bulldozer - wikipedia, the free encyclopedia

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Alargebulldozerwithripper,theCaterpillarD9

ACaterpillarD10Nbulldozerequippedwithasingleshankripper.

BulldozerFromWikipedia,thefreeencyclopedia

Abulldozerisacrawler(continuoustrackedtractor)equippedwithasubstantialmetalplate(knownasablade)usedtopushlargequantitiesofsoil,sand,rubble,orothersuchmaterialduringconstructionorconversionworkandtypicallyequippedattherearwithaclawlikedevice(knownasaripper)toloosendenselycompactedmaterials.

Bulldozerscanbefoundonawiderangeofsites,minesandquarries,militarybases,heavyindustryfactories,engineeringprojectsandfarms.

Theterm"bulldozer"isoftenusederroneouslytomeananyheavyequipment(sometimesaloaderandsometimesanexcavator),butprecisely,thetermrefersonlytoatractor(usuallytracked)fittedwithadozerblade.

Contents

1Description1.1Blade1.2Ripper

2Modifications2.1Armoredbulldozers

3History4Manufacturers5Historyoftheword6Seealso7References8Externallinks

Description

Mostoftenbulldozersarelargeandpowerfultrackedheavyequipment.Thetracksgivethemexcellentgroundholdingcapabilityandmobilitythroughveryroughterrain.Widetrackshelpdistributethebulldozer'sweightoveralargearea(decreasinggroundpressure),thuspreventingitfromsinkinginsandyormuddyground.ExtrawidetracksareknownasswamptracksorLGP(lowgroundpressure)tracks.Bulldozershavetransmissionsystemsdesignedtotakeadvantageofthetracksystemandprovideexcellenttractiveforce.

Becauseoftheseattributes,bulldozersareoftenusedinroadbuilding,construction,mining,forestry,landclearing,infrastructuredevelopment,andanyotherprojectsrequiringhighlymobile,powerful,andstableearthmovingequipment.

Anothertypeofbulldozeristhewheeledbulldozer,whichgenerallyhasfourwheelsdrivenbya4wheeldrivesystemandhasahydraulic,articulatedsteeringsystem.Thebladeismountedforwardofthearticulationjoint,andishydraulicallyactuated.

Thebulldozer'sprimarytoolsarethebladeandtheripper.

Blade

Thebulldozerbladeisaheavymetalplateonthefrontofthetractor,usedtopushobjects,andshovesand,soilanddebris.Dozerbladesusuallycomeinthreevarieties:

1. Astraightblade("Sblade")whichisshortandhasnolateralcurveandnosidewingsandcanbeusedforfinegrading.2. Auniversalblade("Ublade")whichistallandverycurved,andhaslargesidewingstocarrymorematerial.3. An"SU"combinationbladewhichisshorter,haslesscurvature,andsmallersidewings.Thisbladeistypicallyusedforpushing

pilesoflargerocks,suchasataquarry.

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Bulldozerblade

Multishankripper

Atrackedloader

Bladescanbefittedstraightacrosstheframe,oratanangle,sometimesusingadditional'tiltcylinders'tovarytheanglewhilemoving.Thebottomedgeofthebladecanbesharpened,e.g.tocuttreestumps.

Sometimesabulldozerisusedtopushanotherpieceofearthmovingequipmentknownasa"scraper".ThetowedFresnoScraper,inventedin1883byJamesPorteous,wasthefirstdesigntoenablethistobedoneeconomically,removingthesoilfromthecutanddepositingitelsewhereonshallowground(fill).Manydozerbladeshaveareinforcedcentersectionwiththispurposeinmind,andarecalled"bullblades".

Inmilitaryuse,dozerbladesarefixedoncombatengineeringvehiclesandcanoptionallybefittedonothervehicles,suchasartillerytractorssuchastheType73orM8Tractor.Dozerbladescanalsobemountedonmainbattletanks,whereitcanbeusedtoclearantitankobstacles,mines,anddigimprovisedshelters.Combatapplicationsfordozerbladesincludeclearingbattlefieldobstaclesandpreparingfirepositions.[1]

Ripper

Theripperisthelongclawlikedeviceonthebackofthebulldozer.Ripperscancomeasasingle(singleshank/giantripper)oringroupsoftwoormore(multishankrippers).Usually,asingleshankispreferredforheavyripping.Therippershankisfittedwithareplaceabletungstensteelalloytip.Rippingrockbreaksthegroundsurfacerockorpavementintosmallrubbleeasytohandleandtransport,whichcanthenberemovedsogradingcantakeplace.Withagriculturalripping,afarmerbreaksuprockyorveryhardearth(suchaspodzolhardpan),whichisotherwiseunploughable,inordertofarmit.Forexample,muchofthebestlandintheCaliforniawinecountryconsistsofoldlavaflows.Thegrowershattersthelavawithheavybulldozerssosurfacecropsortreescanbeplanted.Alesscommonrearattachmentisastumpbuster,whichisasinglespikethatprotrudeshorizontallyandcanberaisedtogetit(mostly)outoftheway.Astumpbusterisusedtosplitatreestump.Abulldozerwithastumpbusterisusedforlandclearingoperations,andprobablyhasabrushrakeblade.

Modifications

Bulldozershavebeenfurthermodifiedovertimetoevolveintonewmachineswhichcanworkinwaysthattheoriginalbulldozercannot.

Oneexampleisthatloadertractorswerecreatedbyremovingthebladeandsubstitutingalargevolumebucketandhydraulicarmswhichcanraiseandlowerthebucket,thusmakingitusefulforscoopingupearthandloadingitintotrucks,theseareoftenknownasaDrott.

Othermodificationstotheoriginalbulldozerincludemakingitsmallertoletitoperateinsmallworkareaswheremovementislimited,suchasinmining.Averysmallbulldozerissometimescalledacalfdozer.

Somelightweightformofbulldozerarecommonlyusedinsnowremovalandasatoolforpreparingwintersportsareasforskiandsnowboardsports.

Inanangledozer(imagehere(http://www.travellerdave.co.uk/?p=7194))thebladecanbepushedforwardatoneendtomakeiteasiertopushmaterialawaytotheside.

Nevertheless,theoriginalearthmovingbulldozersarestillirreplaceableastheirtasksareconcentratedindeforestation,earthmoving,groundlevelling,androadcarving.Heavybulldozersaremainlyemployedtoleveltheterraintoprepareitforconstruction.Theconstruction,however,ismainlydonebysmallbulldozersandloadertractors.

Armoredbulldozers

Somebulldozers,especiallybulldozersinmilitaryusage,havebeenfittedwitharmortoprotectthedriverfromenemyfire,enablingthebulldozertooperateinbattlezones.ThebestknownuseofanarmoredbulldozerisprobablytheusebytheIsraeliDefenceForces(IDF)oftheIDFCaterpillarD9,forearthmoving,clearingterrainobstacles,openingroutes,detonatingexplosivecharges,anddemolishingPalestinianhomeswhilstunderfire.TheextensiveuseofarmoredbulldozersduringtheSecondIntifadadrewcontroversyandcriticismfromhumanrightsorganizationswhilemilitaryexpertssawitasakeyfactorinreducingIDFcasualties.

Somebulldozershavebeenfittedwitharmorbynongovernmentcivilianoperatorstopreventbystandersorpolicefrominterferingwiththeworkperformedbythebulldozer,asinthecaseofstrikesordemolitionofcondemnedbuildings.Thishasalsobeendonebycivilianswithadisputewiththeauthorities,suchasMarvinHeemeyer,whooutfittedhisKomatsuD355Abulldozerwithhomemadecompositearmortothendemolishgovernmentbuildings.

History

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AnarmoredCaterpillarD9RBulldozerusedbyIsraelDefenseForces

AworkingbulldozerfromtheFirstTractorCompany,onXinbuIsland,Hainan,China.

ALiebherrbulldozerwithamultishankripper.

ACaterpillarD11Nbulldozerequippedwithadoubleshankripper

ThefirstbulldozerswereadaptedfromHoltfarmtractorsthatwereusedtoplowfields.TheversatilityoftractorsinsoftgroundforloggingandroadbuildingcontributedtothedevelopmentofthearmouredtankinWorldWarI.

In1923,ayoungfarmernamedJamesCummingsandadraftsmannamedJ.EarlMcLeodmadethefirstdesignsforthebulldozer.AreplicaisondisplayatthecityparkinMorrowville,Kansaswherethetwobuiltthefirstbulldozer.[2]OnDecember18,1923,CummingsandMcLeodfiledU.S.patent#1,522,378thatwaslaterissuedonJanuary6,1925foran"AttachmentforTractors."[3]

Bythe1920s,trackedvehiclesbecamecommon,particularlytheCaterpillar60.Rubbertiredvehiclescameintouseinthe1940s.Todigcanals,raiseearthdams,anddootherearthmovingjobs,thesetractorswereequippedwithalargethickmetalplateinfront.(Thebladegotitscurvedshapelater).Insomeearlymodelsthedriversatontopintheopenwithoutacabin.Therearethreemaintypesofbulldozerblades:aUbladeforpushingandcarryingdirtrelativelylongdistances,astraightbladefor"knockingdown"andspreadingpilesofdirt,andabrushrakeforremovingbrushandroots.Theseattachments(homebuiltorbuiltbysmallequipmentmanufacturersofattachmentsforwheeledandcrawlertractorsandtrucks)appearedby1929.

Widespreadacceptanceofthebullgraderdoesnotseemtoappearbeforethemid1930s.Theadditionofpowerdownforceprovidedbyhydrauliccylindersinsteadofjusttheweightoftheblademadethemthepreferredexcavationmachineforlargeandsmallcontractorsalikebythe1940s,bywhichtimetheterm"bulldozer"referredtotheentiremachineandnotjusttheattachment.

Overtheyears,bulldozersgotbiggerandmorepowerfulinresponsetothedemandforequipmentsuitedforeverlargerearthworks.FirmslikeCaterpillar,Komatsu,Case,JCB,Euclid,[4]AllisChalmers,Liebherr,LiuGong,Terex,FiatAllis,JohnDeere,BEML,XGMAandInternationalHarvestermanufacturedlargetrackedtypeearthmovingmachines.R.G.LeTourneauandCaterpillarmanufacturedlargerubbertiredbulldozers.[5]

Bulldozersgrewmoresophisticatedastimepassed.Improvementsincludedrivetrainsanalogousto(inautomobiles)anautomatictransmissioninsteadofamanualtransmissionsuchastheearlyEuclidC6andTC12orModelCTournadozer,blademovementcontrolledbyhydrauliccylindersorelectricmotorsinsteadofearlymodels'cablewinch/brake,andautomaticgradecontrol.Hydrauliccylindersenabledtheapplicationofdownforce,moreprecisemanipulationofthebladeandautomatedcontrols.

AmorerecentinnovationistheoutfittingofbulldozerswithGPStechnology,suchasmanufacturedbyTopconPositioningSystems,Inc.,TrimbleInc,orLeicaGeosystemsforprecisegradecontroland(potentially)"stakeless"construction.Asaresponsetothemany,andoftenvaryingclaimsaboutthesesystems,TheKelloggReport[6]publishedin2010adetailedcomparisonofallthemanufacturers'systems,evaluatingmorethan200featuresfordozersalone.

ThebestknownmakerofbulldozersisprobablyCaterpillarintheUS,whichearneditsreputationbymakingtough,durable,reliablemachines.Komatsu,JCBandJohnDeerearepresentdaycompetitors.Althoughthesemachinesbeganasmodifiedfarmtractors,theybecamethemainstayforbigcivilconstructionprojects,andfoundtheirwayintousebymilitaryconstructionunitsworldwide.Thebestknownmodel,theCaterpillarD9,wasalsousedtoclearminesanddemolishenemystructures.

Manufacturers

Industrystatisticsbasedon2010productionpublishedbyOffHighwayResearchshowedShantuiwasthelargestproducerofbulldozers,makingover10,000unitsthatyearor2in5crawlertypedozersmadeintheworld.[7]ThenextlargestproducerbynumberofunitsisCaterpillarInc.,whichproduced6,400units.[7]

Historyoftheword

19thcentury:termusedinengineeringforahorizontalforgingpress.Around1880:IntheUSA,a"bulldose"wasalargedose(namely,onelargeenoughtobeliterallyorfigurativelyeffectiveagainstabull)ofanysortofmedicineorpunishment.'Bulldosing'meantaseverewhippingorcoercion,or

otherintimidationsuchasatgunpoint.[8]

1886:"bulldozer"meantalargecaliberpistolandthepersonwhowieldedit.[8]

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http://en.wikipedia.org/wiki/Bulldozer 4/4

Bulldozerforsolidwastemanagement.

WikimediaCommonshasmediarelatedtoBulldozers.

Late19thcentury:"bulldozing"meantusingbruteforcetopushoverorthrough

anyobstacle.[8]

1930s:appliedtothevehicle.

Theseappearedasearlyas1929,butwereknownas"bullgrader"blades,andtheterm"bulldozerblade"didnotappeartocomeintowidespreaduseuntilthemid1930s."Bulldozer"nowreferstothewholemachinenotjusttheattachment.Incontemporaryusage,"bulldozer"isoftenshortenedto"dozer".

Seealso

Athanasforthe'bulldozershrimp'(fromthewayitpushessandabout)MarvinHeemeyer,knownforhisrampagewithamodifiedbulldozer.

References

1. ^Trewhitt,Philip(1999).ArmouredFightingVehicles.DempseyParr.ISBN1840843284.2. ^KansasCuriosities:QuirkyCharacters,RoadsideOddities&OtherOffbeatStuff(http://books.google.com/books?

id=OZVrxulVBtoC&pg=PA189&dq=James+Cummings+J.+Earl+McLeod+bulldozer&hl=en&sa=X&ei=Gtt4T_S_L_Cu2AXLoYW2Bg&ved=0CDAQ6AEwAA#v=onepage&q=James%20Cummings%20J.%20Earl%20McLeod%20bulldozer&f=false).Retrieved20120401.

3. ^Patent1522378,AttachmentForTractors,JohnEMcLeodandJamesDCummings,FiledDecember18,1923.(http://www.google.com/patents/US1522378?printsec=abstract&dq=1522378&ei=iagXT7qWCYqbtwe76JHpAg#v=onepage&q=1522378&f=false)

4. ^Haddock,Keith."EuclidGeneralMotors'CrawlerTractor"(http://pendergast.ca/antiqueengine/euclid.htm).PEITractorClub.Retrieved11September2011.

5. ^"TournadozerBuiltforSpeedyEarthmoving"(http://www.constructionequipment.com/tournadozerbuiltspeedyearthmoving).ConstructionEquipment.Retrieved11September2011.

6. ^TheKelloggReportLLC(2010).Article:TheKelloggReport.RetrievedDecember15,2010fromkelloggreport.com(http://www.kelloggreport.com/index.html)

7. ^ab"Shantuiofficiallylargestdozerproducerintheworld"(http://www.earthmover.com.au/newequipment/2011/may/shantuiofficiallylargestdozerproducerintheworld).TheEarthmover&CivilContractor.May2011.

8. ^abc"HistoryoftheBulldozer"(http://inventors.about.com/od/bstartinventions/a/bulldozer.htm).Retrieved20081217.

Externallinks

Themechanismofabulldozer(http://www.kenkenkikki.jp/special/no02/e_index.htm)(Shortillustratedexplanations,withflashanimations,suitableforkids)VanNattaBulldozers(http://www.vannattabros.com/dozer.html)FurtherinformationaboutworkingbulldozersOldengineBulldozerpagesphotos(http://www.oldengine.org/members/holland/images/Australia2005/Australia2005%20440.jpg)Googlesearchforimagesofcalfdozers(http://www.google.com/search?num=10&hl=en&site=imghp&tbm=isch&source=hp&biw=1680&bih=890&q=calfdozer&oq=calfdozer&gs_l=img.3..0j0i24l2.5345.12086.0.12238.11.5.0.6.6.0.72.349.5.5.0...0.0...1ac.1.brueBQwyDps)

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