                                                               (16)
5.05 cm3 = 1/6×b3

b3 = 5.05  cm3×6 = 30.27 cm3

b = ∛(30,270.84) = 3.12 cm≈4 cm   
So, the 4 cm ×4 cm size of  the share was developed from 
a mild steel material. 
Bending Stress, σb causing the tine to bend was calculated 
by the expression(Kumar et al., 2017).
σb = (6Dt (H1+a))/(tb2 )                                                   (17)
= (6×49,442.4(35+20))/(0.6×402 ) = 16,995.82 N/cm2

Where, (i) Dt= draft at the tip of  tine, N; (ii) HI  = length 
of  tine, cm; (iii) a = Effective working depth of  tine, cm; 
(iv) t = thickness of  the tine, cm and (v) b = width of  
tine, cm.
Torsional stress acting on the tine when turning the 
openers inside the soil at headland is given by (Kumar et 
al., 2017).
τ = (9Dt (Ww/4))/(2b2 )                                                 (18)
= (9×49,442.4(40/4))/(2(40)2)
= 4 ,449,816/3200 = 1,390.57  N⁄cm2 

Where, (i) Ww = Effective working width of  tine, cm, and 
(ii) b = width of  tine, cm
Then, the reduced stress is calculated as;
δ = √(σb2+4τ2)                                                             (19)     
= √((16,995.82)2+(1,3902.57)2)
= 17,052.61  N⁄cm2 = 170.53 N/mm2

Where, (i) δ = Reduced stress, kg/cm2; (ii) σb =  bending 
Stress, N/cm2 and (iii) τ = Torsional shear stress, N/
cm2. Since the calculated stress (170.53 N/ mm2) was less 
than the allowable stress of  mild steel (200 N/mm2), the 
design was safe and the tine can perform well.

Figure 2: Schematic Diagram of  Cultivator Tine



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Design of  Pulverizing Roller 
Basic Design Parameters and Specifications
Pulverizing roller attachment to the cultivator pulverizes 
the soil to a greater degree. The pulverizing roller consists 
of  discs, a central shaft, and pulverizing members. The 
pulverizing roller was designed for cutting, mixing, and 
clod breaking which ultimately pulverizes the soil by 
impact force. The cutting and clod-breaking action of  
this unit provides better soil preparation. 
Roller diameter = 45 cm
Length of  roller = 130 cm
Circumference = π×D                                                (20)
= 3.14×45=141.3 cm
Spacing between pulverizing blades was calculated by the 
following formula (Prem et al., 2016).
Sb = (π×D)/Nb                                                             (21)
= 143.3/6 = 23.55 cm (taking, Nb=6)
Where, (i) Sb = Spacing between the pulverizing blade; (ii) 
Nb = number of  pulverizing blade
Depending upon the type of  soil and moisture content 
in the soil, the torque required to break big clods varies 
between 0.5 Nm. Therefore, the power required to 
operate the pulverizer generally ranges between 1-2 hp at 
an operating speed of  1.1 m/s and 10% slippage (Prem 
et al., 2016).
Speed = πDN                                                               (22)
1.1 = 3.14×45×N
N = 1.1/141.3 = 0.008≈1
We know that,
P = 2πNT/60                                                                 (23)
Where, (i) p = power required, W; (ii) N = rpm of  the 
roller; (iii) T = torque applied, N-m
T = (p×60)/(2π×N)                                                      (24)                
2 = (2×3.14×1.×T)/4500
T = (2×4500)/(2×3.14×1)=9000/6.28=1433.12 Nm
When the pulverizer was operated on the ground it was 
subjected to a sudden load, therefore while designing, the 
torque was taken as 2 times the rated torque. 
Tmax= 2×T                                                                    (25)    
Tmax= 2×1433.12=2866.24 Nm

Design of  Pulverizing Blades
Pulverizing blades were fabricated and fixed into the 
disc at 900 in such a way that it has continuously come 
in contact with soil. Pulverizing blades were designed as 
follows.
AT = pL×Tb   (Parmar & Gupta,2001)                                                  (26)
= 130 cm×0.4 cm=52 cm2

Where, (i) AT = total area of  pulverizing blade striking 
on soil, cm2;(ii) pL = pulverizing length, cm; (iii) Tb = 
thickness of  blade, cm.
The maximum soil resistance = Total area of  pulverizing 
blade × the specific soil resistance
Msr = AT×Ssr                                                                (27)
= 52 cm2×0.75  Kg⁄cm2 =39 Kgf
Where, (i) Msr= maximum soil resistance, Kgf; (ii)  AT= 
total area of  the blade, cm2; Ssr = specific soil resistance 
Kg/cm2.

The maximum bending moment in the blade was 
calculated by the following formula.
Mb= Sr×Rd                                                                   (28)  
= 39 Kg×22.5 cm=877.5 Kg cm   
Where, (i)Mb= maximum bending moment, Kg cm; (ii) 
Sr= soil resistance, Kg⁄cm2 ; (iii)Rd= radial distance, cm.   
The maximum bending stress for mild steel is 700 MPa, 
calculating actual bending stress as per the following 
formula (Sharma & Mukesh, 2010).
σb = (Mb × y)/I                                                          (29)  
700 = (877.5×12×w×2)/(2×0.4×w3)
w = √(21060/560)=6.14 cm≈7 cm=7 cm
Where, (i) Mb= maximum bending moment; (ii)σb= actual 
bending stress, N/cm2 (iii) y = distance height, = d/2; 
(iv) I = moment of  inertia,= bt3/12; (v) w = width of  
pulverizing blades.
Hence design is safe. Mild steel flat with 7 cm width, 130 
cm length, and 0.4 cm thick was selected for pulverizing 
blades.

Design of  the Pulverizing Roller Drive Shaft
The design of  the shaft must involve the determination 
of  the minimum diameter of  the shaft material to 
ensure satisfactory strength and rigidity when the shaft is 
transmitting power under various operating and loading 
conditions. The shaft was initially decided to be fabricated 
from ductile material (mild steel rod). 
Hence, the design was based on ductile material whose 
strength is controlled by the maximum shear stress. For a 
shaft having little or no axial loading, the diameter of  the 
shaft was obtained using the ASME code Equation (39), 
(ASME, 1995) given as:
d3 = 16/πSs [(kbmb)

2+(kt mt)
2](1/2)                                   (30)

Where, (i) d = diameter of  the shaft, mm; (ii) Mt = 
torsional moment, Nm; (iii) Mb = bending moment, Nm; 
(iv) Kb = combined shock and fatigue factor applied to 
bending moment; (v) Kt = combined shock and fatigue 
factor applied to torsional moment; (vi) Ss = allowable 
stress, MN/m2.         
For rotating shafts when the load is suddenly applied with 
minor shock (Khurmi & Gupta, 2005), recommended 
that values of  Kb = 1.2 to 2.0 and Kt = 1.0 to 1.50 be 
used. Furthermore, it was noted that for the shaft without 
the keyway, the allowable stress (Ss) must be 55 MN/m2, 
and for the shaft, with the keyway, the allowable stress (Ss) 
should not exceed 40 MN/m2.        
The torsional moment (Mt) on the shaft was calculated 
using Eqn. below (Ryder, 1989).
Mt = (p×60)/(2π×N)                                                   (31)   
p = V×F                                                                       (32)
Where, (i) P = power required to drive the pulverizer; (ii) 
N = speed of  the shaft, (1 rev/sec.); (iii) V = forward 
speed (0.833 m/s); (iv) F = force required to drive the 
machine (2.4 N).
Figure 6 shows the load distribution on the shaft. The 
maximum bending moment on the shaft was determined 
from the following expressions.
Mb= (Mv

2+Mh
2 )                                                          (33) 



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Where, (i) Mv = vertical bending momentum, Nm; (ii) 
Mh= horizontal bending momentum, Nm
The reaction of  forces on the driven shaft is as shown 
below for vertical forces
The total resultant components of  horizontal and vertical 
bending moments on the shaft can be obtained as follows.
Mb = (Mv

2+Mh
2 )1⁄2 =62,655,333.955 Nmm

Mt = (p×60)/(2π×N)
= (2×60)/(2×3.14×1)=51,858.25 Nmm
d3 = 16/(3.14×55) [(2×62,655.33)2+(1.5×51.86)2 ]1/2

d3 = 6,768,148.8/172.7= 39,304 mm
d = ∛39,304= 34 mm
Mt = torsional moment; Nm
Mb = bending moment; Nm
Kb = 2;  Kt = 1.5, and Ss = 55 MN/m2

Therefore, the standard size of  50 mm shaft diameter was 
used.
Since the actual diameter was greater than the calculated 
diameter. Therefore, the shaft has proper strength for 
operation. 

Selection of  Bearing 
The size of  a bearing to be used depends on the size of  
the shaft required and the available space. In addition, the 
bearing must have a high enough load rating to provide 
an acceptable combination of  life and reliability. 
The bearing size was determined using the maximum 
load acting on it and the desired maximum lifespan. The 
dynamic equivalent radial load (W) is calculated by the 
equation given below.
W = X.V.WR+Y.WA                                                      (34)
W = 0.4 × WR+ 1.6 × WR=  2 × 20 × WR= 80 kN   
WR = 40 KN                                                                                                
Where, (i) WA= dynamic axial load; (ii) WR= dynamic 
radial load; (iii) X= radial load factor; (iv) Y= axial load 
factor; (v) V = A rotation factor, 1, for all types of  
bearings when the inner race is rotating. Dynamic load 
rating can be determined using Eqn. 35.
C= W (L/106 )1/k                                                          (35) 
= 40× (20,000/106 )1/3=11 kN
Where, (i) L = Rating life; (ii) C = Basic dynamic load 
rating; (iii) W = Equivalent dynamic load, and k = 3, for 
ball bearings, = 10/3, for roller bearings.
Therefore the maximum lifespan value of  20,000 hr 
was selected to determine the basic dynamic load rating. 
Bearing number 207 with a bore of  35 mm was selected 
since the minimum shaft diameter has been determined 
to be 35 mm. Hence, two bearings used for the shaft of  
the cultivator with pulverizing attachment were selected 
based on the general criteria for bearing selection.

Determination of  Weight and Power Requirements 
Weight of  the Implement
To estimate the loads on every part of  the cultivator with 
pulverizing attachment, it should be necessary to estimate 
the weight of  all parts. Accordingly, the weights of  the 

cultivator tyne, frame, pulverizing blade, share (cutting 
unit of  the cultivator), and disc were estimated (ITSI-SU, 
2011). The total weight of  the cultivator with a pulverizing 
attachment including the weights of  the frame, pulverizer 
blade, three-point linkage unit, cultivator tine, and share 
of  the cultivator was 1331.48 N. Taking 2% margins 
for weights of  welding, bolts, nuts, etc. Finally, the total 
weight of  the cultivator with pulverizing attachment was 
found 1358.11 N.

Draft Requirement
The draft requirement of  the tractor-operated cultivator 
with a pulverizing attachment was estimated using factors 
related to implement and the type of  soil. The specific 
soil resistance of  medium black soil of  the area was 0.75 
kgcm-2 (Parmar & Gupta, 2001). 
Total working width of  the cultivator 
= number of  tine × tine spacing                                      (36) 
= 7 × 22.86 cm =160 cm or 1.6 m
Cross section area of  furrows = Total working width of  
the cultivator x depth of  furrow                                 (37)                                                
= 160 cm × 30 cm = 4800 cm2. 
The maximum draft required to drive the cultivator is 
calculated as follows.
D = CAC×SR×g×FOS                                                  (38)  
= 4800 cm2 × 0.75 Kg/cm2 × 9.81 m/s2 × 1.5 
= 52,974 N
Where, (i) D = Maximum draft; (ii) CAC= Cross-section 
area of  the furrows; (iii) SR = maximum soil resistance; 
(iv) g = force due to gravity; (v) FOS= factor of  safety

Power Requirement
The power required to pull the designed implement was 
estimated as follows.
Pd = (D×S)/1000=(52,974×0.833)/1000=44.13kW    (39)
Where, (i) Pd = power required to drive the implement; 
(ii) D = draft required to drive a cultivator; (iii) S = speed 
of  operation.
The power required to operate the cultivator with 
pulverizing attachment was calculated as follows;
P= (Power required to drive the implement)/(Coefficient 
of  friction)                                                                 (40)
P= 44.13/0.85=51.82≈52 kW
Where, (i) P = power required to operate the implement; 
(ii) D = draft requirement of  the implement; (iii) S = 
forward speed of  the tractor.

Laboratory Testing of  Prototype
Preliminary performance tests were carried out to obtain 
actual data on overall implement performance and 
work capacity. Performance evaluation (in terms of  soil 
tilling quality and machine parameters) was determined. 
The parameters that were taken during the preliminary 
test were; the mean weight diameter of  the soil, wheel 
slippage,  soil inversion, draft, the width of  cut, and 
volume of  soil handled.



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Figure 3: Prototype Cultivator with Pulverizing Attachment after Fabrication and during Testing

Mean Weight Diameter of  the Soil
Soil samples were collected randomly from the tilled plots, 
with three replications, using an auger at 0-30 cm depth 
after the tillage process to estimate the clod mean weight 
diameter. At room temperature, the moist soil samples 
were allowed to air. The air-dried soil samples were sieved 
with a set of  sieves. Clod’s mean weight diameter was 
calculated using the following formula.

 (41)

Where, wi=the weight of  soil on each special sieve (kg)
w = the total weight of  experimented soil (kg) 
Di = Net diameter of  each sieve (mm)

Wheel Slippage
The distances the tractor traveled a head at every 10 
revolutions under load and no load on the same surface 
were measured after a mark was created on the tractor 
drive wheel with colorful tapes. The speed reduction can 
be calculated as follows.
Travel reduction = (M2-M1)/M2 ×100                          (42)
Where, M2 = Distance covered at every 10 
revolutions of  a tractor drive wheel with no load (m)                                                                                                                                         
M1 =Distance covered at every 10 revolutions of  tractor 
drive wheel with load (m).

Width of  Cut
The width of  the tillage implement’s cut was taken by 
measuring the width of  the furrow using a measuring 
tape every 5 meters along its length. The width of  the cut 
was determined by averaging ten readings. 

Draft
The following equation was used to calculate the draft of  
the implement (ASME, 1995).
D=Fi [A+B(S)+C(S)2 WT]                                             (43)
Where, D = drawbar pull, N 
F= a dimensionless soil texture adjustment parameter 
i = soil factor = (1 for fine, 2 for medium, and 3 for 
coarse texture soils)
A, B & C = machine – specific parameters   
S = forward speed, km/h 

T = tillage depth (cm) for major tools 
W = machine working width, m.

Soil Inversion
The number of  weeds or residues of  the previous crop 
remaining on the soil surface after the operation was 
compared to the number before the operation. For 
counting weeds or stubbles, a square frame with sides of  
100 cm was employed. 
F(%) = (B-A)/B×100                                                  (44)
Where, F= indicator for soil inversion,% 
B= number of  weeds or crop residue before operation 
per unit area, 
A = number of  weeds or crop residue exposed on the 
surface after operation.

Volume of  Soil Handled
As shown in the equation below, the amount of  soil 
handled was estimated by multiplying the field capacity 
with depth of  cut. 
V(m3/h) = 10000EFC DC                                                (45)
Where, V = Volume of  soil handled (m3 /ha)  
EFC = Effective field capacity (ha/h) 
DC = Depth of  cut (m)

RESULTS AND DISCUSSION
Physical Properties of  Soil
Moisture Content of  Soil
The mean data on soil moisture content before tillage 
operations at 0-20 cm depth was recorded and presented 
in Table 2. The moisture content of  the soil varied from 
13.9 to 14.54% with an average value of  14.14%. 

Table 2: Soil moisture content (dry basis)
Sample 
No.

Mass of  
wet
soil
(gm)

Mass 
of  dry 
soil 
(gm)

Soil 
Moisture 
content 
(%)

Average 
(%)

1 256.68 220.8 13.98
14.142 265.26 226.69 14.54

3 244.52 210.5 13.91



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Bulk Density of  Soil
Values of  bulk density before tillage operations at 0-20 
cm depth were recorded and presented in Table 3. The 

Table 3: Bulk density (gm/cc)
Sample No. Mass of  wet 

soil (gm)
Mass of  dry 
soil (gm)

The volume of  
the core sampler 
(cc)

Bulk density (gm/
cc)

Average

1 256.68 220.8 147.2 1.5
1.49                                                              2 265.26 226.69 147.2 1.54

3 244.52 210.5 147.2 1.43

bulk density of  the soil was found to be in the range of  
1.43 g/cm3 to 1.54 g/cm3 with an average value of  1.49 
g/cm3.

Laboratory Testing Results
Mean Weight Diameter of  the Soil
The range of  the clod means weight diameter was 
observed between 10.21 to 11.77 mm. Maximum clod 
means weight diameter of  was at a tractor forward speed 
of  2.5 km/hr. The minimum value of  clod means weight 
diameter was at a tractor forward speed of  3.5 km/hr. It 
is seen from the result that a smaller clod percentage was 
produced as the tractor’s forward speed increased. The 
bigger clod percentage decreased and the smaller clod 
percentage increased. 
The increase in speed that causes a decrease in bigger clod 
percentage might be a result of  the vibrating effect of  the 
implement associated with an increase in the operating 
speed of  the tractor. More clods break into smaller ones 
as the implement with higher speeds throws the soil. The 
improved soil aggregation was attainable at higher tractor 
forward speed. 

Wheel Slippage
Maximum wheel slippage (12.85%) was obtained at 3.5 
km/hr tractor forward speed. Minimum wheel slippage 
(13.44%) was obtained at 2.5 km/hr tractor forward 
speed. Wheel slippage increased negatively as the tractor’s 
forward speed increased for the tested implement. The 
negative increase in wheel slippage might be a result of  
the rolling resistance of  the tractor tires and the rolling 
action of  the implement that oppose the rotational 
movement for the increased tractor forward speed. A 
negative increase in slippage percentage was observed 
with an increase in tractor forward speed. 

Width of  Cut
The width of  cuts varied between 140.00 to 143.83 cm. 
The width of  cuts was found maximum (143.83 cm) at 
3.5 km/hr tractor forward speed while the minimum 
width of  cuts (140.00) was obtained at 2.5 km/hr tractor 
forward speed. The width of  cuts increased with the 
tractor’s forward speed. The reason might be due to the 
high soil thrown by the implement at a higher tractor 
forward speed than a lower tractor forward speed.

Draft
The draft of  the implement ranged between 8.19 to 8.59 
KN. The maximum draft was obtained at 3.5 km/hr 
tractor forward speed. The minimum draft was observed 

at 2.5 km/hr tractor forward speed. The draft requirement 
of  the implement increased as the tractor’s forward speed 
increased. The reason might be due to higher force 
requirement at a higher speed than lower speed.

Soil Inversion
The maximum soil inversion (89.17%) was found at 3.5 
km/hr tractor forward speed. Minimum soil inversion 
(82.41%) was found at 2.5 km/hr tractor forward speed. 
Soil inversion increased as the tractor’s forward speed 
increased. There was an increase in the percentage of  soil 
inverted as the tractor’s forward speed increased. It might 
be a result of  the implement’s ability to turn and throw 
the soil when at a higher speed than at a lower speed. 

Volume of  Soil Handled
The amount of  soil handled varied from 671.07 to 672.09 
m3/ha. The maximum volume of  soil handled was at 3.5 
km/hr tractor forward speed. The minimum volume of  
soil handled was observed at 2.5 km/hr tractor forward 
speed. The volume of  soil handled increased as the 
tractor’s forward speed increased. This might be due to 
the increment of  effective field capacity as the tractor’s 
forward speed increased.

CONCLUSION
A cultivator with pulverizing attachment was designed 
and developed to reduce secondary tillage operations to 
a single pass to ensure timeliness in seedbed preparation. 
The cultivator tines were fitted on the frame and at the 
back side of  the frame pulverizing, the roller was attached 
with help of  bearings. 
The pulverizing blades were welded on the discs, in 
such a way that was crushed the soil by impact force. In 
this, the force exerted by the pulverizer on the clod is 
distributed uniformly in the shaft which is used to hold 
the pulverizing roller. 
The roller was attached to a frame that holds cultivator 
tines and a three-point linkage unit. The pulverizer 
was designed to break big clods formed during tillage 
operation. The developed implement was attached to the 
tractor by three point hitch. Cultivator tines open furrow 
and operated roller cut and pulverize soil at optimum 
condition for tillage. 
The preliminary test of  the cultivator with pulverizing 
attachment in terms of  the width of  cuts, draft 



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Am. J. Smart. Technol. Solutions 3(2) 25-33, 2024

requirement, wheel slippage, soil inversion, the volume 
of  soil handled, and clod mean weight diameter was 
evaluated. Maximum clod means weight diameter of  
was observed at a tractor forward speed of  2.5 km/
hr. The minimum value of  clod means weight diameter 
was observed at a tractor forward speed of  3.5 km/hr. 
Maximum wheel slippage (12.85%) was obtained at 3.5 
km/hr tractor forward speed. Minimum wheel slippage 
(13.44%) was obtained at 2.5 km/hr tractor forward 
speed. 
The width of  cuts was found maximum (143.83 cm) at 
3.5 km/hr tractor forward speed while the minimum 
width of  cuts (140.00) was obtained at 2.5 km/hr tractor 
forward speed. The maximum draft was obtained at 3.5 
km/hr tractor forward speed while the minimum draft 
was observed at 2.5 km/hr tractor forward speed. 
The maximum soil inversion (89.17%) was found at 
3.5 km/hr tractor forward speed while minimum soil 
inversion (82.41%) was found at 2.5 km/hr tractor 
forward speed. The amount of  soil handled varied from 
671.07 to 672.09 m3/ha. The maximum volume of  soil 
handled was at 3.5 km/hr tractor forward speed. The 
minimum volume of  soil handled was observed at 2.5 
km/hr tractor forward speed.

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