SAE J1263-1996 ROAD LOAD MEASUREMENT AND DYNAMOMET

SAETechnicalStandardsBoardRulesprovidethat:“ThisreportispublishedbySAEtoadvancethestateoftechnicalandengineeringsciences.Theuseofthisreportisentirelyvoluntary,anditsapplicabilityandsuitabilityforanyparticularuse,includinganypatentinfringementarisingtherefrom,isthesoleresponsibilityoftheuser.”SAEreviewseachtechnicalreportatleasteveryfiveyearsatwhichtimeitmaybereaffirmed,revised,orcancelled.SAEinvitesyourwrittencommentsandsuggestions.QUESTIONSREGARDINGTHISDOCUMENT:[phone]FAX:[phone]TOPLACEADOCUMENTORDER;[phone]FAX:[phone]SAEWEBADDRESS—ThisReaffirmedDocumenthasbeenchangedonlytoreflectthenewSAETechnicalStandardsBoardFormat.ThisprocedurewasoriginallydesignedintheEnglishunitssystemandhasbeenconvertedtothemetric(MKS)systemofunits.Thiswillexplainthesomewhatawkwardvaluesusedinthisprocedure.1.Scope—Thisprocedurecoversmeasurementofvehicleroadloadonastraight,levelroadatspeedslessthan113km/h(70mph).1.1Purpose—ThisSAERecommendedPracticeprovidesuniformtestingproceduresformeasuringtheroadloadforceonavehicleasafunctionofvehiclevelocityandforsimulationofthatroadloadforceat80km/h(50mph)onachassisdynamometer.2.References2.1ApplicablePublications—Thefollowingpublicationsformapartofthisspecificationtotheextentspecifiedherein.Unlessotherwisespecified,thelatestissueofSAEpublicationsshallapply.2.1.1SAEPUBLICATION—AvailablefromSAE,400CommonwealthDrive,Warrendale,PA15096-0001.SAEJ1100—MotorVehicleDimensions2.1.2FEDERALREGULATIONS—AvailablefromtheSuperintendentofDocuments.U.S.GovernmentPrintingOffice,Washington,DC20402-9371.CodeofFederalRegulations,40CFR600,AppendixA2.2RelatedPublications—Thefollowingpublicationsareprovidedforinformationpurposesonlyandarenotarequiredpartofthisdocument.R.A.WhiteandH.H.Korst,TheDeterminationofVehicleDragContributionfromCoast-DownTest,SAEPaper720099,1972T.P.Yasin,TheAnalyticalBasisofAutomobileCoastdownTesting,SAEPaper780334,1978B.Dayman,Jr.,TireRollingResistanceMeasurementsfromCoast-DownTests,SAEPaper760153,1976SAEJ1263ReaffirmedFEB96-2-G.D.Thompson,PredictionofDynamometerPowerAbsorptiontoSimulateLightDutyTruckRoadLoad,SAEPaper770844,1977J.R.Smith,J.C.Tracy,andD.S.Potter,TireRollingResistance—ASpeedDependentContribution,SAEPaper780255,1978B.Dayman,Jr.,RealisticEffectsofWindsontheAerodynamicsResistanceofAutomobiles,SAEPaper780337,19783.Definitions3.1TestWeight—Istheweightofthevehicleastested;includingdriver,operator(ifnecessary),andallinstrumentation.3.2TestMass—Isthemassofthevehicleastested;includingdriver,operator(ifnecessary),andallinstrumentation.3.3EffectiveMass—Isequaltothesumofthetestmassandtheeffectiveinertiasofthedrivenandnon-drivenaxles.3.4FrontalArea—Istheareaoftheorthogonalprojectionofthevehicleincludingtiresandsuspensioncomponentsontoaplaneperpendiculartothelongitudinalaxisofthevehicle.4.Symbolsa=Slopeoftheactualdynamometerhorsepower—1/δtcurve(kW-sorhp-s)A=Vehiclefrontalarea(see8.6)(m2orft2)b=Zerointerceptoftheactualdynamometerhorsepower—1/δtcurve(kWorhp)CD=Aerodynamicdragcoefficient(dimensionless)C′D=Aerodynamicdragcoefficientfornonzeroyaw(dimensionless)(see10.2)CDY=Crosswindaerodynamicdragcoefficient(dimensionless)D=Denominatorofexpressionstodetermineaandbfromvehicle-dynamometercoastdowndatafo,f2=Coefficientsofthezerothandsecondorderterms(respectively)intheroadloadforceequation(NorlbandN/[km/h2]orlb/mph2)f′o,f′2=Coefficientsofthezerothandsecondorderterms(respectively)intheroadloadforceequation(NorlbandN/[kmh2]orlb/mph2)correctedtostandardconditionsg=Accelerationofgravity9.80m/s2or32.174ft/s2l=Momentofinertiaoftire,wheel,andbrakerotorordrumkg-m2orft-lb-s2IW=Inertiaweightorequivalentweightofinertiasimulationmechanism(Norlb)k=Dragcoefficientdependenceonyawangleψkt=Temperaturecoefficientofrollingresistance(°C-1or°F-1)M=Vehicletestmass(kgorslugs)me=Effectivemassofawheel,tire,andbrakeassembly(kgorslugs)MDLC=Totalequivalentmassofdrivetraincomponents(kgorslugs)MIW=Equivalentmassofdynamometerinertiasimulationmechanism(IWC/g)(kgorslugs)Me=Totaleffectivevehiclemass(kgorslugs)N=NumberofdatapointsusedinPart2Po=Referenceatmosphericpressure736.6mmHg(29.00inHg)r=Tirerollingradius(morft)S=+1or-1,dependingonvehiclecoastdowndirectionto=Time(seconds)t-to=Coastdowntimeinterval(seconds)δt=Vehiclecoastdowntimeonthechassisdynamometer(s)T=Ambienttemperatureoftestarea(Kor°R)To=Standardtemperature(20°C=293.15K,68°F=527.67°R)V=Vehiclespeed(km/hormph)SAEJ1263ReaffirmedFEB96-3-V1,Vo=Finalandinitialspeedsinthecalculationofthecoastdowntimeinterval(km/hormph)Vw=Windvelocity(km/hormph)vx=Componentofwindparalleltotrack(km/hormph)vy=Componentofwindperpendiculartotrack(km/hormph)W=Vehicletestweight(Norlb)Ww=Weightoftire,wheel,andbrakerotorordru