Essay, Pages 23 (5675 words)
Horticultural machinery are the various tractors, rotary cultivators, drills, sprayers, root vegetable harvesters and other equipment of interest to horticulturist POWER UNITS USED FOR HORTICULTURAL PURPOSES The need for special types of power unit and or cultivation implements arises when it is necessary to work between fruits trees or halyard, where the planting distance has already been decided and the equipment has to conform to it. narrow rows of fruits and haps sometimes necessitate the use of extremely narrow tractors, with overall widths of about 4 ft (1.
m) such tractors require specially adapted mounted equipment and use among other implements, types of plough which are designed for plugging up or away from both sides of rows of haps or fruits some of special cultivation implements used include.
SMALL ROTARY CULTIVATORS
A rotary cultivator is a tool that is used to loosen, aerate and prepare soil for new planting or to enhance the condition of soil for existing plantings. A rotary cultivator often known as rotatiller or roto cultivator consists of sharp rotating tins or blades that are typically made of steel or aluminum.
The rotating tins dig into the soil, loosening and aerating the soil in a process known as cultivation. Cultivating soil is important because over a period of time soil tends to compact and harden. This can make it more difficult for plant to receive the proper level of water and nutrients. Breaking up and loosening compacted soil makes it easier for water and nutrients to flow through the soil and into plantings.
A small rotary cultivator is hand held cultivator either self propelled or powered. It looks much like a lawn mower.
A self propelled rotary cultivator has tins (blades) attached to a pole that is similar to a long stick and the user simply pushes it to cultivate a lawn or garden. Many self propelled cultivators have aluminum tines which some users have found to be too light weight for anything more than light grader use. There are therefore self-propelled cultivators that utilize a heavier weight metal for the rotating tines, which many find to be more effective. However, the heavier weight of these tools may make it more difficult to use for an extended period of time.
A motorized cultivator is powered by a small gasoline or electric motor; it is often used on large gardens. The tines of a rotary cultivator rotate in the opposite direction of the wheel and till to a depth of 8 to 10 inches normal width of the small rotary cultivator range from 4 – 8 ft (2 – 2. 4m) with power rating ranging from 1 hp to 8 hp (0. 75kw)
The walking tractor or two-wheel tractor is a tractor with one axle self powered and self-propelled which can pull and power various farm implements such as a tractor, cultivator, or harrow, a plough or various seeders and harvesters.
The operator usually walks behind it or sides the implement being towed like a four-wheel tractor, the walking tractor is designed to run many attachments with a single power source and gives thousands of hours of services. These tractors are fitted with engines of up to 3hp (2. 2 kw). Some walking tractors now constructed have a power rating of up to 12 hp.
NARROW TRACT TRACTOR
Narrow track tractors are of interest to horticulturalist who frequently need to pull a heavy spraying machine as well as to carry out plugging and other tillage operations. Such tractors with engines of 25 – 45 hp (19 – 33 kw) may have overall dimensions as small as about 1m wide as 1. 3m high. They are fitted with 4 tyres and articulated frame steering of a type that can provide a very small turning circle, they have low weight to permit work beneath trees. Hydrostatic transmission assists in achieving a sound method of delivering power to the drive wheels.
COMPACT L-WHEEL TRACTOR
A compact utility tractor (CUT) is a smaller version of an agricultural tractor designed primarily for landscaping and use in field with narrow spaced tracks. Typical CUTs range from 20 – 50hp (15 -37 kw) with available PTO horse power ranging from 15 – 45 (11 -34 kw) CUTs are often equipped with both a mid-mounted and standard rear PTO, especially those below 40 hp (30 kw). modern CUTs use hydrostatic transmissions but many variants of gear-drive transmissions are also offered from low priced, simple gear-transmission to advance glide-shift transmissions. CUTs require special smaller implements than full sized agricultural tractors. Very common implements include, the box blade the grader blade, the landscape rake, the post hole digger, the rotary cutter, a broadcast seeder, and a rotary tiller.
SOIL CULTIVATION IMPLEMENTS
The plough is a tool used in farming for initial cultivation of soil in preparation for sowing seed or planting. It has been a basic instrument for most of recorded history and represents one of the major advances in agriculture. The primary purpose of plugging is to turn over the upper layer of the soil, bringing fresh nutrients to the surface while burying weeds and weed seeds, allowing them to breakdown. It also aerates the soil, allows it to hold moisture better and provides a seed-free medium for planting on alternate crop. The plough is made up of the following components:
- The Coulter The function of the coulter is to cut the soil. It is this component of the plough that clears the path. The coulter is a blade or sharp-edged disc attached to a plough so that it cuts through the soil vertically.
- The Mold Board It is the part of the plough which pushes aside the soil, turned over by the coulter. It is either cylindrical, helical, helically cylindrical or a curved rod.
- Plough-Beam The part that connects the rest of the plough with the animal or tractor. Its shape and length influences the depth of the coulter and to a lesser extent ts width.
- Plough Share The plough-share is the central part of the plough on which the other major parts are fixed (plough-beam, mold boards coulter, contre-sep).
- Contre-sep Allows the stabilization of the plough while supporting the hilt. Any standard steel can be used for its construction.
- The Hilt Permits the longitudiral stabilization of the plough pliding on the bottom of the trench longitudinal stability is ensured by reaction between the ground supports on the soil, the support points on the front and the rear of plough and by the wheel.
Soil sterilization is a chemical or physical process that results in the death of soil organisms. This practice provides secure and quick relief of soil from substances and organisms harmful to plants such as bacteria, viruses, fungi, nematodes and other pests. Many of the organisms in the soil helps breakdown larger pieces of organic matter into small particles which are more easily absorbable by plants but they could be in the soil detrimental fungi, bacteria and insects and weed seeds. Soil sterilization helps to do away with these detrimental organisms and seed weeds.
There are two major methods of soil sterilization: Chemical method and physical method.
- Chemical methods includes the use of herbicides and fumigants
- Physical methods include the use of steam and solar energy
Soil steaming is a farming technique that sterilizes soil with steam in open fields or green houses. Detrimental organisms and weeds are killed through induced hot steam which causes their cell structure to physically degenerate. Biologically, the method is considered a partial disinfection. Important heat-resistant, spare-farming bacteria survive and revitalize the soil after cooling down. Steaming leads to a strengthened resistance against plant disease and pests.
METHOD OF STEAMING
Surface steaming: it is the application of heat directly on the surface of the soil using various methods which include area sheet steaming, the steaming hood, the steaming harrow, the steaming plough and vacuum steaming with drainage pipes or mobile pipe system.
- Sheet steaming: Surface steaming with special sheets is a method which has been established for decades in other to steam large areas reaching from 15 to 400m2 in one step. The usage of heat resistant, non-decomposing insulation fleece saves up to 50% energy reduces the steaming time significantly and improves penetration. The streaming time depends on soil structure as well as outside temperature and amounts to 1 – 1. 5 hour per 10 cm steaming depth.
- Steaming with Vacuum: This is induced through a mobile or fixed installed pipe system in the depth of the area to be steamed. It is the method that reaches the best penetration. Despite high capital cost, the fixed installation of drainage system is reasonable for intensively used areas since steaming depth of up to 80 cm can be achieved.
The steaming area is covered with a special steaming sheet and weighted all around as with sheet steaming. The steam is injected underneath the sheet through an injector and protection tunnel while with short areas up to 30m length steam is frontally injected, with longer areas steam is induced in the middle of the beet using a T-connection branching out to both sides. As soon as the sheet is inflated to approximately 1m by the steam pressure, the suction turbine is switched on. First, the air in the soil is removed via the suction hoses. A vacuum is formed and the steam is pulled downward.
When the required steaming depth has been reached, the ventilator runs non-stop and surplus steam is blown out. To ensure that, this surplus steam is not lost, it is fed back under the sheet. iii. Steaming with hoods A steaming hood is a mobile device consisting of corrosion resistant materials such as aluminum, which is put down on to the area to be steamed. In contrast to sheet steaming, cost-intensive working steps such as lying out and weighting the sheet don’t occur, however the area steamed per working step is smaller in accordance to the size of the hood.
Solarization of soil is a much more non-chemical; environmentally friendly way of soil sterilization and this involves using the power of the sun to get rid of many disease and pests that causes damage to different types of grasses. It is a relatively easy method of sterilization and involves covering up the soil that will be established with a clear plastic material to capture the radiant heat and energy from the sun to kill the pathogens in the soil.
Not only does this method get rid of most of the unwanted diseases and pests but it also stimulates the relense of nutrients from organic matter present in the soil.
ELECTRIC SOIL STERILIZER
The electric soil sterilizer is often used for sterilization of small quantity of soil needed for the nursery or in green houses. The equipment is filled to the top of the container and then the unit is plugged in. the thermostat is then set to the correct sterilizing temperature (about 80°c). The indicator light will glow until the batch is done.
After the light goes off, wait 15 minutes, then pick up the unit and the sterilized soil will drop out the bottom. It eliminates weeds and disease, kills weeds practically 100% kills soil-borne insects and in general, all of the bacteria, fungi and virus organisms that are harmful to commercial crops.
CHEMICAL SOIL STERILIZATION
Chemical sterilization of soil refers to the use of various chemical to sterilize soil. The chemicals to be used must give off gas which is sufficiently toxic to ensure the destruction of pest, diseases and weeds, yet without harming the beneficial, organisms in the soil. The efficiency of chemical sterilization varies greatly, not because of precise chemicals involved, but because of the condition of the soil, its moisture content and most importantly, the prevailing temperature. This should also ensure even distribution in the soil to be sterilized some chemicals used for soil sterilization include:
- Methyl bromide gas Methyl bromide is a fumigant that is most often used in vegetable and farm production. It is usually applied s gas injected into the soil and then covered by a thin plastic shield in order to slow the movement of methyl bromide from the soil to the atmosphere in that specific area. It is a dangerous chemical and when humans are exposed to high concentrations of this chemical it can result in respiratory system failure, central nervous system failure and damage to the skin, eyes and lungs. Because of the dangers associated with the application of this gas and the detrimental effects that it has on the ozone, methyl bromide is beginning to become less and less used.
- Vapam Vapam is an effective liquid fumigant for the control of nematodes, insects, weeds and soil borne diseases. It is not very volatile which means that it is not easily evaporated At normal temperatures and before applying this chemical it is always wise to cultivate the area that is being treated in order to deliver the vapam in a uniform manner; Before application the soil moisture of the field be between 50% to 80% field capacity this chemical can be applied in a number of ways some bring through sprinkler; sprinkler and flood applications provide the best coverage and thus the most successful; this product is however toxic to fish so you should not apply this to areas where the surface water can easily be washed on to lakes or streams
- Basamid Basamid is a granular and eliminates weeds, nematodes grasses and soil diseases. When this chemical ingredient hits the moist soil the graduals breakdown and release gases that spread in the soil and these gases eliminate the unwanted disease or pests. When applying basamid it is very important to keep the soil wet for 2 week, prior to the application in order to meet the right soil moisture level and every incorporated on to the soil to about 15cm using a rotary cultivator or something that has this same effect .
After doing this, it is important to seal the area with a plastic of some sort of properly fumigate the soil, keeping all the volatile and highly toxic gases in that specific area.
SOIL STERILIZING EQUIPMENT (LOKO BOILER)
A boilers or steam generator is a device used to create steam by applying heat energy to water. The form and size depends on the application; the locomotive Boiler is portable mobile steam engine with same features as the large one.
The only difference is variation in size of component part the LOKO Boiler is made up of the following part
FIRE TUBE BOILER
This is a single furnace, three phase type fire tube boiler. Heat-flue gases-travel is through three different sets of tubes. All the tubes are surrounded by water which absorbs the heat . As the water turns to steam, pressure builds up with in the boiler one enough pressure has built up the engineer will open the main steam outlet valve slowly. Fire tube boilers are also known as smoke tube and donkey boiler. .
WATER TUBE BOILERS
The large tube like structure at the top of the boiler is called the steam drum. You could call it the heart of the boiler. That is where the steam collects before being discharged from the boiler. The hundreds of tube start and eventually end up at the steam drum. Water enters the boiler, pre-heated at the top. The hot water naturally circulates through the tubes down to the lower area where it is hot the water heats up and flows back to the steam drum where the steam collects. Not all the water gets turn to steam, so the process starts again. Water keep on circulating until all of it turns in to or becomes steam.
BOILER MAIN COMPONENTS
- BOILER SHELL- The out cylindrical portion of a pressure vessel.
- BURNER – A device for the introduction of fuel air in to the furnace at the decreed velocities, turbulence and concentration. The burners is the principal device for the firing of oil and or gas Burners are normally located in the vertical walls of the furnace. Burners along with the furnace in which they are installed, are designed to born the fuel properly.
- SMOKE TUBE – The second/third phase are formed by thick walled smoke tubes which are welded in to the end plates the arrangement of the smoke tubes considers the recommendation of ascending flue passes in order to prevent the information of residual-or lingering gases the first phase is a combination of a furnace tube and combustion chamber suspended by stay bar and completely surrounded by water giving valuable radiant heat transference from all surfaces. The second pass is a nest of straight 50mm boiler tubes expanded in to the upper zone of the combustion chamber and running in parallel to the furnace tube terminating at the front plate of the reversing chamber. The third pass is a further nest of 50mm boiler tubes running from the upper zone of the reversing chamber to the rear smoke box for exhausting to atmosphere.
- FRONT REVERSING CHAMBERS – The front reversing chamber is equipped with large doors allowing free access to the smoke tubes and easy maintenance and cleaning High-quality tightening material guarantees the gastight closing of he doors.
- DRAIN TAP – A valve connection at the lowest point for the removal of all unwanted elements from the pressure parts.
- FEED PUMP – A pump that supplies water to a boiler.
- FEED WATER – water introduced into a boiler during operation. It includes make-up and return condensate.
- FURNACE – An enclosed space provided for the combustions of fuel.
- INSULATION – A material of low thermal conductivity used to reduce heat losses.
- SAFETY VALVE – A spring loaded valve that automatically opens when pressure attains the value setting used to prevent excessive pressure from building up in a boiler.
- SAFETY SHUT- OFF VALVE – A manually opened, electrically latched, electrically operated safety shut-off valve designed to automatically shut-off fuel when de-energized.
- WATER LEVEL – The elevation of the surface of the water in a boiler.
- ACCUMULATOR – A pressure vessel containing water and/or steam which is used to store the heat of steam for use at a lale period at some lower pressure.
- FIRE BOX – The fire box is surrounded by water in the outer fire box shell and so absorbing radiant heat from the fire. The gap between the inner and outer fire boxes is maintained by hundreds of rigid stays.
AIR ATOMIZING OIL BURNER
A burner for firing oil in which the oil is atomized by compressed air, which is forced into and through one or more streams of oil which result in the breaking of the oil into a fine spray.
- BAFFLE-TYPE COLLECTOR; A device in gas paths utilizing baffle so arranged as to deflect dust particles out of the gas stream.
- BAG FILTER; A device containing one or more cloth bags revering particles from the dust lateen gas or air which is blown through it .
- BAG-TYPE COLLECTOR; A filter in which the cloth filtering medium is made in the form of cylindrical bags.
- BREECHING; A duct that transports the products of combustion between parts of a steam generating unit or to the stack.
- CIRCULATOR; A pipe or tube to pass stream or water between upper boiler drums usually lactated where the heat absorption is low. Also used to apply to tubes connecting heater of horizontal water tube boilers with drums.
- STEAM GENERATING UNIT: A unit to which water fuel and air supplied and in which steam is generated. t consists of a boiler furnace and fuel burning equipment, and may include as component parts water walls, super heater, reheater, economizer, air heater, or any combination thereof.
- STEAM SEPARATOR: A device for removing the entrained water from steam.
- STRAINER: A device, such as a filter, to retain solid particles allowing a liquid to pass.
- SMOKE BOX: The smoke box is an extension of the front end of the boiler barrel. Exhaust steam from the cylinder passes through the blast pipe into the chimney and creates partial vacuum. This causes hot gases to be drown through the grate and fine hole door. The smoke box also contains the main steam pipe to the steam chest, blower, super heater header, tube and exhaust for the vacuum ejector where fitted.
- BRICK ARCH: The brick arch serves several purpose. It protects the fire box tube plate from the direct flame of the fire, radiates heat to prevent rapid fluctuation of the tube plate temperature and ensure thorough combustion of volatiles by lengthening their path from the fire to the tube plate. FIRE DOOR: Fire hole door vary from locomotive to locomotive. They gives access to firing and can be adjusted to control the flow of secondary air.
- BAFFLE PLATE: The baffle plate place in the fire hole is designed to direct the secondary air down towards the fired bed in order to mix thoroughly with the hot gases and flames.
- FUSIBLE PLUGS: Fusible plugs are screwed into the fire box crown. They are of brass and have a lead cure. If the water level in the boiler drop and uncovers the fire box crown, the lead melt allowing steam to escape into the fire box. This warns the engine men and help to deaden the fire. Both injectors should be put off immediately if this occurs and steps taken to remove or deaden the fire.
- SUPERHEATER: The super heater consists of super heater header and super heater elements. Steam from the main steam pipe arrives at the saturated steam chamber of the super heater header and is fed into the super heater element. Super heated steam arrives back at the super heater chamber of the super heater header and is fed into the steam pipe to the cylinder. Super heated steam is more expensive.
ENERGY SAVING DEVICES OF THE BOILER
- Economizers: Transfer a portion of the heat in the stack gases to water being fed to the boiler. It is a heat exchanger installed in the exhaust stack that pre-heats the boiler feed water.
- AIR PRE HEATER: Transfer heat from hot stack gas to air that is to be mixed with fuel for combustion this device saves energy by increasing the temperature of the mixture of fuel and air prior to combustion, so more of the heat of combustion is available to heat water.
- TURBULATORS: Twisted pieces of metal inserted in the tubes of fire tub boilers, causes hot gases to travel more slowly and with more turbulence, resulting in better heat transfer to the water.
- OXYGEN TRIM CONTROLS: Measure stack gas oxygen concentration and automatically adjust the inlet air at the burner for optimum efficiency.
Orchard equipments refer to the various machines (simple and complex) used on an orchard. Some of the machines include: pruners, sprayers, weeders, dusters, etc. The selection of choice of any of these machines is dependent on the nature of work to be carried out at that material time.
- PRUNERS – Also known as pruning shears or secateurs are a type of scissors for cutting off hard branches of trees and shrubs. They are strong enough to prune hard branches of trees and shrubs sometimes up to two centimeters thick.
- SPRAYERS: A sprayer is a piece of equipment that has spray nozzle to apply herbicides and fertilizers to agricultural crops. Sprayers range in sizes from man-portable units to trailed types that are connected to a tractor or other self propelled units. There are various types of sprayers which include knap sack, foot, garden, Hand compression, power, stirrup, self-propelled crop sprayer, trailed crop sprayer, etc.
COMPONENTS OF SPRAYING EQUIPMENT
- TANK: The tank is a unit which holds chemicals, and comes in many different shapes and sizes.
- PUMP: The pump creates pressure that forces the chemical to the nozzles.
- CONTROL VALVE: The control valve controls or maintains pressure and turn off the sprayer.
- NOZZLE TIP: The nozzle tip controls application rate and produce the correct size droplets.
- FILTER: The filter is a unit behind the nozzle tip to reduce entrance or passage of dirty particles and blockage into the system.
TYPES OF SPRAYING EQUIPMENTS
ULTRA-LOW VOLUME (ULV) SPRAYERS: ULV equipment is designed to produce very small droplets, thus ensuring even coverage with low volumes. The equipment is based on aerosol, airshear or rotary nozzle techniques. The ultra low volume machines use large volumes of air at low pressures to transform liquid into droplets that are dispersed into the atmosphere. Ultra low volume machines are used for applying pesticides, herbicides, fungicides, sterilizers and disinfectants among other chemicals. The ultra low volume machine consists of a blower, a formulation holding tank and a pump. The blower creates a low pressure area and forces air through the nozzles of the machine. Air pressure can be controlled by adjusting the engine speed. The nozzles of the machines have a very specific shape, which causes a swiring motion of the air stream. The motion is achieved by means of several agitationary fins that forces the air to rotate. The formulation is delivered to the air by means of a supply tube that is situated in the centre of the nozzles. The motion of the airshears the liquid formulation into very small droplets and then disperses it into the atmosphere. Advantages 1. The chemicals dispersed in this type of machine are more concentrated than the chemicals used in other spraying equipments, which increase the killing efficiency. There is lower risk of injury due to low pressure application. The only disadvantage it has is that it requires long application times and higher technical skills.
KNAPSACK PRAYERS: The knapsack sprayer is a back mounted equipment used by farmers. The tank of a knapsack sprayer is not pressurized and made of grass, or galvanized steel. The pump may be fitted into or outside the tank and sucks the liquid from the tank and expels it through the discharge line.
DUSTERS: Dusters usually refer to an aircraft used for dusting or spraying large farms with pesticides, though other types of dusters are also employed. Aerial spraying and dusting permits prompt coverage of large areas at the moment when application of pesticides is most effective and avoid the need for wheeled vehicles that might damage crops.
COMPONENT PARTS OF A DUSTER
- HOPPER – For storing the chemicals in dust form
- AGITATOR – An agitator is used to keep the dust moving freely within the hopper and prevent caking.
- Metering mechanism- which is usually an adjustable orifice that allows the rate of discharge to be varied.
- Delivery blower – which creates an airstream that is used to carry the powder to the target? The major difference between dusters and sprayers is that a sprayer is a machine that applies fluid chemicals to crops in liquid form while a duster is a machine that also applies fluid chemicals but in powdered form.
- WEEDERS: Weeders refers to the various equipments used to ease the task of removing weeds from orchards or gardens. Very common weeders include the fulcrum weeders, the Cape Cod weeders, and the cracle weeder. These weeders come in two styles: short handled weeders and long handled weeders. Short handled weeders are preferred for small gardens with small plants while long handled weeders are for bigger gardens that have bigger weeds.
- SORTING AND GRADING OF HORT. CROPS Sorting separates into groups different physical properties while grading separates into groups with different quality characteristics. Sorting and grading are usually the last separating operations before processing or displaying crops for sale. It should however be noted that damages at the stages of sorting and grading are likely to result in substantial economics loss.
REASONS FOR SORTING AND GRADING OF HORT
Sorting and grading of Horticultural crops controls the effectiveness of the subsequent operations because; 1. Sorted and graded products are better suited to mechanical operations such as peeling, blending , etc e. g. use of caustic soda or boiling water with vegetables which helps flavor. 2. Sorting and grading is necessary in processes which heat transfer is critical e. g. sterilization. 3. Sorting and grading is advantageous in processes in which uniformity of heat transfer is desirable e. g. dehydration. 4. Sorting and grading of crops gives better control weights filled with standard scale container. . Sorted and graded products fare more attractive in consumer use, and allows the sizing of uniformly catering packs like packets of biscuits. Grading and quality separation of Horticultural crops depends on an overall assessment of those properties of the crops which affect its acceptance as a food or as a working substance for the food processor. Grading factors may be grouped under the following: size and shape, maturity (e. g. freshness of eggs, ripeness in fruits, aging in meat), texture (e. g hardness, crispness in corn flakes) and flavor and aroma.
Grading for size and quality is an essential preliminary to marketing of fruits and vegetables grown on commercial holdings, and many types of machines are available to assist this work. Some are cheap and simple sizing or weighing machines for grading produce which has been sorted for quality before hand. Others are complex and expensive machines which incorporate devices to facilitate sorting for quality, accurate sizing mechanisms and bins to facilitate packing. Grading machinery may be grouped broadly into those which grade by diameter and those which grade by weight. Machines which grade3 by diameter very greatly.
Some size in only one or two directions, while others rotate the produce and thereby achieve a more accurate sizing. In general, machines that grade by diameter tend to have higher output, or are rather less expensive for given output then those which grade by Weight. On the other hand, a good weight grader has many advantages. It can be used for any shape, is easily adjustable and can be used for crops that are easily blemished. Grading by weight can also be more accurate than grading by diameter, though good diameter type graders are usually accurate enough for practical purposes.
Good graders do little damage to apples, most of the bruising that does occur being caused when the fruit roots into the receiving bin. This is usually negligible compared with damage incurred in picking, and getting fruit to the grader. Output of graders varies widely according to the number and ability of the operators, as well as according to the machines and auxiliary equipment employed. Some graders are equipped with automatic box-tipping devices for loading. The graders in large-scale apple-packing stations are often fed by first immersing the boxes in water and then handling the fruit on to the drier by floatation.
Outputs on such high-speed machines are frequently limited by the speed of packing. No one grading machine has all the advantages, so choice of a grader requires careful consideration of the most important needs for the conditions in which it is to be used. It is not possible to give an adequate description of any individual machine but below is a brief description of some of the grading machines:
SIZE GRADERS: This operates in two ways as follows;
- Produce falls through a circular hole of fixed size. In machines of this type the sizing board has a number of rows of holes of different sizes , and the crop is carried along by means of a series of wooden laths operated by a crank mechanism. The effect is to move the produce, without pushing or rolling it, to successively larger holes, until it falls through.
- As produce moves along conveyor, size of opening increases. Graders with mechanisms of this type are common, and include apple graders, in which the fruit is rapidly rolled along by a soft rubber belt, while leaning against a rubber barrier set at a gradually increasing distance from the belt, and machines with diverging rubber belts.
WEIGHT GRADERS: In weight graders, each fruit rests in an individual hinged cup, and for much of the journey along the conveyor the cup and fruit are supported in an upright position by a fixed guide rail. At suitable intervals, however, the support is provided by an adjustable lever-type weighing device. When the moment exerted by fruit and cup is sufficient, the cup tips, and deposits the fruit into its appropriate bin.
MECHANICAL HARVESTING OF HORTICULTURAL FRUITS HARVESTING: Is the process of gathering mature crops or fruits from the fields. Harvesting marks the end of the growing cycle for a particular crop, and the harvest is the focus of a growing season. It is the most labour intensive activity of the growing season. Mechanical harvesting equipment tends to be designed mainly for fruits which are to be processed rather than those for fresh market. The main types of equipment used are combing devices and vibrators, Black currant harvester with shakers, as well as redcurrant harvesters with similar shaker units for grapes. Also available are slider cranks, tree shakers which make use of catching and collecting devices mostly applicable for olives.
IMPORTANCE OF TIME OF HARVESITN OF HORTICULTURAL CROPS
- It reduces wastage of crop produce since most fruits tend to rot when not harvested in time.
- It gives the farmer more quality yield. When fruits in particular are harvested before they are fully ripe, they tend to be sour.
- Timely harvesting of leafy vegetables gives room to greater yield as the cut away leaves give room for more to shoot out.
COMPONENTS PARTS OF A MECHANICAL FRUIT HARVESTER
- An impactor for dislodging fruits from a fruit-bearing tree limb mounted on a positioning arm. The arm moves up, down, forward, backward and twists.
- A collecting conveyor for catching and conveying the dislodged fruits. The conveyor is supported by a frame and is comprised of series of supporters covered by a catching surface having an energy-absorbing flexible material.
- A transfer conveyor which is supported by a frame and is placed below the outlet of the collecting conveyor. It receives fruits from the collecting conveyor.
- A collecting Bin which is place below the outlet of the trans conveyor in which harvested fruits are deposited.