(12)SAE J2521-2006 (R) Disc and Drum Brake Dynamo

SURFACEVEHICLERECOMMENDEDPRACTICE(R)DiscandDrumBrakeDynamometerSquealNoiseMatrixSAETechnicalStandardsBoardRulesprovidethat:“ThisreportispublishedbySAEtoadvancethestateoftechnicalandengineeringsciences.Theuseofthisreportisentirelyvoluntary,anditsapplicabilityandsuitabilityforanyparticularuse,includinganypatentinfringementarisingtherefrom,isthesoleresponsibilityoftheuser.”SAEreviewseachtechnicalreportatleasteveryfiveyearsatwhichtimeitmaybereaffirmed,revised,orcancelled.SAEinvitesyourwrittencommentsandsuggestions.Copyright©2006SAEInternationalAllrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,recording,orotherwise,withoutthepriorwrittenpermissionofSAE.TOPLACEADOCUMENTORDER:Tel:[phone](insideUSAandCanada)Tel:[phone](outsideUSA)Fax:[phone]Email:[e-mail]:®J2521REV.JAN2006ForewordAEuropeanworkinggroupthatincludescarmanufacturers,brakingsystemsuppliersandfrictionmaterialcompanies,developedadynamometertestprocedureknownasAKNoise.Thisprocedurefollowsthelinesofthedragmodetestprocedureswithanextensiontoincludedecelerationbraking.AcommonapproachintheUSistousedecelerationmodeproceduresemphasizingthereplicationofvehicleroadtest.Aglobalsquealmatrixhasbeendevelopedthatcombinesdragmodeanddecelerationmodeteststomeetthestrongneedforaglobalstandardizationofsquealnoisedynamometertests.ThisprocedurewasfirstpresentedtotheSAEworkinggroupinFebruary1999.BasedontheAKdrag,deceleration,andfrictioncharacterizationmodules,thematrixwithoptionalColdTemperatureNoisesectionsandoptionalNoiseafterFadeandRecoverysectionscontains31sectionswith2321brakeapplicationstotal.ThisprocedureowesmuchtothepreviousdevelopmentoftheAKprocedures.Thispriorworkisgratefullyacknowledged.Thelatestrefinementofthisrecommendedpracticeincorporatesaspecificallydesignedsegment,PartB,fortheevaluationofdrumbrakenoise.Anewoptionallowtemperaturesectionhasalsobeenaddedtothediscbrakesectiontobetteraccountforcoldbrakesqueal.ThenoisedatafromthesesectionsareintentedtorepresentthesquealsgeneratedunderlowtemperatureoperatingconditionsDrumbrakesareknowntorequirelongerbeddingbeforeestablishingstableperformancepropertiesthataretypicalofcustomerperception.Drumbrakesalsotypicallyprovidelesstorqueoutputthanadiscbrakeatthesamepressure.Thatleadstolowerheatgenerationload.Fortheabovereasonsaswellasothersanoisematrixadaptationfordrumbrakeshasbeenintroduced.Thedrumbrakenoisematrixusesabeddingblock,anoisesearchblock,thenasecondmoreintensivebeddingblock,followedbyasecondnoisesearchblock,andafinalnoisesearchblock.Optionsforheavydutydrumbrakeandcoldnoisetestingarenotincludedasdrumbrakevariationsmakeitimpracticaltohaveasinglestandard.SAEJ2521RevisedJAN2006-2-TABLEOFCONTENTS1.Scope.....................................................................................................................................21.1Purpose..................................................................................................................................31.2Rationale................................................................................................................................32.References.............................................................................................................................33.Definitions...............................................................................................................................33.1GeneralDefinitions.................................................................................................................33.2TestApparatusDefinition.......................................................................................................43.3Measurements.......................................................................................................................53.4DataAnalysisCalculations....................................................................................................63.5BrakeOperations...................................................................................................................84.PartA:DiscBrakeTestMatrix.............................................................................................114.1SummaryofTestMatrixSections........................................................................................114.2NoiseEvaluationSections...................................................................................................114.3OptionalSections–ColdTemperatureNoise....................................................................144.4OptionalSections–NoiseAfterFadeandRecovery..........................................................155.PartB:DrumBrakeTestMatrix..........................................................................................165.1Totalnumbersofbrakeapplications...................................................................