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1、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.Thepurposeoftheseadjustmentsismaximumtirelifeandavehiclethattracksstraightandtruewhendrivingalongastr

2、aightandlevelroad.Thisarticlebeginswithinformationthatanymotoristshouldknow；however,ifyouareinterestedinlearningmoreaboutthistopic,clickontheunderlinedwordsformoredetailedexplanationsofeachterm.Wewillcovervariouslevelsofdetailwiththedeepestlevelscontaininginformationthatevenawheelalignmenttechnician

3、willfindinformative.WheelAlignmentisoftenconfusedwithWheelBalancing.Thetworeallyhavenothingtodowitheachotherexceptforthefactthattheyaffectrideandhandling.Ifawheelisoutofbalance,itwillcauseavibrationathighwayspeedsthatcanbefeltinthesteeringwheeland/ortheseat.Ifthealignmentisout,itcancauseexcessivetir

4、ewearandsteeringortrackingproblems.Ifyouknowanythingaboutwheelalignment,youveprobablyheardthetermsCamber,CasterandToe-in.CamberCamberistheangleofthewheel,measuredindegrees,whenviewedfromthefrontofthevehicle.Ifthetopofthewheelisleaningoutfromthecenterofthecar,thenthecamberispositive,ifitsleaningin,th

5、enthecamberisnegative.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.Thevehiclewillpulltothesidew

6、iththemorepositivecamber.Onmanyfront-wheel-drivevehicles,camberisnotadjustable.Ifthecamberisoutonthesecars,itindicatesthatsomethingiswornorbent,possiblyfromanaccidentandmustberepairedorreplaced.CasterWhenyouturnthesteeringwheel,thefrontwheelsrespondbyturningonapivotattachedtothesuspensionsystem.Cast

7、eristheangleofthissteeringpivot,measuredindegrees,whenviewedfromthesideofthevehicle.Ifthetopofthepivotisleaningtowardtherearofthecar,thenthecasterispositive,ifitisleaningtowardthefront,itisnegative.Ifthecasterisoutofadjustment,itcancauseproblemsinstraightlinetracking.Ifthecasterisdifferentfromsideto

8、side,thevehiclewillpulltothesidewiththelesspositivecaster.Ifthecasterisequalbuttoonegative,thesteeringwillbelightandthevehiclewillwanderandbedifficulttokeepinastraightline.Ifthecasterisequalbuttoopositive,thesteeringwillbeheavyandthesteeringwheelmaykickwhenyouhitabump.Casterhaslittleaffectontirewear

9、.Thebestwaytovisualizecasteristopictureashoppingcartcaster.Thepivotofthistypeofcaster,whilenotatanangle,intersectsthegroundaheadofthewheelcontactpatch.Whenthewheelisbehindthepivotatthepointwhereitcontactstheground,itisinpositivecaster.Pictureyourselftryingtopushthecartandkeepthewheelaheadofthepivot.

10、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,andmustberepairedorreplac

11、ed.Toe-inThetoemeasurementisthedifferenceinthedistancebetweenthefrontofthetiresandthebackofthetires.ItismeasuredinfractionsofaninchintheUSandisusuallysetclosetozerowhichmeansthatthewheelsareparallelwitheachother.Toe-inmeansthatthefrontsofthetiresareclosertoeachotherthantherears.Toe-outisjusttheoppos

12、ite.Anincorrecttoe-inwillcauserapidtireweartobothtiresequally.Thistypeoftireweariscalledasaw-toothwearpatternasshowninthisillustration.Ifthesharpedgesofthetreadsectionsarepointingtothecenterofthecar,thenthereistoomuchtoe-in.Iftheyarepointedtotheoutsideofthecarthenthereistoomuchtoe-out.Toeisalwaysadj

13、ustableonthefrontwheelsandonsomecars,isalsoadjustablefortherearwheels.FourWheelAlignmentsTherearetwomaintypesof4-wheelalignments.Ineachcase,thetechnicianwillplaceaninstrumentonallfourwheels.Inthefirsttypethereartoeandtrackingischecked,butalladjustmentsaremadeatthefrontwheels.Thisisdoneonvehiclesthat

14、donothaveadjustmentsontherear.Thesecondtypeisafull4-wheelalignmentwheretheadjustmentsarefirstmadetotrueuptherearalignment,thenthefrontisadjusted.Afull4-wheelalignmentwillcostmorethantheothertypebecausethereismoreworkinvolved.Otherfactseverydrivershouldknowaboutwheelalignments.Aproperwheelalignmentsh

15、ouldalwaysstartandendwithatestdrive.Thefrontendandsteeringlinkageshouldbecheckedforwearbeforeperforminganalignment.Thetiresshouldallbeingoodshapewithevenwearpatterns.Ifyouhaveatirewithexcessivecamberwear,forinstance,andyoucorrectthealignmentproblemthatcausedthatwear,thetirewillnowbemakingonlypartial

16、contactwiththeroad.(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.WhileCa

17、mber,Caster&Toe-inarethesettingsthatarealwayscheckedwhendoingawheelalignment,theyarenottheonlysettings.Belowisalistofthealignmentsettingsthatareimportantforawheelalignmenttechniciantoknowaboutinordertodiagnosefrontendproblems.CamberWhencamberspecificationsaredeterminedduringthedesignstage,anumberoff

18、actorsaretakenintoaccount.Theengineersaccountforthefactthatwheelalignmentspecificationsusedbyalignmenttechniciansareforavehiclethatisnotmoving.Onmanyvehicles,camberchangeswithdifferentroadspeeds.Thisisbecauseaerodynamicforcescauseachangeinridingheightfromtheheightofavehicleatrest.Becauseofthis,ridin

19、gheightshouldbecheckedandproblemscorrectedbeforesettingcamber.Camberspecsaresetsothatwhenavehicleisathighwayspeed,thecamberisattheoptimalsettingforminimumtirewear.Formanyyearsthetrendhasbeentosetthecamberfromzerotoslightlypositivetooffsetvehicleloading,howeverthecurrenttrendistoslightlynegativesetti

20、ngstoincreasevehiclestabilityandimprovehandling.CasterPositivecasterimprovesstraightlinetrackingbecausethecasterline(thelinedrawnthroughthesteeringpivotwhenviewedfromtheside)intersectsthegroundaheadofthecontactpatchofthetire.Justlikeashoppingcartcaster,thewheelisforcedbehindthepivotallowingthevehicl

21、etotrackinastraightline.Ifthisisthecase,thenwhydidmostcarshavenegativecasterspecspriorto1975?Thereareacoupleofreasonsforthis.Inthosedays,peoplewerelookingforcarsthatsteeredaslightasafeather,andcarsbackthenwerenotequippedwithradialtires.Non-radialtireshadatendencytodistortathighwayspeedsothatthecontactpatchmovedbackpastthecenterlineofthetire(Pictureacartooncarspeedingalong,thetiresaregenerallydrawnasegg-shaped).Thecontactpatchgenerallymovesbehindthecasterlinecausing,ineffect,apositive