eChapters

2.1. Introduction

The engine is the source that generates power. It transforms chemical energy in fuel into mechanical energy for power. Diesel internal combustion engines are invariably used in all the tractors. In these engines, very high compression of the air ignites the fuel as compared to spark plug that ignites fuel in petrol engines. The air in the diesel engine is compressed with a compression ratio typically between 15 and 22 resulting in a 40 bar (about 600 psi) pressure as compared to 8 to 14 bar (about 200 psi) in the petrol engine. This high compression heats the air to 550°C (1022°F). At about this moment, small droplets of fuel are sprayed in an atomized form directly into the compressed air in the combustion chamber.

2.2. How does it work?

Any engine will work with four strokes, namely suction, compression, power and exhaust (Fig 2.1). It will also complete two revolutions of the crankshaft. In the suction stroke, pure air is drawn into the cylinder through the inlet valve. The exhaust valve gets closed and the crankshaft completes half a revolution. In the compression stroke, the piston moves up while the valves remain closed. The air which is drawn into the cylinder during the suction stroke is compressed. There is a rise in temperature. The hot air ignites the fuel injected into the cylinder. The crankshaft again completes half a revolution. In the power stroke, the hot products of combustion, viz., carbon dioxide and nitrogen expand. The piston is forced down. The valves remain closed and the crankshaft completes half a revolution. In the exhaust stroke, the exhaust valve opens while the piston reaches the lowest point of travel. Then the burnt gases are swept out.

3.1.1. Introduction

Clutch is a device which is used to connect and disconnect the tractor engine from the transmission gears and drive wheels. It is fitted in between the engine and gear box. The clutch transmits power by means of friction between driving members and the driven members.

4.2.1. Gear boxes

It is a unit fitted after the clutch. Forms a part of transmission and provides speed and torque conversions from a rotating power source to another device using gear ratios. Its primary function is to change the speed of the tractor to cater to varying field, road and load condition. It also helps in reversing the tractor.

Gears are usually made of alloy steel. Since the tractor has to transmit heavy torque all the time, the best quality lubricants, free from sediments, grit, alkali and moisture, are used for lubrication. SAE 90 oil is generally recommended for gear box.

The description about gear boxes stated below pertains to major tractors manufactured in India. The number of teeth in each of the gear and the engagement between gears of the main shaft and the corresponding gear on the counter/lay shaft also change in different tractors evolved over a period of time. Hence, information hosted in this section is only indicative.

5.3.1. Main components

Shear tube: It absorbs heavy shocks and protects the components of rear transmission and main transmission from breaking.

Crown wheel and pinion: It transmits the drive from the main shaft to the rear axle shaft and inverts the direction of rotation to 90° from the main shaft. It reduces the speed and multiplies the torque.

Rear axle: It is a semi floating type. It transfers the drive from the sun gear to the rear wheel.

5.3.2. How does it work?

The drive from the main shaft of the gear box is taken to the rear drive shaft through the coupler planetary. Depending on the position of the high–low gear and lever which moves the coupler, power is transmitted directly or through epicyclic gear train. The drive from the rear drive shaft is transferred to a safety coupling also known as shear tube. The coupling is a safety device. In case the rear wheels encounter any shock loading, the coupling breaks and disconnects the gear box from the rear transmission. This prevents damage to costly parts in the transmission, clutch and engine. Power is transmitted from safety coupling to a pinion which has a spiral bevel gear at one end. The bevel pinion is supported on two tapered roller bearings carried in a housing which is mounted in the centre housing.

6.4.1. Function

The brake is used to stop or slow down the motion of a tractor. It is mounted on the driving axle and operated by two independent pedals. Each pedal can be operated independently to assist turning of the tractor during field work or both the pedals can be locked together.

6.4.2. Principle of operation

The brake works on the principle of friction. When a moving element is brought into contact with a stationary element, the motion of the moving element is affected. This is due to frictional force which acts in the opposite direction of the motion and converts the kinetic energy into heat energy.

7.5.1. Functions

The two primary functions of tyres, especially rear ones, are to provide maximum work output while ploughing the field and for haulage.

8.6.1. Function

It steers the tractor in the required direction. The rotation of the steering wheel moves the steering column, which in turn rotates the sector shaft. This rotation pulls the pit man arms on one side and pushes at the other side. This motion is conveyed to the wheels by the drag link and makes the front wheel turn in the requisite direction.

9.7.1. Function

The front axle is the unit on which the front wheel is mounted. This wheel is an idler wheel by which the tractor is steered in various directions. The function is to assist the steering and support the tractor. It is a rigid tubular or I-section steel construction, pivoted at the centre. The pivot pin is housed on bushings on a support bolted to the front of the engine. As the track width of a tractor is adjustable, the front axles have provision to be extended on both sides. The tubular front axles have telescopic arrangement for extension, whereas the I-section type of front axles are three-piece axles.

10.8.1. Function

A power take-off (PTO) is a splined drive shaft on a tractor that can be used to provide power to an attachment or a stand alone machine. PTO shaft gets the drive from hydraulic pump shaft. This in turn gets drive from engine. PTO is designed to be easily connected and disconnected (Fig 10.8.1.). It is used to operate implements, viz., rotavator, fertilizer spreader, duster and many more machines which are stationary such as threshers, water pump and portable flour mill. These shafts either run at 540 rpm with 6 splines in the shaft or at 1000 rpm with 21 splines in the shaft. But many old tractors have 540 rpm PTO. The present day equipment is designed to operate with 1000 rpm PTO shaft. The manufacturers of old tractor models provide an auxiliary gear box which increases the speed of PTO to 1000 rpm. Selection of implements, equipment and machinery should be done on the basis of available tractor PTO speed.

11.1. Hydraulic system

It is a mechanism in a tractor to raise, hold or lower the mounted or semi-mounted equipment by hydraulic means. All the present day tractors are equipped with a hydraulic control system for operating three point hitches. Some of the tractors are fitted with a hydraulic brake system and a few others are fitted with a hydraulic steering system. Tipping trailers, front mounted loaders or dozers are examples of multi use of hydraulics.

11.2. Principle

The working principle of a hydraulic system is based on Pascal’s law (Fig 11.1.) This law states that the pressure applied to an enclosed fluid is transmitted equally in all directions. A small force acting on a small area can produce higher force on a surface of larger area.

12.1. Instruments panel

12.1.1. Oil pressure gauge

Indicates oil pressure in Kgf/cm²

13.1. Types

Lamps: Head lamp, plough lamp, indicators

Switches: Safety switch, starter switch, etc

13.2. Components

Battery: A battery provides power to electrical or electronic circuits. The voltage rating of a battery tells how much electrical “pressure” the battery can provide. Battery energy is used to operate starter motor and to provide current to the ignition system during cranking. The electrolyte should always be maintained just below the maximum level, but should not go down below the 1/4^th level.

Alternator: Alternators are electromechanical devices used to convert mechanical energy to alternating current electrical energy. While some of the alternators use rotating magnetic field, some use linear. The functioning of alternators is similar to that of direct current generators. As the magnetic field around a conductor changes, a current is induced in the conductor. The rotating magnet or the rotor turns and cuts the field across the conductors. Thus, an electrical current is produced which causes the rotor to turn. This rotating magnetic field causes an AC voltage in the stator windings. In tractors, alternators are used to charge the battery and to power the electric system when its engine is running. An alternator is superior to a dynamo as it provides more precise output control, requires lesser maintenance, is more compact and requires no cut-out.

Farm tractor designs and styles differ greatly. Tractors are often used on a daily basis for several agricultural and non-agricultural tasks by attaching or operating light, medium to heavy implements, equipment and machineries according to the requirement and hp of tractors. Tractors are very versatile and can be used on sandy (light textured), loamy (medium textured) and clayey (heavy textured) soil at different topographic and agro-climatic conditions. Earlier, the proportion of tractor usage in agricultural and non-agricultural work was 70:30. This proportion has increased to about 55: 45 over the past two to three years. It is expected to reach 50:50 in (agricultural:non-agricultural applications) in the coming years. The major application of farm tractors for agricultural and non-agricultural sectors is given below.

1. Introduction

Agricultural mechanization refers to usage of any improved tool, implement and machine by the farm workers to improve the efficiency of any operation to increase productivity. It also helps to reduce drudgery or stress which adversely affects human mental faculties leading to errors, imprecision and hazards and eventually loss of efficiency if done manually. In developed countries, however, mechanization is synonymous to automation. There is scope to mechanize every operation of crop production, post harvest and agro-processing.

17.1. What?

The soil is prepared to a fine tilth, which is referred to as land preparation or preparatory cultivation. This enables proper sowing of seeds, planting of seedlings and precise application of fertilizers to the crop. Various implements are used to prepare the land. The basic ones are ploughs, harrows, cultivators or tillers, and land levellers. These implements are manually operated or by animals or tractors. Various improvements have been made to increase the efficiency of each one of the implements by research workers. Many products are also available to suit the local regions and soil condition.

17.2. Plough

It has been the basic implement used for decades in agriculture to open up and invert the soil for initial cultivation. While inverting the soil, it also buries the weeds and the remains of the previous crops and allows them to decay. In the process of inverting, it also aerates the soil. Ploughs were initially used with animal power. Later on, many improved implements with heavy weights have been developed. These are drawn by tractors.

18.1. What?

The basic objective of sowing is to place the seed in rows at the desired depth, to maintain proper spacing between seed to seed, cover the seeds with soil and provide proper compaction over the seed if required. Precise sowing/planting helps in better crop stand. This helps to achieve optimum yields. Traditional sowing methods include broadcasting manually, opening furrows by a country plough and dropping seeds by hand (i.e.) dibbling. In the present day, improved seed-cum-fertilizer drills are used for sowing and fertilizer application. These are provided with seed and fertilizer boxes, metering mechanism, furrow openers, covering devices, frame, ground drive system and controls for variation of seed and fertilizer rates.

18.2. Types of sowing/planting equipment

Sowing equipment include seeders and transplanters. Various types of sowing equipment, viz., manually operated, animal drawn, power operated and tractor drawn are used throughout India.

18.2.1. Seed drills

Seeders are available for sowing seeds of various crops. Some seeders have been designed with adjustable metering mechanism which makes them versatile for sowing two or three kinds of seeds. For example, a multicrop planter developed by CIAE is used for sowing garlic, maize, moong, peas and groundnut. Similarly, the institute has developed a small seed sowing drill which is used for sowing small seeds such as bajra, rapeseed and mustard.

19.1. Need for weeding

Weeding is the critical operation to be carried out to obtain a good crop. Weeds are plants which grow in places where they are not wanted. They grow in the fields competing with crops for water, soil nutrients, light and space and thus reduce crop yields. They also harbor insect pests and micro-organisms. Certain weeds release the inhibitors or poisonous substances into the soil which are harmful to plants, human beings and livessecks. They increase the expenditure on labour and equipment, render harvesting difficult and reduce the quality and marketability of agricultural produce. When grown in water channels, they block and or reduce the flow of water.

The weed seeds germinate earlier and grow faster than the crop plant. This phenomenon is more pronounced when coupled with favourable environment like fine soil tilth and the soil receiving adequate water and fertilizers. Weeds flower earlier and produce seeds profusely ahead of the crop. So, these seeds get mixed up with the harvested crop and are distributed to the next season or transported to other places along with the harvested produce.

20.1. What?

Sprayer is equipment used for applying insecticides, fungicides, herbicides and in some cases fertilizers as foliar sprays to agricultural crops. Sprayers range in size from man-portable units (backpacks) to Self propelled units with boom mounts covering 60-150 feet length. Sprayers include the ones used for spraying liquid formulations, dusters for dusting dust formulations and granular applicators for delivering granules.

20.2. Principle of working

Sprayers work based on Bernoulli’s principle. Basically, the sprayers have a storage tank, a plunger, lance and a nozzle. When the plunger is pushed in, the air flows at a high velocity through the nozzle. The flow of air at high velocity creates a region of low pressure just above the lance. The higher atmospheric pressure acts on the surface of the liquid insecticide causing it to rise up the lance and the insecticide leaves out through the nozzle as a fine spray.

Sprayers are fitted with hollow cone nozzles for spraying pesticides and with flat fan nozzles for herbicides.

21.1. What?

Harvest is the process of gathering the end produce from mature crops in the fields. Harvest marks the end of the growing season, or the growing cycle for a particular crop. Harvesting is the most labour-intensive activity. Moreover, timely harvest before shattering of the produce or before rain assumes significance. As adjacent fields sown at the same time come to harvest simultaneously, farmers face great problem in getting manual labour for harvesting and cleaning their produce. To overcome these difficulties, different types of harvesters have been developed from time and again to suit different crops, situation and conditions.

21.2. Harvester and reaper

Harvesters are used to cut the crop after they mature. In such cases, threshing is to be done separately. Harvesters are available for a wide range of crops belonging to cereals, pulses, millets, oilseeds, fruits and plantation crops. Reapers are used to harvest crops such as rice, wheat, soybean, mustard, rapeseed, safflower and other thin stemmed crops. Reapers are operated using power tiller.

22.1. What?

Threshing is the process of separating grains from the straw or pod by impact, friction or both. Threshing should be done at an appropriate time after harvest. Delayed threshing causes rapid deterioration of the grains, especially during field drying or when the crop is stacked in the field. Improper threshing leads to wastage of grains and reduces the quantity of final marketable produce. After threshing, the produce has to be winnowed to remove lighter materials such as unfilled grains, chaff, weed seeds and straw using a blower, air fan or wind. Winnowing improves the ability of the grain to be safely stored, milling output and quality.

22.2. Methods employed

Traditionally, threshing is done by beating the harvested crop on a threshing floor directly or with a stick. Another traditional method of threshing is to make a bull walk in circles on the grain on a hard surface. In some areas, the harvested panicle with grain is spread on the surface of a country road so that the grain may be threshed by the wheels of passing vehicles. In these methods winnowing is separately performed. However, with the development of technology, now it is mostly done by machine referred to as threshers, shellers and stripper. Some of these threshers have inbuilt facility for threshing. Thus, threshing and winnowing are completed in a single process.

23.1. What?

Post harvest and agro-processing refers to activities carried out after harvesting a crop. These include milling, grading, processing and packing of the produce before it reaches the end users. This is also referred to as value addition, as it increases the marketable quality of the harvested produce.

23.2. Milling

It is the process of separating edible portion of the grain after removal of the husk or seed coat. This converts the products into a form that can be readily used for cooking, e.g. rice milling and dal milling.

23.3. Grading

Grading is the process of segregating the harvested produce based on the physical appearance including size and colour. Grading increases the market value of the crop.

24.1. What?

Most of the horticultural crops are raised by following special techniques such as budding and grafting. In case of landscape horticulture, frequent pruning and mowing are required to maintain the architecture. When new area is brought under cultivation, either jungle or unwanted plants have to be cleared. To perform all these operations, certain set of special tools are used. Some tools, though small, are of great need in raising and maintaining horticultural crops at various growth stages.

24.2. Special tools for horticultural crops

24.2.1. Manual

Axe, Dah, Hand shovel, Garden rake, Crow bar, Felling dao, Tea pruning dao, Billhook, Budding knife, Grafting knife, Budding and grafting knife, Pruning and slashing knives, Multipurpose chopping knife, Pruning secateurs, Pneumatic secateurs, Hedge shear, Hedge trimmer, Lopping shear, Forester shear, Grass shear, Garden sword, Flower scissors and coconut tree climber

This chapter deals with equipment and machineries that are used in certain specific operations/ areas.

25.1. Lac cultivation

High-capacity scraper cum grader, scraper cum grader

25.2. Mushroom production

Grain Cleaner, Grain boiler, Boiled grain and Chalk powder mixer, Bag/bottle filler, Spawn inoculators, Substrate mixer - manually operated

26.1. What?

These devices are used to lift water to a height that allows access to water. Lifting devices can be used to lift groundwater, rainwater stored in an underground reservoir and river water. For agricultural use, water is lifted either from a borewell or open well to irrigate the crops. According to power sources, lifting of water can be accomplished either manually or by animal or electricity sources of power.

26.2. Human-powered devices

Man has a limited physical power output, which may be in the range of 0.08 to 0.1 hp. This power can be used to lift water from shallow depths for irrigation. These include swing basket, counterpoise lift, don, Archimedean screw and paddle wheel. However, nowadays these are not commonly used.

26.3. Animal-powered devices

Animal power is abundantly available in India. They are used to lift water, besides being put to use for other field operations and processing works. A pair of bullocks may develop approximately 0.80 horsepower. They can lift water from a depth of 30m or more. Of course, the rate of discharge will go down with increase in the lift. These include rope and bucket lift, self emptying bucket, two bucket lift, Persian wheel and chain pump.

27.1. What?

Seed drills are designed to sow seeds at the recommended seed rate with precision and at the desired depth. Proper adjustments are made to the seed metering system to ensure efficient use of seed drills. This aspect is vital to have a good crop stand.

The seed size varies between crop and their varieties. In addition, the seed metering systems are based on volume displacement. Therefore, if one lot of seeds varies in size and weight from another, two different amounts or number of seeds will be metered if the drill setting is not changed. For this reason, metering systems should be calibrated each time when put to use.

The method of calibration will be given in detail in the manual provided along with the seed drill.

This chapter deals with the maintenance, repair, safety and trouble shooting of agricultural implements, equipment and machinery.

Routine maintenance reduces repair bills and extends the life of equipment. Good maintenance practices are essential for efficient operation of all types of farm machineries. Effort spent in this area of farm management is more than repaid by the consistent, reliable operation of machinery, reduced fuel bills and extended life of equipment. Maintenance of farm machinery is complicated by the usage pattern of short spells of intense activity, followed by periods of non-use or storage.

During the “standing” or non-use periods chemical interactions between metals and fluids can cause more damage than normal wear and tear from active usage. This must be considered in planning machinery maintenance.

1. INFLORESCENCE

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches.

1.1. Types of inflorescence

Inflorescences can be simple or compound.

1.1.1. Simple inflorescence

Inflorescence of sessile disc florets forming the capitulum

1.1.1.1. Indeterminate

Indeterminate simple inflorescences are generally called racemose. The main kind of racemose inflorescence is the raceme. The other kind of racemose inflorescences can all be derived from this one by dilation, compression, swelling or reduction of the different axes. Some passage forms between the obvious ones are commonly admitted.

1. FLOWERING

The flowering goes through a phase of vegetative growth producing more stems and leaves and a flowering phase where they produce the organs for sexual reproduction.

1.1. Synchronisation in flowering

Synchronous flowering refers to the phenomenon of coincident, simultaneous flowering of all population of a given species in a large region.

1. FRUITS

Fruit is a part of a flowering plant that derives from specific tissues of the flower, mainly one or more ovaries.

1.1. Types

1.1.1. Fleshy

1.1.1.1. Simple fleshy fruits

Develop from a flower with a single pistil.

1. SEED

A seed is defined as a ‘mature ovule’ or a reproductive unit formed from fertilized ovule, consisting of an embryo, reserve food and a protective cover.

Seed is the basic input in agriculture upon which other inputs are applied. A good vigorous seed utilities all the resources and realized as a reasonable output to the grower. It is wealth to the farmer, it is the yesterday’s harvest and tomorrow’s hope. Good seed in good soil realize good yield.

Seeds exhibit a great range of variation in shape, size, colour and behaviour. The most essential factor for the success of plantation is the ready availability of quality seeds. The quality of seed is totally responsible for the future return / performance of each and every seedling.

1. VEGETATIVE PROPAGULE

Vegetative propagation or asexual propagation is the method of propagating plants with the use of organs other than the seed and spore. In contrast to sexual propagation, the union of the male and female sexual gametes (fertilization) is not a requisite to the production of new plants. Hence the word “asexual”, which means “without sex” or “not sexual”.

1. OVULE DEVELOPMENT

The development of ovule occurs within the ovary, which provides a location for nurture and development of the female gametophyte, its sexual fusion with in the male gametophyte, and embryo development, survival, and eventual regrowth (Fig. 1). Ovule growth begins as a small outgrowth within the nucellus. As megasporogenesis and megagametogenesis continue, the region of the nucellus that is to become the ovule enlarges and differentiates into definite morphological characteristics. Secondary outgrowths, or collars (integuments), soon appear around the periphery of the nucellar outgrowths and envelop it. These usually consist of the inner and outer integuments and ultimately become the testa (seed coat) of the mature ovule.

1. APOMIXIS

Development of seed without fertilization. When the seed formation occurs without sexual fusion, the process is known as apomixis. This occurs by several mechanism, however all apomitic seed have genetic material only from the female plant Apomixis may or may not require pollination and pollen tube germination to initiate seed formation, however sexual union.

1. DEFINITION

Artificial seed technology involves the production of tissue culture derived somatic embryos encased in a protective coating. Artificial seeds have also been often referred to as synthetic seeds. However, the term ‘synthetic seed’ should not be confused with commercial seeds of a synthetic cultivar which is defined as an advanced generation of an open pollinated population composed of a group of selected inbred clones or hybrids. The concept of artificial or synthetic seed is shown in Figure 1.

1. SEED MATURITY

Harvesting should be done after the attainment of physiological maturity, when the seeds reached complete maturity to avoid harvesting of immature and ill-filled seeds.

1.1. Physiological maturity

It is the stage of accumulation of maximum drymatter within the seeds. It is expressed by maximum seed weight, germination and vigour potential. The moisture content of the seed at this stage is around 25-30% depending up on the species.

1.2. Harvestable maturity

The physiological maturity is represented to a seed and this maturity will not be the same for all the seeds of a single plant / population, due to continuous differential flowering habit. Hence, the stage of attainment of physiological maturity by 80% of the population is considered as the harvestable maturity stage. The moisture content of the seed will be lesser than the physiological maturity stage (18-20%).