車輪和輪胎基本知識

WheelsandTyresWheelsDemandsofthewheelsLowweight,Largeinnerdiameterforlargebrakediscs,Highformstabilityandelasticity,Goodheatdissipation(frictionalheat),Simplechangeofthewheelsandtyreswithtyredamages.AssemblyofawheelThewheelconsistsofthewheelandthewheeldiscwithcentralboringandboltholes.Insteadofthewheeldisc,awheelstarispresentorwheelsorawheelwheresteelspokesareconnectedwiththehub.Thewheelisconnectedontheflangeofthewheelhubwhichispivotedpivotablewiththesteeringknuckleadaptorend,withwheelnutsorwheelbolts.Otherthanthat,thebrakediscsorthebrakedrumsaremountedfirmusingboltstotheflangeofthewheelhub.Withopenlyingbearings,thehubcovertakesoverthetaskofprotectingthebearingandisafatstorageforthefatreservesatthesametime.RimsTherearerimswhicharefittedfirmwiththewheeldiscandthosewhichcanberemoved.Otherthanthat,undividedrimsaredifferedthroughrims(dropcentrerims)andmultiplepartrims(Trilex),whichfindtheirusewithLightandHeavyGoodsVehicles.DropbaserimsForpassengervehicles,generallyundivideddropcentrerimsareused.Theyarerivetedorweldedfestwiththewheeldiscorarecastedorforgedfromalloymetalswiththewheeldiscasonepiece.Thecrosssectionoftherimcanbesymmetricalorunsymmetrical.AT_40_0014RimflangeRimopeningRimdiameterDropcentrerimRimbedseatHumpHumprimsWhenusingtubelessbeltedtyres,dropcentreringrimshavetobeusedofwhichtherimshoulder,neartothedropcentrerim,hasacirculatingroundincrement=Hump(H).AT_40_0014IftheincrementisnotroundandisflattenedthenonetermsthisasaFlat-Hump(FH).Bothoftheseshouldpreventthatthetyrebulgeswhendrivingwithhigherspeedsincurvesthattherimshoulderisnotpressedintothedropcentrerimthroughthehighlateralforces.Withtubelesstyres,theaircanescapequicklysothatanaccidentcouldbetheresult.MeasurementsandtermsontherimsThesedetailsareNormed.Therimtermsarestampedineachwheelbythemanufacturer.Theyconsistprincipallyfrom2dimensions,therimopening(a)ininchesandtherimdiameter(D)ininches.Bothdimensionsareseparatedwithan”x”indropcentrerims.Codedlettersaftertherimdiametergiveinformationaboutthetypeofrim.Example6%Jx13H6%=RimopeninginInchesJ=CodeletterforthemeasurementsoftherimflangeX=undivideddropcentrerim13=RimdiameterininchesH=oneHumpontheoutershoulderPress-indepthThisisthedimensionfromthemiddleoftherimtotheinnercontactsurfaceofthewheeldisc.Throughweldingtherimandwheeldisc,thepress-indepthcanbechosen.Therefore,therimisdeterminedforacertainchassisasthepress-indepthrelatedirectwiththekingpinoffset.Positivepress-indepthTheinnercontactsurface,basedonthemiddleoftherim,isdisplacedtotheoutersideoftherim.Negativepress-indepthTheinnercontactsurfaceisdisplacedtotheinnersideoftherim.Throughusingtherimwithsmallerpositiveornegativepress-indepths,thespurwidthofthevehiclecanbewidened.AT_40_0001AT_40_0015

TyresDemandsoftheTyresAT_40_0001AT_40_0015Absorptionoftheweightofthevehicle,Absorptionofsmallroadsurfaceimpacts,Transformationofdriving,brakeandlateralforces,Loweffortwhenparking,Lowrollingresistancethereforelowerinnerfrictionandheatdevelopment,Sufficientlengthoflife,Alownoiseandvibrationrolling.AssemblyValve,innertubeandtherimbandarecomponentsofatyre.Therimbandisonlyusedinmopedsandvehicleswherethetubehastobeprotectedagainstthenippleheadsofthespokes.Theinnertubehastocomplywiththesizeofthetyre.Thetyreconsistof:Carcass(Fabriccarcass),Belt(principallybyradialtyres),Intermediateconstructionwithcontactsurface(Protector),Bulgeswithinlayingsteelwirecore.AT_40_0008ContactsurfaceIntermediateconstructionSiderubberValveBeltAirtightrubberlayerFabriccarcass(Carcass)RimflangeHumpRimshoulderBulge

CarcassThisisbasedongummedcordthreadswhicharegenerallymanufacturedfromRayon,Steel,PolyesterorAramid.Thethreadsarelayeredovereachotherandthisiseitherinadiagonalleadingangletothedrivingdirection(Diagonaltyre)orrightangulartothedriving6direction(Radialtyres).AT_40_0008BeltAirtightrubberlayerFabriccarcass(Carcass)RimflangeHumpRimshoulderWhenwinding,thethreadsarewoundaroundtwosteelrings(Bulgecores)andarethenanchoredthroughvulcanisationIntermediateconstructionThisconsistsofmultiplefibrelayersandrubberpadding,absorbsimpactsandprotectsthecarcass.BeltThisconsistsofmultiplelayersofrubberembeddedsteelwires,textilethreads,nylonoraramidfibres.Thebeltliesabovethecarcassandisfinishedsothatthewiresorfibrescross.Thebeltcanbefoldedwithhighspeedtyreswhichraisesthestability.ContactsurfaceThisisprovidedwithaprofile.Thelongitudinalprofilegivesthetyrealateralholding,thetransverseprofiletransfersthedrivingforce.Thelateralshouldersofthecontactsurfacecreateatransfertothesidewallwhichprotectsthecarcass.AquaplaningOnawetroadsurface,awaterwedgecanbecreatedbetweenthetyresandthesurfaceoftheroadwhichliftsthevehicleanditisthenunabletobecontrolled.ToreducethedangerofAquaplaning,theprofilegrooveshavetohaveaminimaldepthsothattheycanabsorblotsofwater.AT_40_00091.2.3.FoldedAramidbeltCarcassBulgecoreOtherthanthat,theyneedcertainformssothatthewatercanflowoutwardswithahighspeedandoverashorttime.Thedrivingspeedishastobeadjustedtothestateoftheprofile,theAT_40_00091.2.3.FoldedAramidbeltCarcassBulgecoreDimensionsandtermsofthetyresTyresizeThisisdeterminedthroughthedetailsof2dimensions:Tyrewidthinmm;Rimdiameterininches.CrosssectionratioThedifferenttyrecategories,e.g.balloontyres,lowcrosssectiontyres,beingabletorecognisehowtherelationshipofthetyreheightandtyrewidthisdetermined.Thetyretermisgiveninpercent.Moderntyreshaveagreaterwidththanheight.Iftheheightofthetyrevaluese.g.80%ofthewidththentheheight:width=0,8:1.Asthepercentvalueisusedinthetyreterms,onewouldsay80ertyre.SpeedcategoriesTheydifferthetyresofapassengervehiclethanthatofacommercialvehicleagainsttheirregisteredtopspeed.EveryhighspeedisRegisteredwithaletter.TopspeedSpeedsymbolTerm160km/hQ180km/hS190km/hyt210km/hH240km/hV270km/hW300km/hYOver240km/hZRTyreloadcarryingcapacityThesedifferthetyresagainsttheirstresscapability.Fortheterminginthepast,thePRnumberwasused.Thespecification4PR(PlyRating)meantthatbecauseofthestabilityofitscarcass,thatitcouldbeloadedlikeatyrewith4layersofcottonthread.ThePRnumberisnotactualanymoreandhasbeenreplacedbyaLoadIndexLI.ThisisthecodenumberwhichshowsthehighestcarryingcapacityofthetyreThetyrecarryingcapacityisaccordingtothevehiclemanufacturerinconnectionwiththehighestspeed,airpressureanddownfall.Exampleforthetyreterms195/60R1488H354/35ZR15195=Tyresizeinmm60=Crosssectionratio60%R=Radialtyre14=Rimdiameterininches88=loadcarryingindexH=Speedsymbol354=Tyresizeinmm35=Crosssectionratio35%ZR=Topspeedover240km/h15=RimdiameterininchesBalancingTheweightofaturningtyreisneverthesameoverthecompletecircumference.Onthepointwherethegreatermassappearsiswheretheunbalancingtakesplace,whichmeansthatacentrifugalforceiscreatedandthegreatertheyarethegreatertheturningmomentis.Thesizeandpositionofthecompensatingweightarecalculatedonabalancingmachine.Ifthetyrestillrunsunbalancedthenaradialrunoutispresent.Iftheradialrunoutexceeds1mmonthecontactsurfacethenthetyrehastoberotatedonthewheeltoreducetherunout(Matching).StaticunbalanceIfe.g.throughblockingbrakes,apointonthecontactsurfaceofthetyreisrubbedoff,thenontheoppositepositionallargemassofacentrifugalforcewhich,withhigherspeeds,canleadtothejumpingofthetyreontheroadsurface.Thefaultcanbefoundwhenthewheelisoscillated,theheaviestpartofthewheelwillstopatthebottom.Ontheoppositeside