design and fabrication of agricultural reaper€¦ · the reaper-binder machine has a compact...

DOI:10.23883/IJRTER.2018.4191.NBJIL 721

DESIGN AND FABRICATION OF AGRICULTURAL REAPER

vignesh1, Ranjith Kumar 2 1Department of mechanical engineering, prince shri venkateswara padmavathy engineering College,

2Department of mechanical engineering,prince shri venkateswara padmavathy

Engineering College

Abstract--Grain harvesting is the important part in agricultural mechanization. The use of reaper technology in developing countries to minimize the product cost which will be result in economic

development of agricultural production. This paper tends to provide the design and development of

manually or mechanically operated reaper machine. The current situation in our country the

traditional use of harvesting mechanism is more tedious, time consuming and not able to develop the

agricultural sector of the low farmers in economic. Our research work will focusing on ease of

harvesting operation to the small land holders for harvesting varieties of crop in less time and at low

cost by considering different factors as power requirement , cost of equipment, ease of operation ,

field condition , time of operation and climatologically conditions. The operating, adjusting and

maintaining principle are made simple for effective handling by unskilled operators.

Keywords—Agricultural reaper; Grain harvesting; Reaper operations; labour saving equipment;

field efficiency; decreases the cutting losses;

I. INTRODUCTION

Harvesting is the first and major post-harvest operation for separation, processing and storage of

grains. Harvesting of grains by machines is an important part of mechanized agriculture. At present,

developed countries all over the world are using automatic combine harvester for harvesting grains.

Some developing countries are also using combine harvesters for harvesting as a high-grade

technology. As a medium grade technology, many developing countries are using reaper for

harvesting to minimize production cost, and are thereby, making agricultural production economical.

The harvesting of grain crops in our country Ethiopia is traditionally done by manual methods.

Harvesting of major cereals, pulse and oilseed crops are done by using sickle. All these traditional

methods involve drudgery and consume long time. Mechanized agriculture is the process of using

agricultural machinery to mechanize the work of agriculture, greatly increasing farm worker

productivity.

1.1. HISTORY

Before the 18th and 19th century, people produced their food, clothing, and crops mostly by hand and

using small tools. This often required much time and energy. The Industrial Revolution brought about

change in the way goods were produced. There were several new inventions that allowed for the mass

production of products, especially in the field of agriculture. One such invention was the mechanical

reaper.

The mechanical reaper was invented by Cyrus McCormick in 1831. This machine was used by

farmers to harvest crops mechanically. For hundreds of years, farmers and field workers had to harvest

crops by hand using a sickle or other methods, which was an arduous task at best. The McCormick mechanical reaper replaced the manual cutting of the crop with scythes and sickles. This new invention

allowed wheat to be harvested quicker and with less labor force.

International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 03; March- 2018 [ISSN: 2455-1457]

@IJRTER-2018, All Rights Reserved 722

1.2. AGRICULTURE

The agricultural improvements of the 18th century had been promoted by people whose industrial and

commercial interests made them willing to experiment with new machines and processes to improve

the productivity of their estates. Under the same sort of stimuli, agricultural improvement continued

into the 19th century and was extended to food processing in Britain and elsewhere. The steam engine

was not readily adapted for agricultural purposes, yet ways were found of harnessing it to threshing

machines and even to plows by means of a cable between powerful traction engines pulling a plow

across a field. In the United States mechanization of agriculture began later than in Britain, but

because of the comparative labour shortage it proceeded more quickly and more thoroughly. The

McCormick reaper and the combine harvester were both developed in the United States, as

were barbed wire and the food-packing and canning industries, Chicago becoming the centre for these

processes. The introduction of refrigeration techniques in the second half of the 19th century made it

possible to convey meat from Australia and Argentina to European markets, and the same markets

encouraged the growth of dairy farming and market gardening, with distant producers such as New

Zealand able to send their butter in refrigerated ships to wherever in the world it could be sold.

1.3. REAPER BINDER INTRODUCTION Reaper binder is mainly used to harvest and bind low stem crops such as wheat, rice, grass, barely,

oats, reed and straw, etc. The machine has different structure and working rows to meet different

requirements of customers. The reaper and binder machines can be divided into self-propelled and

wheel tyre types. While according to the working rows of the machine, the reaper binder machine can

be divided into three rows reaper binder and two rows reaper binder.

1.4. Characteristics of Reaper and Binder

Multi-functional. This reaper and binder machine can used for many kinds of low stem crops.

▶ High adaptation. The machine can used in many different kinds of land forms, such as hills, slops,

mountains, etc.

▶ With high flexibility. The reaper-binder machine has a compact structure and small volume. It is

more flexible and easier to operate on the field.

▶ User-friendly. The steer control handle bar can be freely adjusted to up, down, left or right. The

handle can be adjusted around 180°, vertical 30°which is more flexible to be handled in different

environment.

▶ Adopt shaft drive system which works more stable and safe.

▶ Optional working row. There are two kinds of machines with 2 or 3 working rows.

▶ Use advanced technology which makes the grain binder has good threshing ability and low loss rate,

less than 1%.

▶ High reliability and low fuel consumption. The reliability of the harvester binder is above 90% and

the machine consume less than 8 kg fuel per hm2.

1.5. Application of Reaper Binder Machine 1. The reaper and binder machine is a popular machine among farmers. It is used in the harvesting of

many kinds of crops as wheat, rice, barely, etc.

2. Reaper binder equipment is applicable in the plain, hills, slops, small field and mountains or areas

where general combined harvesters can not enter in.

1.6. MANUFACTURING HISTORY

True or not, the singular-invention legend was valuable to the McCormick Harvesting Machine Co. —

not for patent purposes by the 1880s, but to bolster the company’s standing with populist farmers

(reaper customers) who tended to hate big business. To justify its higher prices, the company began to

https://www.britannica.com/technology/food-processing

https://www.britannica.com/topic/agriculture

https://www.britannica.com/topic/reaper-agriculture

https://www.britannica.com/technology/combine

https://www.britannica.com/technology/barbed-wire

https://www.britannica.com/technology/refrigeration

https://www.britannica.com/topic/dairying

https://www.britannica.com/place/New-Zealand

https://www.britannica.com/place/New-Zealand



portray Cyrus Sr. as a heroic farmer whose mechanical genius had made him a great benefactor of

mankind in general and farmers in particular. According to the ever-expanding legend, Cyrus Sr. fed

the hungry around the world (by making bread cheaper) and elevated farmers from simple sodbusters

to sophisticated managers of employees and capital. Ott documented these exaggerations in his 2015

dissertation, Producing a Past: Cyrus McCormick’s Reaper from Heritage to History. Ott argued that

the company used the sole-invention legend to draw parallels between the populist “labor theory of

value” and the company’s “technological surplus value ideology.” The propaganda reached a

crescendo at the 1893 World’s Columbian Exposition in Chicago, where a large banner over the

company’s exhibit proclaimed that “all harvesters of to-day are based upon the features C.H.

McCormick invented and built in 1831.” McCormick’s competitors quickly complained that this claim

was patently false, and the Inventors’ Congress, an international group that was acting as the

exhibition’s jury, “forced the McCormick Harvesting Machine Company to take down all of its

placards claiming inventive priority,” Ott wrote. Undaunted, Cyrus Jr. lobbied the U.S. Treasury

Department to get his father’s image printed on the $10 silver certificate. Treasury Secretary John

Carlisle embraced the idea and unveiled an engraving of the proposed new currency in 1896. But he

pulled the plug on “McCormick money” after the company’s competitors vigorously challenged the

story that Cyrus alone had invented the reaper. This time, the challenge to the singular-invention

legend was more public and more damaging to the company’s reputation, according to Ott. This

embarrassing loss of prestige came at a difficult time. Grain prices were falling, farmers were

struggling, and the company’s farm machinery sales were dwindling. After waging a five-year price

war, the company merged with its four largest competitors in 1902 to form International Harvester.

The merger agreement called for J.P. Morgan and Co. to manage International Harvester for 10 years,

but when the McCormick family wrested control of the company away from the other partners in 1912,

Cyrus Jr. reasserted the legend to help fend off federal antitrust charges. The company never got Cyrus

Sr.’s image printed on currency, but a depiction of a mid-19th century reaper graced the back of the

Federal Reserve’s first $10 note in 1914.

II. PROJECT LAYOUT AND DESCRIPTION

The figure shows the base frame which acts as a chassis of a reaper machine is fabricated with the help

of square tubes and channels with the help of metal cutting and metal joining process called welding,

dc motor which act as a drive is mounted on side of the chassis. The rear wheel mounted shaft get

coupled to the engine with the help of chain drive for easy handling of vehicle. The shaft which is

mounted in between two bevel gears get rotated through the pulley which is mounted on the same shaft

with the help of belt drive. In order to hold and throwing the crop aside, we are going to place pairs of

belts with holding attachment connected to the rotating shaft which is mounted on two sets of bevel



gears. Similarly in order to cut the crop, we are going to place pairs of cutters on chain drive which is

mounted on same rotating shaft.

III COMPONENT DESCRIPTION

3.1. FRAME

A truss or frame may be defined as a structure, made up of several bars, riveted or welded together.

These are made up of angle irons or channel sections and are called members of the frame or framed

structure. The frames may be classified into the following two groups:

1. Perfect frame, and

2. Imperfect frame.

A perfect frame is that which is composed of members just sufficient to keep it in equilibrium, when

loaded, without any change in its shape. A perfect frame should satisfy the following expression:

n = 2j-3

Where

n = Number of members, and

j = Number of joints.

An imperfect frame is one which does not satisfy the above equation (n = 2j — 3). The imperfect

frame which has number of members (n) less than 2j - 3, is known as deficient frame. If the number

of members are greater than 2j - 3, then the imperfect frame is known redundant frame.

3.2. WHEEL

A wheel is a circular component that is intended to rotate on an axle bearing. The wheel is one of the

main components of the wheel and axle which is one of the six simple machines. Wheels, in

conjunction with axles, allow heavy objects to be moved easily facilitating movement or

transportation while supporting a load, or performing labour in machines. Wheels are also used for

other purposes, such as a ship's wheel, steering wheel, potter's wheel and flywheel. Common

examples are found in transport applications. A wheel greatly reduces friction by facilitating motion

by rolling together with the use of axles. In order for wheels to rotate, a moment needs to be applied

to the wheel about its axis, either by way of gravity or by the application of another external force

or torque.

The low resistance to motion (compared to dragging) is explained as follows (refer to friction):

The normal force at the sliding interface is the same.

The sliding distance is reduced for a given distance of travel.

The coefficient of friction at the interface is usually lower.

Bearings are used to help reduce friction at the interface. In the simplest and oldest case the bearing

is just a round hole through which the axle passes (a "plain bearing").

Example situation

If a 100 kg object is dragged for 10 m along a surface with the coefficient of friction μ = 0.5,

the normal force is 981 N and the work done (required energy) is (work=force x distance) 981 × 0.5

× 10 = 4905 joules.

Now give the object 4 wheels. The normal force between the 4 wheels and axles is the same (in total)

981 N. Assume, for wood, μ = 0.25, and say the wheel diameter is 1000 mm and axle diameter is

50 mm. So while the object still moves 10 m the sliding frictional surfaces only slide over each other

a distance of 0.5 m. The work done is 981 × 0.25 × 0.5 = 123 joules; the work done has reduced to

1/40 of that of dragging.

https://en.wikipedia.org/wiki/Newton_(unit)

https://en.wikipedia.org/wiki/Energy

https://en.wikipedia.org/wiki/Diameter



Additional energy is lost from the wheel-to-road interface. This is termed rolling resistance which is

predominantly a deformation loss. This energy is also lowered by the use of a wheel (in comparison

to dragging) because the net force on the contact point between the road and the wheel is almost

perpendicular to the ground, and hence, generates an almost zero network. This depends on the

nature of the ground, of the material of the wheel, its inflation in the case of a tire, the net torque

exerted by the eventual engine, and many other factors.

A wheel can also offer advantages in traversing irregular surfaces if the wheel radius is sufficiently

large compared to the irregularities.

The wheel alone is not a machine, but when attached to an axle in conjunction with bearing, it forms

the wheel and axle, one of the simple machines. A driven wheel is an example of a wheel and axle.

Note that wheels pre-date driven wheels by about 6000 years, themselves an evolution of using

round logs as rollers to move a heavy load—a practice going back in pre-history so far, it has not

been dated.

3.3. BEARING

Basic Rating Life (L10)

Defined as the life associated with 90 percent reliability.

According to ABMA Std. 9, for an individual bearing, or a group of apparently identical bearings

operating under the same conditions, the life associated with 90% reliability, with contemporary,

commonly used material and manufacturing quality, and under conventional operating conditions.

The calculation is based on JIS B 1518

If the speed is constant, the life is usually expressed in hours. The relationship between basic rating

life and life hours is as follows:

There are two types of bearing load to consider with a ball bearing: radial load, which represents

loads perpendicular to the shaft, and axial, or thrust, load, which represents loads parallel to the shaft.

A ball bearing can handle both of these kinds of loads, but different loads affect bearings in different

ways, so multiple bearing rating calculations are required. The load bearing calculations are outlined

by the JIS / ISO, which provides standards for not only the ball bearing but also for a wide variety of

industrial activities requiring accurate measures. JIS / ISO measurements are widely accepted

standards throughout the world. You will find all ball bearing standards under JIS B, as B is the

classification regarding mechanical engineering, which is the classification the bearing falls under

(other classifications include A for civil engineering and C for electrical engineering).

http://www.nmbtc.com/wp/wp-content/uploads/2014/05/Life-Calculations-2-.png



Use the load ratings to determine how many of each type of ball bearing you will need and which

type of bearing will be appropriate to your needs, so that you can enjoy long, effective life for your

bearing-using applications. Bearing information regarding various load ratings follows below.

3.3.1. Basic Dynamic Radial Load Rating (Cr)

Defined as the calculated, constant radial load that a group of apparently identical bearings will

theoretically endure for a rating life of one million revolutions. The calculation is explained in JIS

B 1518. The Basic Dynamic Radial Load Ratings are for reference only.

3.3.2. Dynamic Equivalent Radial Load (Pr)

Bearings subjected to primarily dynamic radial loads are often also subject to some axial force. To

interpret this combined radial and axial load it is convenient to consider a hypothetical load with a

constant magnitude passing through the centre of the bearing. This hypothetical load is referred to as

the Dynamic Equivalent Radial Load and is calculated with the following equation.

Pr = XFr + YFa

X and Y are taken from the table below

Fr = Radial load (N)

Fa = Axial load (N)

3.3.3. DATA

Basic dynamic radial load rating(Cr): 553N

Ball Diameter (Dw):1.5875mm

Number of Balls (Z):6

Speed in rpm (n):3000min-1

Radial load(Fr):6N

Axial load (Fa):8N



3.3.4. BASIC STATIC RADIAL LOAD RATING (COR)

The load ratings shown were calculated in accordance with the ABMA standard. The ABMA has

established the maximum acceptable stress level resulting from a pure radial load. In a static

condition, to be 4.2 GPa (609,000 psi).

3.3.5. BASIC STATIC LOAD RATING (COR):

The static radial load rating (Cor) given on the product listing pages is the radial load which a

non-rotating ball bearing will support without damage, and will continue to provide satisfactory

performance and life.

The static radial load rating is dependent on the maximum contact stress between the balls and either

of the two raceways.



3.3.6. STATIC EQUIVALENT RADIAL LOAD (POR):

For a stationary or slow rotating bearing, the theoretical static radial load that produces the same

contact stress at the area of contact between the most heavily stressed ball and raceway, as the

contact that occurs under the actual load conditions.

Using the calculations below, the larger of the two values should be used as the Static Equivalent

Radial Load:

Por = XoFr+ YoFa

Por = Fr

Xo, Yo: JIS B 1519

Coefficient of deep groove ball bearings:

X0=0.6; Y0=0.5

Fr= Radial Load (N)

Fa= Axial Load (N)

If you have any further questions regarding ball bearing loads or ball bearing life, please feel free

to contact NMB at any time in order to get more specific information. Our highly qualified ball

bearing engineers will be happy to answer any questions you may have promptly and completely.

3.4. SHAFT

A shaft is a rotating machine element, usually circular in cross section, which is used

to transmit power from one part to another, or from a machine which produces power to a machine

which absorbs power. The various members such as pulleys and gears are mounted on it.

3.4.1. TYPES They are mainly classified into two types.

Transmission shafts are used to transmit power between the source and the machine absorbing

power; e.g. counter shafts and line shafts.

Machine shafts are the integral part of the machine itself; e.g. crankshaft.

3.4.2. MATERIALS The material used for ordinary shafts is mild steel. When high strength is required, an alloy

steel such as nickel, nickel-chromium or chromium-vanadium steel is used.

Shafts are generally formed by hot rolling and finished to size by cold

drawing or turning and grinding.

3.4.3. STANDARD SIZES

MACHINE SHAFTS Up to 25 mm steps of 0.5 mm

TRANSMISSION SHAFTS 25 mm to 60 mm with 5 mm steps

60 mm to 110 mm with 10 mm steps



The standard lengths of the shafts are 5 m, 6 m and 7 m.



STRESSES The following stresses are induced in the shafts.

Shear stresses due to the transmission of torque (due to torsional load).

Bending stresses (tensile or compressive) due to the forces acting upon the machine elements

like gears and pulleys as well as the self-weight of the shaft.

Stresses due to combined torsional and bending loads.

DESIGN STRESSES The maximum permissible (design) stresses in bending (tension or compression) may be taken as:

112 N/mm2 for shafts with allowance for keyways.

84 N/mm2 for shafts without allowance for keyways.

The maximum permissible (design) shear stresses may be taken as:

56 N/mm2 for shafts with allowance for keyways.

42 /mm2 for shafts without allowance for keyways.

3.5. CHAIN DRIVE

Chain drives consist of an endless series of chain links that mesh with toothed sprockets. Chain

sprockets are locked to the shafts of the driver and driven machinery. Chain drives represent a form of

flexible gearing. The chain acts like an endless gear rack, while the sprockets are similar to pinion

gears. Chain drives provide a positive form of power transmission. The links of the chain mesh with

the teeth of the sprockets and this action maintains a positive speed ratio between the driver and driven

sprockets.

3.5.1. Chain Functions

Chains can be used to perform three basic functions:

1. Transmitting power

2. Conveying materials

3. Timing purposes

Chains and sprockets are used to deliver positive power transmission in the forms of torque and speed

ratio from one rotating shaft to another. Chains can be used in many forms to carry, slide, push, or pull

a variety of materials found in countless industrial settings.

Different types of chains are used as devices to synchronize or time movements such as valve timing in

four-cycle engines.

3.5.2. Chain Drive Advantages

Chain drives, unlike belt drives, do not slip or creep.

There is no power loss due to slippage; therefore, chain drives are more efficient than belt

drives.

Chain drives are more compact than belt drives. A chain drive, for a given capacity, is narrower than a belt, and the sprockets are smaller in diameter than the belt sheaves.

Chain drives are more practical for slow speed drives.

Chains can operate effectively at high temperatures.

Chains are usually easier to install than belts on power transmission drives.

Chains do not deteriorate due to oil, grease, sunlight, or age.

Chains withstand chemicals and abrasive conditions.

Chains can operate in wet conditions.

Chains are effective when several shafts are to be driven from a single shaft, as positive timing between the driven shafts is usually required.

Chain stretch due to normal wear is a slow process.



Chains require less take-up adjustment than belts.

Chains can be used with varying shaft centre distances, whereas gears usually cannot.

Chain drives are simpler and less costly than gear drives.

Chains can be used on reversing drives.

3.5.3 Chain Drive Principles

Chain drives normally transmit power from one rotating shaft to another.

Chain drives maintain a positive speed ratio between driver and driven sprockets.

The driver and driven sprockets will rotate in the same direction on typical chain drives.

If the chain has an even number of pitches, the sprockets have an odd number of teeth. If the

sprockets have an even number of teeth, the chain has an uneven number of pitches. This

design feature prevents a single link from contacting the same tooth each time, causing wear

and vibration.

Small diameter sprockets cause the chain to bend sharply; therefore, the chain wears more quickly.

Short chain links bend less and should be used on small diameter sprockets.

Chains may be installed as single or multiple-strand drives, depending on speed and load.

Chain slack must be adjusted periodically by shifting one of the sprockets or by using a chain tightener.

Horizontal chain drives should have slack on the bottom (do not allow the chain to rub on the guard or casing).

Tighteners or idlers should be located on the slack side of the chain.

3.5.4. Dimensional Variables

Chain drives are used in many different applications, covering a large range of speeds and

loads. With the exception of a few specialized cases, the dimensions of roller chains remain in

proportion to each other as the overall size changes. The four dimensional variables that describe a

roller chain are pitch, width, pin diameter, and the thickness of the link plates. Understanding these

common dimensions will allow personnel to more efficiently communicate issues with regards to the

chain drive during maintenance, replacement, or any other process involving chain drives.

https://www.myodesie.com/wiki/index/returnEntry/id/3058#Horizontal Chain Drives



Pitch – As described earlier, pitch is the measured length between the centres of the holes in the

link plates. The pitch of the chain links must reflect the size of the sprocket teeth. The other three

measurements are directly proportional to the chain’s pitch.

Width – The width is defined as the distance between the inner link plates. The width is

approximately 5/8th of the link pitch.

Pin Diameter – The pin diameter is the diameter of the pin connecting the inside and outside

link plates together. The pin diameter is approximately 5/16th of the link pitch, and about half the size

of the roller diameter.



Link Plate Thickness – The inner and outer link plates are the same thickness, which is

approximately 1/8th of the link pitch. The thickness of link plates for the heavy series of any pitch chain

is approximately the same as the thickness of the plates on the next larger pitch standard series chain.

3.5.5. Basic Formula for Chain Drive

Chain speed: S

P: Chain pitch (inch)

N: Number of teeth of sprocket

n : Revolution per minute (rpm)

Chain tension: T

S: Chain Speed (ft. /min.)

HP: Horsepower to be transmitted (hp)

Number of pitches of chain: L

N1: Number of teeth (small sprocket)

N2: Number of teeth (large sprocket)

C: Centre distance in pitches

Any fraction of L is counted as one pitch.

Centre distance in pitches: C



3.6. CRANK WHEEL

The crank set (in the US) or chain set (in the UK), is the component of a bicycle drivetrain that

converts the reciprocating motion of the rider's legs into rotational motion used to drive

the chain or belt, which in turn drives the rear wheel. It consists of one or more sprockets, also

called chain rings or chain wheels attached to the cranks, arms, or crank arms to which the pedals

attach. It is connected to the rider by the pedals, to the bicycle frame by the bottom bracket, and to the

rear sprocket, cassette or freewheel via the chain.

3.6.1. Sizes Bicycles

Bicycle cranks can vary in length to accommodate different sized riders and different types of cycling.

Crank length is measured from the centre of the pedal spindle to the centre of the bottom bracket

spindle or axle. The larger bicycle component manufacturers typically offer crank lengths for adult

riders from 165 mm to 180 mm long in 2.5 mm increments, with 170 mm cranks being the most

common size. A few small specialty manufacturers make bicycle cranks in a number of sizes smaller

than 165 mm and longer than 180 mm. Some manufacturers also make bicycle cranks that can be

adjusted to different lengths. While logic would suggest that, all other things being equal, riders with

shorter legs should use proportionally shorter cranks and those with longer legs should use

proportionally longer cranks, this is not universally accepted. However, very few scientific studies

have definitively examined the effect of crank length on sustained cycling performance and the studies'

results have been mixed. Bicycle crank length has not been easy to study scientifically for a number of

reasons, chief among them being that cyclists are able to physiologically adapt to different crank

lengths. Cyclists are typically more efficient pedalling cranks with which they have had an adaptation

period. Several different formulas exist to calculate appropriate crank length for various riders. In

addition to the rider's size, another factor affecting the selection of crank length is the rider's cycling

specialty and the type of cycling event. Historically, bicycle riders have typically chosen

proportionally shorter cranks for higher cadence cycling such as criterium and track racing, while

riders have chosen proportionally longer cranks for lower cadence cycling such as time trial racing and

mountain biking. However, the evolution of very low rider torso positions to reduce aerodynamic drag

for time trial racing and triathlon cycling can also affect crank selection for such events. Some have

suggested that proportionally shorter cranks may have a slight advantage for a rider with a very low

torso position and an actuate hip angle, especially as the rider pedals near the top-dead-centre position

of the pedal stroke. Cranks can be shortened for medical reasons using shorteners such as Ortho Pedal.

3.6.2. TO THE PEDALS

Crank arms have a threaded hole (or "eye") at their outboard end to accommodate the pedal spindle.

Adult or multi-piece cranks have a 9/16 inch hole with 20 TPI (a combination that appears to be

unique to this application). One-piece or children's cranks use a 1/2 inch hole. Some cranks on

children's bikes have more than one pedal hole so that the pedal can be moved to accommodate growth.

The right-side (usually the chain side) hole is right-hand threaded, and the left-side hole is left-hand

(reverse) threaded to help prevent it from becoming unthreaded by an effect called precession.

Pedal spindles are hard steel, and gradually fret and erode the crank arm where the two meet. This can

eventually be a cause of crank breakage, which commonly occurs at the pedal eye. Some

manufacturers advise the use of a thin steel washer between the pedal and crank, but this is ineffective

because the hard washer frets against the crank instead. A solution, suggested by Jobst Brandt, is to use

a 45 degree taper at the surface where crank and pedal meet, as this would eliminate

precession-induced fretting and loosening (it is already done for most automobile lug nuts for the latter

reason). However, this would require manufacturers to change a well-established standard which

currently allows most pedals to be fitted to most cranks.

https://en.wikipedia.org/wiki/Bicycle_drivetrain_systems

https://en.wikipedia.org/wiki/Reciprocating_motion

https://en.wikipedia.org/wiki/Human_leg

https://en.wikipedia.org/wiki/Bicycle_chain

https://en.wikipedia.org/wiki/Belt-driven_bicycle

https://en.wikipedia.org/wiki/Bicycle_wheel

https://en.wikipedia.org/wiki/Sprocket

https://en.wikipedia.org/wiki/Crank_(mechanism)

https://en.wikipedia.org/wiki/Bicycle_pedal

https://en.wikipedia.org/wiki/Bottom_bracket

https://en.wikipedia.org/wiki/Cassette_(bicycle_part)

https://en.wikipedia.org/wiki/Freewheel

https://en.wikipedia.org/wiki/Ortho_Pedal

https://en.wikipedia.org/wiki/Threads_per_inch

https://en.wikipedia.org/wiki/Precession_(mechanical)

https://en.wikipedia.org/wiki/Jobst_Brandt

https://en.wikipedia.org/wiki/Lug_nut



The solution to the issue of fretting is to use a metal based anti-seize lubricant; being composed of

assorted mixtures of aluminium, copper, graphite and nickel powders in a grease base – that allows

repeated assembly and disassembly without wear and the elimination of fretting corrosion during use.

3.7. SPROCKET

The sprockets are connected to the shaft by one of several available methods. However, connection by

a keyway and grub screw is common. Sprockets give the same drive speed, increased drive speed or

decreased drive speed. This is achieved by varying the number of teeth in each sprocket. The same

number of teeth gives the same speed to the driven shaft. If the driven sprockets teeth are less, then the

speed increases and if the driven sprockets teeth are more, this will decrease the speed of the driven

shaft.

A sprocket or sprocket-wheel is a profiled wheel with teeth, or cogs, that mesh with a chain, track or

other perforated or indented material. The name 'sprocket' applies generally to any wheel upon which

radial projections engage a chain passing over it. It is distinguished from a gear in that sprockets are

never meshed together directly, and differs from a pulley in that sprockets have teeth and pulleys are

smooth.

Sprockets are used in bicycles, motorcycles, cars, tracked vehicles, and other machinery either to

transmit rotary motion between two shafts where gears are unsuitable or to impart linear motion to a

track, tape etc. Perhaps the most common form of sprocket may be found in the bicycle, in which the

pedal shaft carries a large sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket

on the axle of the rear wheel. Early automobiles were also largely driven by sprocket and chain

mechanism, a practice largely copied from bicycles.

Sprockets are of various designs, a maximum of efficiency being claimed for each by its originator.

Sprockets typically do not have a flange. Some sprockets used with belts have flanges to keep the

timing belt centred. Sprockets and chains are also used for power transmission from one shaft to

another where slippage is not admissible, sprocket chains being used instead of belts or ropes and

sprocket-wheels instead of pulleys. They can be run at high speed and some forms of chain are so

constructed as to be noiseless even at high speed.

3.7.1. Sprocket Tooth Design Formulas

The tooth form of a sprocket is derived from the geometric path described by the chain roller as it

moves through the pitch line, and pitch circle for a given sprocket and chain pitch. The shape of the

tooth form is mathematically related to the Chain Pitch (P), the Number of Teeth on the Sprocket (N),

and the Diameter of the Roller (Dr). The formulas for the seating curve, radius R and the topping curve

radius F include the clearances necessary to allow smooth engagement between the chain rollers and

sprocket teeth. The following formulas are taken from the American Chain Association Chains for

Power Transmission and Material Handling handbook, and they represent the industry standards for

the development of sprocket tooth forms.

https://en.wikipedia.org/wiki/Wheel

https://en.wikipedia.org/wiki/Roller_chain

https://en.wikipedia.org/wiki/Caterpillar_track

https://en.wikipedia.org/wiki/Gear

https://en.wikipedia.org/wiki/Pulley

https://en.wikipedia.org/wiki/Bicycle

https://en.wikipedia.org/wiki/Motorcycle

https://en.wikipedia.org/wiki/Automobile

https://en.wikipedia.org/wiki/Continuous_track

https://en.wikipedia.org/wiki/Machine

https://en.wikipedia.org/wiki/Flange



3.8. DC MOTORElectrical motors are everywhere around us. Almost all the electro-mechanical

movements we see around us are caused either by an AC or a DC motor. Here we will be exploring

DC motors. This is a device that converts DC electrical energy to a mechanical energy.

3.8.1. Principle of DC Motor

This DC or direct current motor works on the principal, when a current carrying conductor is

placed in a magnetic field, it experiences a torque and has a tendency to move.

This is known as motoring action. If the direction of current in the wire is reversed, the direction of

rotation also reverses. When magnetic field and electric field interact they produce a mechanical

force, and based on that the working principle of DC motor is established.



The direction of rotation of a this motor is given by Fleming’s left hand rule, which states that if the

index finger, middle finger and thumb of your left hand are extended mutually perpendicular to each

other and if the index finger represents the direction of magnetic field, middle finger indicates the

direction of current, then the thumb represents the direction in which force is experienced by the

shaft of the DC motor.

Structurally and construction wise a direct current motor is exactly similar to a DC generator, but

electrically it is just the opposite. Here we unlike a generator we supply electrical energy to the input

port and derive mechanical energy from the output port. We can represent it by the block diagram

shown below.

Here in a DC motor, the supply voltage E and current I is given to the electrical port or the input port

and we derive the mechanical output i.e. torque T and speed ω from the mechanical port or output

port.

The input and output port variables of the direct current motor are related by the parameter K.

So from the picture above we can well understand that motor is just the

opposite phenomena of a DC generator, and we can derive both motoring and generating operation

from the same machine by simply reversing the ports.

3.8.2. Detailed Description of a DC Motor

To understand the DC motor in details let us consider the diagram below,



The direct current motor is represented by the circle in the centre, on which is mounted the brushes,

where we connect the external terminals, from where supply voltage is given. On the mechanical

terminal we have a shaft coming out of the Motor, and connected to the armature, and the

armature-shaft is coupled to the mechanical load. On the supply terminals we represent the

armature resistance Ra in series. Now, let the input voltage E, is applied across the brushes. Electric

current which flows through the rotor armature via brushes, in presence of the magnetic field,

produces a torque Tg. Due to this torque Tg the dc motor armature rotates. As the armature

conductors are carrying currents and the armature rotates inside the stator magnetic field, it also

produces an emf Eb in the manner very similar to that of a generator. The generated Emf Eb is

directed opposite to the supplied voltage and is known as the back Emf, as it counters the forward

voltage.

The back emf like in case of a generator is represented by

Where,

P = no of poles

φ = flux per pole

Z= No. of conductors

A = No. of parallel paths and

N is the speed of the DC Motor.

So, from the above equation we can see Eb is proportional to speed ‘N’. That is whenever a direct

current motor rotates, it results in the generation of back Emf. Now let us represent the rotor speed

by ω in rad/sec. So Eb is proportional to ω. So, when the speed of the motor is reduced by the

application of load, Eb decreases. Thus the voltage difference between supply voltage and back emf

increases that means E − Eb increases. Due to this increased voltage difference, armature current will

increase and therefore torque and hence speed increases. Thus a DC Motor is capable of maintaining

the same speed under variable load.

Now armature current Ia is represented by

Now at starting, speed ω = 0 so at starting

Eb = 0.

Now since the armature winding electrical resistance Ra is small, this motor has a very high starting

current in the absence of back Emf. As a result we need to use a starter for starting a DC Motor.

Now as the motor continues to rotate, the back Emf starts being generated and gradually the current

decreases as the motor picks up speed.

3.8.3. Types of DC Motors

Direct motors are named according to the connection o the field winding with the armature. There

are 3 types:

Shunt wound DC motor

Series wound DC motor

Compound wound DC motor

https://www.electrical4u.com/what-is-flux-types-of-flux/



3.8. BEVEL GEAR

Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears

themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees

apart, but can be designed to work at other angles as well. The pitch surface of bevel gears is a cone.

3.8.1. INTRODUCTION Two important concepts in gearing are pitch surface and pitch angle. The pitch surface of a gear is the

imaginary toothless surface that you would have by averaging out the peaks and valleys of the

individual teeth. The pitch surface of an ordinary gear is the shape of a cylinder. The pitch angle of a

gear is the angle between the face of the pitch surface and the axis.

The most familiar kinds of bevel gears have pitch angles of less than 90 degrees and therefore are

cone-shaped. This type of bevel gear is called external because the gear teeth point outward. The pitch

surfaces of meshed external bevel gears are coaxial with the gear shafts; the apexes of the two surfaces

are at the point of intersection of the shaft axes.

Bevel gears that have pitch angles of greater than ninety degrees have teeth that point inward and are

called internal bevel gears.

Bevel gears that have pitch angles of exactly 90 degrees have teeth that point outward parallel with the

axis and resemble the points on a crown. That's why this type of bevel gear is called a crown gear.

Miter gears are mating bevel gears with equal numbers of teeth and with axes at right angles. Skew

bevel gears are those for which the corresponding crown gear has teeth that are straight and oblique.

3.8.2. TYPES

Bevel gears are classified in different types according to geometry:

Straight bevel gears have conical pitch surface and teeth are straight and tapering towards apex.

Spiral bevel gears have curved teeth at an angle allowing tooth contact to be gradual and

smooth.

Zero bevel gears are very similar to a bevel gear only exception is the teeth are curved: the ends of each tooth are coplanar with the axis, but the middle of each tooth is swept circumferentially

around the gear. Zerol bevel gears can be thought of as spiral bevel gears (which also have

curved teeth) but with a spiral angle of zero (so the ends of the teeth align with the axis).

Hypoid bevel gears are similar to spiral bevel but the pitch surfaces are hyperbolic and not conical.

3.8.3. GEOMETRY OF THE BEVEL GEAR

The cylindrical gear tooth profile corresponds to an involute, whereas the bevel gear tooth profile is an

octoid. All traditional bevel gear generators (such as Gleason, Klingelnberg, Heidenreich & Harbeck,

WMW Modul) manufacture bevel gears with an octoidal tooth profile. IMPORTANT: For 5-axis

milled bevel gear sets it is important to choose the same calculation / layout like the conventional

manufacturing method. Simplified calculated bevel gears on the basis of an equivalent cylindrical gear

in normal section with an involute tooth form show a deviant tooth form with reduced tooth strength by

10-28% without offset and 45% with offset [Diss. Hünecke, TU Dresden]. Furthermore those

"involute bevel gear sets" causes more noise.

http://en.wikipedia.org/wiki/Gears

http://en.wikipedia.org/wiki/Cone_(geometry)

http://en.wikipedia.org/w/index.php?title=Miter_gears&action=edit&redlink=1

http://en.wikipedia.org/w/index.php?title=Skew_bevel_gears&action=edit&redlink=1

http://en.wikipedia.org/w/index.php?title=Skew_bevel_gears&action=edit&redlink=1

http://en.wikipedia.org/wiki/Crown_gear

http://en.wiktionary.org/wiki/oblique

http://en.wikipedia.org/wiki/Hyperboloid

http://en.wikipedia.org/wiki/Gleason_Corporation



IV. 3-D LAYOUT OF PROJECT

V. THE REAPING MECHANISM

When the motor gets turned on, rotating motion is transferred to the rear wheel mounted shaft

through chain drive as well as pulley which is mounted on the shaft placed in between two sets of

bevel gears, due to this two pairs of bevel gears get rotated, at the same time shafts which are

connected to the bevel gears also rotates. Since the pairs of belts with holding attachment are

mounted on two rotating shafts, belt drive get rotated and start the shifting process of crops.

Similarly cutters cut the crop which are mounted on chain drive which is placed on same rotating

shaft at the bottom of shaft.



VI. RESULT

After modification of automatic operated reaper it work continuously and gives more efficiency than

the machine before modify. Conveying mechanism now help to stop clogging and decreases the

cutting losses. Continuous working leads to harvest crop in less time with minimum man power.

Based on analysis of results following conclusion are drawn:

The automatic operated reaper is high labour saving equipment.

The cost of reaper is low so it is affordable to small farmers. The field efficiency is satisfactory which more than 66%, it increases from 59% due to its modifications.

REFERENCE I. Http://Www.Countrystudies.Us/Ethiopia

II. Alemu Yemane, “Design of Mechanical Driven Reaper” Ethiopia, 2012.

III. CADU 1969 Progress Report No.1. “Implement Research Section” CADU Publication No. 32.

IV. Ankur S. S, & Prof, Sachin V.D, “conceptual model preparation for wheat cutter for small scale farmer”

IJPRET, 2013 vol. 1(9)

V. Siddaling S & B.S.Ravaikiran, 2015, “Design And Fabrication Of Small Scale Sugarcane Harvesting Machine,”

IJERGC Vol 3.

VI. Prof. P.B.Chavan, et al, 2015, “Design and Development of Manually Operated Reaper,” Vol 12.

VII. Rayapura V.R. 1947, “Design and Development or Reaper for Indian Conditions,” India.

design and fabrication of agricultural reaper€¦ · the reaper-binder machine has a compact...

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