The document provides information on machine design principles and farm machinery design. It defines key terms like machine, mechanism, machine elements, and machinery. It then discusses machine design considerations and the process, which includes planning, concept design, detailed design, manufacturing, and commercialization. Specific to farm machinery, it discusses design parameters, differences from other machines including operating conditions and human factors, features of well-designed machines, and power transmission components like belts and chains.

1. ADAMA SCIENCE AND TECHNOLOGY UNIVERSITY
School of Mechanical, Chemical, and Materials Engineering
Department of Mechanical Engineering
Agricultural Machinery Design (MEng5329 )

2. CHAPTER ONE: Introduction
Farm Machinery Design Principles and Reliability
Definitions:
Machine
Mechanism
Machine elements
Machinery
Machine: A machine is a device that employs power to accomplish a desired function to
benefit humankind.
Involve a vast variety of mechanical products in the fields of
manufacturing,
Transportation,
aerospace,
construction,
agriculture,
energy, and many others.

3. Introduction Cont…
Some Examples of Machine

4. Introduction Cont…
Mechanisms
A mechanism is a combination of elements formed and connected to transmit motion in a
predetermined fashion. Typical mechanisms include linkages, cams and follower systems,
gears, gear trains, and so on.
Valve gear mechanism Sliding crank

5. Introduction Cont…
Machine Elements
A machine composes individual machine elements properly designed and arranged to work
together.
Are the fundamental components of a machine, and are broadly classified as universal
elements, such as bolts, keys, splines, pins, belts, chains, gears, bearings, and springs
that are widely used in different kinds of machines, and special elements such as
turbine blades, crankshafts, and aircraft propellers, which perform specific functions.

6. Introduction Cont…
Some machine Elements

7. Introduction Cont…
Machinery
Machinery is a derived term and refers to a grouping of mechanisms and machines
Engineering design
• Design is widely considered to be the central or distinguishing activity of engineering.
• It aims to create and execute a purposeful plan to meet commercial, industrial, and social
needs.
• When design is discussed in the mechanical engineering domain, especially about
mechanical products or machines, it is termed mechanical or machine design.
• Machine design is the art of
• envisioning,
• creating, and
• developing a brand new or improving on an existing mechanical device
• It is an innovative, iterative, decision-making and problem-solving process involving
comprehensive utilization of scientific knowledge and creative capability

8. Introduction Cont…
Machine Design Consideration.
An important assessment of design quality is the machine’s safe and reliable performance of its intended
function for the prescribed design life without serious breakdown.
During the design process, the total life cycle of a product, from
initial ideation, design, manufacturing, assembly to service, and
final disposal,
should be reviewed, and situations that may practically occur during
manufacturing,
transporting,
Storing,
installing,
servicing,

9. Machine Design Process
To develop a safe, efficient, and reliable product with excellent functionality and high
competitiveness, proper design procedures, and approaches should be established and
followed.
The development of a new machine from inception through elaboration to termination can
be broadly classified into four stages:
planning,
concept design,
detailed design,
manufacturing, and
commercialization

10. Introduction Cont…
Planning
Design starts with the recognition of needs.
The desire or expectation for a new product may be acquired from
a target market,
dissatisfaction with existing products, or
a particular adverse circumstance; for example, a need for a robot to work in a hostile
environment.
The vague or subjective needs are then translated into detailed quantitative specifications to define
the function of the expected product.
These specifications are the input and output quantities, such as power, operating speeds, expected
life or safety, and space or weight limitations.
Financial investment, estimated price, cost targets, expected profits, and other business issues,
together with sales operations and time schedules also need to be considered at this stage.

11. Introduction Cont…
Concept design
• A design concept consists of sketches, images, and short descriptions that define the general
aesthetic quality of a product.
• The purpose of a design concept is to help designers and developers visualize what the
product should look like and, in doing so, drive additional value for customers.
• A good design concept visually demonstrates the product’s core objective and often serves as
a design guide.
• To achieve an outstanding product design concept, designers must understand the problem,
target user, stakeholder expectation, and aesthetic of view.
• A design concept is an early-stage idea that provides designers with in-depth and meaningful
direction.

12. Introduction Cont…
Detailed design
Once the optimum concept design is determined, an initial design is proposed and developed
into an analytical model or a computer model for pertinent analyses as required, including
kinematics, force, strength, rigidity, heat transfer, and so on.
If analytical results are not satisfactory, designers return to the initial design to revise the
previous tentative design.
Otherwise, a physical prototype will be built, tested, and evaluated.
After reiterations of analysis, optimization, and evaluation, an optimal solution is finally
achieved.
The initial tentative design is converted into a workable product, and a set of detailed
production drawings and design documents are produced to facilitate manufacturing.

13. Introduction Cont…
Manufacturing and commercialization
Once the initial design has been converted into a workable product successfully, practical
manufacturing is organized to produce products.
A full-scale production can be launched and products can be sold to customers by both
domestic and global markets.
Commercialization also involves customer service and especially warranty. Finally, service
data on failure modes, failure rates, maintenance, and safety problems are collected for future
product improvement.

14. Introduction Cont…
Design Parameters of Farm Machinery
1. Power requirement of machine and source of power availability
2. Functional requirements of the machine and its interrelationships of various components
3. Optimum expected life of the machine
4. Strength requirement of various components
5. Material selection based on force analysis and availability in the local market
6. Wear characteristics of various components
7. Ease of operation of various components
8. Reliability of components and the machine
9. Possibility of designing a multipurpose machine combining more than one function into a single
machine

15. Introduction Cont…
Design Parameters of Farm Machinery… cont
10. Cost of a machine and farmer’s paying capacity
11. Ease of operation, adjustment & maintainability
12. Safety aspects
13. Human factor in design
14. Aesthetic appeal and durability of the machine
15. Cultural requirements of the community
16. Suggestions and feedback from the user
17. Other competitive products in the market

16. Introduction Cont…
The design of farm machine differs from other machines
1. A farm machine should be capable of performing its function under a variety of
conditions.
 The various conditions may be due to the geographical location of the field, crop
growth and season, specific needs of farmers’ farm size, and production trends.
 Methods of their control and adjustment of the machine should be adequately
simple
The machine should be easy to operate, reliable in action, and precise in function

17. The design of farm machine differs cont…
2. A farm machine comes to work rather than work coming to the machines. Most farm
machines perform various functions in motion mostly on uneven or bumpy grounds e.g.
combine harvesters, and root crop harvesters.
3. Safety; Proper engineering design of agricultural machines can reduce the number of
accidents on the farm.
4. Human factors; in farm machinery design several environmental variables and machine
parameters can materially affect a person’s performance while operating the machine in
actual field conditions.

18. Introduction Cont…
The design of farm machine differs cont…
4. Human factors cont…
 Some of these factors are:
 Air temperature, humidity, and purity
 Noise level
 Vibration
 Seat design
 Arrangement of workspace
 Placement of controls and instruments
 The shape and coding of controls
 The amount of physical effort required for controls
 Overall visibility of machine components and functions that need to be watched

19. The design of farm machine differs cont…
4. Human factors cont…
 Equipment designed with the proper application of human factors
principles can lead to the following performance results
 Increased efficiency and productivity
 Increased reliability
 Improved safety
 Decrease the operator’s efforts
 Improved flexibility
 Increased comfort and better operation

20. The design of farm machine differs cont
5. Draft and power requirements: The draft and power requirements of farm machinery
vary from one farm to another farm and on the same farm from location to location, season to
season, and from year to year.
6. Design of frames of farm machines: The frame of farm machines must be as light as
possible to reduce cost, soil compaction and propelling power but strong enough to resist the
shocks due to rough fields and obstacles

21. Design features of a well-designed farm machines
 A well-designed machine should have the following important features for its
satisfactory performance at the user level
 Efficient use of power sources
 Efficient use of human power in doing work
 Best possible quality of work with minimum cost
 Easily workable and cheaper material of construction
 Fewer parts- to reduce the cost and complexity of the machine
 Standard and interchangeable parts
 Resistance of mechanical wear due to friction
 Corrosion resistance
 Provided with appropriate safety devices
 Low cost of repair

22. CHAPTER TWO
Design of power transmission components and systems in farm machinery
Power transmission is the movement of energy from its place of generation to
a location where it is applied to performing useful work.
The power is transmitted from one shaft to the other by means of belts, chains,
and gears
The belts and ropes are flexible members which are used where the distance
between the two shafts is large
The chains also have flexibility but they are preferred for intermediate
distances.
The gears are used when the shafts are very close to each other. This type of
drive is also called positive drive because there is no slip
There is a possibility of slip and creep and that is why, this drive is not a
positive drive

23. Belts
In the case of belts, friction between the belt and pulley is used to transmit
power.
In practice, there is always some amount of slip between the belt and pulleys,
therefore, an exact velocity ratio cannot be obtained
That is why, belt drive is not a positive drive.
Therefore, the belt drive is used where an exact velocity ratio is not required.
The types of belts most commonly used belts

24. Belts
Flat belts
rectangular in cross-section
utilizes the friction between the flat surface of the belt and the pulley
V-belt
trapezoidal in section
utilizes the force of friction between the inclined sides of the belt and pulley
preferred when the distance is comparatively shorter
Several V-belts can also be used together
Circular belt or rope
circular in section
Several ropes also can be used together to transmit more power
Types of belt drives (reading assignment)

25. V-belt Drive Design
Belt construction
A. Wrapped v-belts
protected by covering fabric made of cotton or polyester
fabric is coated with rubber to reinforce the wear resistance
Used for agricultural machinery
B. Raw edge v-belts
have no fabrics on the belt sides
special rubber compound ensures greater wear resistance

26. Product Classification
Classical v-belts
are most widely used power transmission belts
Multi v-belt
are made up of two or more standard v-belts connected together
have the advantage of preventing the belts from turning over or getting thrown off the
drive even when belt vibration occurs.

27. Product Classification
Double v-belts
Recommended for serpentine drives where the power must be transmitted by both the
top and the bottom of the belts
Excellent flexibility in both directions
Perforated open end v-belt
designed for easy installation with metal fasteners and screw driver
recommended for temporary use or when installation of standard v-belts is difficult.

28. Design process for Classical V-Belts
1. Set conditions required in design work
a. Type of machine
b. Transmission power
c. Running hours in a single day
d. Small pulley speed
e. Speed ratio
f. Interim center distance
g. Special uses and environmental conditions for the case of exposure to high or low
temperature, water, oil, acid, or alkali

29. Design process for Classical V-Belts
2. Set the design power
calculate the service factor (Ks)
Wherein, Ks: Service factor
Ko: Service correction factor (Table 2-1)
Ki: Idler correction factor (Table 2-2)
Ke: Environment correction factor (Table 2-3)
calculate the design power (Pd)

30. Design process for Classical V-Belts
Wherein, Pd: Design power (kW)
Pt: Transmission power (kW)
Ks: Service factor
3. Select the belt type
 Select the belt type in the selection charts below according to design power and small
pulley speed.
 If the intersection is located near the dividing line, select belt type considering other
conditions such as pulley cost.

31. Design process for Classical V-Belts

32. Design process for Classical V-Belts
4. Select the pulley size.
Select the small pulley datum diameter larger than the minimum specified in Table 2-
Inappropriate pulley reduces transmission efficiency and belts' durability significantly
 Calculate the large pulley datum diameter.
• The difference between the pulley outside diameter and datum diameter is
specified in the following table.

33. Design process for Classical V-Belts
5. Determine the belt length.
Determine the interim belt datum length
Select the standard belt length closest to the Ld' from our lineup. The center
distance is calculated from the following formula
 If the center distance is predetermined, use the following formula to determine
the interim belt datum length.

34. Design process for Classical V-Belts
• …Belt length
6. Determine the required number of belts
Required number of belts (nb) is determined as follows. Round up the
calculation results.

35. Example
• Based on the conditions given, design the v-belt. Show all the necessary
steps.
a. Type of machine ··· Compressor
b. Transmission power ··· Four pole motor 3.75kW/1750rpm
c. Running hours in a single day ··· 8 hours/day
d. Small pulley speed ··· 1750rpm
e. Speed ratio ··· 2 : 1 (Deceleration)
f. Interim center distance ··· 300mm
g. Special uses and environmental conditions ··· None

36. Chain Drive Design
• The chains are made up of number of rigid links which are hinged together by pin joints in
order to provide the necessary flexibility for wrapping round the driving and driven wheels.
• These wheels have projecting teeth of special profile and fit into the corresponding recesses
in the links of the chain
• The toothed wheels are known as sprocket wheels or simply sprockets.
• The sprockets and the chain are thus constrained to move together with minimum slipping
and ensures fair velocity ratio.
Chain and Sprocket

37. Terms Used in Chain Drive
Pitch of chain: It is the distance between the hinge center of a link and the corresponding
hinge center of the adjacent link
Pitch circle diameter of chain sprocket: It is the diameter of the circle on which the hinge
centers of the chain lie, when the chain is wrapped round a sprocket.
• The points A, B, C, and D are the hinge centres of the chain and the circle drawn through
these centres is called pitch circle and its diameter (D) is known as pitch circle diameter.

38. Classification of Chains
• The chains, on the basis of their use, are classified into the following three groups:
1. Hoisting and hauling (or crane) chains,
2. Conveyor (or tractive) chains, and
3. Power transmitting (or driving) chains.
The hoisting and hauling chains are of the following two types:
Such type of chains are used only at low speeds such as in chain hoists and in
anchors for marine works.

39. Design Procedure of Chain Drive
The chain drive is designed as discussed below:
1. First of all, determine the velocity ratio of the chain drive.
2. Select the minimum number of teeth on the smaller sprocket or pinion from
Table 21.5.
3. Find the number of teeth on the larger sprocket.
4. Determine the design power by using the service factor, such that
Design power = Rated power × Service factor
5. Choose the type of chain, number of strands for the design power and r.p.m. of
the smaller sprocket from Table 21.4.
6. Note down the parameters of the chain, such as pitch, roller diameter, minimum
width of roller etc. from Table 21.1.
7. Find pitch circle diameters and pitch line velocity of the smaller sprocket.
8. Determine the load (W) on the chain by using the following relation, i.e.

40. Design Procedure of Chain Drive cont….
9. Calculate the factor of safety by dividing the breaking load (WB) to the load on the
chain ( W ). This value of factor of safety should be greater than the value given in
Table 21.2.
10. Fix the centre distance between the sprockets.
11. Determine the length of the chain.
Example.
Design a chain drive to actuate a compressor from 15 kW electric motor running at 1000
r.p.m., the compressor speed being 350 r.p.m. The minimum centre distance is 500 mm. The
compressor operates 16 hours per day. The chain tension may be adjusted by shifting the
motor on slides.

41. Standard tables for chain drive design

42. CHAPTER 3: Design of Tillage implements
Mould Board Plough
 It is one of the oldest of all agricultural implements.
 Considered to be the most important Village implement.
 It consumes more traction energy than any other operation
 It is a primary tillage equipment used primarily in areas with sufficient rainfall for better soil
inversion, green manuring, burying heavy weed growth underneath the soil for better decay.
 It is available for animals and tractor operation.
Conventional Moldboard Reversible moldboard

43. Does four major jobs
• cutting the soil
• lifting the furrow slice.
• inverting the furrow slice and.
• pulverizing the soil.
Parts of moldboard plow

44. Parts of moldboard plow
a) Share: It is the part of plow bottom which
actually penetrates into the soil and makes a
horizontal cut below the surface.
b) Mould Board: It is the curved part which lifts
and turns the slice.
c) Landslide: It is the flat plate which bears
against and transmits the rear side lateral thrust
of plow bottom to the furrow wall.
d) Frog: It is the base of the plow bottom to
which other parts are attached.
e) Tail Piece: It is the extension of mould board
which helps in turning the furrow slice.

45. DISC PLOUGH
• A Disc plow consists of a series of
individually mounted, inclined disk blades
on a frame supported by furrow wheel.
• Disc Plough is equipped with heavy-duty
tubular frame specially designed for deep
ploughing / land preparation of rough soil.
• The disc plough is a rolling type plough
unlike the MB plough, which is dragged
inside the soil.
• The disc plough can operate in soils
where a MB plough is either difficult or
not advisable to operate.
• The disc plough creates no suction like
MB plough and its penetration depends
on the disc angles and the weight on the
plough.
• Disc plough inverts the soil when used
with scrapers otherwise; it gives more
mixing action than inversion.
• Disc ploughs cannot be used at high speed
because for cutting action slow speed is
necessary.

46. A few important terms connected with disc plough are explained below
Disc: It is a circular, concave revolving steel plate used for
cutting and inverting the soil.
Disc angle: It is the angle at which the plane of the cutting edge
of the disc is inclined to the direction of travel .Usually the disc
angle of good plough varies between 42° to 45°.
Tilt angle: It is the angle at which the plane of the cutting edge
of the disc is inclined to a vertical line.
The tilt angle varies from 15° to 25° for a good plough.
Scraper: It is a device to remove soil that tends to stick to the
working surface of a disc.
Concavity: It is the depth measured at the center of the disc by
placing its concave side on a flat surface.

47. Adjustments in disc plough
To obtain proper degree of pulverization and depth of cut
there are certain adjustments to be made n the disc plough as
follows
1. Increase the tilt angle to increase penetration ( depth of
cut)
2. Increase the disc angle to increase the width of cut.
But increasing disc angle will reduce the depth of cut
3. Addition of weights on the plough will increase the
penetrations
4. Keep the disc edges sharp.
This will reduce the draft requirement Adjust the plough
wheels properly to keep the plough running level

48. Disc Harrow
Harrow is one of the most important farm equipment used in soil
preparation by farmers.
It is a multi-purpose tool used for different operations from leveling of
heavy soil to eliminating dead grass and creating the seedbed for root
aeration
Harrow is used to break up the clods in the soil in an easy, efficient and
fast manner giving it a rich finish, so it can be used to make a seedbed.

49. Types of disc harrow
Single Action
Double Action
Offset
Single action disc harrow
It is a harrow with two gangs placed end to end,
which throw the soil in opposite directions.
The discs are arranged in such a way that right
side gang throws the soil towards right and left
side gang throws the soil towards left.
Double action disc harrow
It is a disc harrow consisting of two or more
gangs, in which a set of one or two gangs
follow behind the set of the other one or two,
arranged in such a way that the front and back
gangs throw the soil in opposite directions.
Offset disc harrow
consists of two rows (left and right) operating
in tandem; the harrow is usually placed in the
offside of the tractor so it is not in the same line
of pulling as the tractor.

50. Disc Types.
-Plain smooth discs are used to cut and invert
the soil.
-Notched discs are used for entering crop
residue into the soil.

51. Individual assignment (15%)
1. Define the following terms with typical example for each
A/. Machine element
B/. Mechanisms
C/. Machine
D/. Machinery
2. What is the aim of Engineering design?
3. What are the terms inception, elaboration and termination in machine design Process?
4. Why the design process of farm machinery differs from others?
5. What are the similarities and differences between belt and chain drives?
6. Based on the conditions given, design the v-belt. Show all the necessary steps.
a. Type of machine ··· Brick making machine
b. Transmission power ··· 4kW
c. Running hours in a single day ··· 16 hours/day
d. Small pulley speed ··· 1450 rpm
e. Speed ratio ··· 2 : 1 (Deceleration)
f. Interim center distance ··· 325 mm
g. Special uses and environmental conditions ··· None