外文翻譯--四輪定位簡(jiǎn)介.doc

遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）11英文翻譯原文AShortCourseonWheelAlignmentbyCharlesOfriaInitsmostbasicform,awheelalignmentconsistsofadjustingtheanglesofthewheelssothattheyareperpendiculartothegroundandparalleltoeachother.Thepurposeoftheseadjustmentsismaximumtirelifeandavehiclethattracksstraightandtruewhendrivingalongastraightandlevelroad.Thisarticlebeginswithinformationthatanymotoristshouldknow；however,ifyouareinterestedinlearningmoreaboutthistopic,clickontheunderlinedwordsformoredetailedexplanationsofeachterm.Wewillcovervariouslevelsofdetailwiththedeepestlevelscontaininginformationthatevenawheelalignmenttechnicianwillfindinformative.WheelAlignmentisoftenconfusedwithWheelBalancing.Thetworeallyhavenothingtodowitheachotherexceptforthefactthattheyaffectrideandhandling.Ifawheelisoutofbalance,itwillcauseavibrationathighwayspeedsthatcanbefeltinthesteeringwheeland/ortheseat.Ifthealignmentisout,itcancauseexcessivetirewearandsteeringortrackingproblems.Ifyouknowanythingaboutwheelalignment,youveprobablyheardthetermsCamber,CasterandToe-in.CamberCamberistheangleofthewheel,measuredindegrees,whenviewedfromthefrontofthevehicle.Ifthetopofthewheelisleaningoutfromthecenterofthecar,thenthecamberispositive,ifitsleaningin,thenthecamberisnegative.Ifthecamberisoutofadjustment,itwillcausetirewearononesideofthetirestread.Ifthecamberistoofarnegative,forinstance,thenthetirewillwearontheinsideofthetread.遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）2CamberwearpatternIfthecamberisdifferentfromsidetosideitcancauseapullingproblem.Thevehiclewillpulltothesidewiththemorepositivecamber.Onmanyfront-wheel-drivevehicles,camberisnotadjustable.Ifthecamberisoutonthesecars,itindicatesthatsomethingiswornorbent,possiblyfromanaccidentandmustberepairedorreplaced.CasterWhenyouturnthesteeringwheel,thefrontwheelsrespondbyturningonapivotattachedtothesuspensionsystem.Casteristheangleofthissteeringpivot,measuredindegrees,whenviewedfromthesideofthevehicle.Ifthetopofthepivotisleaningtowardtherearofthecar,thenthecasterispositive,ifitisleaningtowardthefront,itisnegative.Ifthecasterisoutofadjustment,itcancauseproblemsinstraightlinetracking.Ifthecasterisdifferentfromsidetoside,thevehiclewillpulltothesidewiththelesspositivecaster.Ifthecasterisequalbuttoonegative,thesteeringwillbelightandthevehiclewillwanderandbedifficulttokeepinastraightline.Ifthecasterisequalbuttoopositive,thesteeringwillbeheavyandthesteeringwheelmaykickwhenyouhitabump.Casterhaslittleaffectontirewear.Thebestwaytovisualizecasteristopictureashoppingcartcaster.Thepivotofthistypeofcaster,whilenotatanangle,intersectsthegroundaheadofthewheelcontactpatch.Whenthewheelisbehindthepivotatthepointwhereitcontactstheground,itisinpositivecaster.Pictureyourselftryingtopushthecartandkeepthewheelaheadofthepivot.Thewheelwillcontinuallytrytoturnfromstraightahead.Thatiswhathappenswhenacarhasthecastersettoofarnegative.Likecamber,onmanyfront-wheel-drivevehicles,casterisnotadjustable.Ifthecasterisoutonthese遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）3cars,itindicatesthatsomethingiswornorbent,possiblyfromanaccident,andmustberepairedorreplaced.Toe-inThetoemeasurementisthedifferenceinthedistancebetweenthefrontofthetiresandthebackofthetires.ItismeasuredinfractionsofaninchintheUSandisusuallysetclosetozerowhichmeansthatthewheelsareparallelwitheachother.Toe-inmeansthatthefrontsofthetiresareclosertoeachotherthantherears.Toe-outisjusttheopposite.Anincorrecttoe-inwillcauserapidtireweartobothtiresequally.Thistypeoftireweariscalledasaw-toothwearpatternasshowninthisillustration.Ifthesharpedgesofthetreadsectionsarepointingtothecenterofthecar,thenthereistoomuchtoe-in.Iftheyarepointedtotheoutsideofthecarthenthereistoomuchtoe-out.Toeisalwaysadjustableonthefrontwheelsandonsomecars,isalsoadjustablefortherearwheels.FourWheelAlignmentsTherearetwomaintypesof4-wheelalignments.Ineachcase,thetechnicianwillplaceaninstrumentonallfourwheels.Inthefirsttypethereartoeandtrackingischecked,butalladjustmentsaremadeatthefrontwheels.Thisisdoneonvehiclesthatdonothaveadjustmentsontherear.Thesecondtypeisafull4-wheelalignmentwheretheadjustmentsarefirstmadetotrueuptherearalignment,thenthefrontisadjusted.Afull4-wheelalignmentwillcostmorethantheothertypebecausethereismoreworkinvolved.Otherfactseverydrivershouldknowaboutwheelalignments.Aproperwheelalignmentshouldalwaysstartandendwithatestdrive.Thefrontendandsteeringlinkageshouldbecheckedforwearbeforeperforminganalignment.Thetiresshouldallbeingoodshapewithevenwearpatterns.Ifyouhaveatirewithexcessivecamberwear,forinstance,andyoucorrectthealignmentproblemthatcausedthatwear,thetirewillnowbemakingonlypartialcontactwiththeroad.(see遼寧工程技術(shù)大學(xué)畢業(yè)設(shè)計(jì)（論文）4illustrationonright)Pullingproblemsarenotalwaysrelatedtowheelalignment.Problemswithtires(especiallyunequalairpressure),brakesandpowersteeringcanalsoberesponsible.Itisuptoagoodwheelalignmenttechniciantodeterminethecause.AdvancedWheelAlignmentInformation.WhileCamber,Caster&Toe-inarethesettingsthatarealwayscheckedwhendoingawheelalignment,theyarenottheonlysettings.Belowisalistofthealignmentsettingsthatareimportantforawheelalignmenttechniciantoknowaboutinordertodiagnosefrontendproblems.CamberWhencamberspecificationsaredeterminedduringthedesignstage,anumberoffactorsaretakenintoaccount.Theengineersaccountforthefactthatwheelalignmentspecificationsusedbyalignmenttechniciansareforavehiclethatisnotmoving.Onmanyvehicles,camberchangeswithdifferentroadspeeds.Thisisbecauseaerodynamicforcescauseachangeinridingheightfromtheheightofavehicleatrest.Becauseofthis,ridingheightshouldbecheckedandproblemscorrectedbeforesettingcamber.Camberspecsaresetsothatwhenavehicleisathighwayspeed,thecamberisattheoptimalsettingforminimumtirewear.Formanyyearsthetrendhasbeentosetthecamberfromzerotoslightlypositivetooffsetvehicleloading,howeverthecurrenttrendistoslightlynegativesettingstoincreasevehiclestabilityandimprovehandling.CasterPositivecasterimprovesstraightlinetrackingbecausethecasterline(thelinedrawnthroughthes