Farm mech. lectrz


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Farm mech. lectrz

  1. 1. FARM MECHANIZATION AEN-321 3(2-2) By DR. FAISAL ZAHOOR Department of Agronomy Faculty of Agriculture Rawalakot
  2. 2.  FARM: A farm is an area of land, or aquaculture, lake, river or sea, including various structures, devoted primarily to the practice of producing and managing food (produce, grains, or livestock), fibres. Farms may be owned and operated by a single individual, family, community, corporation or a company. A farm can be a holding of any size from a fraction of a hectare to several thousand hectares.
  3. 3. TYPES OF FARMS:Crop and Vegetable Farms: Crops and vegetable farms aredevoted to produce various crops and vegetablesDairy farms: Dairy farming is a class of agriculture farms, wherefemale cattle, goats, or other mammals are raised for their milk,which may be either processed on-site or transported to a dairyfor processing and eventual retail sale.Poultry farms: Poultry farms are devoted to raising chickens,turkeys, ducks, and other fowl, generally for meat or eggs.Prison farms: Prison farms are farms which serve as prisonsfor inmates sentenced to hard labour by a court. On prison farmsinmates run the essential tasks of a farm, producing crops.
  4. 4. Farm MechanizationThe process of developing agricultural machines and substituting thismachine power for human and animal power in agricultural productionpractices is farm mechanizationorMechanization of farms means the use of machines for conductingagricultural operations, replacing the traditional methods which involvehuman and animal labor. Farm mechanization is one of the packagesof green revolution technology. Farm mechanization implies the use ofmechanical technology in the varied farming operations like sowing,harvesting, thrashing, leveling, watering, spraying, weeding etc.
  5. 5. SCOPE OF MECHANIZATION Farm mechanization has been helpful to bring about a significant improvement in agricultural productivity. The timeliness of operations has assumed greater significance in obtaining optimal yields from different crops, which has been possible by way of mechanization. For instance, the sowing of wheat in Punjab is done up to the first fortnight of November. A delay beyond this period by every one week leads to about 1.50 quintals per acre decrease in the yield. Secondly, the quality and precision of the operations are equally significant for realizing higher yields. The various operations such as land leveling, irrigation, sowing and planting, use of fertilizers, plant protection, harvesting and threshing need a high degree of precision to increase the efficiency of the inputs and reduce the losses. For example, sowing of the required quantity of seed at proper depth and uniform application of given dose of fertilizer can only be possible with the use of proper mechanical devices. Thirdly, the time taken to perform sequence of operations is a factor determining the cropping intensity. So as to ensure timeliness of various operations, it is quite inevitable to use such mechanical equipments
  6. 6. Farm Mechanization History of Pakistan Royal Commission on Agriculture (1928) in which the commission had recognized the need for replacing the bullocks with tractor As a result of recommendations by the commission, the Engineering Workshop of the Agriculture Department at Faisalabad, established in 1914 was strengthened to undertake research and development work on agricultural implements. Famine Inquiry Commission (1945) emphasized the need for reducing the pressure of animals on land by using tractors for cultivation. Continued …
  7. 7.  The Pakistan Agricultural Inquiry Committee (1951) recognized the desirability of using machinery. The Food and Agricultural Commission of (1960) also considered the scope of introducing mechanization. Revelle report (1964) commented on farm machinery and implements and suggested that major attention should be paid to the problem of designing agricultural equipment and proper systems suitable for small holdings. It also suggested the development of small horse power tractors. The five-year development plans have successively provided funds of the expansion of land development work with heavy machinery and for setting up of a network of agricultural workshops in the province (Report of the Farm Mechanization Committee, 1970). The Agriculture Machinery Organization (AMO) was thus established in the Agriculture Department, Government of West Pakistan in Continuation of its activities already in progress under the “Power Farming”, Agriculture Research Station Faisalabad with the mandate of developing lands and augmenting water supplies with the help of machinery. Bulldozers and power drilling rigs were added to the system to supplement activities being under taken by the Thal Development Authority.
  8. 8.  Constraints of Farm Mechanization It is true that farm mechanization has shown good results as of raising the agricultural production and improving the standard of living of farmers within very short period. But a number of arguments have been advanced against farm mechanization such as:1. Small size and scattered holdings of the farmers stand in the way of mechanization. As a result of this, farm machinery generally remains underutilized.2. Majority of small cultivators are poor who are not in a position to purchase the costly machinery like tractors, combine harvesters etc.3. The farm machinery have large turning radius and thus require comparatively larger farm for economical use. Mechanization may lead to structural change in agriculture in respect of the occupational distribution in the rural economy. No doubt, the increasing farm mechanization is going to increase employment in secondary and tertiary sectors but it does displace labor in farm operations. Continued …
  9. 9. 4. Lack of proper knowledge of farmer to purchase farm machinery, operateand maintain it properly leads to wrong choice, makes it uneconomical andrisky5. There is great shortage of diesel in the country as a whole. Thus, to use soextensive oil based farm machinery is not desirable.6. The lack of repair and replacement facilities especially in the remote ruralareas is another hindrance in efficient small farm mechanization.7. Due to the seasonal nature of the agriculture, the farm machinery remainsidle for much of the time. Thus, idle machinery means unnecessary high costsunless proper alternate use of such machinery in the off-season is made.
  10. 10.  The farm mechanical technology includes:1. CHEMICAL TECHNOLOGY: Plant Protection measures, Sprayers2. HYDROLOGICAL TECHNOLOGY: Tube wells3. MECHANICAL TECHNOLOGY: Tractors, Thrashers, Bulldozers etc.
  11. 11. Farm MachineryIn Pakistan Farm Machinery Institute (FMI) of PARC has developedand introduced the following farm mechanization technologies: Reaper (wheat and rice) Threshers (wheat, rice, groundnut, soybean, chickpea, sunflower, rapeseed/canola) Groundnut Digger Zero-till Drill (for sowing wheat after harvesting rice) Fertilizer Band Placement Seed Drill (Wheat) Row-crop Planter (sunflower and maize/corn) Wheat Straw Chopper-cum-blower Solar-cum-gas fired Fruits and Vegetables Dehydration System Mobile Seed Processing Unit
  12. 12. Mechanization technologies commercialized Reaper (Wheat and rice) Groundnut Digger Groundnut Thresher Sunflower Thresher Paddy Thresher Zero-till Drill (for sowing wheat after harvesting rice) Row-crop Planter (Sunflower and maize/corn) Wheat Straw Chopper-cum-blower Mobile Seed Processing Unit Mobile Flat-bed Dryer (sunflower and canola) Wheat-cum-rapeseed/canola Thresher Solar-cum-gas fired Fruits and Vegetable Dehydration System FMI Seeder (Zero-till drill for combine harvested rice fields)
  13. 13.  Petroleum is a mixture of a very large number of different hydrocarbons; the most commonly found molecules are alkanes (linear or branched), cycloalkanes, aromatic hydrocarbons. Each petroleum variety has a unique mix of molecules, which define its physical and chemical properties, like color and viscosity etc The alkanes, also known as paraffins, are saturated hydrocarbons with straight or branched chains which contain only carbon and hydrogen. They generally have from 5 to 40 carbon atoms per molecule. The alkanes from pentane (C5H12) to octane (C8H18) are refined into petrol, the ones from no-nane (C9H20) to hexa-decane (C16H34) into diesel fuel, kerosene and jet fuel). Alkanes with more than 16 carbon atoms can be refined into lubricating oil.
  14. 14. Octane, a hydrocarbon found in petroleum. Lines represent single bonds; blackspheres represent carbon; white spheres represent hydrogen.
  15. 15. Petrol combustion: 2C8H18 + 25O2 → 16CO2 + 18 H2O + energy/HeatDiesel/Petro-diesel combustion: 2C16H34 + 49O2 → 32CO2 + 34H2O + energy/HeatNatural Gas (CNG) combustion: CH4 + O2 → CO2 + H2O + energy/Heat
  16. 16. Engine TerminologiesBore (d):The internal diameter of the cylinderStroke (l): The maximum length of travel of piston from one extreme position to other extreme position in one directionTop dead centre (TDC): The position of the piston at the end of its travel when moving towards cylinder headBottom dead centre (BDC): The position of the piston at the end of its travel when moving towards the crankcase
  17. 17. Piston displacement (PD): The volume displaced or covered by the piston when it moves from TDC to BDCClearance volume (CV): The space or volume between the top of the piston and the engine cylinder head, when the piston is at the TDC. It is also called combustion chamberTotal cylinder volume (TCV): The volume designated by PD and Clearance volume TCV = PD + CVCompression Ratio (CR): The ratio of total cylinder volume and the clearance volume CR = TCV/CVEngine Size: It is the product of diameter of piston and the stroke of the engine
  18. 18. Cylinder head CVTop dead centre (TDC) PD Cylinder Stroke d Piston BDC Connecting rod Crankshaft D= bore (internal diameter of cylinder) CV= Clearance volume
  19. 19. Heat Engine Classification1. Internal Combustion Engine (I.C.E.) a. Reciprocating b. Rotary2. External Combustion Engine (E.C.E.) a. Reciprocating (Old tractors, boilers) b. Rotary (Steam turbines, Power plants) Turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work. The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and impart rotational energy to the rotor
  20. 20. Internal Combustion EngineIt is a machine which converts thereciprocating motion into rotarymotion as a result of thermalexpansion caused by combustibleGasesAs combustion takes place insidethe engine cylinder, so the engineis called internal combustion engine
  21. 21.  C: Crankshaft E: Exhaust camshaft I: Inlet camshaft P: Piston R: Connecting rod S: Spark plug V: Valves. Red: exhaust, Blue: intake W: Cooling water ducts
  22. 22. External combustion engineAn external combustion engine (EC engine) is a heat engine where an(internal) working fluid is heated by combustion of an external source, throughthe engine wall or a heat exchanger. The fluid then, by expanding producesmotion and usable work. The working fluid can be a gas or steam as in asteam engine.Reciprocating motion, also called reciprocation, is a repetitive up-and-downor back-and-forth motion. It is found in a wide range of mechanisms, includingreciprocating engines and pumps. . The piston moves in a reciprocating motion,which is converted into circular motion of the crankshaft, which ultimatelypropels the vehicle or does other useful work.Rotary motion, Rotation around a fixed axis is a special case of rotationalmotion.
  23. 23. I.C.E:a. Reciprocating: a.1: C.I. Engines a.1.1 Four stroke (Tractors, cars, buses) a.1.2 Two stroke (Motor cycles) a.2: S.I. Engines a.1.1 Four stroke (Tractors, cars, buses) a.1.2 Two stroke (very rare) The SI spark plug is timed to start combustion at the ideal moment, usually some degrees before the piston reaches the top (TDC or Top Dead Centre). The burning mixture then drives the piston down for the power stroke. The CI fuel is injected (sprayed) into the cylinder at the ideal moment - this too is usually some degrees before TDC, and the red-hot air in there then starts the fuel burning. This then drives the piston down for the power stroke.b. Rotary Engines: Airplanes, Power plants
  24. 24. Tractor Engine Parts:  Base or Frame  Cylinder  Cylinder head  Piston  Piston rings  Piston pins  Connecting rod  Crankshaft  Fly Wheel  Valve System  Fuel supply System  Ignition System  Cooling System  Lubrication System  Governing System
  25. 25. BASE or FRAME Made up of cast iron Other parts of engine are attached directly or indirectly Equipped with holes by which engine may be firmly anchored to its foundationCYLINDER Made up of high grade gray cast iron and may be attached with engine base or some time separate. In small size engines usually cylinders are attached with the base while in large size engines cylinders are detachable. Attaching a cylinder and base together produces a rigid construction but require greater outlay if cylinders are to be replaced when worn or damaged. If cylinders are not a part of the base but bolted to it, care should be taken to keep the bolts tight and retain the proper cylinder alignment all the time, it reduces breakage and wear. Cast iron: excellent heat retention iron Gray cast iron: Has graphite in its chemistry, auto-trop of carbon with high thermal conductivity
  26. 26. PISTONS: Made up of cast iron but aluminum alloy pistons are frequently used in multiple cylinders engines. Aluminum alloy offer the advantage of being lighter in weight and has greater co-efficient of thermal expansion. Piston move back and forth in cylinder owing to the explosion of the fuel mixture, this back and forth movement of the piston is transmitted through connecting rod and cranckshaft to the belt pully and thus power is generated. Piston clearance is the space between piston head and cylinder head, for cast iron pistons clearance is about 0.001 in. of the cylinder diameter. Too much clearance cause loss of compression Too little clearance cause the piston to seize in the cylinder as the engine gets hot A piston may seize in a cylinder even though it has the proper clearance but owning to lack of cylinder lubrication Co-efficient of thermal expansion: It is the change in the size of the object with the change in temperature
  27. 27. CYLINDER HEAD Made up of cast iron They are detachable from the cylinders but some time cast with it The detachable type of cylinder heads allow better accessibility and is more convenient to get to the valves and clean the carbon from the cylinder pistonPISTON PINS: Made up of hard steel It contact the connecting rod with the piston and provide a hinge like connection between the two A hinge is a type of bearing that connects two solid objects, typically allowing only a limited angle of rotation between them.
  28. 28. PISTON RINGS: Made up of cast iron The number of rings per piston varies from three to seven depending upon type of engine and the compression desired Ordinary type of engines seldom have three or four rings, but five or more rings are present in tractors or heavy duty engine Piston rings retain compression and reduce the cylinder wall and piston wall contact area to a minimum, thus preventing fraction losses and excessive wear Piston rings are classified as compression rings and oil rings depending upon their function and location on the piston Compression pins are plain one piece rings and are always placed in the grooves near the piston head. Oil rings are present in the lowest groove above the piston pin or near the piston skirt. It controls the distribution of the lubricating oil to the cylinder and piston
  29. 29. CONNECTING ROD: Connecting rod are made up of drop forged steel, it must be of some material that is neither brittle nor ductile The I-beam type is prevailing connecting rod shape, it gives strength with less weight and material That end of the rod fastened to the piston pin is known as the small end and the other end which is attached with to the crank shaft is spoken as large end of the connecting rod Drop forged: Motion of dropping hammer onto the hot steel or referred to the process in which super heated steel is formed into items such as tools etc
  30. 30. CRANKSHAFT: Made up of drop forged steel and carefully machined, ground and polished at the journals. The journals that support the crankshaft and hold it in position are called main journals, whereas the part to which the connecting rod is attached is spoken of a crank journals
  31. 31. FLYWHEEL: Made up of cast iron Assist in maintaining a uniform engine speed and provide a mean of balancing the engine properly Uniformity of the speed is maintained by the inertia of the heavy flywheel
  32. 32. VALVE SYSTEM: Each engine cylinder has at least two valves an intake and an exhaust valve. Intake valves are usually larger than the exhaust valves. The reason is that when intake valve is open the only force moving air fuel mixture or air is atmospheric pressure. The intake valve opens just before the intake stroke begins and allows the air fuel mixture to enter the cylinder. When the exhaust valve opens on the exhaust stroke, there is still high enough pressure in the cylinder to exhaust the gases outside the cylinder. The exhaust valve opens just before the exhaust stroke begins so that the burnt gases can escape the cylinder. For the Exhaust Valve, Chromium or Silicon is used which makes it resistant to corrosion due to high temperature and hot gases. Some engines have three valves per cylinder two for intake and one for exhaust, while in some engines four valves per cylinder two for intake and two for exhaust are present.
  33. 33. VALVE COOLING: The intake valve runs relatively cool. This is because the cool air-fuel mixture flows around the head of the intake valve. However, very hot exhaust gases flows around the head of the exhaust valve. As a result exhaust valve may become red in operation with temperature of upto 16000F. The engine cooling system cools the valves seat and stem. Coolant circulates through the water jackets in cylinder head. For the cooling purpose of exhaust valves some have hollow stems partly filled with metal sodium that keeps the exhaust valve cool. Valve Seat: The valve seat is a machined surface upon valve face rests when the valve is closed.
  34. 34. COOLING SYSTEM OF ENGINE: Temperatures in the combustion chamber of the engine can reach 4,500 F (2,500 C), so cooling the area around the cylinders is critical. Areas around the exhaust valves are especially crucial, and almost all of the space inside the cylinder head around the valves that is not needed for structure is filled with coolant. If the engine goes without cooling for very long, it can seize. When this happens, the metal has actually gotten hot enough for the piston to weld itself to the cylinder. This usually means the complete destruction of the engine. One interesting way to reduce the demands on the cooling system is to reduce the amount of heat that is transferred from the combustion chamber to the metal parts of the engine. Some engines do this by coating the inside of the top of the cylinder head with a thin layer of ceramic. Ceramic is a poor conductor of heat, so less heat is conducted through to the metal and more passes out of the exhaust.
  35. 35. TYPES OF COOLING SYSTEM:1. Air Cooling System2. Liquid Cooling System3. Combine Air & Liquid Cooling System
  36. 36. Air Cooling System: Air cooling is a method of dissipating heat. It works by making the object to be cooled have a larger surface area or have an increased flow of air over its surface, or both. An example of the former is to add fins to the surface of the object, either by making them integral or by attaching them tightly to the objects surface (to ensure efficient heat transfer). Instead of circulating fluid through the engine, the engine block is covered in aluminum fins that conduct the heat away from the cylinder. A powerful fan forces air over these fins, which cools the engine by transferring the heat to the air. Mostly it is done by using a fan blowing air into or onto the object one wants to cool. In many cases the addition of fins adds to the total surface area. In all cases, the air has to be cooler than the object or surface from which it is expected to remove heat. This is due to the second law of thermodynamics, which states that heat will move spontaneously from a hot reservoir (the heat sink) to a cold reservoir (the air).
  37. 37. Air Cooling System:Advantages No need for radiator No coolant No water pump etc. Less weightDisadvantages Noisy Difficult to control temperature properly.
  38. 38. WATER COOLING SYSTEM: Water cooling is a method of heat removal from engine components As opposed to air cooling, water is used as the heat conductor. Water cooling is commonly used for cooling automobile internal combustion engines and large industrial facilities such as steam electric power plants, hydroelectric generators, petroleum refineries and chemical plants.[ The cooling system on liquid-cooled vehicles circulates a fluid through pipes and passageways in the engine. As this liquid passes through the hot engine it absorbs heat, cooling the engine. After the fluid leaves the engine, it passes through a heat exchanger, or radiator, which transfers the heat from the fluid to the air blowing through the exchanger.
  39. 39. COOLANT/ANTI-FREEZ: Vehicles operate in a wide variety of temperatures, from well below freezing to well over 50 C. So whatever fluid is used to cool the engine has to have a very low freezing point, a high boiling point, and it has to have the capacity to hold a lot of heat. Water is one of the most effective fluids for holding heat, but water freezes. The fluid that most vehicles use is a mixture of water and ethylene glycol (C 2H6O2), also known as antifreeze. By adding ethylene glycol to water, the boiling and freezing points are improved significantly. The temperature of the coolant can sometimes reach 250 to 275 F (121 to 135 C). Even with ethylene glycol added, these temperatures would boil the coolant, so something additional must be done to raise its boiling point. Its distinctive odor also indicates cooling system leaks and problems that would go unnoticed in a water-only cooling system.
  40. 40. 50/50 70/30 Pure Water C2H6O2/Water C2H6O2/WaterFreezing Point 0C -37 C -55 CBoiling Point 100 C 106 C 113 C
  41. 41. COOLING MECHANISM: Heat is conveyed from working parts to the RADIATOR hence to the air Water/Coolant takes this heat from Cylinder and Combustion chamber by circulating in the water jacket Water jacket is connected to the radiator by two hoses, one from the cylinder head to the radiator tank and the other base of the cylinder block to the base of the radiator The radiator consist of fine tubes called fins that increase the surface area Water is confined in these tubes in thin films, which allow it to cool rapidly under the influence of an air flow
  42. 42. COMPONENTS OF WATER COOLING SYSTEM:RADIATOR: Radiator contains a vertical or horizontal finned tubing section It is designed to hold an abundant amount of water and ethylene glycol, or antifreeze The outside air that passes through the radiator grille helps to cool the liquid The radiator reduces the temperature of the coolant, which has absorbed the heat from the engine, keeping it within a normal operating temperature. Overheating an engine can cause permanent damage. A leaking radiator will cause engine to run at a higher than normal temperature and may cost you huge money in engine repair costs. A radiator should always be completely filled with water, antifreeze/coolant or a mixture The radiator can also accumulate internal residues. The cooling efficiency can be dramatically reduced as a result. If you find your vehicle is running at higher than normal temperatures, it may be time to install a new replacement or high performance radiator.
  43. 43. Water Pump: The water pump is a simple centrifugal pump driven by a belt connected to the crankshaft of the engine. The pump circulates fluid whenever the engine is running. If your water pump isnt operating, the engine coolant just sits in the block and heads. It doesn’t circulate or flow to the radiator to displace its heat. No coolant heat displacement from the radiator means your vehicle will quickly overheat. This will lead to costly damage even irreversible damage such as blown engineThermostat: The thermostat in a vehicle regulates the flow of coolant throughout the system. It controls the amount of coolant moving through the cooling system to help keep the vehicle’s engine from overheating It controls the flow in such a way that the operating temperature is kept within a narrow margin. Your vehicle’s engine operates at peak efficiency within this narrow band of temperature regulation.
  44. 44. Water Cooling System:Advantages quieter accurate temperature control warm water available for heaterDisadvantages Need for radiator Water pump Coolant Water jacket around cylinders More weight
  45. 45. LUBRICATION SYSTEM:All moving parts in the engine require lubrication i.e the application of oil to the moving parts to reduce the friction between themObjective and Functions: Reduces friction and wear by introducing a film of oil or grease between sliding surfaces Cools surface of the piston Saves power that may be lost in friction Lengthen the life of the piston Minimize repair bills Absorbs heat
  46. 46. COMPONENTS & FUNCTIONS OF LUB. SYSTEM:Oil Sump The sump is at the base or bottom of an engine. It can be used as a storage container.Oil pump Oil is drawn from the sump by an oil pump. It is driven by camshaft. On the suction side of pump a Strainer (sieve) is arranged to check impuritiesOil filters The oil filter helps to clean the oil by removing the impurities. If the filter clogs, a valve opens and directs unfiltered oil to the engine. Most oil-filters on diesel engines are larger than those on similar gasoline engines.Oil Galleries: These are the small passages in the cylinder block that direct oil to the moving parts.Oil Level indicator (Dip stick) Oil level indicators is a graduated rod used to check when there are safe oil levels in an engine.
  47. 47. Lubrication System of an ENGINE:Oil galleriesOil filter Crank shaftOil pumpOil sump
  48. 48. OIL FILTER:OutflowInflowOil passageFilter
  49. 49. GRADES OF ENGINE OILS: The society of Automotive Engineers grades oils according to their viscosity e.g. SAE-20, SAE-30, SAE-40, SAE-50, SAE-60. Some times like SAE-30 W etc. Usually less viscous oils quickly flow when engine is started cold verses dry running until lubricant either warms up sufficiently Less dry running means much less engine wear
  50. 50. FUEL SYSTEM:Fuel tank: It hold fuelCarburetor: Premixes air and fuel mixture and supply it to the injectorsFuel Supply Pump: Supply the fuel to the system from the tankSedimenter: It filter out water from the dieselFuel Filter: To filter fuel and remove minor particles from the fuel. Fuel injectors have tiny openings which clog easily so filtering the fuel is the only way to prevent this.Injection Pump: To deliver highly pressurized fuel to the injectorsInjection pipes: Connects injection pump with injectorsInjectors: One for each cylinder to spray fuel into the combustion chamberReturn lines/ Overflow pipes: To return excess fuel from injection pump and injectors to the tankGovernors: To control engine speedControl Lever: Provide connection between governor and drivers accelerator
  51. 51. FUEL SYSTEM: Injectors Fuel filter Injection pipes Return lines Injection pump Fuel supply Pump Sedimenter Fuel tank
  52. 52. IGNITION SYSTEM: An ignition system is a system for igniting a fuel-air mixture. Ignition systems are well known in the field of internal combustion engines such as those used in petrol (gasoline) engines used to power the majority of motor vehicles.Types of Ignition System:1. Conventional Ignition system a) Battery Ignition (Chemical eng. is converted to electrical eng.) b) Magneto Ignition (Mech. eng. is converted to electrical eng.)1. Electronic system a) Mechanically timed ignition b) Electronic Ignition c) Digital Electronic Ignition
  53. 53. GOVERNING SYSTEM/ ENGINE CONTROL UNIT: An engine control unit is a type of electronic control unit that determines the amount of fuel, ignition timing and other parameters an internal combustion engine needs to keep running.Control of fuel mixture For an engine with fuel injection, an engine control unit will determine the quantity of fuel to inject If the engine has not warmed up, more fuel will be injected (causing the engine to run slightly rich until the engine warms up).Control of ignition timing A spark ignition engine requires a spark to initiate combustion in the combustion chamber. An ECU can adjust the exact timing of the spark (called ignition timing) to provide better power and economy.Control of variable valve timing
  54. 54. DIFF. B/W PETROL AND DIESEL ENGINES: Both are Internal combustion IC engines. Petrol and Diesel oil are two separate fractions of crude oil. Petrol is lighter, more volatile, and contains hydrocarbons with around 8 carbon atoms per molecule. Diesel oil is heavier, less volatile, but with greater lubricity, and contains hydrocarbons with around 10 carbon atoms per molecule.1. Petrol engines use spark plugs (Spark Ignition) to ignite the fuel which is a mixture of air and petrol. A diesel engine uses a higher compression ratio (compression Ignition) when it compresses the incoming air, which creates a temperature inside the cylinder which is high enough to ignite the fuel when it is injected into the compressed air. In a diesel engine the Air is compressed to 21 times its normal volume (Approx) and then Fuel is injected into the Cylinder head/ or piston. Due to the high compression the temperature rises and as Fuel is injected it ignites. The Thermal efficiency of a Diesel engine is more as initially the gas was compressed to a higher level and hence the pressure generated on piston is more. Due to the high pressure generated in a Diesel engine the cylinder head , Block, connecting rod, crank Shaft bearing, pistons etc have to be built stronger to withstand higher stress and loads.
  55. 55. 2. Diesel engines consume around 30% less fuel than petrol engines and this results in much lesser carbon dioxide emissions. The diesel engines produce virtually no carbon monoxide and are much safer than petrol engines.3. A diesel engine can relatively last longer, due to the fact that petrol destroys lubrication and diesel doesn’t.4. A major advantage of petrol engines is that they are relatively lighter than diesel engines. Engine weight is an important factor which affects speed and performance of a car. This is one of the reasons why some of the fastest cars in the world run on petrol.5. Carburetor is used to vaporize the fuel mixture in petrol engines and injection pump is used to uplift and forward the fuel to the injectors
  56. 56. Types of tractors General or multipurpose tractor Garden tractor Crawler tractor Industrial tractor Row crop tractor
  57. 57. General purpose tractorCharacteristics Horse power ranges from 45-65. Rear wheels are usually drive wheels Front wheels are used for stearing Distance from centre to rear wheel is fixed and is not adjustable Useful for operation like ploughing seeding and harvesting etc. threshing Can also be used for transportation.
  58. 58. Row Crop Tractors: A row-crop tractor is a tractor tailored specifically to the growing of row crops and most especially to cultivating. Cultivating can take place anytime from soon after the crop plants have sprouted until soon before they are harvested. The earliest win from introducing tractors to mechanize agriculture was in reducing the heavy efforts of plowing and harrowing before planting, which could often be backbreaking tasks for humans and draft animals. Early tractors were used mainly to alleviate this drudgery.
  59. 59. Garden tractor Garden Tractors (also called Mini Tractors) are small, light and simple tractors designed for use in domestic gardens Designed primarily for cutting grass, being fitted with horizontal rotary cutting disks. Horse power ranges from 5-12 Engine possess air cooling system Garden Tractors are generally capable of mounting other implements such as harrows, cultivators/rotavators, sweepers and rollers etc. More skills and great effort is required to drive and operate such tractor Such tractor cannot be used for operating threshers and Harvesting equipment.
  60. 60. Crawler Tractors:
  61. 61. Horsepower (HP) It is the unit of measurement of power. The most common definitions equal between 735.5 and 750 watts. Horsepower was originally defined to compare the output of steam engines with the power of draft horses. The unit was widely adopted to measure the output of piston engines, turbines, electric motors, and other machinery.Mechanical horsepower hp(1) = 33,000 ft-lb/min = 550 ft-lb/s = 745.699872 Watt
  62. 62. Engine troublesFollowing are the general troubles of an engine Engine will not start Engine cranks but not start Engine does not develop full power Exhaust smoke of engine Engine over heated
  63. 63. Engine will not start Starting motor (generator) at fault Battery may be week High resistance in circuits Defective starting switch Engine oil too heavyEngine cranks but not start injection pump faulty Air intake restricted Battery low in charge
  64. 64. Engine does not develop full power Moisture in fuel Fuel filter clogged Poor fuel Injection pump not timed correctly Air leaks around intake parts Low compression Faulty fuel supply pumpExhaust smoke of engine Wrong value system Problematic piston rings and cylinder walls Defective fuel nozzle Clogged air cleaner Wrong type fuel Engine over loaded
  65. 65. Engine over heated Inefficient cooling Clogged cooling system Fan belt slipping or fan not working Poor circulation through radiator Insufficient lubrication oil Engine over loaded Defective water pump Defective thermostat value
  66. 66. Tractor MaintenanceDaily maintenance Check fuel Check water level in cooling system Check oil level Check brakesMaintenance after a week (50 hours) Attend various lubrication points Check tyre pressure Check oil level in hydraulic system Clean the battery terminals
  67. 67. Maintenance after month (120 hours) Change engine oil Change oil filter Attend lubrication points Check fan belt Check liquid level in battery cell Clean hydraulic oil filterMaintenance after 600 hours Change transmission oil Check fuel oil and air cleaner Check front wheel assembly Change hydraulic oil Clean air cleaner upper part and air intake pipe
  68. 68. Tillage Tillage in general may be defined as the mechanical manipulation of soil for any purpose. From agriculture point of viewTillage involves the breaking, stirring, turning or conditioning of soil surface to develop a favorable soil environment for the germination and growth of crops.
  69. 69. Objective of tillage To develop a desirable soil structure for seed bed or root zone To increase soil aeration by loosening soil and thereby reducing soil density To minimize soil resistance to root penetration To control weeds or to eradicate unwanted plants To improve soil fertility by incorporating crop residues or green manuring crops etc To minimize soil erosion by employing deep tillage, mulch tillage, contour tillage Continued …
  70. 70. Continued … To establish specific soil surface configuration such as beds, furrows, ridges etc for planting, irrigation, drainage or harvesting operations etc To incorporate and mix fertilizer, pesticides or soil amendments into the soil To accomplish segregation of roots, rocks, foreign objects from soil To break hardpan, tillage pan or sodic pan developed underneath the root zone
  71. 71. Tillage terminologiesTilth It is defined as degree of aggregation of soil particles. Ideal tilth is secured when soil is aggregated into crumble like particles that allow free access of air and water and not easily broken down by rainfall.Tillage tool: It is defined as an individual soil working element such as disc blade, cultivator shovel, tine of cultivator etcTillage implement: A tillage implement is made of a single tillage tool or a group of tillage tools, together with a frame, wheels (if any) control and protection devices and any other structural and power transmission components.
  72. 72. Types of tillageTillage operation are often classified as Primary tillage Secondary tillagePrimary tillage The initial breaking up of soil after crop harvest is generally called as primary tillageSecondary tillage The operation carried out after primary tillage such as breaking / pulverization of clods to prepare seed bed ready for planting is called as secondary tillage.
  73. 73. Conventional Tillage: Both primary and secondary tillage operations are involvedReduced Tillage: No. of primary tillage operations are reduced to minimum e.g. Minimum tillage, zero tillage and no tillage
  74. 74. Minimum tillage It refers to the cultivation of only that part of the soil on which is going to be used for seeding/sowing of crops. This is some times called as strip tillage or zone tillage.Objectives: To reduce mechanical energy and labor requirement. To conserve moisture in draught hits areas by controlling water evaporation and reduce soil erosion. To save time by doing operations necessary to optimize soil conditions for crop growth.
  75. 75. Zero tillage It is termed as direct drilling or seeding. In this tillage method, seed is directly drilled or planted into the stubbled field of previous crop by opening upto 5 to 8 cm soil strip with the help of zero till drill.Mulch tillage/conservation tillage This tillage involves cutting the roots of weeds and plants and leaving the crop residues over the soil surface or mix into the top few centimeters of soil. The main purpose of the tillage is to reduce the wind and water erosion + moisture conservation.
  76. 76. Types of tillage implementsPrimary tillage implementsSecondary tillage implementsPrimary tillage implements These implements are used for initial/major soil working operation. They are normally designed to cut and invert the soil and thereby reduce soil strength, incorporate plant materials and rearrange aggregates. The primary implements are given as; Mould board plow Disc plow Chisel plow Sub soiler
  77. 77. Secondary tillage implements These implements are used after primary tillage implements mainly to pulverize the soil. Secondary implements are used to prepare seed bed by greater pulverization. The secondary implements work at comparatively shallow depths ranging from 3 to 6 inches. Secondary tillage implements are Disc harrow Bar harrow Tine cultivator Sweep cultivator Rotavator
  78. 78. Primary tillage implementsMould board (MB) plow: It is used after harvesting the crop to cut/loosen and invert the soil into furrow slices with varying degree of pulverization depending upon type of mould board plow, soil type and speed of plowing.The specific functions of MB plow are; To cut and break the soil To lift the soil To turn the soil To pulverize the soil To burry weeds, trash, and manure To plough deep
  79. 79. Mould board BeamFrameShinFrogShareLand side
  80. 80. Parts of mould board plowShare: It is the first part of the plough to enter the soil and cut a furrow slice.Mould board: The cut soil is lifted upward to the mould board where it is inverted by the curvature of this component.Land side: Assist in making a neat furrow. It presses against furrow wall absorbing the side way thrust of the plough.Frog: The component that joins the share, mould board and land side.
  81. 81. Beam : Provides connection between the plough and source of power.The shin: This is the cutting edge of mould board just above the land side and behind the share.
  82. 82. Disc plow: It has same functions as those of M.B. plow but disc plow is preferred in stony, rocky and sticky soils (clay soil) because the disk rolls over the stones. Due to rolling action of disks, the soil that is stuck with disc is removed automatically.Uses and advantages: It is primary tillage implements It is used in stony and rocky areas In obstruction, this plow will ride over In sticky soils (clay) the soil would be removed and cleaned by rolling action of disk. It penetrate deeper than mould board plow Its maintenance cost is less since there are no shares or shin As it rolls over the stones, so it has longer life than mould board plow.
  83. 83. Disadvantages: It does not turn soil so effectively as mould board plow It does not incorporate vegetation and trash effectively It is heavier It is more costly Since it goes to deeper depth, it requires more horsepower. It does not pulverize the soil so effectively It leaves the soil cloddy and rougher
  84. 84. Design and construction It consist of round, concave, heat treated disks with sharp edges in order to cut the soil. Diameter of disks varies from 20-40 inches (50-100 cm). Size of plow is specified by diameter of disk. Thickness of disk varies from 0.5 cm to 1.0 cm. The disk are placed 22.5- 30 cm a partDisk angle: The disk blades are set at an angle from the forward line of travel called the disk angle it varies from 42 to 45 degree. It controls the width of the furrow as well as degree of pulverization.Tilt angle: The angle of disk from the vertical line is called the tilt angle. It varies from 15 to 25 degree. It controls the depth of penetration.
  85. 85. Chisel plow: The implement such as mould board plow, disk plow work on top soil but chisel plow is used for subsurface tillage.Features: Chisel plow work in hard pan The chisel plow goes upto a depth of 25-38 cm In erodible soils the chisel plow has been considered the best to overcome the problem of runoff. It consist of two and three shanks fixed at box type structure The shank may be straight, curved or tapered The horsepower can be cut to 25 % by using tapered or curved shanks as compared to straight shanks. The bottom part of shanks are fitted with tine or shovel If narrow tines are used, the implement will go a greater depth. It works in hard pan below level of plowing
  86. 86. ShanksTine/ shovel
  87. 87. Sub- soiler: It is identical in shape to chisel plow except that a single shank is used. It works upto a depth of 100 cm It goes much deeper It is simple in construction It is operated in sub soil below to break hard pan and make soil suitable for root development. It is usually operated after 3-5 years. It should be operated in dry and hard land, if it is operated in wet soil, it will produce a compacted path in soil which is of little value. The horsepower required to pull a soiler is 65-85hp.
  88. 88. Secondary tillage implementsDisk harrow Disc harrow is similar in shape as disc plow except they are smaller in size. Five or six disks are mounted on one axle to make a gang. The concavity of disk harrow is less as compared to disk plow, which results into less soil inversion and more pulverization. Note: disc harrows are general purpose tillage tools as their 2 passes are just equivalent to 5 passes of tine cultivator.
  89. 89. Bar harrowThe bar harrow are of two types; Spike tooth bar harrow Spring tooth bar harrow
  90. 90. Spike tooth bar harrowIt consists of sections The width of section is usually from 1.5 -2.0cm The section is rectangular in shape, containing the rods on which pegs or spikes are mounted or welded. A number of sections may be used depending upon horsepower available. The thickness of peg varies from 0.25 to 0.75 inches. The pegs are made of heat treated steel and may be replaced or sharpened when worn out. The pegs are slightly tilted from vertical No of pegs in a section varies from 20-30 Length of peg is around 9 inches
  91. 91. Uses: It breaks crust of soil formed by beating action of rain and reduce the compaction occurred by human, animal or machinery. It smoothes and levels soil surface to some extent It stirs soil It covers the seed that is broadcast It penetrates to a depth of about 5 cm It can mix up the manure It can be used for intercultural operation.
  92. 92. Spring tooth harrow It consists of section on which curved bars are mounted The thickness of the curved bar is 0.25 to 0.50 inches The curved bars are made up of spring steel The number of curved bars in a section is around 12 The number of sections may vary according to horsepower available The length of curved bars may be up-to 10 inchesUses: Because of spring action it can move easily on rocks and stones Because of curved bars it can pull out weeds It can break up crust It is used to increase moisture retention capacity of soil It pulverizes the soil to greater extent.
  93. 93. Rotavator: It consists of number of curved blades fitted on horizontal revolving shaft. The shafts rotates with 200-300 rpmUses and advantages: It is used particularly for puddling operations It cuts and invert the soil It pulverizes the soil It mix crop residues and organic matter with the soil. These operation like cutting, inversion, pulverization are carried out in one operation.
  94. 94. Limitations: It requires more horsepower It is expensive implement Rotating blades may destroy useful bacteria. It is particularly used for puddling operation in rice zone and since it has to work in flooded area, its working parts must be covered.
  95. 95. Harvesting and threshing The basic principle of cutting the crop remains the same as manual harvesting with stickle or scissor i.e two straight blades or serrated blades shear the stalk of crop at certain speed. This action is known as reaping or mowing. In Pakistan harvesting machinery is mostly limited for rice and wheat The following are three types of harvesting machinery introduced in Pakistan Reaper Mower Reaper- cum-binderReaper A reaper cuts the crop and then moves it to one side to make a windrow. So it consist of a cutter bar assembly and a crop conveying unit.
  96. 96. MowerThe mower consist of; Cutter bar Pitman wheel FramePower transmission elements The cutter bar cuts the crop with the help of reciprocating of knife or blade moving along a stationary blade/knife. The cutter bar is operated through pitman wheel which changes rotary motion of tractor PTO into reciprocating or back and forth motion. The mower is mostly used for to cut grasses as for lawn mowing and fodder such as alfalfa, berseem etc. Note: the basic difference between a mover and a reaper is that it only cuts the crop and lay behind the mower, which is collected by labor or raking machinery, while the reaper makes a windrow of the crop.
  97. 97. Reaper –cum-binder It has all the elements of a reaper mentioned above along with bundling and knotting units in addition. The cutter bar cuts the crop with normally serrated blades or knives. The harvested crop is then accumulated in the centre with the help of guards and fingers and is fed in the knotting unit, where bundles are made automatically.
  98. 98. Threshing machinery: Threshing is a simple operation of removing grain from the straws but it is defined as processes of separating the grain from the mixture of grain, chaff, impurities, etc and finally grading it for use. The stationary thresher is commonly used in Pakistan. The mechanism will be discussed later in combine harvester.
  99. 99. Combine harvester: A combine harvester harvest and thresh the crop simultaneously. Practically, all combines consist of the mechanism of a reaper attached to a travelling thresher. Most of the combines in Pakistan are self propelled type and are being used to cut and thresh wheat, rice and sunflower. Combines perform the following operations at one time. These are; Harvesting Conveying of cut crop Feeding Threshing (separation of grains from straw) Cleaning of grains from dust, weeds and chaff.
  100. 100. The main components of the combine harvester are; Reel Cutter bar Augur Elevator to cylinder Front and rear beater Threshing cylinder Concave Grain elevator to tank Straw walkers Fan Sieve Grain tank Unloading augur