ARMYTM9-2320-272-24-1AIRFORCETO36A12-1C-1155-2-1ThispublicationsupersedesTM9-2320-272-20-1,October1985,andchanges1through4;TM9-2320-272-20-2,October1985,andchanges1through3;TM9-2320-272-34-1,June1986,andchanaes1through2;TM9-2320-272-34-2,June1986,andchanges1and2;andTM9-2320-358-24&P,October1992TECHNICALMANUALVOLUME 1 OF 4UNIT,DIRECTSUPPORT,ANDGENERALSUPPORTMAINTENANCEMANUALFORTRUCK,5-TON,6X6,M939,M939A1,M939A2SERIESTRUCKS(DIESEL)HOWTOUSETHISMANUAL VINTRODUCTION l - lSERVICEANDTROUBLESHOOTINGINSTRUCTIONS2-lPREVENTlVEMAINTENANCECHECKSANDSERVICES(PMCS)2-2UNITTROUBLESHOOTING 2-60UNIT MAINTENANCE3-1TRUCK,CARGO:5-TON,6X6,DROPSIDE,M923(2320-01-050-2084)(EIC:BRY);M923Al(2320-01-206-4087)(EIC:BSS);M923A2(2320-01-230-0307)(EIC:BS7);M925(2320-01-047-8769)(EIC:BRT);M925Al(2320-01-206-4088)(EIC:BST);M925A2(2320-01-230-0308)(EIC:B58);TRUCK,CARGO:5-TON,6X6XLWB,M927(2320-01-047-8771)(EIC:BRV);M927A1(2320-01-206-4089)(EICBSW);M927A2(2320-01-230-0309)(EIC:BS9);M928(2320-01-047-8770)(EIC:BRU);M928Al(2320-01-206-4090)(EIC:BSX);M928A2(2320-01-230-0310)(EIC:BTM);TRUCK,DUMP:5-TON,6X6,M929(2320-01-047-8756)(EIC:BTH);M929Al(2320-01-206-4079)(EIC:BSY);M929A2(2320-01-230-0305)(EIC:BTN);M930(2320-01-047-8755)(EIC:BTG);M930Al(2320-01-206-4080)(EIC:BSZ);M930A2(2320-01-230-0306)(EIC:BTO);TRUCK,TRACTOR:5-TON,6X6,M931(2320-01-047-8753)(EIC:BTE);M931Al(2320-01-206-4077)(EIC:BS2);M931A2(2320-01-230-0302)(EIC:BTP);M932(2320-01-047-8752)(EIC:BTD);M932Al(2320-01-205-2684)(EIC:BS5);M932A2(2320-01-230-0303)(EIC:BTQ);TRUCK,VAN,EXPANSIBLE:5-TON,6X6,M934(2320-01-047-8750)(EIC:BTB);M934A1(2320-01-205-2682)(EIC:BS4);M934A2(2320-01-230-0300)(EIC:BTR);TRUCK,MEDIUMWRECKER:5-TON,6X6,M936(2320-01-047-8754)(EIC:BTF);M936Al(2320-01-206-4078)(EIC:BS6);M936A2(2320-01-230-0304)(EIC:BTT).DISTRIBUTIONSTATEMENTA-Approvedforpublicrelease;distributionisunlimited.DEPARTMENTS OF THE ARMY AND THE AIR FORCEJUNE1998TM9-2320-272-24-1WARNINGEXHAUSTGASESCANKILL1. DONOToperatevehicleengineinenclosedarea.2 DONOTidlevehicleenginewithwindowsclosed.3. DONOTdrivevehiclewithinspectionplatesorcoverplatesremoved.4. BEALERTatalltimesforodors.5. BEALERTforexhaustpoisoningsymptoms.Theyare:HeadacheDizzinessSleepinessLossofmuscularcontrol6. IFYOUSEEanotherpersonwithexhaustpoisoningsymptoms:RemovepersonfromareaExposetoopenairKeeppersonwarmDonotpermitpersontomoveAdministerartificialrespirationorCPR,ifnecessary**Forartificialrespiration,refertoFM21-11.7. BEAWARE:ThefieldprotectivemaskforNuclear,Biological,orChemical(NBC)protectionwillnotprotectyoufromcarbonmonoxidepoisoning.THEBESTDEFENSEAGAINSTEXHAUSTPOISONINGISADEQUATEVENTILATION.WarningaTM 9-2320-272-24-1WARNINGSUMMARYHearingprotectionisrequiredforthedriverandpassenger.Hearingprotectionisalsorequiredforallpersonnelworkinginandaroundthisvehiclewhiletheengineisrunning(AR-40-5andTBMED501).Ifrequiredtoremaininsidevehicleduringextremeheat,occupantsshouldfollowthewaterintake,work/restcycle,andotherstresspreventivemeasures(FM21-10,FieldHygieneandSanitation).IfNBCexposureissuspected,allairfiltermediashouldbehandledbypersonnelwearingprotectiveequipment.ConsultwithyourunitNBCofficerorNBCNC0forappropriatehandlingordisposalinstructions.ThisvehiclehasbeendesignedtooperatesafelyandefficientlywithinthelimitsspecifiedinthisTM.OperationbeyondtheselimitsisprohibitedbyIAWAR70-lwithoutwrittenapprovalfromthecommander,U.S.ArmyTank-automotiveandArmamentsCommand,ATTN:AMCPEO-CM-S,Warren,MI48397-5000.Neverworkunderdumpbodyunlesssafetybracesareproperlypositioned.Failuretodothiswillresultininjurytopersonnel.Duringwinchingoperation,neverstandbetweenvehicles.Assistantmustremaininsecondaryvehicletoengageservicebrakeifcablesnapsorautomaticbrakefailswhiletowingvehicle.Failuretodothismayresultininjurytopersonnel.Accidentalorintentionalintroductionofliquidcontaminantsintotheenvironmentisinviolationofstate,federal,andmilitaryregulations.RefertoArmyPOL(para.l-7)forinformationconcerningstorage,use,anddisposaloftheseliquids.Failuretodosomayresultininjuryordeath.Cleaningsolventsareflammableandtoxic.Donotusenearopenflameandalwayshaveafireextinguishernearbywhensolventsareused.Useonlyinwell-ventilatedplaces,wearprotectiveclothing,anddisposeofcleaningragsinapprovedcontainer.Failuretodothiswillresultininjurytopersonneland/ordamagetoequipment.Eyeshieldsmustbewornwhencleaningwithcompressedair.Compressedairsourcewillnotexceed30psi(207kPa).Failuretodosomayresultininjurytopersonnel.Extremecareshouldbetakenwhenremovingsurgetankfillercapiftemperaturegaugereadsabove175F(79C).Steamorhotcoolantunderpressurewillcauseinjury.Alcoholusedinthealcoholevaporatorisflammable,poisonous,andexplosive.Donotsmokewhenremovingalcoholevaporatororaddingfluid,anddonotdrinkfluid.Failuretodothiswillresultininjuryordeath.Donotperformelectricalcircuittestingfueltankwithfillcaporsendingunitremoved.Fuelmayignite,causinginjurytopersonnel.Whenperformingbatterymaintenance,ensurebatteriesareseatedandclampeddown,allrubberbootsareinstalled,clampsarewelldownonbatteryposts,andallbatterycableslieflatagainstthetopofthebatteries.Failuretodothismayresultininjurytopersonneland/ordamagetoequipment.Ensurecompanionseatbeltsarenotcaughtinsidebatterybox.Thiswillcausebeltstorotwhichmayleadtoiujuryofpersonnel.OnM938/Al/A2modelvehicles,removesparetirepriortochangingtireandinstalltireinsparetirecarrieraftertirechangeiscomplete.Operationofcraneand/orvehicleenginewhilevehicleisonjacksmayresultininjurytopersonnelordamagetoequipment.Neverassembleordisassembletireandrimassemblywhileinflated,useinflationtoseatlockringonsplitrimortireontwo-piecerim,orinflateatirewithoutatireinflationcage.Injurytopersonnelmayresult.Donotdisconnectairlinesorhoses,removesafetyvalvesorCTIScomponents,orperformbrakechamberrepairsbeforedrainingairreservoirs.Smallpartsunderpressuremayshootoutwithhighvelocity,causinginjurytopersonnel.WarningbTM9-2320-272-24-1WARNlNGSUMMARY(Contd)Removealljewelrywhenworkingonelectricalcircuits.Jewelrycomingincontactwithelectricalcircuitsmayproduceashortcircuit,causingextremeheat,explosions,andflingparticlesofmetal.Failuretodosowillresultininjuryordeathanddamagetoequipment.Useeyeshieldsandfollowinstructionscarefullywhenperformingassembling,disassembling,ormaintenanceonthisdevice.Componentsofthisdeviceareunderspringtensionandmayshootoutatahighvelocity.Failuretodosowillresultininjurytopersonnel.Donotremovehoseswithenginerunningorstartenginewithhosesremoved.High-pressurefluidsmaycausehosestowhipviolentlyandsprayrandomly.Failuretodosomayresultininjurytopersonnel.Keephandsoutfrombetweenmetalsurfaceswhenremovingheavycomponents.Failuretodosomayresultininjurytopersonnel.Keeppersonneloutfromunderequipmentandcomponentsofequipmentwhensupportedbyonlyaliftingdevice.Suddenlossofliftingpowerorshiftinloadmayresultininjuryordeath.Donotdrainengine,transmission,orradiatorfluids,orremovelinescontainingthesefluids,whenhot.Doingsomayresultininjurytopersonnel.Vehiclewillbecomechargedwithelectricityifitcontactsorbreakshigh-voltagewires.Donotleavevehiclewhilehigh-voltagelinesareincontactwithvehicle.Failuretodosomayresultininjurytopersonnel.Wearhandprotectionwhenhandlingliftingandwinchingcables,hotexhaustcomponents,andpartswithsharpedges.Failuretodosomayresultininjurytopersonnel.Donotperformfuelsystemprocedureswhilesmokingorwithin50ft(15.2m)ofsparksoropenflame.Dieselfuelishighlyflammableandcanexplodeeasily,causinginjuryordeathtopersonneland/ordamagetoequipment.Ensuredrainvalveonaftercoolerisopenwhenfillingcoolingsystem.Failuretodosomayresultininjurytopersonnel.Turbochargerintakefinsareextremelysharpandturnatveryhighrpm.Keephandsandlooseitemsawayfromintakeopenings.Failuretodosomayresultininjurytopersonnel.Donotplacehandsbetweenframeandradiatorwhenremovingscrewsfromtrunnionorliftingradiator.Suddenchangesinsupportmaycausetheradiatortoshift,causinginjurytopersonnel.Airpressuremaycreateairbornedebris.Useeyeprotectionorinjurytopersonnelmayresult.Airsystemcomponentsaresubjecttohighpressure.Alwaysrelievepressurebeforelooseningorremovingairsystemcomponents.Wearsafetygoggleswhenusingahammer.Etherisextremelyflammable.Donotperformetherstartsystemproceduresnearfire.Injurytopersonnelmayresult.Warningc/(Warningdblank)ARMYTM9-2320-272-24-lAIRFORCETO36A12-1C-1155-2-lTECHNICALMANUALNO.9-2320-272-24-1TECHNICALORDERNO.36A12-1C-1155-2-1HEADQUARTERSDEPARTMENTSOFTHEARMYANDTHEAIRFORCEWashington,D.C.,30JUNE1998TECHNICALMANUALVOLUME1OF4UNIT, DIRECT SUPPORT, ANDGENERALSUPPORTMAINTENANCEMANUALFORTRUCK,5TON,6X6,M939,M939A1,M939A2SERIESTRUCKS(DIESEL)TRUCK MODEL EIC NSNWITHOUTWINCH NSNWITHWINCHCargo,DropsideCargo,DropsideCargo,DropsideCargo,DropsideCargo,DropsideCargo,DropsideCargoCargoCargoCargoCargoCargoDumpDumpDumpDumpDumpDumpTractorTractorTractorTractorTractorTractorVan,ExpansibleVan,ExpansibleVan,ExpansibleMediumWreckerMediumWreckerMediumWreckerM923M923AlM923A2M925M925AlM925A2M927M927AlM927A2M928M928AlM928A2M929M929AlM929A2M930M930AlM930A2M931M93lAlM931A2M932M932AlM932A2M934M934AlM934A2M936M936AlM936A2BRYBSSBS7BRTBSTBS8BRVBSWBS9BRUBSXBTMBTHBSYBTNBTGBSZBTOBTEBS2BTPBTDBS5BTQBTBBS4BTRBTFBS6BTT2320-01-050-20842320-01-206-40872320-01-230-03072320-01-047-87712320-01-206-40892320-01-230-03092320-01-047-87692320-01-206-40882320-01-230-03082320-01-047-87562320-01-206-40792320-01-230-03052320-01-047-87702320-01-206-40902320-01-230-03102320-01-047-87532320-01-206-40772320-01-230-03022320-01-047-87552320-01-206-40802320-01-230-03062320-01-047-87502320-01-205-26822320-01-230-03002320-01-047-87522320-01-205-26842320-01-230-03032320-01-047-87542320-01-206-40782320-01-230-0304REPORTINGOFERRORSANDRECOMMENDINGIMPROVEMENTSYoucanhelpimprovethismanual.Ifyoufindanymistakesorifyouknowofawaytoimprovetheprocedures,pleaseletusknow.MailyourletterorDAForm2028(RecommendedChangestoPublicationsandBlankForms),orDAForm2028-2locatedinbackofthismanual,directlyto:Director,ArmamentandChemicalAcquisitionandLogisticsActivity,ATTN:AMSTA-AC-NML,RockIsland,IL61299-7630.Areplywillbefurnishedtoyou.YoumayalsoprovideDAForm2028-2informationviadatafaxore-mail:E-mail:am&a-ac-nml.@ria-emh2.army.milFax:DSN783-0726orcommercial(309)782-0726DISTRIBUTIONSTATEMENTA-Approvedforpublicrelease;distributionisunlimited.iTM9-2320-272-24-1*ThispublicationsupersedesTM9-2320-272-20-1,24October1985,andchanges1through4;TM9-2320-272-20-2,25October1985,andchanges1through3;TM9-2320-272-34-1,10June1986,andchanges1through2;TM9-2320-272-34-2,10June1986,andchanges1and2;andTM9-2320-358-24&P,21October1992.Thispublicationispublishedinfourvolumes.TM9-2320-272-24-1containschapters1,2,and3(throughsectionIX).TM9-2320-272-24-2containschapters3(sectionsXthroughXVI)and4(sectionsIthroughIII).TM9-2320-272-24-3containschapter4(sectionsIVthroughXVI).TM9-2320-272-24-4containschapters5and6andappendicesAthroughH.Volume1containsatableofcontentsfortheentiremanual.Volumes1,2,and3containanalphabeticalindexcoveringtasksfoundintheirrespectivevolume.Volume4containsanalphabeticalindexcoveringalltasksfoundintheentiremanual.CHAPTER 1Section I.SectionII.SectionIII.CHAPTER 2SectionI.SectionII.SectionIII.SectionIV.CHAPTER 3Section I.SectionII.SectionIII.SectionIVSectionV.Section VI.SectionVII.SectionVIII.SectionIXSectionX.Section XI.SectionXII.SectionXIII.SectionXIVSection XVSectionXVI.TABLE OF CONTENTSVOLUME 1 OF 4HOWTOUSETHISMANUALPage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vINTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l - lGeneralInformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l - lEquipmentDescriptionandData . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l-5PrinciplesofOperation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l-25SERVICEANDTROUBLESHOOTINGINSTRUCTIONS. . . . . . . . . . . . . . . . . . 2-lRepairParts;Tools;SpecialTools;Test,Measurement,andDiagnosticEquipment(TMDE);andSupportEquipment . . . . . . . . . . . . . . . . . . . . . . 2-lServiceUponReceipt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-lPREVENTIVEMAINTENANCECHECKSANDSERVICES(PMCS). . . . . . . . 2-2UNITTROUBLESHOOTINGPROCEDURES. . . . . . . . . . . . . . . . . . . . . . . . . . . 2-60UNITMAINTENANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-lEngineSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-lAirIntakeSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-41FuelSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-55ExhaustSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-139CoolingSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-149ElectricalSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-220TransmissionandTransferCaseMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-353PropellerShafts,Axles,andSuspensionSystemMaintenance . . . . . . . . . . . . . . . . . . . . . 3-403CompressedAirandBrakeSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-476Wheels,Hubs,Drums,andSteeringMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-615FrameMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-683Body,Cab,andAccessoriesMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-730WinchandPowerTakeoff(PTO)Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-823SpecialPurposeBodiesMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-869SpecialPurposeKits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-968CentralTireInflationSystem(CTIS)Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1231iiTM9-2320-272-24-1TABLEOFCONTENTS(Contd)CHAPTER 4SectionI.SectionII.SectionIII.SectionIVSectionVSection VI.SectionVII.SectionVIII.SectionM.Section X.Section XI.Section XII.SectionXIII.SectionXIV.Section XVSectionXVI.PageDIRECTSUPPORT(DS)MAINTENANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-lDirectSupport(DS)andGeneralSupport(GS)MechanicalTroubleshooting . . . . . . . . . . 4-1PowerPlantMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-35Engine(M939lAl)Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-117Engine(M939A2)Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-271CoolingSystemMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-352ElectricalSystemMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-388TransmissionMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-465TransferCaseMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-504FrontandRearAxleMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-548CompressedAirandBrakeSystem. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-584PowerSteeringSystemMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-605FrameMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-681Body,Cab,andHoodMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-691SpecialPurposeBodiesMaintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-715Winch,Hoist,andPowerTakeoff(PTO)Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-808SpecialPurposeKitsMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1002CHAPTER5 GENERALSUPPORT(GS)MAINTENANCEINSTRUCTIONS . . . . . . . . . . . . . 5-lSectionI. Engine(M939/Al)Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-lSectionII. Engine(M939A2)Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-157SectionIII. TransmissionMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-280SectionIV. TransferCaseMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-398Section V. FrontandRearAxleMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5432Section VI. SpecialPurposeBodiesMaintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-463Section VII. Winch,Hoist,andPowerTakeoff(PTO)Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-606CHAPTER6 SHIPMENTANDLIMITEDSTORAGEINSTRUCTIONS. . . . . . . . . . . . . . . . . 6-lSection I. GeneralPreparationofVehicleforShipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-lSectionII. LoadingandMovement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2SectionIII. LimitedStorage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2APPENDIX AAPPENDIX B. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-lMAINTENANCEALLOCATIONCHART. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-lSectionI. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-lSectionII. MaintenanceAllocationChart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-4SectionIII. ToolandTestEquipmentRequirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-25SectionIV Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-26REFERENCESAPPENDIXCSectionI.SectionII.EXPENDABLE/DURABLESUPPLIESANDMATERIALSLIST. . . . . . . . . . . . C-lIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-lExpendable/DurableSuppliesandMaterialsList. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3APPENDIXD MANDATORY REPLACEMENT PARTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D-liiiTM9-2320-272-24-1APPENDIXECOMMONANDSPECIALTOOLIDENTIFICATIONLIST. . . . . . . . . . . . . . . . E-lAPPENDIXF ILLUSTRATEDLISTOFMANUFACTUREDITEMS. . . . . . . . . . . . . . . . F-lAPPENDIX G TORQUE LIMITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G-lAPPENDIXH SCHEMATICANDWIRINGDIAGRAMS . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .H-1ivTM9-2320-272-24-lHOWTOUSETHISMANUALABOUTYOURMANUALSpendsometimelookingthroughthismanual.Youllfindthatithasanewlook,differentthanmostTMsyouvebeenusing,includingitspredecessors,TM9-2320-272-20-1,TM9-2320-272-20-2,TM 9-2320-272-34-1, TM 9-2320-272-34-2, and TM 9-2320-358-24&P.Newfeaturesaddedtoimprovetheconvenienceofthismanualandincreaseyourefficiencyare:a. AccessingInformation-Theseincludephysicalentryfeaturessuchasthebleed-to-edgeindicatorsonthecoverandedgeofthemanual.Extensivetroubleshootingguidesforspecificsystemsleaddirectlytostep-by-stepdirectionsforproblemsolvingandmaintenancetasks.b. Illustrations-Avarietyofmethodsareusedtomakelocatingandfixingcomponentsmucheasier.Locatorillustrationswithkeyedtext,explodedviews,andcut-awaydiagramsmaketheinformationinthismanualeasiertounderstandandfollow.c. Commonality-Onlyitemsthatareuniquetoaspecificseriesorvehiclewillbegivenaseparateprocedure.Whenonlyminordifferencesoccur,notesareaddedtotellyoutoalterthenormalprocedureinonewayoranothertoaccommodatethedifferences.d. KeyingTextwithIllustrations-Instructions/textarelocatedtogetherwithillustrationsofthespecifictaskyouareperforming.Inmostcases,thetaskstepsandillustrationsarelocatedonfacingpages,withtextontheleftandillustrationsontheright.Continuereadingforanexampleofmodulartextandillustrationlayout,HOWTOUSETHISMANUALHeresanexampleofhowtouseyourmanual:Task:TheunitmaintenancemechanicofanM939seriesvehiclereportsthattheenginecranksbutfailstostart.Troubleshootingsteps: 1. Lookatthecoverofthismanual.Youllseesubjectslistedfromtoptobottomontheright-handside.2. Lookattherightedgeofthemanual.Onsomeofthepagesyoullseeblackbars(edgeindicators)thatarealignedwiththesubjectbarsonthecover.Thesearethelocationsofthesubjectsinthemanual.3. LookforUNITTROUBLESHOOTINGinthesubjectlistonthecover,4. TurntothepagewiththeedgeindicatormatchingthesubjectbarforUNITTROUBLESHOOTING.Pagenumbersarealsolistednexttothesubjecttitles.5. AnedgeindicatorisplacedonthefirstpageoftheUNITTROUBLESHOOTING.NOTEIfthefirstpageofasubjecthasaneven-numberedpage,itwillappearonyourleft,buttheedgeindicatorwillstillbeonthepagetoyourright.So,iftheinformationyouarelookingfordoesnotstartonthepagetoyourright,itwillonthepagetoyourleft.6. LookdownthelistuntilyoufindENGINE.Beneaththatheadingyouwillfindthesymptomsnotedbythemaintenancemechanic:Enginecranks,failstostart.7. Turntothepageindicated:page2-9.8. Onpage2-9,steps/testrelatingtoresolvingthemalfunctionofEnginecranks,failstostart,are:Step1.Youinspectthefuelpumpshutoffvalveandfinditisdefectiveandmustbereplaced.Youseepara.4-6referenced.Step2.Therestoftheinspectionshowsnoothercausefortheproblem.9. Locatepara.4-5,andyouwillfindthedetailedprocedureforremovingtheoldfuelpumpshutoffvalveandreplacingitwithanewone.vTM9-2320-272-24-1HOWTOUSETHISMANUAL(Contd) NOTEBeforestartingthemaintenancetask,lookthroughtheentireproceduretofamiliarizeyourselfwithit.a.Theentireprocedure(4-5.FUELPUMPSHUTOFFREPLACEMENT),accordingtotheTHISTASKCOVERSheader,includes:a.Removalandb.Installation.b. TheninebasicsubheadingslistedunderINITIALSETUPoutlinethetaskpreconditions,materials,tools,manpowerrequirements,andgeneralsafetyinstructions.Theyare:APPLICABLEMODELS:Anymodelsthatrequirethatparticularmaintenancetask.TESTEQUIPMENT:Testequipment needed to complete a task.SPECIALTOOLS:Thosetoolsrequiredtocompletethetask.MATERIALS/PARTS:Allpartsormaterialsrequiredtocompletethetask.PERSONNELREQUIRED:Thenumberandtypeofpersonnelneededtoaccomplishatask.NOTEIfyouthinkyouneedmorehelptocorrectlyorsafelycompletethetask(perhapsasaresultofanunusualcondition,etc.),alertyoursupervisorandaskforhelp.REFERENCES(TM):Thosemanualsrequiredtocompletethetask.EQUIPMENTCONDITIQNNotestheconditionsthatmustexistbeforestartingthetask.For(4-5.FUELPUMPSHUTOFFREPLACEMENT),thehoodmustberaisedandsecured(TM9-2320-272-10),andtheleftsplashshieldremoved(TM9-2320-272-10).SPECIALENVIROMENTALCONDITIONS:Outlinesspecificenvironmentalconditionsnecessarytoperformthetask.Forexample:Darkenanareawhenadjustingheadlightbeams.GENERALSAFETYINSTRUCTIONS:Summarizesallsafetywarningsforthemaintenancetask.c. Astep-by-stepmaintenanceprocedurefollowstheINITIALSETUP.d. Attheendoftheprocedure,FOLLOW-ONTASK(S)willlistthoseadditionaltask(s)thatmustbeperformedtocompletetheprocedure.Thefollow-ontasksfor4-5.FUELPUMPSHUTOFFREPLACEMENTare:Startengine(TM9-2320-272-10),checkfuelpumpshutoffvalveforproperoperation (TM 9-2320-272-101, install left. splash shield (TM 9-2320-272-10), and lower and securehood(TM9-2320-272-10X10. Refertoourexampleprocedure,4-5.FUELPUMPSHUTOFFREPLACEMENTaswereviewthefollowingpoints:a. ModularText:Bothpagesoftextandillustrationsaretobeusedtogether.Thismanualwasdesignedsothatthetwopagesarevisibleatonce,makingpartidentificationandproceduresequenceeasytofollow.b.InitialSetup:Outlinestaskconditions.c. Illustrations:Anexplodedviewofthecomponentsremovedfromthevehicleshowspartlocations,attachments,andspatialrelationships.11. RefertoTM9-2320-272-24P,Unit,DirectSupport,andGeneralSupportMaintenanceRepairPartsandSpecialToolsListforTruck,5-Ton,6x6,M939,M939A1,M939A2SeriesTrucks,whenrequisitioningpartsandspecialtoolsforUnit,DirectSupport,andGeneralSupportmaintenance,12. Yourmanualiseasiertouseonceyouunderstanditsdesign.Wehopeitwillencourageyoutouseitmoreoften.viTM9-2320-272-24-1CHAPTER1INTRODUCTIONSectionI. GeneralInformation(page1-1)SectionII. EquipmentDescriptionandData(pagel-5)SectionIII. PrinciplesofOperation(page1-25)SectionI.GENERALINFORMATION1-1. SCOPE a. Thismanualcontainsinformationandinstructionsneededtoserviceandmaintain5-ton,6x6,M939,M939A1,andM939A2(M939/A1/A2)seriesvehiclesbyunit,directsupport,andgeneralsupportmaintenancepersonnel.ThismanualisintendedtobeusedinconjunctionwithTM9-2320-272-10andTM9-2320-272-24Pforoverallcompletionoftasksfoundinthismanual.b. Thevehiclemodelnumbersanddescriptionofvehiclescoveredinthismanualare:Table 1-1. Vehicle Cross-Reference Table.VEHICLEDESCRIPTIONTruck,Cargo,Dropside,Without Winch (WO/W)Truck,Cargo,Dropside,With Winch (W/W)Truck,Cargo,ExtraLongWheelbase(XLWB),Without Winch (WO/W)Truck,Cargo,ExtraLongWheelbase(XLWB),WithWinch(W/W)Truck,Dump,Without Winch (WO/W)Truck,Dump,With Winch (W/W)Truck,Tractor,Without Winch (WO/W)Truck,Tractor,With Winch (W/W)Truck,Van,ExpansibleTruck,MediumWreckerM939SERIES M939Al SERIES M939A2SERIESM923(EIC:BRY) M923Al(EIC:BSS) M923A2(EIC:BS7)M925(EIC:BRT) M925Al(EIC:BST) M925A2(EIC:BS8)M927(EIC:BRV) M927Al(EIC:BSW) M927A2(EIC:BS9)M928 (EIC: BRU) M928Al (EIC: BSX) M928A2(EIC:BTM)M929 (EIC: BTH) M929Al (EIC: BSY) M929A2 (EIC: BTN)M930(EIC:BTG) M930Al(EIC:BSZ) M930A2(EIC:BTOM931 (EIC: BTE) M931Al(EIC:BS2) M931A2 (EIC: BTP)M932(EIC:BRD) M932Al(EIC:BS5) M932A2(EIC:BTQ)M934(EIC:BTB) M934Al(EIC:BS4) M934A2(EIC:BTR)M936 (EIC: BTF) M936Al(EIC:BS6) M936A2(EIC:BTT)1-2.MAINTENANCEFORMS,RECORDS,ANDREPORTSDepartmentoftheArmyformsandproceduresusedforequipmentmaintenancewillbethoseprescribedbyDAPam738-750,TheArmyMaintenanceManagementSystem(TAMMS).l - lTM9-2320-272-24-1 1-3. DESTRUCTION OF ARMY MATERIEL TO PREVENT ENEMY USE ProceduresfordestructionofArmymaterieltopreventenemyusecanbefoundinTM750-244-6. 1-4. PREPARATION FOR STORAGE OR SHIPMENT Storageandshipmentinstructionsarefoundinchapter6.AdditionalinformationcanbefoundinTM740-90-1,Marking,Packing,andShipmentofSuppliesandEquipment:GeneralPackagingInstructionsforFieldUse.l-5.OFFICIALNOMENCLATURE Thenomenclature,names,anddesignationsusedinthismanualareinaccordancewithMIL-HDBK-63038-2.l-6.REPORTINGEQUIPMENTIMPROVEMENTRECOMMENDATIONS(EIRs);REPORTINGOFERRORSANDRECOMMENDINGIMPROVEMENTSYoucanhelpimprovethismanual.Ifyoufindanymistakesorifyouknowofawaytoimprovetheprocedures,pleaseletusknow.Mailyourletter,DAForm2028(RecommendedChangestoPublicationsandBlankForms),orDAForm2028-2locatedinbackofthismanualdirectto:Commander,U.S.ArmyTank-automotiveandArmamentsCommand,ATTN:AC-NML,RockIsland,IL61299-7630.Areplywillbefurnishedtoyou.1-7.WARRANTYINFORMATIONThe5-ton,6x6,M939/AlseriesvehicleCumminsengine(modelNHC250)andAllisontransmission(modelMT564CR)arewarrantedinaccordancewithTB9-2300-295-15/21.Thewarrantystartsonthedatefoundinblock23,DAForm2408-9,inlogbook.Reportalldefectsinmaterialorworkmanshiptoyoursupervisor,whowilltakeappropriateaction.1-8.ARMYPETROLEUM,OILS,ANDLUBRICANTS(POL) Properdisposalofhazardouswastematerialisvitaltoprotectingtheenvironmentandprovidingasafeworkenvironment.Materialssuchasbatteries,oils,andantifreezemustbedisposedofinasafeandefficientmanner.Thefollowingreferencesareprovidedasameanstoensureproperdisposalmethodsarefollowed:TechnicalGuideNo.126(fromtheU.S.ArmyEnvironmentalHygieneAgency)NationalEnvironmentalPolicyActof1969(NEPA)Clean Air Act (CAA)ResourceConservationandRecoveryAct(RCRA)ComprehensiveEnvironmentalResponse,Compensation,andLiabilityActEmergencyPlanningandCommunityRighttoKnowAct(EPCRA)ToxicSubstancesControlAct(TSCA)OccupationalHealthandSafetyAct(OHSA)ThedisposalofArmyPetroleum,Oils,andLubricants(POL)productsareaffectedbysomeoftheseregulations.StateregulationsmayalsobeapplicabletoPOL.Ifyouareunsureofwhichlegislationaffectsyou,contactstateorlocalagenciesforregulationsregardingproperdisposalofArmyPOL.l-2TM9-2320-272-24-11-9.USEOFMETRICSYSTEMTheequipment/systemdescribedhereincontainsmetriccommonandspecialtools;therefore,metricunitsinadditiontoU.S.standardunitswillbeusedthroughoutthispublication.1-10.LISTOFABBREVIATIONSAOAP-ArmyOilAnalysisProgrambx-boxCAGEC-CommercialandGovernmentEntityCodecm-centimeterCTIS-CentralTireInflationSystemcu-ft-cubicfeetcu-yd-cubicyardcuM-cubicMeterea-eachft-feetGM-Grease,AutomotiveandArtilleryGTW-GrossTowedWeightgal.-gallonin. inchkg-kilogramskm/h-kilometersperhourkm/L-kilometersperliterkPa-kiloPascalL-literlb-ft-pound-feetlb-poundmax-maximummin-minimum1-11.GLOSSARYmm-millimetermpg-milespergallonmph-milesperhourNm-NewtonmeterNATO-NorthAtlanticTreatyOrganizationOZ-ouncepara.-paragraphPMCS-PreventiveMaintenanceChecksandServicesPOL-Petroleum,Oils,andLubricantspsi-poundspersquareinchpt-pintPTO-PowerTakeoffqt-quartrpm-revolutionsperminuteSEA-Standard,Engineering,andAutomotiveTMDE-Test,Measurement,andDiagnosticEquipmentU/M-UnitofMeasureW/W-WithWinchWO/W-WithoutWinchXLWB-ExtraLongWheelbaseAPPROACHANGLE-AnglebetweenfronttireandfrontbumperDEPARTUREANGLE-AnglebetweenreartireandrearbumperFORDING-CrossingthroughwaterGRADE-SteepnessofterrainHYDRAULIC-OperatedbyoilpressureOPERATOR-DriverofvehiclePAULIN-Canvascoverortarpaulin(tarp)SLAVING-Jumpstarting1-3/( 1-4blank)TM9-2320-272-24-1SectionII.EQUIPMENTDESCRIPTIONANDDATAl-l2.EQUIPMENTDESCRIPTIONANDDATAINDEX PARA.NO.1-13.1-14.1-15.TITLEEquipmentCharacteristics,Capabilities,andFeaturesLocationandDescriptionofMajorComponentsDifferencesBetweenModelsPAGENO.1-51-16l-201-16. EquipmentData1-17. DescriptionofDataPlates1-22l-241-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURESa. TheM939,M939A1,andM939A2(M939/A1/A2)seriesofvehiclesarevariedindesignandcapabilities.TheM939wasaredesignandretrofitoftheMS09seriesofvehicles,providingenhancedcapabilities.(1)TheleadingfeaturesoftheM939are:(a) Automatictransmission(AllisonMT654)(b)Hydraulic-assistedpowersteeringsystem(c)Completeairbrakesystem(d)Improvedcoolingsystem(e)Three-crewmembercab(f)Tilthood(2)Changeswereincorporatedintolaterproductionengines(afterengineserialnumber11246663)whichprovidedforcontrolofexhaustgasrecirculationbacktotheairintakemanifoldandtheuseoftop-stopinjectorstomakeupacleanairconfiguration.(3)TheM939AlimprovedontheM939byadding14:00xR20super-sizedtires,increasingtheminimumroadclearanceandapproachanddepartureangle.Thisnecessitatedamodificationtothesparetirerackandliftingdeviceusedonallseriesvehicles.(4)TheM939A2incorporatedanewengine(Cummins6CTA8.3)andtheCentralTireInflationSystem(CTIS).b. TheM939/A1/A2seriesvehiclescanbedistinguishedfromtheM809seriesbythefollowingfeatures:(1)Ontheleftside,theexhaustwasmovedbehindthecabandtiltedoutsoexhaustgasesclearthesideofthevehicle.Hoodlatcheswereinstalledonthesidesofthehoodnearthemirrors.Thebatteryboxwasincorporatedintothecompanionseattoimprovebatterylifeincoldclimates.Asteering-assistcylinderwasinstalledbetweentherightfrontframerailandtherightaxlehub.(2)Fromthefront,thehoodandfendersareanassemblywhichtiltforwardforaccesstotheenginecompartment.Atilthandleandlockingdevicewasinstalledtotiltandholdthehoodinasecuredopenposition.(3)Theairfilterwasmovedunderthedriversdoorandtheintakestackwasbroughtupbehindthecab,evenwiththecabtop.1-5TM9-2320-272-24-11-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)c. CargoTrucksWithDropsides:M923/A1/A2WO/WandM925/A1/A2W/W.PURPOSE:Thesemodelsareusedtotransportcargoandtroops.Thevehicleshaveapayloadratingof10,000lbs(4,540kg)andprovide550cu-ft(15.4CuM)ofcargospace.Removabledropsidesandtailgatepermithaulingofextrawideloadsandeasyaccessforunloadingcargo.Troopseats,bows,andcanvasarealsoavailable.TheM925/A1/A2modelshavefrontwinchesandcanbeusedforrecoveryoperation.ThebedoftheM923A1/A2andM925Al/A2hasbeenshiftedbacktofacilitateanewliftingdavitandsparetiremount.WhenthetireismountedinitsstoragelocationontheM923A1/A2andM925Al/A2,thetopofthetireextendsabovetheminimalreducibleheightandmayneedtoberemovedtoobtainthenecessarymeasurement.1-6TM9-2320-272-24-11-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)1-7 TM9-2320-272-24-11-l3.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)d. CargotickWithExtraLongWheelbase(XLWB):M927/A1/A2WO/WandM928/A1/1A2W/W.PURPOSE:Thesemodelsareusedtotransporttroopsandlongercargoloads.TheyhavethesamecharacteristicsastheM923/Al/A2andM925/A1/A2,buthaveadditional76in.(193cm)ofbedspacethatallowsanextra194cu-ft(5.4cuM)ofcargospace.Troopseats,bow,andtarpaulinareavailable.Thisvehiclehaspermanentsteel-weldedsides.TheM928/A1/A2modelvehicleshavewinchesandcanbeusedforrecoveryoperations.ThebedoftheM923A1/A2andM925A1/A2hasbeenshiftedbacktofacilitateanewliftingdavitandsparetiremount.WhenthetireismountedinitsstoragelocationontheM923A1/A2andM925A1/A2,thetopofthetireextendsabovetheminimalreducibleheightandmayneedtoberemovedtoobtainthenecessarymeasurement.1-8TM9-2320-272-24-11-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)1-9 TM9-2320-272-24-11-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)e. Dump Truck: M929/A1/A2 WO/W and M930/A1/A2 W/W.PURPOSE:Thesemodelsareforhaulinganddumpingcargo.Theyhaveacapacityof5cu-yd(3.84cuM).Thebodieshaveprovisionsforsideracksandtroopseats,andbowandtarpaulinfortrooptransport.TheM930/A1/A2havefrontwinchesandcanbeusedforrecoveryoperations.AdditionalsupportbracketshavebeendesignedontheM929A1/A2andM930A1/A2modelvehiclesandareavailabletosupportthebedinaslightlyraisedpositionforremovalofthe14:00xR20sparetire.1-10TM9-2320-272-24-11-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)1-11TM9-2320-272-24-11-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)f. Tractor Trucks: M931/A1/A2 WO/W and M932/A1/1A2 W/W.PURPOSE:Thesevehiclesareequippedwithafifthwheelandareusedforhaulingsemitrailers.Thefifthwheeliscapableofpivoting21degreesup,15degreesdown,or7degreessideways.TheM932/A1/A2modelvehicleshavefrontwinchesandcanbeusedforrecoveryoperations.1-12TM9-2320-272-24-1l-13. EQUIPMENT CHARACTERISTICS, CAPABILITIES, AND FEATURES (Contd)1-13TM9-2320-272-24-11-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd)g.ExpansibleVans:M934/A1/A2.PURPOSE:Thesevehiclesareusedforelectronics,maintenance,supply,power,andbasestationoperation.Thevanbodycanbeexpandedwhensetupinastationarymodeofoperation;whenmissionrequiresmoremobile-typeoperation,thebodyisleftintheretractedposition.1-14TM9-2320-272-24-l1-13.EQUIPMENTCHARACTERISTICS,CAPABILITIES,ANDFEATURES(Contd) h.MediumWrecker:M936/Al/A2.PURPOSE:Thesevehiclesareusedforwreckerandsalvageoperations.Theyhavearevolvinghydrauliccranewithaself-supportedextendableboom.Boom-to-groundsupportsandoutriggersareprovided.Craneliftingcapacityis20,000lb(9,080kg).Thevehiclehasafrontwinchwitha20,000lb(9,080kg)capacity.M936/A1modelsareequippedwithfrontanchorbracketsforheavystraightandsidepullsusingthefrontwinch.Allmodelsareequippedwitha45,000lb(20,250kg)capacityrearwinch,rearanchorbracketsforheavystraightandsidepulls,andspringbrakeoverrideofthePowerTakeoff(PTO)airswitchforself-recoveryoperations.1-15TM9-2320-272-24-11-14.LOCATIONANDDESCRIPTIONOFMAJORCOMPONENTS a. ExteriorComponents.Thecomponentsdescribedhereinarecommontomostvehiclescoveredinthismanual.SpecificdifferencescanbefoundinTM9-2320-272-10orintable1-2,DifferencesBetweenModels(para.1-15),ofthismanual.LIFTINGSHACKLE(S)ENGINETRANSMISSIONPRIMARY AND SECONDARY AIRRESERVOIRSTRANSFERCASEWETTANKRESERVOIRREARPROPELLERSHAFT(S)UNIVERSALJOINT(S)SERVICEBRAKECHAMBERREARBOGIESPRINGBRAKECHAMBERTOWINGPINTLEREARDIFFERENTIAL(S)FUELTANK(S)SPARETIRECARRIERAIRCLEANER1-16TM9-2320-272-24-1 1-14. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (Contd) Key12 3 4 5 6 78910111213141516ItemandFunctionLIFTINGSHACKLE(S)-Permitvehicletobetowedbyanothervehicleorusedfortiedownattachmentwhentransportingvehicle.ENGINE-TherearetwodifferentCumminsmodelenginesused,theNHC250(M939/A1seriesvehicles)and6CTA8.3diesel(M939A2seriesvehicles),whichprovidemechanicalpowertothevehicleandengine-drivensubsystems.TRANSMISSION-TheAllisonMT546CRautomatic,usedonallM939/A1/A2seriesvehicles,adaptstheenginesoutputforavaryingrangeofoperatingspeeds.PRIMARYANDSECONDARYAIRRESERVOIRS-Providesstorageofcompressedairandisolationbetweenairsubsystems.TRANSFERCASE-Directstheengineandtransmissionoutputtothespecifiedaxlesand/orauxiliaryequipment.WETTANKRESERVOIR-Providesreservestorageofcompressedaircreatedbytheaircompressororexternalsourcewhendemandislowandreleasesitwhenrequired.Thislessensthecyclingoftheengine-drivenaircompressor.REARPROPELLERSHAFT(S)-Transmitspowerbetweentransfercaseandforward-rearaxleassemblies,andbetweenforward-rearandrear-rearaxlesassemblies.UNIVERSALJOINT(S)-Providesaflexiblepointbetweenacomponentandthepropellershafts.Thisallowscomponentsthatcannotmaintainprecisionalignmenttotransferpowerfromonepointtoanother,withoutunduestressorbreakage.SERVICEBRAKECHAMBER-Mechanicalbrakeactuatorthatisactivatedbyapplyingairpressuretoanexpandablecylinder,causingittoapplybrakingforcetothebrakedrum.REARBOGIE-Thesuspensionsystemcomprisedofbothrearaxles,upperandlowertorquerods,springs,andseatsthatsupporttherearvehicleweight.SPRINGBRAKECHAMBER-Mechanicalbrakeactuatorthatisspring-loadedtoapplybrakeswhenairislowornotpresent.Duringnormalvehicleoperation,airpistoncounteractsthespringtensionandallowsthebrakestorelease.SpringbrakescanbebypassedbypushinginthespringbrakeOVERRIDEswitchontheinstrumentpanel,orreleasedusingproceduresfoundinTM9-2320-272-10.TOWINGPINTLE-Providesasecurequick-connect/disconnectfortowingvehiclesorequipment.REARDIFFERENTIAL(S)-Bi-directionallytransferpowerfromthepropellershafttotheaxles,andprovideastraight-throughconnectiontopoweradditionalpropellershafts.FUELTANK(S)-Providesstorageoffuel.SPARETIRECARRIER-Storessparetire.Davi t - UsedtoloadandunloadsparetireonM923/A1/A2,M925/A1/A2,M927/A1/A2,M928/A1/A2,M931/A1/A2,andM9321/A1/A2modelvehicles.WinchandSwingingDavit-UsedtoloadandunloadsparetireonM934A1/A2modelvehicles.OptionalkitisavailableforM934modelvehicle.HoistandLiftingEye-UsedtoloadandunloadsparetireonM929/A1/A2,M930/A1/A2,andM934modelvehicles.Optionalkitisavailabletosupportdumpbedinsemi-raisedpositionduringtireremoval.VehicleCrane-UsedtoloadandunloadsparetireonM936/A1/A2modelvehicles.NOTE:OnM936/A1/A2modelvehicles,removesparetirepriortochangingtire,andinstalltireinsparetirecarrieraftertirechangeiscomplete.Operationofcraneand/orvehicleenginewhilevehicleisonjacksmaycausethevehicletoslipoffjack.AIRCLEANER-Filtersairbeforeitenterstheintakemanifoldorturbochargerandcollectsdustinremovablesectionoffiltercanister.1-17TM9-2320-272-24-1 1-14. LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (Contd) b. InteriorCabComponents.Thecomponentsdescribedhereinarecommontooneormorevehiclescoveredinthismanual.ComponentsnotfoundherecanbefoundinTM9-2320-272-10orintable1-2,DifferencesBetweenModels(para.1-15),ofthismanual.KeyItemandFunction1 FRONT-WHEELDRIVELOCK-INSWITCH-Apneumaticswitchthatpermitsfront-wheeldrivetobeengagedwhenthetransfercaseisinHIGHposition.OperationofswitchisnotrequiredwhentransfercaseisinLOWposition;systemwillautomaticallyswitchintosix-wheeldrive.1-18TM9-2320-272-24-11-14LOCATIONANDDESCRIPTIONOFMAJORCOMPONENTS(Contd)Key23456 7 8 9 10111213141516171819ItemandFunctionPOWERTAKEOFF(PTO)SPRINGBRAKEOVERRIDESWITCH-Usedduringrearwinchself-recoveryoperationsofM936/A1/A2modelvehiclesonly.ThisaircontrolswitchmustbeheldintooverridespringbrakeairdumpswitchontransfercasePTOlever.INSTRUMENTPANEL-Housescontrolsandindicators.TRANSMISSIONSELECTORLEVER-Manualcontroltoselectdrivinggear.SPRINGBRAKEOVERRIDESWITCH-Pressedintoreleasespringbrakesindependentofthemechanicalparkingbrakefortestsandadjustments.Canbeusedtoreleasespringbrakesintheeventaleakorstoppageoccursinlinesbetweenprimaryandspringbrakereservoirs,orprimarysystemairshutoffvalveisclosed.TRANSMISSIONPOWERTAKEOFF(PTO)LEVER-UsedonM925/A1/A2,M928/A1/A2,M929/A1/A2,M930/A1/A2,M932/A1/A2,andM936/A1/A2modelvehiclesonly.Provideshydraulicpowerforfrontwinchand/ordumpbodyoperation.WINCHCONTROLLEVER-Providescontrolofwinchunwindingandwindingoperationsfrominsidethecab.TRANSFERCASESHIFTLEVERSWITCH-UsedinconjunctionwithtransmissionselectorleverinNEUTRALpositiontoallowtransfercasetobeshiftedbetweenHIGHandLOWgears.PASSENGERSEAT-Combinationtwo-personcrewseat,batterybox,andstoragebox.Seatsareequippedwithtwosetsofseatbelts,thebatteryboxhousesfourbatteries,andthestoragecompartmentstorestechnicalmanuals.NOTE:Ensurecompanionseatbeltsarenotcaughtinsidebatterybox.TRANSFERCASESHIFTLEVER-PusheddowntoshifttransfercaseintoHIGHgear,centerpositionforNEUTRAL,anduppositionforLOWgear.WhentransfercaseisplacedinLOW,itwillautomaticallyengagesix-wheeldrive.InHIGH,theinstrumentpanel-mountedfront-wheeldrivelock-inswitchmustbeusedtoachievesix-wheeldriveoperation.SPRINGBRAKECONTROLSWITCH-Sensesthepositionoftheparkingbrakecontrolleverandsignalsthespringbrakestoengagewhentheleverisupanddisengagewhenitisdown.Springbrakescanbetestedindependentlyfromparkingbrakebyraisingthisswitchwithoutpullinguptheparkingbrakecontrollever(TM9-2320-272-10).(a)DUMPBODYCONTROLLEVER-UsedonM929/A1/A2andM930/A1/A2tocontrolraising(pulledback)andlowering(pushedforward)ofdumpbody.(b)TRANSFERCASEPOWERTAKEOFF(PTO)-Used onM936/A1/A2tocontrolthehydraulicpumpthatdelivershydraulicpressuretotherearwinchandcrane.Aspringbrakeairdumpswitchisinstalledontheleverwhenusedonthesevehicles,whichengagesthespringbrakes.Tooverridethisfeatureduringself-recoveryoperationwiththerearwinch,thedrivermustdepressandholdthePTOspringbrakeoverrideairswitchontheinstrumentpanel.DUMPBODYCONTROLLEVERSAFETYLATCH-SecuresdumpbodycontrolleverortransfercasePTOinNEUTRALwhennotinuse.FUELTANKSELECTORLEVER-Usedondualtankmodelvehiclesonly.NOTE:Tanksmustbeswitchedperiodicallytolessenthebuildupofcontaminantsandfungus.PARKINGBRAKECONTROLLEVER-Pulleduptosetmechanicalbrakeonoutputoftransfercaseandtoengagethespringbrakes,anddowntodisengagebrakes.Knobontopofhandleisturnedclockwisetoincreasebrakingactionontheoutputoftransfercase,andcounterclockwisetodecreasebrakingaction.Springbrakesengagementiscontrolledbythespringbrakecontrolswitchlocatedonthebackofthelever.ACCELERATORPEDAL-Footcontroltovarythespeedoftheengine.BRAKEPEDAL-Appliestheservicebrakes.DIMMERSWITCH-DepressedtochangebetweenHIGHandLOWbeamsettingonheadlights.FUELGAUGETANKSELECTORSWITCH-Usedtoswitchfuelgaugetoreadeitherleftorrightfueltank.Installedonlyondualtankmodelvehicles.1-19TM9-2320-272-24-11-15. DIFFERENCES BETWEEN MODELSTable 1-2. Differences Between Models.EQUIPMENT/FUNCTIONBODYTYPECargoDropsideCargoFixedSide(XLWB)CraneDumpTractorVanCENTRALTIREINFLATlONSYSTEMFIELDCHOCKSANDANCHORSFrontRearFLOODLIGHTSFUELTANKSDualTanks116gal.(439.1L)DualTanks139gal.(526.1L)SingleTank81gal.(306.6L)HEAT/AIRCONDlTlONEDBODYOPERATIONSCargo/PersonnelCommunications/ElectronicRepairDumpVEHICLEM923, M923A1, M923A2, M925,M925A1,M925A2M927, M927A1, M927A2, M928,M928A1,M928A2M936, M936A1, M936A2M929, M929A1, M929A2, M930,M930A1, M930A2M931, M931A1, M931A2, M932,M932A1,M932A2M934, M934A1, M934A2M923A2,M925A.2,M927A2,M928A2, M929A2, M930A2,M931A2, M932A2, M934A2,M936A2M936,M936AlM936, M936A1, M936A2M936, M936A1, M936A2M929, M929A1, M929A2, M930,M930A1,M930A2,M931,M931AlM931A2, M932, M932A1, M932A2M936, M936A1, M936A2M923, M923A1, M923A2, M925,M925A1,M925A2,M927,M927A1,M927A2,M928,M928A1,M928A2,M934, M934A1, M934A2M923, M923A1, M923A2, M925,M925A1,M925A2,M927,M927A1,M927A2,M928,M928A1,M928A2,M929, M929A1, M929A2, M930,M930A1,M930A2,M934,M934A1,M934A2M934, M934A1, M934A2M929, M929A1, M929A2, M930,M930A1,M930A2FifthWheelWreckerOPERATIONSM931, M931A1, M931A2, M932,M932A1,M932A2M936, M936A1, M936A21-20TM9-2320-272-24-11-15.DIFFERENCESBETWEENMODELS(Contd)Table 1-2. Differences Between Models (Contd).EQUIPMENT/FUNCTION VEHICLETIRESll:00xR20M923, M925, M927, M928, M929,M930, M931, M932, M934, M93614:00xR20M923A1, M923A2, M925A1,M925A2, M927A1, M927A2,M928A1, M928A2, M929A1,M929A2, M930A1, M930A2,M931A1,M93IA2,M932A1,M932A2, M934A1, M934A2,M936A1,M936A2WHEELBASES167 in. (424.2 cm)M929, M929A1, M929A2, M930,M930A1,M930A2,M931,M93IA1,M931A2, M932, M932A1, M932A2179in.(454.7cm) M923, M923A1, M923A2, M925,M925A1, M925A2, M936, M936A1,M936A2215in.(546.1cm)M927, M927A1, M927A2, M928,M928A1, M928A2, M934, M934A1,M934A2FrontRearWINCHM925, M925A1, M925A2, M928,M928A1, M928A2, M930, M930A1,M930A2, M932, M932A1, M932A2,M936, M936A1, M936A2M936, M936A1, M936A21-21TM9-2320-272-24-ll-16.EQUIPMENTDATAVehicleperformancedatafortheM939/A1/A2seriesvehiclesarelistedintable1-3.AdditionalinformationandequipmentservicedataareinTM9-2320-272-10.Table 1-3. Vehicle Performance Data.STANDARD1. PAYLOADCarriedWeight:M923, M923A1, M923A2, M925, M925A1, M925A2, M927,M927A1, M927A2, M928, M928A1, M928A2, M929, M929A1,M929A2, M930, M930A1, M930A2.. . . . . . . . . . . . . . . . . . . . . . . . .M934, M934A1, M934A210,000 lb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .M936, M936A1, M936A25,000 lb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,000 lbTowedLoadonPintle:All(exceptM936,M936A1,M936A2). . . . . . . . . . . . . . . . . . . . . . . . . .M936, M936A1, M936A215,000lb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20,000lbOnFifthWheel:M929, M929A1, M929A2, M930, M930A1, M930A2 . . . . . . . . . . . . . . 15,000lbSemitrailerGTW:M929, M929A1, M929A2, M930, M930A1, M930A2 . . . . . . . . . . . . . . 37,500 lb2.CAPACITIESCoolingSystem:AllModels . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .4 7 q tDifferentials(Each):AllModels. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12qtEngine Crankcase Only:M9 3 9 / A l S e r i e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23qtM939A2Seri es. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 qtEngineCrankcaseandFilter:M939/AlSeries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27qtM939A2Seri es. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2OqtFuelTank:M923, M923A1, M923A2, M925, M925A1, M925A2, M927, M927A1,M927A2, M928, M928A1, M928A2, M934, M934A1, M934A2(SingleTank). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .M936,M936A1,M936A2DualTanks..81gal.. . . . . . . . . . . . . . . . . . . . . . . . . .M929, M929A1, M929A2, M930, M930A1, M930A2, M931, M931A1,116gal.M931A2, M932, M932A1, M932A2(DualTanks) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 9 g a l .HydraulicTank:M925, M925A1, M925A2, M928, M928A1, M928A2, M932, M932A1,M932A2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .M929,M929Al,M929A2... . 8gal .M930, M930A1, M930A2.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 g a 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .M936,M936Al,M936A2.6.25gal.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100galSteeringSystem:M939/AlSeries(Ross) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .M939A2Series(Sheppard).. 5 q t. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 q tMETRIC4,540kg2,270kg3,178kg6,810kg9,080kg6,810kg17,025 kg44.5 L11.3L21.8 L17.0L25.5 L18.9 L306.6 L439.1L526.1L30.3L18.9L23.7 L378.5L4. 7L2.83L1-22TM9-2320-272-24-ll-16.EQUIPMENTDATA(Contd)Table 1-3. Vehicle Performance Data (Contd).STANDARD METRICTransmission:AllModels(w/oPTO). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17qtAllModels(w/PTO). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 qtAllModels(w/oPTOandconverterdry). . . . . . . . . . . . . . . . . . . . . . . . . . . 23qtAllModels(w/PTOandconverterdry). . . . . . . . . . . . . . . . . . . . . . . . . . . 25qtTransferCase:AllModels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.25gal.WinchGearCase(Front):AllModels(W/W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. 6ptWinchGearCase(Rear):M936, M936A1, M936A2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 pt3.ENGINEM939/AlSeriesVehicles:BrakeHorsepower. . . . . . . . . . . . . . . . . . . . . . . . . 250horsepower@2,100rpmCylinders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6(in-line)FuelConsumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4mpgIdleSpeed(enginerpm) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 600-650rpmModel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CumminsNHC250Mount(Front). . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . ..TrunnionMount(Rear). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RubberbiscuitOilPressureatIdle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15psiOperatingSpeed(enginerpm) . . . . . . . . . . . . . . . . . . . . . . . . . 1,500-2,100rpmType . . . . . . . . . . . . . . . . . . . . . . . . . . Diesel,normally-aspirated,liquid-cooledM939A2 Series Vehicles:BrakeHorsepower. . . . . . . . . . . . . . . . . . . . . . . . . 240horsepower@2,100rpmCylinders.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..6(in-line)FuelConsumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.5-6-0mpgIdleSpeed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6 5 - 6 3 5 r p mModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cummins6CTA8.3Mount(Front). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..TrunnionMount(Rear). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RubberbiscuitOilPressureatIdle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10psiOperatingSpeed(enginerpm) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,100rpmType . . . . . . . . . . . . . . . . . . . . . Diesel,liquid-cooled,turbocharged,after-cooled4. COOLING SYSTEMM939/A1SeriesVehicles:CoolantOperatingTemperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175-195FFan,6-blade.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..26in.Thermostat:StartstoOpen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..175FFully Open. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . 185F16.1L18.0 L22.1 L23.7 L23.7 L1.2L3.3 L1.3-1.7 km/L103kPa2.3-2.6km/L69kPa79-91C660mm79C85CM939A2SeriesVehicles:CoolantOperatingTemperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190-200FFan,7-blade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..26.5in.Thermostat:88-93C673mmStarts to Open. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181F83CFullyOpen.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .203F95C1-23TM9-2320-272-24-1l-16.EQUIPMENTDATA(Contd) Table 1-3. Vehicle Performance Data (Contd).RadiatorType . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CrossflowSurgeTankCapPressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14psi5.ELECTRICALSYSTEMAlternator:AmpereOutput(maximum) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60ampModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .VoltageOutput. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..28voltsVoltageRegulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MountedinternalBatteries:Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6TNNumberRequired . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 4PlatesPerCell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..23SpecificGravityFullCharge. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 070FVoltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 voltsProtectiveControlBox. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WSU-4001-UT97kPa@21CStarter:M o d e l. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MES6 4 0 1 - CUTVoltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 24vol t s6. TRANSMISSION (MT654CR)DriveSequence. . . . . . . . . . . . . . . . . . . . . . . . . . . . Reverse,Neutral,1,2,3,4,5DriveRangeandShiftControl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ManualOi l Pr es s ur e. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 6 p s iOilType . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . O E / H D O - 1 0OilCapacity:DrainandRefill. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.25gal.w/o PTO (dry) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..5.75gal.w / P T O ( d r y ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. 25gal .Oil Temperature:Maximum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 300FNormalOperatingTemperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120-220FPower Takeoff:T y p e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conve r t e r - dr i ve nMountingFlange . . . . . . . . . . . . . . . . . . . . . . . . . . . . One-opening,SAE,6-bolt7.TRANSFERCASEMo d e l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T- 1138Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Two-speedsynchronized179.3kPa16.1L21.8 L23.7 L149C49-104C1-17.DESCRIPTIONOFDATAPLATES Thelocationandcontentsofcaution,data,andwarningplatesareprovidedinTM9-2320-272-10,andacompletelistandlocationofallcaution,data,warning,andidentificationplatesisinTM9-2320-272-24PIfanyoftheseplatesareworn,broken,paintedover,missing,orunreadable,theymustbereplaced.l-24TM9-2320-272-24-lSectionIII.PRINCIPLESOFOPERATION1-18.GENERAL ThissectionexplainshowcomponentsoftheB-tonM939/Al/A2seriesvehiclesworktogether.Afunctionaldescriptionofthesecomponentsandtheirrelatedpartswillbecoveredinthefollowingparagraphs.Tofindtheoperationofaspecificsystemorcomponent,seetheprinciplesofoperationreferenceindexbelow.1-19.PRINCIPLESOFOPERATIONREFERENCEINDEX PARA.NO.TITLEPAGENO.l-20. ControlSystemOperation1-21. PowerSystemOperationl-22. ElectricalSystemsOperationl-23. CompressedAirandBrakeSystemOperationl-24. HydraulicSystemOperationl-25. CentralTireInflationSystem(CTIS)Operationl-25l-341-451-551-71l-78l-20.CONTROLSYSTEMOPERATIONThecontrolsystemincludesthosecontrolsandtheirrelatedpartsessentialtotheoperationofthevehicle.ThesecontrolsarecommontoallvehicleswiththeexceptionofthetransmissionandtransfercasePowerTakeoff(PTO)controls.Alloriginatefromthecab.Eachofthesecontrolsandrelatedpartswillbedescribedaspartofthefollowingsystems:a. StartingandEtherStartingSystemOperation(pagel-26).b. AcceleratorControlsSystemOperation(pagel-28).c. ParkingBrakeSystemOperation(pagel-29).d. SteeringSystemOperation(pagel-30).e. TransmissionControlSystemOperation(pagel-31).f. TransferCaseControlSystemOperation(page1-32).1-25TM9-2320-272-24-ll-20. CONTROL SYSTEM OPERATION (Contd)a. StartingandEtherStartingSystemOperation.Thestartingsystemisidenticalonallmodelscoveredinthismanual.Itwillstarttheengineinalltypesofweatherandhasbuilt-inprotectionthatpreventsstartingcomponentsfromreengagingoncetheenginehasbeenstarted.Majorcomponentsofthestartingandetherstartingsystemare:Key12345671-26ItemandFunctionHANDTHROTTLECONTROL-Usedtosetenginespeedwithoutapplyingpressuretotheaccelerator(rotatedtolock).BATTERYSWITCH-Activatesallelectricalcircuitsexceptarcticheaters.IGNITIONSWITCH-HasOFF,RUN,andSTARTpositions.SwitchautomaticallyreturnsfromSTARTtoRUNwhenhandpressureisreleased.TACHOMETER-Indicatesspeedofengine.VOLTMETER-Indicateschargingconditionofthebattery.EMERGENCYENGINESTOP-Controlusedtoshutdownengineduringemergencies(M934/A1seriesvehiclesmustberesetbyunitmaintenance).ETHERSTARTSWITCH-Injectsetherintoengineforcold-weatherstarting.TM9-2320-272-24-ll-20.CONTROLSYSTEMOPERATION(Contd)KeyItemandFunction8 PROTECTIVECONTROLBOX-Preventsreengagementofstartermotoronceengineisrunning.9 BATTERIES-Provide24-voltelectricalcurrentforenergizingelectricalcircuits.10 STARTERSOLENOID-Relays24-voltbatterypowertoenergizestartermotor.11 STARTERMOTOR-Whenenergized,convertselectricalenergytomechanicalpowerasitengagesflywheeltocrankengine.12 ETHERSTARTCYLINDER-Storesetherusedforcold-weatherstarting.l-27TM9-2320-272-24-1l-20. CONTROL SYSTEM OPERATION (Contd)b. Accel eratorControl sSystemOperati on.Theacceleratorcontrolssystempermitstheoperatortocontrolvehiclespeedandenginepower.Itisidenticalonallmodelscoveredinthismanual.Majorcomponentsoftheacceleratorcontrolsystemare:KeyItemandFunction1 HANDTHROTTLECONTROL-Usedtosetenginespeedwithoutmaintainingpressuretotheaccelerator(rotatedtolock).2 EMERGENCYENGINESTOPCONTROL-Ispulledouttocutofffueltoengine.Usedonlyinanemergency.3 ACCELERATORPEDAL-Controlsenginespeed.4 MODULATOR-Withtransmissionselectorleverindrive,modulatorcontrolstransmissionupshiftinganddownshiftingasenginerpmchanges.5 CABLE-Connectsmodulatortofuelpump.6 ACCELERATORLINKAGE-Linksacceleratorpedalandthrottlecontroltofuelpump.1-28TM9-2320-272-24-ll-20.CONTROLSYSTEMOPERATION(Contd)c. Parki ngBrakeSystemOperati on.Amechanicalandair-actuatedbrakesystemperformsthefollowingforallvehiclescoveredinthismanual:(1)Keepsvehiclefromrollingonceithasstopped.(2)Slowsdownorstopsvehiclemovement.(3)Providesemergencystoppingifthereisacompleteairsystemfailure.Themechanicalbrakesystemiscoveredbelow.Thecompressedairfunctionofthebrakesystemwillbecoveredinafollowingparagraph.Majorcomponentsoftheparkingbrakesystemare:KeyI t emandFunct i on7 PARKINGBRAKEWARNINGLIGHT-Illuminateswhenparkingbrakeisengaged.8 PARKINGBRAKECONTROLLEVER-Ispositioneduptoengageparkingbrake;downtodisengageparkingbrake.9 PARKINGBRAKECONTROLLEVERADJUSTINGKNOB-Permitsoperatortomakeminortensionadjustmentofparkingbrake.10 PARKINGBRAKECABLE-Linksparkingbrakecontrollevertobrakeshoelever.11 BRAKESHOELEVER-Leverturnscamwhichpushesbrakeshoesagainstdrum.12 PARKINGBRAKEADJUSTINGNUT-Permitsmajortensionadjustmentbetweenparkingbrakeleverandbrakeshoes.1-29TM9-2320-272-24-1l-20. CONTROL SYSTEM OPERATION (Contd)d. Steeri ngSystemOperati on.Thesteeringsystemisidenticalforallmodelscoveredinthismanual.Itisahydraulically-assistedsystemthatprovideseaseofturningandcontrolfortheoperator.Majorcomponentsofthesteeringsystemare:Key1234567891011l-30ItemandFunctionOILRESERVOIRANDSTEERINGPUMP-Combinedinoneunit,thereservoirservesasanoilfillpointandthepumpcreatespressure.ACCESSORYDRIVEBELTS-Transmitmechanicalpowerfromaccessorydrivepulleytosteeringpumppulleytodrivethesteeringpump.STEERINGWHEEL-Servesasmanualsteeringcontrolforoperator.STEERINGCOLUMNUNIVERSALJOINT-Connects,atanangle,thesteeringwheelcolumnandinputshaftofpowersteeringgear.POWERSTEERINGASSISTCYLINDER-Receiveshydraulicpressurefromsteeringgeartoassistinturningfrontwheels.STEERINGKNUCKLE-Servesaspivotpointandlinkforfrontwheelsfromtierodassembly.TIERODASSEMBLY-Connectssteeringknucklessobothwheelsturnatthesametime.STEERINGARM-Connectsdraglinktosteeringknuckle.DRAGLINK-Transmitsmovementfromsteeringarmtopitmanarm.PITMANARM-Transferstorquefrompowersteeringgeartodraglink.STEERINGGEAR-Convertshydraulicpressurefromsteeringpumptomechanicalpoweratpitmanarm.TM9-2320-272-24-ll-20.CONTROLSYSTEMOPERATION(Contd)e.TransmissionControlSystemOperation.Thetransmissioncontrolsystempermitsshiftingoftransmission,preventsstartingofenginewithtransmissioningear,andpreventsshiftingoftransfercaseunlesstransmissionisinneutral.ThissystemalsopermitsengagementofthetransmissionPowerTakeoff(PTO)toprovidehydraulicpowerforauxiliaryequipmentonM925/A1/A2,M928/A1/A2,M929/A1/A2,M930/Al/A2,M932/A1/A2,andM936/A1/A2vehicles.Majorcomponentsofthetransmissioncontrolsystemare:Key121314151617ItemandFunctionTRANSMISSIONSELECTORLEVER-Isusedtoselectvehicledrivinggearrange.PTOCONTROLLEVER-Engagestransmissionpowertakeofftoprovidepowerforauxiliaryequipment.TRANSMISSIONCONTROLSWITCH-ActuatestransmissionlockupsolenoidvalvewhentransmissionselectorleverisplacedinNEUTRALandtransfercaseshiftleverlockoutswitchispressed.TRANSMISSIONNEUTRALSTARTSWITCH-Theneutralstartswitch,wiredtothestarterswitch,preventstheenginefrombeingstartedwithtransmissioningear.TRANSMISSION5TH-GEARLOCKUPSOLENOIDVALVE-Activatedbytransmissioncontrolswitchandtransfercaseswitch,the5th-gearlockupsolenoidvalvedirectsmainoilpressureoftransmissiontothetransmissiongovernorsystem.Thisputstransmissionin5th-gear,creatinglessdragontransfercasesynchronizerwhichpermitssmoothershiftingfromonetransfercasedriverangetoanother.Refertopara.l-20f,TransferCaseControlSystemOperation,forfurtherdetails.TRANSMISSIONPTO-Drivenbythetransmission,thePTOdrivesthehydraulicpumpwhichprovideshydraulicpressuretopowerthefrontwinchonM925/A1/A2,M928/Al/A2,M930/Al/A2,M932/Al/A2,andM936/A1/A2vehicles,andtopowerthedumpbodyonM929/A1/A2andM930/Al/A2vehicles.ThePTOismountedontherightfrontsideofthetransmission.1-31TM9-2320-272-24-1l-20.CONTROLSYSTEMOPERATION(Contd) f. TransferCaseControlSystemOperation.Thetransfercasecontrolsystemconvertsfour-wheeldrivingpowerintosix-wheeldrivingpower,providessmoothshiftingoftransfercaseintohighorlowdrivingrangeswhilevehicleisinmotion,preventstransfercasefrombeingshiftedwithtransmissioningear,andprovideshydraulicpowerforauxiliaryequipmentthroughPTO.(1)Six-wheeldriveisachievedtwodifferentways,dependingonthedriverange(highorlow)desired.Inlowrange,thetransfercaseshiftlinkageautomaticallymovesacam-actuatedvalvewhichdumpsairintothefrontdrivecylinder.Thisforcesapistonagainstthetransfercaseclutchtoengagefront-wheeldrive.Inhighrange,front-wheeldriveisengagedinthesamemannerexceptthatthefront-wheeldrivevalveismanuallyactuatedbythefront-wheeldrivelock-inswitchontheinstrumentpanel.(2)Inordertoshiftthetransfercasefromonedrivingrangetoanother,aninterlocksystemworkinginconjunctionwiththe5th-gearlockupsolenoidisused.Thissystempreventsthetransfercasefrombeingshiftedunlessthetransmissionisinneutral.(3)Withtheautomatictransmission,severalactionsmustoccurinordertoshifttransfercasefromonedrivingrangetoanother.Becauseoftheinterlocksystem,thetransmissionmustbeplacedinneutral.Thetransfercaseshiftleverswitchmustalsobedepressed.(4)Thetransfercasecontrolsystem,throughuseofaPTOdrivenbythetransfercase,alsoprovideshydraulicpowertooperatethecraneandrearwinchonM936/A1/A2wreckers.(5)Majorcomponentsofthissystemare:1-32TM9-2320-272-24-ll-20.CONTROLSYSTEMOPERATION(Contd)Key12345ItemandFunctionTRANSFERCASESHIFTLEVERSWITCH-WhendepressedwithtransmissioninNEUTRAL,signalsinterlocksolenoidvalvetoexhaustairpressurefrominterlockaircylinderandactuateslockupsolenoid.TRANSFERCASESHIFTLEVER-IspusheddowntoHIGHforlightloadoperations,anduptoLOWforheavyloadoperations.Six-wheeldriveisachievedautomaticallywhentransfercaseshiftleverisplacedinLOW.TRANSFERCASEPTOCONTROLLEVER-ManualcontrolforengagingPTO.TRANSFERCASEPTO-Mountedandmechanicallydrivenatrearoftransfercase,thePTOdrivesapumptosupplyhydraulicpressuretopowertherearwinchandcraneontheM936/A1/A2wreckers.FRONT-WHEELDRIVELOCK-INSWITCH-Manualcontrolforactivatingfront-wheeldrivevalvetoprovidefront-wheeldrivewithtransfercaseinHIGHdriverange.6 INTERLOCKAIRCYLINDER-Underairpressure,apistonintheinterlockaircylinderforcesashaftagainstoneofthreegroovesintransfercaseshiftlever,Thispreventstransfercasefrombeingshiftedwithtransmissioningear.7 INTERLOCKSOLENOIDVALVE-ReleasesairfrominterlockaircylinderwhentransmissionisinNEUTRALandtransfercaseshiftleverswitchisdepressed.Thispermitsthetransfercasehigh/lowshiftshafttomove.8 FRONT-WHEELDRIVEAIRCYLINDER-Whenunderpressure,itmovestransfercaseclutchforwardtoengagefront-wheeldrive.9 FRONT-WHEELDRIVEVALVE-Whentrippedbyacamontransfercaseshiftshaft,thefront-wheeldrivevalveroutesairtofront-wheeldriveaircylinder.1-33TM9-2320-272-24-1 1-21. POWER SYSTEM OPERATION Thepowersystemincludescomponentsthatsupplyallvehiclescoveredinthismanualthepowertomove.Eachofthesecomponentswillbedescribedaspartofthefollowingsubsystems:a. AirIntakeSystemOperation(pagel-34).b. FuelSystem(DualTank)Operation(pagel-36).c. FuelSystem(SingleTank)Operation(pagel-38).d.ExhaustSystemOperation(pagel-39).e. CoolingSystemOperation(pagel-40).f. EngineOilSystemOperation(pagel-42).g.PowertrainSystemOperation(pagel-44).a.AirIntakeSystemOperation.Theairintakesystemchannelsandcleansairgoingtothecombustionchamber,whereitmixeswithfuelfromtheinjectorstoprovidepowerfortheengine.Thissystemisidenticalonallmodels,exceptwhereindicated.Majorcomponentsoftheairintakesystemare:1-34TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd) Key1234567891011ItemandFunctionRAINCAP-Preventsrainandlargeobjectsfromenteringairintakesystem.AIRINTAKEEXTENSIONTUBE-Routesairtoairintakesystem.Canberemovedforshipping.STACK-TO-AIRINTAKEEXTENSIONTUBE-Routesairtoaircleanerandishighenoughtokeepintakeopeningabovefordinglevel.STACK-TO-AIRCLEANERELBOW-Flexibleconnectionbetweenairstackandaircleaner.AIRCLEANER-Filtersdirtanddustfromair.HUMPHOSE-Flexibleconnectionbetweenaircleanerandaircleaneroutlettube.AIRCLEANEROUTLETTUBE-Routesairfromaircleanertointakemanifold.INTAKEMANIFOLD-Distributesairtocombustionchambersineachcylinderhead(M939/Alseriesonly).AIRCLEANERINDICATOR-Showsredwhenengineairfilterneedsservicing.TURBOCHARGER-Mountsonexhaustmanifoldandusesspentexhaustgasestodriveimpellerandpressurizeairenteringaftercooler(M939A2seriesonly).AFTERCOOLER-Distributescompressedairfromturbochargertocombustionchamberswhilecoolingairintakeoutofturbocharger(M939A2seriesonly).1-35TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd)b.FuelSystem(DualTank)Operation.(1)Thefuelsystemstores,cleans,andsuppliesfueltothefuelinjectors,whereitismixedwithairtoinitiateenginecombustion.(2)Thefuelsystemisnotidenticalforallmodels.Vehiclescoveredinthismanualhaveeitheroneortwotanks.Thesetankscanalsodifferincapacity.Seetable1-3,VehiclePerformanceData,forthesedifferences.(3)Atypicaldualtankfuelsystemisdescribedbelow.Asingletankfuelsystemisdescribedinpara.1-21c.Bothsystemsincludefuelsupply,return,andventlinestoprovidefuelflowandreleasethefumesthroughoutthesystem.Majorcomponentsofthedualtankfuelsystemare:1-36TM9-2320-272-24-l1-21.POWERSYSTEMOPERATION(Contd)KeyItemandFunction1 RIGHTTANK(FRONT)VENTLINE-Ventsvaporsfromfueltanktoventholeinairintakestack.2 RIGHTTANKFILLERCAP-Coversfuelfilleropeningonrightfueltank.3 RIGHTFUELTANK-Storesfuelforvehicleuse.4 RIGHTTANKFUELRETURNLINE-Returnsunusedfuelbacktofueltank.5 RIGHTTANK(REAR)VENTLINE-Ventsvaporsfromfueltanktoventholeinairintakestack.6 RIGHTTANKFUELSUPPLYLINE-Directsfuelfromtanktofuelfilter.7 RIGHTTANKFUELLEVELSENDINGUNIT-Electricalsignalregistersfuellevelinrighttankatgaugeoninstrumentpanel.8 LEFTTANKFUELLEVELSENDINGUNIT-Electricalsignalregistersfuellevelinlefttankatgaugeoninstrumentpanel.9 LEFTTANKFUELSUPPLYLINE-Directsfuelfromtanktofuelfilter.10 LEFTFUELTANK-Storesfuelforvehicleuse.11 LEFTTANK(REAR)VENTLINE-Ventsvaporsfromfueltanktoventholeinairintakestack.12 LEFTTANKFILLERCAP-Coversfuelfilleropeningonleftfueltank.13 LEFTTANKFUELRETURNLINE-Returnsunusedfuelbacktofueltank.14 LEFTTANK(FRONT)VENTLINE-Ventsvaporsfromfueltanktoventholeinairintakestack.15 FUELSELECTORVALVE-Manualcontrolvalvethatopensfuelflowtoenginefromleftorrightfueltank.16 FUELFILTER/WATERSEPARATOR-Filterswateranddirtfromfuel.17 FUELFILTER-TO-PUMPSUPPLYLINE-Directsfuelfromfuelfiltertofuelpump.18 FUELRETURNLINE-Returnsunusedfuelbacktofueltanks.19 FUELSUPPLYLINE-Directsfuelfromfuelpumptofuelinjectors.20 FUELPUMP-Drawsfuelfromtank(s)andpumpsitthroughsupplylinetofuelinjectors.21 FUELPRIMERPUMP-Purgesairfromfuelsystem.1-37TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd) c. Fuel System(Si ngl eTank)Operati on.Majorcomponentsofthesingletankfuelsystemare:Key12345 TANK(FRONT)VENTLINE-Ventsvaporsfromfueltanktoventholeinairintakestack.6 FUELFILTER/WATERSEPARATOR-Filterswateranddirtfromfuel.7 FUELRETURNLINE-Returnsunusedfuelbacktofueltank.8 FUELPUMP-Drawsfuelfromtankandpumpsitthroughsupplylinetofuelinjectors.9 FUELSUPPLYLINE-Directsfuelfromfuelpumptofuelinjectors.10 FUELPRIMERPUMP-Purgesairfromfuelsystem.1-38ItemandFunctionTANK(REAR)VENTLINE-Ventsvaporsfromfueltanktoventhole-inairintakestack.TANKFILLERCAP-Coversfuelfilleropening.FUELTANK-Storesfuelforvehicleuse.FUELTANKLEVELSENDINGUNIT-Electricalsignalregistersfuellevelintankatgaugeoninstrumentpanel.TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd)d.ExhaustSystemOperation.Theexhaustsystemdirectsexhaustgasesawayfromthevehicleforallmodelscoveredinthismanual.Majorcomponentsoftheexhaustsystemare:KeyItemandFunction11 EXHAUSTSTACK-Directsexhaustfrommufflerawayfromvehicle.12 EXHAUSTMANIFOLD-Collectsexhaustfromcylinderheadportsanddirectsittofrontexhaustpipe.13 FRONTEXHAUSTPIPE-Directsexhausttorearexhaustpipe.14 FLEXPIPE-Partofrearexhaustpipe;allowsflexibilityforvibrationandexpansioninsystem.15 REAREXHAUSTPIPE-Directsexhausttomuffler.16 MUFFLER-Quietsexhaustnoises.17 MUFFLERSHIELD-Protectspersonnelfrommufflerheat.1-39TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd)e.CoolingSystemOperation.Thissystemprovidescoolingoftheengineandtransmission.ItdiffersslightlybetweentheM939/A1seriesandM939A2seriesvehiclesbecausedifferentenginesareused.Majorcomponentsofthecoolingsystemare:1-40TM9-2320-272-24-11-21. POWER SYSTEM OPERATION (Contd)KeyItemandFunction1 SURGETANK-Fillingpointforcoolingsystem.OnM939A2vehicles,afloatsensormonitorswaterlevelandilluminatesalightoninstrumentpanel.COOLANTPRESSURECAP-Designedtodepressurizecoolingsystemandtoaccesscoolingsystemfortilling.WATERMANIFOLD-Collectscoolantfromcylinderheadsanddirectsittothermostathousing(M939/A1seriesonly).SURGETANK-TO-WATERMANIFOLDVENT-Ventsairtrappedinwatermanifold(M939/A1seriesonly).SURGETANK-TO-RADIATORVENT-Ventsairincoolingsystem.THERMOSTAT-Shutsoffcoolantflowtoradiatoruntiltemperaturereaches175F(79C)onM939/A1seriesvehiclesand181F(83C)onM939A2seriesvehicles.Coolantisthendirectedtotheradiatorthroughtheradiatorinlethose.RADIATORINLETHOSE-Directscoolantfromwatermanifoldtoradiatorafterthermostathasopened.BYPASSTUBE-Directscoolantbacktotransmissionoilcooler,whereitisthenrecirculatedthroughtheengineblockuntilthethermostatopens.RADIATORSHROUD-Concentratesairflowthroughtheradiator.RADIATOR-Directscoolantthroughaseriesoffinsorbafflessooutsideaircanremoveexcessiveheatfromcoolant.FANCLUTCH-Regulatesuseoffantocontrolenginetemperaturefantobelt-drivenpulleywhenconditionsrequireadditionalcooling.WATERPUMP-Providesforcetomovecoolantthroughengine.FAN-Providesforcetopullairthroughradiator.RADIATORDRAINVALVE-Permitscoolanttobedrainedfromradiator.TRANSMISSIONOILCOOLERHOSE-Directscoolanttotransmissionoilcooler.ENGINEOILCOOLER-Reducesheatofengineoil(M939/A1seriesonly).TRANSMISSIONOILCOOLER-Reducesheatoftransmissionoil.ENGINEOILCOOLER-TO-HEATERHOSE-Directscoolanttopersonnelwaterheaterwhenshutoffvalveisopen(M939/A1seriesonly).PERSONNELWATERHEATER-Providesheatforcabandpersonnel(M939/A1only).23456789101112131415161718191-41TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd)f. EngineOilSystemOperation.Theengineoilsystemprovideslubricatingoilforinternalmovingparts.Majorcomponentsoftheengineoilsystemare:M939/A1SERIESM939A2SERIES1-42TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd)M939/A1SERIESM939A2SERIESKeyItemandFunction123OILDIPSTICK-Indicatesengineoillevel.CRANKCASEBREATHER-Ventshotengineoilfumesfromengineandallowsfreshairtoenter.ENGINEOILCOOLER-Removesheatfromengineoilascoolantcirculatesthroughinternaltubesof oil cooler.4567891011OILFILTER-Filtersoutforeignparticlessuspendedinoil.OILFILLERCAP-Locatedonrockerlevercover,capcoversengineoilfillopening.OILPRESSURETRANSMITTER-Sendsanelectricalsignalthatindicatesengineoilpressuretogaugeoninstrumentpanel.OILPANDRAINPLUG-Plugsengineoildrainopening.OILPAN-Reservoirforengineoil.OILSUPPLYLINE-Carriesoilfromoilpantooilpump.OILBYPASSRETURNLINE-Returnsoilfromoilpumptooilpan.OILPUMP-Providesmechanicalpressurizationofoiltocirculateitthroughoilsystem.1-43TM9-2320-272-24-11-21.POWERSYSTEMOPERATION(Contd)g.PowertrainSystemOperation.Thepowertrainsystemisthesameonallmodelsinthismanualexcepttheextra-longwheelbasemodels,whichhaveanadditionalpropellershaftandcenterbearing.Thissystemtransmitsenginepowertotheaxlestoputthevehicleinmotion.Majorcomponentsofthepowertrainsystemare:KeyItemandFunction123ENGINE-Providespowerneededforpowertraincomponentoperation.TRANSMISSION-Adaptsenginepowertomeetdifferentdrivingconditions.CENTERBEARING-Providessupportforpropellershafttodecreasevibrationandwearonuniversaljoints(M927/A1/A2,M928/A1/A2,andM934/A1/A2seriesonly).TRANSFERCASE-Distributespowerevenlytofrontandrearaxles.UNIVERSALJOINTS-Connectionsbetweentwopropellershaftsthatpermitonetodrivetheothereventhoughtheymaybeatdifferentangles.DIFFERENTIALS-Distributepowertoleftandrightaxleshafts.AXLES-Transmitpowerfromdifferentialstorotatewheels.PROPELLERSHAFTS-Serveasdrivingshaftsthatconnecttransmissiontotransfercaseandtransfercasetodifferentials.456781-44TM9-2320-272-24-11-22.ELECTRICALSYSTEMSOPERATIONNearlyeverycomponentofmodelscoveredinthismanualisaffectedbytheelectricalsystem.Thesecomponentsandtheirelectricalconnectionsaredescribedaspartofthefollowingelectricalsubsystems:a.BatterySystemOperation(page1-46).b.StartingSystemOperation(page1-47).c. EtherStartingSystemOperation(page1-48).d.GeneratingSystemOperation(page1-49).e. DirectionalSignalSystemOperation(page1-50).f. HeatingSystemOperation(page1-51).g. Indicator,Gauge,andWarningSystemOperation(page1-52).h.TrailerandSemitrailerConnectionSystemOperation(page1-54).ElectricalTermsandDefinitions.Thefollowingelectricaltermsanddefinitionswillbefrequentlyreferredtothroughoutthissectionandshouldbeunderstoodbeforeproceeding:AlternatingCurrent(ACsignal)-Currentinacircuitthatflowsinonedirectionfirst,thenintheotherdirection.Circuit-Acompletepathforelectriccurrentflowbetweencomponents.CircuitBreaker-Anautomaticswitchthatinterruptscurrentflowinacircuitwhenthecurrentlimitisexceeded.DirectCurrent(DCsignal)-Currentinacircuitthatflowsinonedirection.FemaleConnector-One-halfofaconnectorwhichfitsovertheotherhalf.Ground-Acommonreturntocompleteapathforcurrentflowinacircuit.Harness-Agroupofwiresconnectedbetweendevicesthatarebundledandroutedtogethertopreventdamageandmakerepairandreplacementeasier.MaleConnector-One-halfofaconnectorwhichfitstheotherhalf.Polarity-Thedirectioncurrentflowsinacircuit(usuallypositivetonegative).Relay-Anelectromagneticdevicethatoperateslikeanautomaticswitchtocontrolflowofcurrentinthesameordifferentcircuit.ReversePolarity-Theconditionthatexistswhencircuitpolarityisconnectedoppositeofthatwhichwasintended.SendingUnit-Adevicethatproducesanelectricalsignalandsendsthissignaltothedevicewhichwillmakeuseofit.Sensor-Anelectricalsensortakesaphysicalcondition(temperature,oilpresenceorabsence)andconvertsitintoanelectricalsignal.Splice-Apermanentphysicalconnectionoftwoormorewires.Terminal-Fasteneratendofwireusedtoconnectthewiretoanelectrically-powereddevice.1-45TM9-2320-272-24-11-22. ELECTRICAL SYSTEMS OPERATION (Contd)a.BatterySystemOperation.Thebatterysystemisidenticalforallmodelscoveredinthismanualandconsistsofthefollowingmajorcomponentsandcircuits:KeyItemandFunction123456STARTERSOLENOID-Junctionpointforbatterypositivelead(circuit6)andvehicleelectricalfeedwire(circuit81).CIRCUIT6-Connectsbatteriestostartingmotorandtoprotectivecontrolboxthroughcircuit81.BATTERIES-Four6TNbatteriesareconnectedinseriesparalleltoprovide24-voltsDCforelectricalstartersystemand12-voltsDCfortheheaterfanlowspeed.SLAVERECEPTACLE-Linksanexternalpowersourcedirectlytotheslavedvehiclesbatteriestoassistincrankingenginewhenbatteriesarenotsufficientlycharged.CIRCUIT7-Providesagroundbetweenstarter,battery,andchassis.PROTECTIVECONTROLBOX-Protectsthevehicleelectricalsystemintheeventbatterysystempolarityisreversed.Connectsbatterypowertovehicleelectricalleadthroughcircuit81andcircuit5.Connectspositivegroundthroughcircuit94tothestarter.BATTERYSWITCH-Controlsarelayinprotectivecontrolboxthroughcircuit459thatconnectsbatteriestovehicleelectricalload.71-46TM9-2320-272-24-11-22.ELECTRICALSYSTEMSOPERATION(Contd)b.StartingSystemOperation.Thestartingsystemisidenticalforallmodelscoveredinthismanualandconsistsofthefollowingmajorcomponentsandcircuitry:KeyItemandFunction8910111213BATTERYSWITCH-Completescircuit459,closingarelayintheprotectivecontrolboxtosupplypowertoignitionswitchthroughcircuits5and5B.PROTECTIVECONTROLBOX-Locksoutstartercircuit,whichpreventsstarterfromreengagingwhileengineisrunning.IGNITIONSWITCH-Providesbatterypowertofuelsolenoidthroughcircuit54andtheneutralstartsafetyswitchthroughcircuit498.NEUTRALSTARTSAFETYSWITCH-Preventsstarterfromenergizingwhenvehicleisnotinneutral,bydeenergizingcircuit499andarelayintheprotectivecontrolbox,whichdisconnectspowerfromcircuit74andthestartersolenoid.STARTERSOLENOID-Amagneticrelaythatispoweredbycircuit74totransmit24-voltbatterypowertothestartermotorthroughcircuit6.STARTERMOTOR-Cranksengineforstarting.Suppliedwith24-voltbatterypowerthroughcircuit6.1-47TM9-2320-272-24-11-22. ELECTRICAL SYSTEMS OPERATION (Contd)c. EtherStartingSystemOperation.Theetherstartingsystemisidenticalforallmodelscoveredinthismanualandconsistsofthefollowingmajorcomponentsandcircuitry:KeyItemandFunction1 BATTERYSWITCH-Provides24-voltbatterypowertoprotectivecontrolboxthroughcircuits459,81A,and81.2 PROTECTIVECONTROLBOX-Energizesetherfeedswitchthroughcircuits5,5A,27,5C,and570.3 ETHERFEEDSWITCH-Controls24-voltpowertoetherpressureswitchthroughcircuit570.4 ETHERPRESSURESWITCH-Connectsetherfeedswitchtoethertankvalvethroughcircuit570.5 ETHERTANKVALVE-Isactivatedthroughcircuit570whenetherpressureswitchisclosedandetherfeedswitchispressed.1-48TM9-2320-272-24-11-22. ELECTRICAL SYSTEMS OPERATION (Contd)d.GeneratingSystemOperation.Thegeneratingsystemisidenticalforallvehiclescoveredinthismanualandconsistsofthefollowingmajorcomponentsandcircuitry:KeyItemandFunction6 VOLTMETER-Indicateselectricalsystemvoltage.Itisconnectedtotheelectricalsystemthroughcircuit27.7 ALTERNATOR-Ratedat26-30volts,60amperes,thealternatorassistsandrechargesbatteriesduringoperation.Al00-amperemodelisavailableasakit.8 CIRCUIT3-Providesagroundcircuittoalternator.9 CIRCUIT566-Controlsarelayinprotectivecontrolboxthatpreventsstarterfromreactivatingwhileengineisrunning.10 CIRCUIT568-Sensessystemvoltageandexcitesthealternatorfield.11 PROTECTIVECONTROLBOX-Connectscircuit5to81topowertheelectricalsystemandchargethebatteries.12 CIRCUIT5-Conductsalternatoroutputtochargebatteriesandmaintainvehiclevoltage.13 BATTERYSWITCH-Closesrelayinprotectivecontrolboxthatconnectsbatterycircuits.1-49TM9-2320-272-24-11-22.ELECTRICALSYSTEMSOPERATION(Contd)e.DirectionalSignalSystemOperation.Thedirectionalsignalsystemisidenticalonallmodelscoveredinthismanualandconsistsofthefollowingmajorcomponentsandcircuitry:KeyItemandFunction123456FRONTCOMPOSITELAMP-Receivespowerfromturnsignalcontrolthroughcircuits460and461toindicateturningdirection.LIGHTSWITCH-Providesbatterypowertodirectionalsignalswitchthroughcircuits460and461andtostoplightswitchthroughcircuit75.STOPLIGHTSWITCH-Closingthisswitchallowspowertoflowfromlightswitchthroughcircuit75tocircuit22todirectionalsignalswitch.REARCOMPOSITELAMPS-Receivepowerfromturnsignalcontrolthroughcircuit22-460and22-461toindicateturningdirection.DIRECTIONALSIGNALSWITCH-Afour-positionswitchthatdirectspowertocompositeandsignallampsthroughcircuits460,461,22-460,and22-461toindicatedirectionofturn.TURNSIGNALFLASHER-Receivespowerthroughcircuit467Aandsendsintermittentcurrenttothesignallampthroughcircuit467B.1-50TM9-2320-272-24-11-22. ELECTRICAL SYSTEMS OPERATION (Contd)f.HeatingSystemOperation.Theelectricalportionoftheheatingsystemisidenticalforallmodelscoveredinthismanualandconsistsofthefollowingmajorcomponentsandcircuitry:KeyItemandFunction789101112PROTECTIVECONTROLBOX-Provides24-voltpowertocircuitbreakerthroughcircuits5and5Aandtoheaterswitchthroughcircuits27and5C.CIRCUITBREAKER-Providesoverloadprotectionfor24-voltcircuits5,5A,27,and5Cleadingtotheheaterswitch.BATTERYSWITCH-Provides12-voltbatterypowerfromcircuit569through569Atotheheater.CIRCUITBREAKER-Providesoverloadprotectionfor12-voltcircuit569Aleadingtoheaterswitch.HEATERSWITCH-Controlslowandhighblowermotorspeedandhastwosourcesofpower:12-voltpowerissuppliedthroughcircuit569Afrombatteryswitchandisusedtoprovidelowspeed;24-voltpowerissuppliedthroughcircuit5Cfromprotectivecontrolboxandisusedtoprovidehighspeed.HEATERBLOWERMOTOR-Adirectcurrentmotorcontrolledbyheaterswitchthroughcircuit400.1-51TM9-2320-272-24-11-22. ELECTRICAL SYSTEMS OPERATION (Contd)g. Indicator,Gauge,andWarningSystemOperation.Theindicator,gauge,andwarningsystemiscomprisedofseveralsubsystems:1-52TM9-2320-272-24-11-22.ELECTRICALSYSTEMSOPERATION(Contd)KeyItemandFunction1 VOLTMETER-Indicatessystemvoltageandisconnectedtobatteriesthroughcircuit27Aandtochassisgroundthroughinstrumentpanel.23456789ENGINECOOLANTTEMPERATUREINDICATOR-Indicatesenginecoolanttemperatureandreceivesbatterypowerthroughcircuit27A.Circuit33completesthecircuittogroundthroughacoolanttemperaturesensorthatreactstochangesinenginecoolanttemperaturebyincreasingordecreasingtheresistanceingroundcircuit.ENGINEOILPRESSUREINDICATOR-Indicatesengineoilpressureandreceivesbatterypowerthroughcircuit27A.Circuit36completesthecircuittogroundthroughtheoilpressuretransmitterlocatedontheengineblock.FUELINDICATOR-Indicatesfuellevel.Receivesbatterypowerthroughcircuit27A.Circuit28or29,dependinguponwhichpositionfuelselectorswitchisin,completesthecircuittogroundthroughfuellevelsensor.TRANSMISSIONOILTEMPERATUREINDICATOR-Indicatestransmissionoiltemperatureandreceivesbatterypowerthroughcircuit27A.Circuit324completescircuittogroundthroughatemperaturesensorlocatedintransmission.FRONT-WHEELDRIVEENGAGEMENTLIGHT-Informstheoperatorthatfront-wheeldriveisengaged.Thesystemconsistsofanormallyopenpressureswitch,whichispoweredthroughcircuit27Aandanindicatorlamppoweredthroughcircuit27A.HORNSYSTEM-Thehornsystemconsistsofanair-operatedhornthatiscontrolledbyanelectricsolenoid.Thesolenoidispoweredthroughcircuit26andcontrolledbythehornswitchthroughcircuit25.SPRINGBRAKEWARNINGSYSTEM-Warnstheoperatorthatspringbrakesareapplied.Thesystemconsistsofnormallyopenpressureswitchpoweredthroughcircuit37andanindicatorlampwhichispoweredthroughcircuit37.FAILSAFEWARNINGSYSTEM-Intendedtogivetheoperatoranaudibleaswellasvisualsignalofamalfunctioninoneoftheprimarysystems.Powerforthesystemissuppliedfromtheignitionswitchthroughcircuit564.Thefailsafemodulecausesanindicatorlamptoilluminateandanalarmtosoundwhenairpressurefallsbelow60psi(414kPa)orwhenparkingbrakeisset.1-53TM9-2320-272-24-11-22. ELECTRICAL SYSTEMS OPERATION (Contd)h.TrailerandSemitrailerConnectionSystemOperation.Thetrailerreceptacleisidenticalonallmodelscoveredinthismanual.Thesemitrailerreceptacleisonthetractorbodyonly.KeyItemandFunction1 TRAILERRECEPTACLE-Providesvehiclelighting,auxiliarypower,andagroundcircuitfortrailers.2 SEMITRAILERRECEPTACLE-M931/A1/A2andM932/A1/A2vehiclesequippedwithafifthwheelareprovidedwithasemitrailerreceptacle.Thisreceptacleprovidesvehiclelighting,auxiliarypower,andagroundcircuitforsemitrailers.1-54TM9-2320-272-24-11-23.COMPRESSEDAIRANDBRAKESYSTEMOPERATIONThecompressedairandbrakesystemtakesfilteredair,compressesit,andsuppliesittovariouscomponentsthatenabletheoperatortoslowdownorstopthevehicle.Thissystemalsosuppliescompressedairtoair-actuatedaccessoriesthroughoutthevehicle.Thesecomponentsandaccessorieswillbedescribedaspartofthefollowingsystems:a. MediumWreckerAutomaticBrakeLockSystemOperation(page1-55).b.AirPressureSupplySystemOperation(page1-56).c. SecondaryServiceAirbrakeSystemOperation(page1-60).d. SpringAirbrakeSystemOperation(page1-62).e. PrimaryServiceAirbrakeSystemOperation(page1-63).f. AuxiliaryAir-PoweredSystemOperation(page1-66).g.AirVentingSystemOperation(page1-68).h. CentralTireInflationSystem(CTIS)(M939A2seriesvehicles)(page1-70).a. MediumWreckerAutomaticBrakeLockSystemOperation.TheM936/A1/A2MediumWreckerAutomaticBrakeLockSystemlockstheserviceairbrakeswhenthetransfercasePTOleverisengaged.Majorcomponentsoftheautomaticbrakelocksystemare:KeyItemandFunctionA TRANSFERCASEPTOLEVER-Opensthebrakelockcontrolvalvethroughmechanicallinkagewhenengaged.B BRAKELOCKCONTROL-Allowsairpressuretoflowfromsecondaryairreservoirtopressureregulatorandactivatevariablespeedgovernor.C PRESSUREREGULATOR-Reducesandregulatessystemairpressureto70psi(483kPa)forautomaticbrakelockapplication.D TREADLEVALVE-Connectspressureregulatorandserviceairbrakes.1-55TM9-2320-272-24-11-23.COMPRESSEDAIRANDBRAKESYSTEMOPERATION(Contd)b.AirPressureSupplySystemOperation.(1)Aconstantairpressuresupplyisdevelopedbythecompressorwhichisregulatedbythegovernortomaintain90-120psi(621-827kPa)fortheairbrakesystem.Moisturewithinthesystemiscontrolledthroughtheuseofeitherthealcoholevaporatororairdryer.Themajorcomponentsofthesystemare:1-56TM9-2320-272-24-11-23.COMPRESSEDAIRANDBRAKESYSTEMOPERATION(Contd)KeyItemandFunctionA AIRDRYER-Installedinsupplylinetowettankandremovesmoisturefrominletairtowettank(M939/A1airdryerkitinstalledonly).AIRCOMPRESSOR-Drawsinairfromtheintakemanifoldandforcesitintobrakesystemandwettankreservoir.BC SAFETYVALVE-Locatedatinletsideofwetreservoir,itpreventspressurebuildupbyreleasingairpressureexceeding150psi(1,034kPa)whenthegovernorfailstoregulateairsuppliedbythecompressor.DEFGHIJWETTANKRESERVOIR-Performstwofunctions:l Trapswaterinairreservoirtoprotectotherairsystemsfromfreezingorcorroding.l Storesreserveairsupplyenablingoperatortomakenormalstopswhenenginestallsorcompressorfails.PRESSUREPROTECTIONVALVE-Performstwofunctions:l Allowsairpressuretobuildto60-65psi(414-448kPa)beforesupplyingairtoauxiliaryair-poweredequipment.l Closesoffauxiliaryairsystemfromothersystemsifanaccessoryfailsandpreventslossofairfromsecondaryreservoir.ALCOHOLEVAPORATOR(M939/A1series)-Helpsprotectairlinesfromfreezing.WETTANKRESERVOIRDRAINVALVE-Providesadrainformoistureandairfromreservoir.AIRDRYER-Removesmoisturefrominletairtowettank(M939A2only).EXPELLOVALVE-Augmentsairdryercondensationblowdownbyventingmoisturewhencompressorcycles.GOVERNOR-Tripsvalveinsidecompressortoregulateflowofairtothesystem.Whenpressurebuildsto120-127psi(827-876kPa),thegovernorwillclosevalve.1-57TM9-2320-272-24-11-23.COMPRESSEDAIRANDBRAKESYSTEMOPERATION(Contd)(2)Theconstantairpressuresupplyisdistributedtotheprimaryserviceairbrakesystem(para.e.)andsecondaryairbrakesystem(para.c.)throughashutoffandcheckvalve.Airpressurecaneitherbefedfromorsuppliedtoanothervehiclethroughtheemergencycouplings.1-58TM9-2320-272-24-11-23.COMPRESSEDAIRANDBRAKESYSTEMOPERATION(Contd)KeyItemandFunctionA FRONTEMERGENCYCOUPLING-Whenvehicleisbeingtowed,couplingreceivescompressedairfromtowingvehiclesbrakesystemtochargeitsownbrakesystem.PRIMARYAIRRESERVOIR-Storessufficientairpressuretoallowoperatortomakenormalbrakeapplicationsifsystempressurefailsorenginestalls.PRIMARYFEEDCUTOFF-Manually-operatedvalveusedtoisolatepressureleaksinprimaryairsystemfromdrainingwettank(TM9-2320-272-10).PRIMARYAIRRESERVOIRCHECKVALVE-Preventsbackflowofairfromprimarytankifwetsystemdevelopsaleak.SECONDARYFEEDCUTOFF-Manually-operatedvalveusedtoisolatepressureleaksinsecondaryairsystemfromdrainingwettank(TM9-2320-272-10).SECONDARYAIRRESERVOIRCHECKVALVE-Preventsbackflowofairfromsecondarytankifwetsystemdevelopsaleak.REAREMERGENCYCOUPLING-Whentowinganothervehicle,couplingallowspressurizedairfromwettanktochargetowedvehicleswettank.SECONDARYAIRRESERVOIR-Storesenoughairpressureincaseconstantpressuresystemfailsorenginestalls.Theoperatorcanmakenormalbrakeapplicationbeforerunningoutofair.PRESSUREPROTECTIONVALVE-Performstwofunctions:(1)Allowsairpressuretobuildto60-65psi(414-448kPa)beforesupplyingairtoauxiliaryair-BCDEFGHIpoweredequipment.(2)Closesoffauxiliaryairsystemfromothersystemsifanaccessoryfailsandpreventslossofairfromsecondaryreservoir.1-59TM9-2320-272-24-11-23.COMPRESSEDAIRANDBRAKESYSTEMOPERATION(Contd)c. SecondaryServiceAirbrakeSystemOperation.(1)Thesecondaryserviceairbrakesystemismadeupoftwosubsystems:(a)Secondaryconstantpressuresystemprovidescontinuousairpressureto:lPedalvalvelRearrelayvalvelSpringbrakeairreservoirlSpringparkingbrakevalve(b)Secondarysignalsystemservesthreefunctions:lContainsairpressureonlywhenoperatorstepsonbrakepedal.lIsregulatedbyvariousvalvestocontrolamountofbraking.lProvidespressuretoapplyreartwoservicebrakesandintermediateandrearaxlesstampedwithB.Servicebrakesonrearaxlearepiggybackedtospringbrakes,butoperateindependentlyofthem.(2)