机械毕业设计英文外文翻译549载货汽车主减速器.docx

机械毕业设计英文外文翻译549载货汽车主减速器.docx

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机械毕业设计英文外文翻译549载货汽车主减速器

附录

TruckMainReductionGear

Inthehighlycompetitiveperiodfollowingtheenergycrisisoftheearly1970's,theautomotiveindustryhadtoshiftattentionincreasinglytowardsimprovementofthequalityoftheproduct,yetstillkeepingitspricesaslowaspossible.PriortothatGKNAxlesLtd,totakeoptimumadvantageofeconomiesofscale,hadbeenproducingathighlycompetitivepricesastandardrangeofaxlesofdifferenttypesandsizes,fromwhichallcustomers'needscouldbesatisfied.Becausevehiclemanufacturershadnothithertohadtoplacesuchagreatemphasisonfueleconomy,andthereforeonlightweight,thesestandardaxlescouldcaterreliablyforallconditionslikelytobemetinawidevarietyofapplications.Nowvehiclemanufacturersrequireaxlesdesignedanddevelopedfortheirspecificapplications.Asaxledesignisbecomingincreasinglyspecialised,customersareincreasinglyraisingtheiraspirationsintermsofperformanceanreliability.Forthisreason,theyareturningtospecialistssuchasGKNAxlesLtdwhohavetheabilitytoprovideaxlesforawidevarietyofvehicles。

Sincethe1970s,however,incommonwithvirtuallyallothersupplierstothehighvolumeproducersinthemotorindustry,GKNhasradicallymodifieditsapproachtosuittheprevailingconditionsastheychangethroughthe1980sandonintothe1990s.Itsaimnowisatsupplyingcompleteaxleassembles,including,forexample,thebrakes,alldesignedandfullydevelopedforandintegrated,asamatterofcourse,intospecificvehicledesignsincluding,inparticular,thoseforthespecialistmarket.

Emphasisisnowonrationalizationofmaterials,methodsandcomponents.Thisoverallchangehasbeennecessarybecauseofthegreatlyincreasedsophisticationdemandedofthemodernvehicle,intermsofoverallefficiency,compactness,lightweight,reliability,durability,refinementandmaintenance-freeoperation.AnotherareaintowhichGKNAxleshasexpandedisthesupplyofcomponentsandassembliessuchaslimited-slipdifferentials,ball-joints,transferboxes,gearsandsometypesofsuspension.

 Foroff-roadoperation,thedutycyclesmaybeentirelydifferentinbothtorsionalandbeamloading-denpendingontheapplication.Forexample,sometypesofvehiclespendaconsiderableproportionoftheirrunningtimeathightorqueinlowgear.Inmostcircumstances,theterrainmaybesuchthatthetyrestendtoslipmorereadilythanontarmac;inothers,however,forexampleinfairlyfirmsandyscrees,itmayallowtyrestobiteintoit,andthusleadtotorsionalfatigueloadingsignificantlygreaterthanonsmoothroads.Verticalandlateralloading,too,maybemuchmoresevere,thoughthisdosedependtoamajorextentonspeeds.Shockloadingcanalsoaffectbrakingandaccelerationtorquesthough,again,sucheffectsarespeed-dependent.

  Hypoidgearsystemsaremorecommonlyusedthanspiralbevels.Theirprincipleadvantagesarethatpinionsofaspecificratioarebigger,theirteethprofilesareoflargeradius,theyareinherentlystrongerandmoredurable,theirmeshingareasarelarger,andtheygeneratelessnoise

  Hostreductiongeareffectistobeusedtoreducetherotationratethatthetransmissionshaftsendsinbuttoenhancerevolutionmomentoftorsion,changesdrivedirectionwithmomentoftorsion,passesontohalfaxesafterdifferentialmechanismand.Thehostreductiongearstructureformisthattheformisdifferentbutdifferentaccordingtogearwheeltype,reductiongearmainly.Hostreductiongeargearwheelhashelixconeformssuchasgearwheel,hypoidgear,columngearwheelandwormgearwormmainly.

Pairoflevelhostreductiongeariscomparedwithsinglestage,thegapmaybe7~12transmissionratio,i0eachotheratthesametimeinsweartobeawayfromafield12.Butthedimension,massarewithoutexceptionbigger,costishigher.Itappliestomiddle,heavytypefreighttrain,go-anywherevehicleandmotorbusmainlygoahead.

Dyadicoverallpairoflevelhostreductiongearhasthevariousstructurescheme:

Firstorderisaconegearwheel,thesecondstageisacolumngearwheel;Firstorderisaconegearwheel,thesecondstageisepicyclicgear;Firstorderisepicyclicgear,thesecondstageisaconegearwheel;Firstorderisacolumngearwheel,thesecondstageisaconegearwheel.

Horizontal,askew,faceanddroopovertothethreekindstofirstorderfortheconegearwheel,thesecondstagearethatpairofcolumngearwheellevelbetokensreductiongear,buthasdirectionarrangementscheme.

Directionlevelarrangementcanusetheassemblydroopingovertooutlinedimensiondiminution,reducingtheautomobilequalityheartaltitudethereby,makesthedirectiondimensionincreasebybut,thattheuseonlongdistancebetweenshaftsautomobilebutappropriatediminut