Agricultural weeder mechanism for multi-row crops

1. D E S I G N O F A G R I C U LT U R A L
W E E D E R M E C H A N I S M
P R O J E C T BY :
A D I T YA N A K I L ( U - 1 3 )
P R A N J A L K E N G E ( U - 2 4 )
T E J A S P U N WAT K A R ( U - 2 8 )
R O H I T K H A R AT ( U - 3 4 )
G U I D E : P R O F. D R . M . K . N A L AWA D E

2. ABSTRACT
• To remove weed from agricultural field in early stages of crop, an agricultural
equipment used called “kolpe”
• Kolpe removes weed from one row of crops only, with the effort of a person
• Kolpe is usually used for Maize, Jowar and Bajra crop fields. In early stages, these crops
have small height about 15-20 cm.
• We aim to modify the kolpe mechanism to use it for removing multiple rows of crops
with same effort of one person

4. OBJECTIVE
• To design and build a mechanism which will remove weeds from multiple rows of
crops
• In order to get high mechanical advantage, that is to create more effect in less effort,
by a single operator in weed removal mechanism
• In this mechanism stationary blades are attached, which will remove the weed from
multiple rows
• We aim to reduce cost of the equipment and making it less time consuming than
conventional mechanism

5. LITERATURE SURVEY
• Conventional Kolpe needs high effort, also we can remove weeds from only one row at
a time with one pass
• It can be used for Maize, Jowar, Bajra and wheat crops, in early stages when the crop’s
height is about 10-15 cm
• Usually the distance between the 2 rows of crop is 20 cm
• The motor operated weeders are costly and costs about Rs. 15,000 for one unit which
works for one row only
• A multiple row weeder costs about 50,000 to 1,00,000; which is not affordable by most
of the farmers

6. FORCE CALCULATIONS
• The force needs to be exerted by the operator is the addition of two forces: the force
experienced by the cutter and friction force between wheel and ground.
1. Force experienced by the cutter:
Soil resistance: 0.2 kgf/cm2
Depth of cut: 5 cm
Effective width of cut: 6 cm
Normal human walking speed: 140 cm/s = Tangential velocity of wheel
Angular velocity of wheel: 4.667 rad/s
Considering mechanical advantage, the angular velocity of cutter shaft is 3 x 3.667 =
13.998 rad/s
Power developed = Soil resistance x depth of cut x width of cut x velocity/76 = 0.075 hp
= 55.125 W
Torque = Power/ angular velocity = 3.938 N-m
Force = 13.1266 N

7. Design can accommodate 12 cutter blades
So, total force experience by cutters = 12*13.1266 = 157.51 N
• Friction force between wheel and ground:
Total weight of model= 7.2 kg
Normal reaction N=7.2 kg
Let, µ=coefficient of friction= 0.4
Friction force F=µ*N
F= 0.4*7.2=28.25 N
Total force= 157.51+28.25= 185.76 N

8. MATERIAL
Part Quantity
Wheel 4
Bearings 6
Shafts 2
Chain drive 1
Cutter blades 2 sets

9. DESIGN
• Diameter of wheel: 660.4 mm
• Wheel thickness: 35mm
• Frame thickness: 20mm
• Cutter length: 310mm
• Shaft length: 480mm
• Primary shaft diameter: 20mm
• Secondary shaft diameter: 20mm
• Frame and cutter material: Mild steel

10. CAD MODEL- PARTS

12. OLD MODEL PROPOSED

13. CHAIN DRIVE SELECTION
• The service requirement is light duty.
• Also power requirement and speed of faster shaft are less.
• Chain of 08-A (ANSI 40) type is selected.
• Pitch=12.7 mm
• Distance between two shafts= 700 mm
• No. of teeth on driving sprocket= 16
• No. of teeth on driven sprocket= 32
• The transmission ratio is 2, so a mechanical advantage of around 2 is expected out of
this mechanism.

14. BEARING SELECTION
• Single row deep groove ball bearings
• There are two kinds of bearings used in our model:
1. 6004
• Shaft diameter=20 mm
• So, bearings inner diameter, d=20 mm
• Outer diameter, D=42
• Axial width, b=12
2. 6007
• Put on rear wheel
• Acts as isolator
• inner diameter, d=35mm
• Outer diameter, D=62mm
• Axial width, b=14mm

15. FUTURE SCOPE
• Engine or motor can be incorporated into the design.
• Design can be extended for number of rows more than two.
• Can be made automatic.
• Design can be modified for using rotating blades.

16. ADVANTAGES
• When compared to weeders that are already available in the market, our mechanism
would cost around Rs.5000 which is quite affordable.
• If we also include motor the cost would go up to Rs.30000 which means 55% reduction
in cost.
• Less physical work required as compared to conventional equipment.
• Standard pulleys, bearings, chain drive etc. are used, which ensures easy mass
production.

17. CONCLUSION
• The mechanism developed can successfully be used to remove weed in the Maize,
Bajra, Jawar and cotton fields.
• The objectives of getting the mechanical advantage and removing the weed from
multiple crop rows is achieved.
• Cost effective design
• Simple and easy to maintain mechanism
• Easily mass producible product

18. REFERENCES
• Friction Coefficients of Selected Agricultural Soil and Agro-Products – A Review
Ahmad Suhaizi Mat Su and Desa Ahmad.
Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia.
43400 Serdang Selangor, Malaysia.
Department of Agricultural and Biological Engineering, Faculty of Engineering, Universiti
Putra Malaysia 43400 Serdang Selangor, Malaysia.
• Development of Single wheel multi use manually operated weed remover
Sridhar.H.S
Asst. Professor Department of Mechanical Engineering, Sri Basaveshwara institute of
technology, Tiptur-572202, Tumkur (D), India.

19. • Mechanized Weed Mower
Vikas V. Amange
Amit K. Bhujbal
Priyank K. Gala
Anil B. Gange
Prof. A. J. Patil

20. THANK YOU!