Different systems of IC Engine

Different systems of IC Engine
Fuel supply and cooling system of I.C. engine – types, components and their functions, working principle of forced circulation cooling system.
Ignition and power transmission system of I.C engine – types, components and their functions,
working principle of battery ignition system
Lubrication system of I.C. engine – types, purpose, components and their functions, working principle of forced feed system.

1. Subject
Farm Machinery and Power
Topic
Different Systems of IC Engine
by
Dr. Sanjay Singh Chouhan
Assistant Professor
College of Agriculture, JNKVV,
Powarkheda, Hoshangabad

2. Different systems for efficient functioning of an engine are as follows
1.Fuel supply system
2.Lubrication system
3.Cooling system
4.Power Transmission system
5.Hydraulic system
6.Ignition System
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3. Fuel Supply System
•Fuel is a substance consumed by the engine to produce power.
•The quality of fuel mainly depends upon the following properties:
(i) Volatility
(ii) Calorific value
(iii) Ignition quality of fuel
•A good fuel contains a combination of qualities such as good volatility,
high antiknock value, chemical purity, and freedom from gum.
•The common fuel for Internal Combustion engines are
1.Petrol 2. Power kerosene 3. High speed diesel
3
JNKVV
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College of Agriculture,
Powarkheda

4. JNKVV-College of Agriculture, Powarkheda
Thefuelsupplysystem
ofsparkignitionengine
consistsof
1. Fuel tank
2. Sediment bowl
3. Fuel lift pump
4. Carburetor
5. Fuel pipes
4
FUEL SUPPLY SYSTEM IN SPARK IGNITION ENGINE
Gravity Flow

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FUEL SUPPLY SYSTEM IN SPARK IGNITION ENGINE (Forced Flow)

6. •Insomesparkignitionenginesthefueltankisplacedabovethelevelofthe
carburetor.
•Thefuelflowsfromfueltanktothecarburetorundertheactionofgravity.
•Thereareoneortwofiltersbetweenfueltankandcarburetor.
•Atransparentsedimentbowlisalsoprovidedtoholdthedustanddirtofthefuel.
•Ifthetankisbelowthelevelofcarburetor,aliftpumpisprovidedinbetweenthe
tankandthecarburetorforforcingfuelfromtanktothecarburetoroftheengine.
•Fromtherethefuelgoestothecarburetorthroughsuitablepipes.
•Fromcarburetorthefuelgoestotheenginecylinderthroughinletmanifoldofthe
engine.
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7. Carburetor
Theprocessofpreparingair-fuelmixtureawayfromtheengine
cylinderiscalledcarburetionandthedeviceinwhichthis
processtakesiscalledcarburetor.
Functions of carburetor
1. To mix the air and fuel thoroughly
2. To atomize the fuel
3. To regulate the air-fuel ratio at different speeds and loads on
the engine.
4. to supply correct amount of mixture at different speeds and
loads
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8. JNKVV-College of Agriculture, Powarkheda
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9. Fuel supply system of diesel engine consists
of the following components
1. Fuel tank
2. Fuel lift pump or fuel feed pump
3. Fuel filter
4. Fuel injection pump
5. High pressure pipe
6. Over flow valve
7. Fuel injector
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FUEL SUPPLY SYSTEM IN DIESEL ENGINE

10. JNKVV-College of Agriculture, Powarkheda 10
FUEL SUPPLY SYSTEM IN DIESEL ENGINE

11. •Fuel is drawn from fuel tank by fuel feed pump and forced to injection pump
through fuel filter.
•The injection pump supplies high pressure fuel to injection nozzles through
delivery valves and high pressure pipes.
•Fuel is injected into the combustion chamber through injection nozzles.
•The fuel that leaks out from the injection nozzles passes out through leakage
pipe and returns to the fuel tank through the over flow pipe.
•Over flow valve installed at the top of the filter keeps the feed pressure under
specified limit.
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12. Fueltank
Itisastoragetankfordiesel.Awiregaugestrainerisprovidedunderthecapto
preventforeignparticlesenteringthetank.
Fuelliftpump
Ittransfersfuelfromfueltanktoinletgalleryoffuelinjectionpump
Preliminaryfilter(sedimentbowlassembly)
Thisfilterismostlyfittedonfuelliftpump.Itpreventsforeignmaterialsfrom
reachinginsidehefuelline.Itconsistsofaglasscapwithagasket.
Fuelfilter
Mostlytwostagefiltersareusedindieselengines1.Primaryfilter2.Secondaryfilter
Primaryfilterremovescoursematerials,wateranddust.Secondaryfilterremoves
finedustparticles.
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13. Fuel injection pump
•It is a high pressure pump which supplies fuel to the injectors according to
the firing order of the engine.
•It is used to create pressure varying from 120 kg/cm2 to 300 kg/cm2.
•It supplies the required quantity of fuel to each cylinder at appropriate time.
Air venting of fuel system
•When air has entered the fuel lines or suction chamber of the injection pump,
venting should be done properly.
•Air is removed by the priming pump through the bleeding holes of the
injection pump.
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14. Fuel injector
•It is the component which delivers finely atomized fuel under high pressure to combustion
chamber of the engine.
•Modern tractor engines use fuel injectors which have multiple holes.
•Main parts of injectors are nozzle body, and needle valve.
•The needle valve is pressed against a conical seat in the nozzle body by a spring.
•The injection pressure is adjusted by adjusting a screw.
•In operation, fuel from injection pump enters the nozzle body through high pressure pipe.
•When fuel pressure becomes so high that it exceeds the set spring pressure, the needle
valve lifts off its seat.
•The fuel is forced out of the nozzle spray holes into the combustion chamber.
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15. Fuel injector
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16. LUBRICATION SYSTEM
ICengineismadeofmovingparts.Duoto
continuousmovementoftwometallicsurfaces
overeachother,thereiswearingofmovingparts,
generationofheatandlossofpowerinengine.
Lubricationofmovingpartsisessentialto
preventalltheseharmfuleffects.
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17. Purpose of lubrication-
(i)Reduces the wear and prevents seizure of rubbing surfaces (Reduce
wear)
(ii)Reduces the power needed to overcome the frictional resistance
(Reduce frictional effect).
(iii)Removes the heat from the piston and other parts (Cooling effect)
(iv)Serves as a seat between piston rings and cylinder (Sealing effect)
(v)Removes the foreign material between the engine working parts
(Cleaning effect)
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18. Engine lubrication system
The lubricating system of an engine is an arrangement of mechanisms which
maintains the supply of lubricating oil to the rubbing surfaces of an engine at correct
pressure and temperature.
The parts which require lubrication are:-
1. Cylinder walls and piston 2. Piston pin
3. crankshaft and connecting rod bearings 4. Camshaft bearings
5. Valve operating mechanism 6. Cooling fan
7. Water pump 8. Ignition mechanism
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19. Types of Lubricants
Lubricantsareobtainedfromanimalfat,vegetablesandminerals.Lubricantsmadeof
animalfat,doesnotstandmuchheat.Itbecomeswaxyandgummywhichisnotvery
suitableformachines.
•Vegetable lubricants are obtained from seeds, fruits and plants. Cotton seed oil, Olive oil,
linseed oil and Castor oil are used as lubricant in small simple machines.
•Mineral lubricants are most popular for engines and machines. It is obtained from crude
petroleum found in nature. Petroleum lubricants are less expensive and suitable for IC
Engines.
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20. Types of Lubrication System
Therearethreecommonsystemsoflubricationusedonstationeryengines,tractorengines
andautomobiles:
(i)Splashsystem
(ii)Forcedfeedsystem
(iii)Combinationofsplashandforcedfeedsystem.
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21. JNKVV-College of Agriculture, Powarkheda 21
Forced Feed Lubrication System

22. Forced feed system
•Inthissystem,theoilispumpeddirectlytoallthemovingparts(i.e.,crankshaft,
connectingrod,pistonpin,timinggearsandcamshaft)oftheenginethroughsuitablepaths
ofoil.
•Lubricatingoilpumpisapositivedisplacementpump,usuallygearorvanetype,whichis
drivenbythecamshaft,forcesoilfromthecrankcasetoallcrankshaft,andconnectingrod
bearings,camshaftbearingsandtiminggears.
•Usuallytheoilfirstentersthemaingallery,whichmaybeapipeorachannelinthe
crankcasecasting.Fromthispipe,itpassestoeachofthemainbearingsthroughholes.
•Frommainbearings,itpassestobigendbearingsofconnectingrodthroughdrilledholesin
thecrankshaft.
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23. •Fromthere,itpassestolubricatethewalls,pistonsandrings.
•Thereisseparateoilgallerytolubricatetiminggears.
•Theoilalsopassestovalvestemandrockerarmshaftunderpressurethroughanoil
gallery.
•Theexcessoilcomesbackfromthecylinderheadtothecrankcase.
•Thepumpdischargesoilintooilpipes,oilgalleriesorducts,leadingtodifferentpartsof
theengine.
•Thesystemiscommonlyusedonhighspeedmulti-cylinderengineintractors,trucksand
automobiles.
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24. Forced Feed Lubrication System
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25. Splash
Lubrication
System
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26. Components of Lubrication System
Oil Pump
It is usually a gear type pump, used to force oil into
the oil pipe. The pump is driven by the camshaft of the
engine. An oil pressure gauge fitted in the line,
indicates the oil pressure in the lubricating system.
About 3 kg/cm
2
pressure is developed in the
lubrication system of a tractor engine.
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27. Oil filters
Lubricatingoilinanenginebecomescontaminatedwithvariousmaterialssuchas
dirt,metalparticlesandcarbon.Anoilfilterremovesallthedirtyelementsofthe
oilinaneffectiveway.Itisatypeofstrainerusingcloth,paper,felt,wirescreenor
similarelements.Itisnormallychangedafterabout120hoursofengineoperation.
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28. Cooling System
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29. Cooling System
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30. Cooling System
•Fuelisburntinsidethecylinderofaninternalcombustionenginetoproducepower.
•Thetemperatureproducedonthepowerstrokeofanenginecanbeashighas1600ºCand
thisisgreaterthanmeltingpointofengineparts.
•Thecylinderandcylinderheadareusuallymadeofcastironandpistonsinmostcasesare
madeofaluminumalloy.
•Itisestimatedthatabout40%oftotalheatproducedispassedtotheatmosphereviathe
exhaust,30%isremovedbycoolingsystemandonlyabout30%isusedtoproduceuseful
power.
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31. Purpose of cooling
1.To maintain optimum temperature of engine for efficient operation under all
conditions.
2.To dissipate surplus heat for protection of engine components like cylinder,
cylinder head, piston, piston rings, and valves
3.To maintain the lubricating property of oil inside engine
Methods of cooling
•1. Air cooled system
•2. Water cooled system
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32. AIR COOLING SYSTEM

33. AIR COOLING SYSTEM
Aircooledenginesarethoseenginesinwhichheatisconductedfromtheworking
componentsoftheenginetotheatmospheredirectly.
Principleofaircooling-
Thecylinderofanaircooledenginehasfinstoincreasetheareaofcontactofairfor
speedycooling.
Thecylinderisnormallyenclosedinasheetmetalcasingcalledcowling.
Theflywheelhasbladesprojectingfromitsface,sothatitactslikeafandrawingair
throughaholeinthecowlinganddirecteditaroundthefinnedcylinder.
Formaintenanceofaircooledsystem,passageofairiskeptcleanbyremoving
grassesetc.byastiffbrush.
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34. Advantages of air cooled engine
1. It is simple in design and construction
2. Water jackets, radiators, water pump, thermostat, pipes, hoses
are not required
3. It is more compact
4. Lighter in weight
Disadvantages
1. There is uneven cooling of engine parts
2. Engine temperature is generally high during working period
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35. WATER COOLING SYSTEM
Enginesusingwaterascoolingmediumarecalledwatercooledengines.Wateris
circulatedroundthecylinderstoabsorbheatfromthecylinderwalls.Theheated
waterisconductedthrougharadiatortoremovetheheatandcoolthewater.
Methods of water cooling
1. Open jacket or hopper method
2. Thermo siphon method
3. Forced circulation method
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36. Forced Circulation system
•Inthismethod,awaterpumpisusedtoforcewaterfromradiatortothewater
jacketoftheengine.
•Aftercirculatingtheentirerunofwaterjacket,watercomesbacktotheradiator
whereitlosesitsheatbytheprocessofradiation.
•Tomaintainthecorrectenginetemperature,athermostatvalveisplacedatthe
outerendofcylinderhead.
•Coolingliquidisby-passedthroughthewaterjacketoftheengineuntiltheengine
attainsthedesiredtemperature.
•Thethermostatvalveopensandtheby-passisclosed,allowingthewatertogoto
theradiator.
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37. The system consists of the following components
1.Waterpump
2.Radiator
3.Fan
4.Fan-belt
5.Waterjacket
6.Thermostatvalve
7.Temperaturegauge
8.Hosepipe
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38. Waterpump
Itisacentrifugaltypepump.Ithasacasingandanimpeller,mountedonashaft.Attheend
oftheshaft,asmallpulleyisfittedwhichisdrivenbyaV-belt.Waterpumpismountedatthe
frontendofthecylinderblockbetweentheblockandtheradiator.
Radiator
Radiatorisadeviceforcoolingthecirculatingwaterintheengine.Itholdsalargevolumeof
waterinclosecontactwithalargevolumeofairsothatheatistransferredfromthewaterto
theaireasily.Hotwaterflowsintotheeradiatoratthetopandcoldwaterflowsoutfromthe
bottom.Tubesorpassagescarrythewaterfromthetopoftheradiatortothebottom,passing
itoveralargemetalsurface.Airflowsbetweenthetubesorthroughthecellsatrightangles
tothedownwardflowingwater.Thishelpsintransferringtheheatfromthewatertothe
atmosphere. JNKVV-College of Agriculture, Powarkheda 38

39. Thermostat valve: It is a control valve, used in the cooling system to control the flow of water when
activated by a temperature signal. It is a special type of valve, which closes the inlet passage of the
water connected to the radiator. The thermostat is placed in the water passagebetween the cylinder
head and the top of radiator. Its purpose is to close this passage when the engine is cold, so that
water circulation is restricted, causing the engine to reach operating temperature more quickly.
Thermostats are designed to start opening at 70ºC to 75 ºC and then fully open at 82 ºC for petrol
engine and 88-90 ºC for diesel engine.
Water jackets: Water jackets are cored out around the engine cylinder so that water can circulate
freely around the cylinder as well as around the valve opening.
Fan: The fan is usually mounted on the water pump shaft. It is driven by the same belt that drives
the pump and the dynamo. The purpose of the fan is to provide strong draft of air through the
radiator to improve engine cooling.
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40. 40
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Power Transmission System

41. Power Transmission System
•Transmissionisaspeedreducingmechanism,equippedwithseveralgears.
•Itmaybecalledasequenceofgearsandshafts,throughwhichtheenginepoweris
transmittedtothetractorwheels.
•Thesystemconsistsofvariousdevicesthatcauseforwardandbackwardmovementof
tractortosuitdifferentfieldcondition.
•Thecompletepathofpowerfromtheenginetothewheelsiscalledpowertrain.
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43. Function of Power Transmission System
(i)Totransmitpowerfromtheenginetotherearwheelsofthetractor.
(ii)Tomakereducedspeedavailable,torearwheelsofthetractor.
(iii)Toaltertheratioofwheelspeedandenginespeedinordertosuitthefieldconditions.
(iv)Totransmitpowerthroughrightangledrive,becausethecrankshaftandrearaxleare
normallyatrightanglestoeachother.
Thepowertransmissionsystemconsistsof:
(a)clutch (b)transmissiongears (c)differential
(d)finaldrive (e)rearaxle (f)rearwheels
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44. Clutch
Clutchisadevice,usedto
connectanddisconnectthe
tractorenginefromthe
transmissiongearsanddrive
wheels.Clutchtransmits
powerbymeansoffriction
betweendrivingmembersand
drivenmembers.
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45. Necessity of clutch in a tractor
Clutchinatractorisessentialforthefollowingreasons:
(i)Engineneedscrankingbyanysuitabledevice.Foreasycranking,theengineis
disconnectedfromtherestofthetransmissionunitbyasuitableclutch.Afterstarting
theengine,theclutchisengagedtotransmitpowerfromtheenginetothegearbox.
(ii)Inordertochangethegears,thegearboxmustbekeptfreefromtheenginepower,
otherwisethegearteethwillbedamagedandengagementofgearwillnotbeperfect.
Thisworkisdonebyaclutch.
(iii)Whenthebeltpulleyofthetractorworksinthefielditneedstobestoppedwithout
stoppingtheengine.Thisisdonebyaclutch.
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46. Essential features of a good clutch
(i) It should have good ability of taking load without dragging and chattering.
(ii) It should have higher capacity to transmit maximum power without slipping.
(iii) Friction surface should be highly resistant to heat effect.
(iv) The control by hand lever or pedal lever should be easy.
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47. Gears
Speedvariesaccordingtothefieldrequirementsandsoanumberofgearratiosareprovidedto
suitthevaryingconditions.Gearsareusuallymadeofalloysteels.Asthetractorhasto
transmitheavytorqueallthetime,bestqualitylubricantsfreefromsediments,grit,alkaliand
moisture,isusedforlubricationpurpose.SAE90oilisgenerallyrecommendedforgearbox.
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49. Differential
Differential unit is a special arrangement of gears to permit one of the rear wheels of the
tractor to rotate slower or faster than other. While turning the tractor on a curve path, the inner
wheel has to travel lesser distance than the outer wheel. The inner wheel requires lesser power
than the outer wheel, this condition is fulfilled by differential unit, which permits one of the
rear wheels of the tractor to move faster than the other at the turning point.
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College of Agriculture,
Powarkheda
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50. Differentiallock
Differentiallockisadevicetojoinbothhalfaxlesofthetractorsothatevenifonewheelis
underlessresistance,thetractorcomesoutfromthemudetcasbothwheelsmovewith
thesamespeedandapplyequaltraction.
Finaldrive
Finaldriveisarearreductionunitinthepowertrainsbetweenthedifferentialanddrive
wheels
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51. Ignition System
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52. Ignition System
•Fuel mixture of I. C engine must be ignited in the engine cylinder at proper
time for useful work.
•Arrangement of different components for providing such ignition at proper
time in the engine cylinder is called ignition system.
•There are Twodifferent systems of igniting fuel:
1.Ignition by electric spark(Spark ignition)
2.Ignition by heat of compression (Compression ignition)

53. Components
of Ignition
System
Spark plug
Distributor
Ignition coil
Condenser
Ignition switch
Dynamo
Storage battery.
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54. Sparkplug
•Sparkplugignitestheair–fuelmixtureincombustionchamber.
•Itisadeviceforthehighvoltagecurrenttojumpandignitethecharge.Eachsparkplug
consistsofathreadedoutershellwithanoutsideelectrode,insulatorandacoppergasket.
•Thewidthofthegapbetweenthepointsofthetwoelectrodesofasparkplugshouldconform
tothemanufacturers.Iftheclearanceistoowide,itdoesnotgivesatisfactoryoperation.
•Usuallythesparkpluggapsettingsarekeptbetween0.5and0.85mm.
Distributor
•Thisisarotaryswitchdrivenbytheenginethroughgearsathalftheenginespeed.
•Thisdeviceusedforinterruptingthelowvoltageprimarycurrentanddistributingthe
resultinghighvoltagecurrenttotheenginecylinderinpropersequenceandinpropertime.
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55. Ignition coil
•Itservesthepurposeofasmalltransformer,which
setsuplowvoltage(maybe6volts)toveryhigh
voltage(maybe20,000volts).
•Itisnecessarytojumpthegapofthesparkplug.
•Theignitioncoilissealedtoprevententryof
moisturewhichwouldcauseshortcircuiting
withinthecoil.
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56. Condenser
•Acondenserconsistsofapairofflatmetalplates,separatedbyair.Thecondenserinthe
distributorisconnectedacrossthecontactbreakerpoints.
•Itisusedtoproduceaquickcollapseofthemagneticfieldinthecoiltoobtainextremely
highvoltage.
•Indoingso,thecondenserpreventssparkingacrossthecontactbreakerpoints,thus
preventingthepointsfromburning.
Ignitionswitch
•Aswitchisprovidedintheprimarycircuitforstartingandstoppingtheengineiscalled
ignitionswitch.
•Itmaybepushpulltypeorkeytype.
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57. Dynamo
Thepurposeofthedynamoistokeepthebatterychargedandto
supplycurrentforignition,lightandotherelectricalaccessories.
Thedynamosuppliesdirectcurrenttothebatteryandkeepsit
fullycharged.
Storagebattery
Storagebatteryisadeviceforconvertingchemicalenergyinto
electricalenergy.Thereareseveraltypesofbattery,butlead-
acidbatteryismostcommonforICengines,usedfortractors
andautomobiles.Abatteryconsistsofplates,separators,
electrolyte,containerandterminalwire.
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58. Spark ignition
Thepurposeofsparkignitionistodelivera
perfectlytimedsurgeofelectricityacrossan
opensparkpluggapineachcylinderattheexact
moment,sothatthechargemaystartburning
withmaximumefficiency.
There are two methods in spark ignition:
(a)Battery ignition
(b)Magneto ignition
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59. BatteryignitionPrinciple
•Batteryignitionsystemincludestwocircuits:lowvoltage(primarycircuit)andhighvoltage
(secondarycircuit).
•Thelow-voltagecircuitconsistsof:(i)battery(ii)ignitionswitch(iii)aseriesregister(IV)
primarywindingand(v)contactbreaker.Allareconnectedinseries.
•Thehighvoltagecircuitconsistsof:(i)secondarywinding(ii)distributorrotor(iii)high
voltagewiringand(iv)sparkplugs.Theyarealsoconnectedinseries.
•Batteryignitionsystemonamoderntractorincludesastoragebattery,ignitionswitch,
hightensioncoil,distributor,contactbreakermechanism,condenser,sparkplugs,
generatorandcutout.
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62. Working of Spark Ignition System
•Electriccurrentissuppliedbythebatterytotheignitioncircuit.
•Whenthedistributorbreakerpointsareclosed,lowvoltagecurrentflowsthroughthe
primarywindingoftheignitioncoiltothedistributorterminalandthroughthebreaker
pointstotheground.
•Duringthistime,astrongmagneticfieldbuiltupinthecoil.
•Whenthepistonisattheendofcompressionstroke,thedistributorpointsareopened,the
magneticfieldinthecoilstartscollapsing.
•Thus,acurrentisinducedintheprimarywindingofthecoil,whichtendstopreventbreak
downofthemagneticfield.
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63. •Averyhighvoltageisproducedinthesecondarywindingduetosuddencollapseofthe
magneticfield.
•Thissuddencollapseofthemagneticfieldinthecoil,producesaveryhighvoltageacross
thesecondarywindingterminalstoavalueof20to24thousandvolts.
•Thehigh-voltagesurgeisdeliveredtothecenterterminalofthedistributorcap,whereitis
pickedupbytherotoranddirectedtothepropersparkplug.
•Thehighvoltageiscapableofjumpingthesparkacrossthegapofthesparkplugand
ignitesthecompressedair-fuelmixture
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64. Hydraulic System
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65. Hydraulic System
HydraulicSystemofaTractorisprovidedtoenablethetractortoraiseorlowerheavy
implementsasperrequirementsandtocontrolimplementdepthduringfieldoperations
withminimumefforts.
Fundamentals for fluid power transmission
•Fluid power is based on the principle of Pascal’s law which states that pressure
applied to a fluid is transmitted equally in all direction.
•Hydraulic Fluid is assumed as incompressible.
•The fluid pressure controls the force of output. (P= F/A= force/area).
•The fluid flow controls the speed of output.
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66. The basic components of fluid power transmission are:
1.Reservoir
2.Pump
3.Motor
4.Cylinder
5.Valves
6.Fittings and tips
7.Lines and Hoses
8.Hydraulic oil
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67. Hydraulic System
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68. Air Cleaner
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69. Air Cleaner
It is a device, which filters and removes dust, moisture and other foreign matter from the air
before if reaches the engine cylinder.
Air cleaner is usually of two types:
(1)Dry type air cleaner and
(2)Oil bath type air cleaner.
Dry type air cleaner
The filtering element in this case is a type of felt. The felt has got larger surface area, reduces
the air speed while passing through and consequently particle or dirt in the air is deposited on
or stopped by its surface.
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70. Oil bath type air cleaner
Inthistypeofaircleaner,theincoming
airimpingesuponthesurfaceoftheoil,
keptinacontainerinthelowerpartof
thecasing.Theforeignparticlesoftheair
aretrappedintheoilandthentheair
passesthroughawireelementbefore
reachingtheinletmanifoldoftheengine.
Thewireelementalsoarreststhe
remainingdirtparticlesoftheair.
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71. Governor
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72. Governor
Governorisamechanicaldevicedesignedtocontrolthespeedofanenginewithinspecified
limitusedontractororstationaryenginefor:
(i)maintaininganearlyconstantspeedofengineunderdifferentloadconditions
(ii)protectingtheengineandtheattachedequipmentsagainsthighspeeds,whentheloadis
reducedorremoved.
Tractorenginesarealwaysfittedwithgovernor.Thereisanimportantdifferenceinprinciple
betweenthecontrolsofatractorengineandthatofamotorcar.
Incaseofmotorcar,thefuelsupplyisunderdirectcontroloftheacceleratorpedal,butin
tractorengine,thefuelsupplyiscontrolledbythegovernor.
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73. Theoperatorchangestheenginespeedbymovingthegovernorcontrollever.
Agovernorisessentialonatractorengineforthereasonthatloadonthetractorengineis
subjectedtorapidvariationinthefieldandtheoperatorcannotcontroltherapidchangeof
theenginespeedwithoutanyautomaticdevice.
Forexample,iftheloadonthetractorisreduced,theenginewouldtendtoracesuddenly.If
theloadisincreased,theenginewouldtendtoslowdownabruptly.
Underthesecircumstances,itbecomesdifficultfortheoperatortoregulatealwaysthe
throttlelevertomeetthetemporarychangesintheengineload.
Agovernorautomaticallyregulatestheenginespeedonvaryingloadconditionandthusthe
operatorisrelievedofthedutyofconstantregulatingthethrottlelevertosuitdifferentload
conditions.
JNKVV-College of Agriculture, Powarkheda 73

74. JNKVV-College of Agriculture, Powarkheda
74
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