... 301References 316Chapter 14 Engineering Standards for ClutchesandBrakes 317I. SAE Standards 317II. American National Standards Institute (ANSI) 320III. Other Standards Organizations 320Bibliography ... according to the SAE J661 standard. Field perform-Friction Materials 92Band Brakes Band brakes are simpler and less expensive than most other braking devices,with shoe brakes, as perhaps their ... derive, where possible, the design formulas for the major types of clutchesandbrakes listed in the contents and to display an example of their use in a typical design. Some pertinentcomputer...
... Inc.suchasbronze,glass,andgraphite,significantlyaddtothewearresistanceofPTFE[3].Glassappearstobethemostcommonlyused.B.KevlarKevlaristheDuPonttradenameforanaramid(aromaticpolyamidefiber)thathasatensilestrengthgreaterthansomesteels,i.e.,someofthesefibershaveamodulusupto27Â106psi(1.86Â105Mpa).Neverthelesstheyareflexibleenoughtobewovenandprocessedastextiles,soKevlarbrakeliningsandclutchfacingsareavailableineitherwovenornonwovenforms.Theyareusedalongwithproprietarypolymerbindersinthemanufactureofbrakeliningsandclutchfacingsforbothwet(oilbath)anddryclutchapplications.Indrybrakeandclutchapplications,aflexible,nonwovenformcanwithstanddynamicpressureupto3100kPa(450psi),arenonabrasivetoiron,steel,andcoppersurfaces,anddisplayandnominalcoefficientoffrictionof0.36F0.1,asstatedbyonemanufacturer.Thismanufactureralsostatesthatinadryenvironmentthesebrakeliningsshowsignificantfadeat260jC(500jF)thatbecomesgreaterat370jC(700jF)[7].Hence,theymaybeusedinthoseindustrial,marine,andoff-roadapplicationswherefadeisnotalimitingfactor;applicationscanincludeagricultural,industrial,marine ,and off-roadequipment.Inwetapplicationsthisnonwovenformoffacingmaterialissaidtowithstanddynamicpressureupto2760kPa(400psi)withanominalcoefficientoffrictioninthe0.10–0.15rangewhendissipating23–290W/cm2(0.2–2.5hp/in2)[7].Ambientoperatingtemperaturesarereplacedbypowerperunitareaattheliningfaceinwetapplicationsbecausetheenvelopingfluidbathcoolstheliningasittransferstheheattocoolingfinsortoanoilcooler.Clutchfacingsandbrakeliningsthatcontainnometalreinforcingwiresorsegmentsprovidelowwearonmatingsurfacesandeliminatethepossibilityofmetalfragmentsincoolingsystemfilters.KevlarhasalsobeenusedinaproprietarysolidformtoobtainhighercoefficientsoffrictioninawovenmaterialinwhichKevlarfibersaremixedwithotherorganicandinorganicfibersthatenclosebrasswireyarnstoproducealiningthatmaybeusedasadirectreplacementforolderliningsthatcontainasbestos[8].Becauseofthebrasswireandinorganicfibers,theseliningmaybemoreabrasivethanthosewithoutthesematerials.Thisis,ofcourse,anaturalconsequenceofhavinghigherfrictioncoefficientsontheordersof0.40dynamicand0.42static.Representativesecondfadeandsecondrecoverycurvesofthefrictioncoefficientvs.temperatureofarepresentativeofsuchliningsareshowninFigure4,asdeterminedaccordingtotheSAEJ661standard.Fieldperform-Friction ... Inc.indicatesachangeinAfromapproximately0.45toapproximately0.07,forachangeof84.4%.Incontrasttothis,Figure7forsteelbrakeswithsinteredliningsshowsachangeinAfromamidrangevalueofabout0.25toamidrangevalueofabout0.14,forachangeof44%.However,carbon–carbonbrakesarelighterthansteelbrakesandcanbemadefromasinglematerial[11].F.OtherProprietaryMaterialsFrictionmaterialsproducedbymostmanufacturersareproprietarytotheextentthatnotalloftheiringredientsaredisclosed.Noneoftheingredientsmaybelistedforthoseliningmaterialsthatperformsatisfactorilywithoutcomponentsprovidedbyothers,suchasKevlar.AbsenceofasbestosalwayswillbenotedbyU.S.suppliers.Manymanufacturersofentirelyorpartiallyproprietaryliningsprovidedataonthenominalfrictioncoefficients,wear,andrecommendedtemper-aturerangesoftheirproducts,althoughafewwillsupplydataonlytoamanufacturingcustomer.Thisdatamaybeineithertabularorgraphicalform.TypicaltabulardatafordryliningmaterialsmaybesimilartothatshowninTable2,andtypicaldataforwet(oil,transmissionfluid)liningmaterialsmaybesimilartothatshowninTable3fortwodifferentliningmaterials.Thefirstofthese,GL483-110,isdescribedasalayeredKevlarmatwithembeddedcarbonparticlesthatarehighlywearresistant.Thislayeredcompositionisboundtogetherwithahighstrength,temperatureresistantphenolicsresin.Thesecond,GL383-114,isanon-asbestos,cellulosefibercompositefrictionpaperthatissaturatedwithasimilarphenolicsresin.(SeeFig.1.)Datainbothtableswereobtainedfromconditionsthatmaydifferfromthose ... material and carbon–carbon composites arewidely used in brakes for large aircraft, such as long-range commercial jets, and in military aircraft. Their typical construction is shown in Figure 6.Brakes...
... 1 and 230j between detents 2 and 3130j between detents 8 and 3 and that the angular separation between detent centers 1 and 5 is given by25j between detents 1 and 230j between detents 2 and ... detents 3 and 440j between detents 4 and 5130j between detents 1 and 5The second instance occurs when balls 8 and 1 engage detents 1 and 5,where ball centers 8 and 1 are separated by 75j and detent ... Inc.MaximumpressureontheliningmaybefoundfromF¼rowZfo=2Àfo=2pcosfx¼rowpmaxZfo=2Àfo=2cosðfÞ2df¼pmax2rowðfoþsinfoÞð1-8Þuponusingthepressuredistributionfromequation(1-2)inChapter4.Hence,pmax¼2FrowðfoþsinfoÞð1-9ÞTheangularvelocityoftheinputshaftwhentheweightsmakeinitialcontactwiththedrummaybefoundbysettingthesquarebracketinequation(1-6)equaltozero.Substitutionofx=2kn/60,wherenisinrpm,followedbysolvingtheresultingexpressionforn,yieldsn¼k30ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffingrcðhÞþyð1þDÞrð1-10ÞTheroleofparametershandEinequation(1-5)uponforceF,equation(1-3),andthereforeuponpmax,equation(1-9)andthespeedatwhichtheyfirstcontactthedrumareshowninFigures2(a)through(d).Observethatthevariationofthepressure,andhencetheforce,thateachweightexertsagainstthedrumisalinearfunctionofparameterEandthatitbecomesanearlylinearfunctionofh,andhenceofri,forhgreaterthanabout0.3.Thedependenceofthewidthofeachweight,however,becomesincreas-inglynonlinearashincreasesandasEdecreases.Therotationalspeedforinitialcontactisalsonearlylinearforh<0.6,especiallyforthelargervaluesofE.ExampleDesignacentrifugalclutchtoprovideatorqueof2400N-mwhentherota-tionalspeedreaches870rpmusingsectorweightshavingthegeometryshowninFigure3(a).Preferredcharacteristicsarethatinitialcontactbetweenweightsanddrumoccuratbetween22 0and2 30rpmandthatthewidthoftheweightsbelessthan30cm.Assumealiningcoefficientoffrictionof0.35anddesign foraninsidedrumradius(minustheliningthickness)of15cm,adisplacementyof3mmforthe...
... Nd1ld1ln1tan2f and Nn2¼Ndrd2rn2¼ Ndld 2ln2tan2fð3-1Þwhere rd1 and rnlare the radii of the driver and driven cones, respectively, atpoint 1, rd 2 and rn2are driver and driven ... Inc.setofunitstobeusedforeachratio,andtheresultingratiosareindependentoftheunitsused.Relativelybroadcurvesareshowninthefollowingcomputer-generatedgraphsforeasyreadingtoshowcharacteristicbehaviorandtoprovidecontrastagainstthegridlines.Associatedroutines,suchasMathcadTrace,appeartoreadthemfromtheoriginatingdata,therebyeliminatingtheread-ingerrorsassociatedwithtracewidths.I.BELTDRIVESEquipmentusingnonmetallicbeltdrivesmayincludetheclutchcapabilitybymountingthemotor(becauseitisusuallysmallerthanthedrivenmachine)eitheruponahingedbaseoruponaslidingbasefittedwithaleveroralinkagethatpermitsthemotortobemovedtoandfromthedrivenmachineinordertoapplyandrelievethebelttensionandtherebygiveclutching(applyingbelttension)anddeclutching(relievingbelttension)capability.Thesedesignseliminatetheneedforamechanicalclutch.Theirsim-plicityisachieved,however,attheriskofintroducingthepossibilitythatfrictionalheatingofthebeltduringidling,whenthebelt(orbelts)mayrestonthemotor’srotatingsheave(pulley).Thatmaygenerateenoughheattocausebeltingmaterialstoslowlyshrink.Thisreductioninthecenterdistancebetweenthedrivinganddrivenpulleys,orsheaves,maybegreatenoughtocauseanunintendedre-engagementofthemotorandthedrivenmachine.Itmayalsoinhibittheirdisengagement.Consequently,somebeltmanufacturersproducebeltsthatresistshrinkageduetoheatingforuseintheseclutchinganddeclutchingapplications.Torquecapabilityforthesedrivesisaseparatecalculationtobeperformedaccordingtotheproceduresgivenbythebeltmanufacturers.Therefore,itwillnotbeconsideredinthefollowingdiscussion.A.HingedBaseAtfirstglanceitmayappearthatmovingamotorbymountingiteitheronahingedbaseoronaslidingbaseissosimplethatnoanalysisisnecessary.Ananalysis,however,doesbringforthseveralconsiderationsthatmaybemissedinselectingthedimensionsofthebaseplate,inlocatingthepositionofthebaseplatehinge,orindesigningthelinkagefortheslidingbaseplate.Twosimilar,butdistinct,mountingdesignsforhingedbaseswillbeconsidered.Intheseconfigurationsitistheweightofthemotoralonethatprovidesthebelttension.ThetensionvectorshowninFigure1(a )and( b)acting ... Inc.maximuminFigure16,setg=13.52j,asreadusingtheMathcadTracefeature.Evaluationofequation(1-13)forn=0.2,g=180,U=0.3,a=14j,andh=20foru=13.52jandforu=20jgivesadetentforceof4.544lb,whichiswithintheacceptablerange.Substitutionofg=180andq=1/32in.intoa=gq=180/32=5.625in.enablesdeterminationofrfromr=Ua=0.(5.625)=1.688in.Withlengthlgivenbyl=r/n=1.688/0.2=8.44in.,itfollowsthattheclearancegivenbylÀr=8.440À1.688=6.752in.exceedsthatspecified.Thisclearancerequirementmaybesatisfiedbyincreasingthemagni-tudeofnandreducingthemagnitudeofg.Thus,ifn=0.28andg=150,thedetentforcebecomes4.702lb,aisreducedto4.688in.,andrbecomes1.406in.Thesevaluesgivel=5.021in.,sotheclearanceis5.021À1.406=3.615in.,whichiswithinthedesiredrange.VI.EXAMPLE3:CONEDRIVESelectaconedriveforacombinationgolfcardandaproposedcongestedareacommutercartforuseincommunitiesthatacceptthem.Analysisoftorquetransmissiononthebasisofthedynamiccoefficientsoffrictionforacceptableliningsindicatesthata2.00-in.overlapwouldbesufficient.Forcomparison,consideronedesignwiththedriverconehavinganapexhalf-angleof40janddrivenconeshavingapexhalf-anglesof50jandaseconddesigninwhichboththedriveranddrivenconeshaveapexhalf-anglesof45j.Inbothcasesinitiallyselectaconegeneratorlengthof6.00in.toallowtheoverlaptobegreaterthan2.00in.intheeventthattheprototypeshouldrequiremodification.Beginwiththe40j,50jcombinationandturntoFigure11toselectthedimensionsoftheconesbyenteringthecurveatz=6andreadinguptothe40jline.Theprincipalradiusofcurvatureatthatpointis5.0346.Sincezismeasuredininches,theprincipalradiusofcurvatureis5.0346in.ReadingtotheleftatthisvalueofUyieldsthatatz=4.25in.,theprincipalradiusofcurvatureofthe50jhalf-angleconeis5.0650in.Aplotofthex-dimensionforeachcone,showninFigure17(a),confirmsthatthetwoconesshouldrollwithout...
... between values E1 and E2, in which E1may be 10% and E2may be 20%, for example. This may beachieved by returning to equation (1-4) and solving for v1 and then replacingv1 and v0with the ... slip and v0represents the actualvehicle velocity. Associated wheel angular velocities are represented by N1 and N0.For additional information on published details of ABS and TCSdesigns, ... such as Ref. 9, and from otherautomotive engineering journals.Example 1To demonstrate that equation (4-5), (4-6), (4-9), and (4-10) yield the angular and linear accelerations and the magnitude...
... the brakeassembly (drum, backplate, shoes, and lining in the case of drum brakes and disk and caliper in the case of disk brakes) as it vibrates and have shown thatbrake vibration is the result ... Inc.II.RECENTEXPERIMENTALDATAUsingexperimentaltechniquesnotavailableinthe1960sfortheexaminationofbothdiscanddrumbrakevibration,Felske,Hoppe,andMattha¨iemployedholographicinterferometrytodemonstrateconclusivelythatitisthecalipervibrationthatisthemajorcontributortobrakenoisefromdiskbrakes[11]andthebackplatevibrationthatisthemajorcontributorfromdrumbrakes[12].Typicalstandingwaveshapes,orthenodalpatterns,forthediskareshowninFigures 2and3 .VibrationofthecaliperisshowninFigures 4and5 .Thealternatingblackandwhitelineboundariesrepresentcontourlines,orelevationlines,onthecaliperanddiskandconsequentlymeasurethede-flectionofthediskandcaliperinadirectionperpendiculartotheplaneofthephotograph,asindicatedinFigure6foranantinodeonthedisk.FIGURE3 ... Inc.II.RECENTEXPERIMENTALDATAUsingexperimentaltechniquesnotavailableinthe1960sfortheexaminationofbothdiscanddrumbrakevibration,Felske,Hoppe,andMattha¨iemployedholographicinterferometrytodemonstrateconclusivelythatitisthecalipervibrationthatisthemajorcontributortobrakenoisefromdiskbrakes[11]andthebackplatevibrationthatisthemajorcontributorfromdrumbrakes[12].Typicalstandingwaveshapes,orthenodalpatterns,forthediskareshowninFigures 2and3 .VibrationofthecaliperisshowninFigures 4and5 .Thealternatingblackandwhitelineboundariesrepresentcontourlines,orelevationlines,onthecaliperanddiskandconsequentlymeasurethede-flectionofthediskandcaliperinadirectionperpendiculartotheplaneofthephotograph,asindicatedinFigure6foranantinodeonthedisk.FIGURE3...
... Performance Standard, Power Press Brakes R(2002).BSMI B2004400: Hand Brakes for Bicycles.BSMI B4003700: Axles with Brakes of Trailer for Power Tiller.Engineering Standards for ClutchesandBrakes ... rNormung(DIN).Italy:EuteNazionaleItalianodiUnificazione(UNI).Japan:JapaneseIndustrialStandards(JIS).Korea:KoreanStandardsAssociation(KSA).Malaysia:StandardsandIndustrialResearchofMalaysia(SIRIM).Netherlands:NederlandsNormalisatie-Instituut(NEN).Norway:NorwegianStandardsAssociation(—)Slovenia:StandardsandMetrologyInstitute(SMIS).Taiwan:BureauofStandardsandMetrologyInstitute(BSMI).UnitedStates:DepartmentofDefense(DoD—STD—),(MIL—).A.SelectedStandardsfromtheseOtherOrganizationsThetitlesofthefollowingstandardswerecopiedfromtheNSSNWebsiteasapartialindicationofthetopicsandapplicationsconsidered.Atthistimeofthiswriting,thestandardslistedbyNSSNmaybefoundbygoingtowww.ossn.org,wherealeft-clickofacomputermouseonthewordsSearchforStandards,whicharedirectlyunderthewordswww.NSSN.ORGatthetopleft ... thatstandard.JIS D 4421:1996: Method of Hardness Test for Brake Linings, Pads and Clutch Facings for Automobiles.JIS D 0152:1997: ClutchesandBrakes Vocabulary.ASME B5.55M: Specification and...