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1、FARMTRACTORThehistoryoftractordevelopmentistolangtorelatehere.LandmarksalongtheroadincludethefiresuseofaninternallcombustionengineinatractorintheUnitedStatesin1890;the‘Ivel’tractorof1901;theAmericanFordof1917,andtheInternational‘Farmall’of1923.Duringthe1930s,theuseoflow-pressurepneumatictyr
2、essoonbecamepopular,andthefirstFergusonsystemtracrorsincorporatingthree-pointlinkagewithhydraulicdraughtcontrolwereintroduced.Classificationoftractortypes.Tractorsasnowmanufacturedcanbeclassifiedasfollows:A.Accordingtomethodofsecuringtractionandself-propulsion:1.Wheeltractorsa.Threetractors
3、b.Fourwheels2.Track-typetractorsB.Accordingtoutility:1.General-purposeorutility2.All-purposeorrow-croptypeWheeltractors.Thewheel-typetractoristhepredomingatingtype,particularlyforagriculturalpurposes.Wheeltractorsaremadeeitherwiththreewheelsorwithfourwheels.Theusualarrangementconsistsoftwor
4、ear-drivewheelsandoneortwofrontsteeringmembers.Track-typetractors.Thetractionmechanisminthe11track-typetractor consistsessentiallyoftwoheavy,endless,metal-linkeddevicesknownastracksthemselvesbyreducingthemovementofonetrackbelowthespeedoftheother.General-purposeorutilitytractor.Ageneral-purp
5、osetractorisoneofmoreorlessconventinaldesignsuchasanordinaryfour-wheelmachineoratrack-typemachine.Thistypeisalsoreferredtoasautilitytroctor.Itismadetoperformonlytheusualtractorjops,includingbothfieldandbeltworksuchasplowing,harrowing,roadgrading,combining,feedgrinding,andthelike.All-purpose
6、tractors.Anall-purposeorrow-croptypeisatractordesignedtohandlepracticallyallthefieldandbeltjopsontheaveragefarm,includingtheplantingandintertillageofrowcrops.Theconventionaltractorconsistsbasicallyoftwoengine-driwenwheels,usuallyattherear,andtwosupportwheelsstthefront.Thetypeoftheengineused
7、topowertheheartofthetractor;itisherethatthefuel,thechemicalpotentialenergy,isconvertedintothemechanicalemergywhichcausesthewheelstoturn.Thedifferencebetweenninternalandexternalcombustionengineissimplythatinaninternalcombustionengine,theconversionofpotent
