Hyster G138 (N45XMR3) Forklift Service Repair Manual

General

Thismanualdescribesthedisassemblyandassemblyofthesteeringsystemforrepairs.Thereisadescriptionforeachpartofthesteeringsystem.The steeringsystemrotatesthemasterdriveunit(MDU) tosteerthelifttruck.Thesteeringpumpforthissystemalsosuppliesoiltooperateauxiliaryhydraulic functionswhenthelifttruckhasthesefunctions.

Thesteeringsystemforthenarrow-aisleandgrocery-reach-serieslifttrucksfeaturesahydrostatic steeringsystem.Thissystemutilizesasteering controlunit(SCU)andahydraulicmotorassembly. Thecomponentsaremountedinsidethedriveunit compartment.TheSCUisconnectedtothesteering disk.Thesteeringdiskispositionedforeasyoperationandrequiresonlyfourandone-quarterturnsto obtainfullsteeringof180degrees.

WhentheSCUisactivated,hydraulicoilisdirected tothehydraulicmotorassembly.Thehydraulic motorassembly,mountedonthearticulatingaxle weldment,isconnectedtotheMDUwithachain. ThehydraulicoilfromtheSCUdrivesthehydraulic

motorassemblytoturntheMDUinthedesired direction.

WARNING

Thenarrowaisleandgroceryreachserieslift trucksmaybe furnishedwithautomotiveorreversesteering.Beforeworkingonanyofthese lifttrucks, besureofthetypeofsteeringthatis usedonthelifttruckbeingworkedon.Reverse steeringmay beobtainedbyreversingthetwo hosesfromtheSCUtothesteermotorassembly.

Thesteeringsystemdrawshydraulicoilfromthe samehydraulictankusedbythemastandreachassembly.The hydraulicoilisdirectedtotheSCUby thepowersteeringpump.Thisgearpumphasapriorityflow valve,whichwillprovidehydraulicoilfor powersteeringfirstifboththepowersteeringand auxiliary functionsarebeingusedatthesametime. Thegearpumpisdrivenbya24-or36-voltpermanentmagnetmotor.

Description

Thepowersteeringsystemisahydrostaticsteering system.SeeFigure1.Thecontrolofthesteeringis throughahydrauliccircuit.Anelectricmotorforthe steeringpumpisenergizedwhenthebrakeswitch andtheoperatorsensingswitchareclosedandthe keyswitchisinthe ON position.Whentheelectric pumpmotoroperatesthesteeringpump,hydraulic oilflowsthroughthepowersteeringsystem.Moving thesteeringdiskrotatestheshaftoftheSCU.The SCUmeterstheflowofoiltothehydraulicmotor ontheaxleweldment.Thehydraulicmotormoves achaintorotatetheMDUandsteerthelifttruck.

Whenthesteeringdiskisnotbeingmoved,the hydraulicoilflowsfromthegearpumpthroughthe excessflowportofthesteeringpumptotheproportionalcontrolvalveforsupplyingtheauxiliary functions.Iftheauxiliaryfunctionsarenotselected, theoilisreturnedtothehydraulictank.When thesteeringdiskisbeingmoved,thehydraulicoil flowsthroughthepriorityflowlinefromthegear pumptotheSCU,thentothehydraulicmotor.This hydraulicoilreturnsfromthehydraulicmotorto theSCU,thentothehydraulictank.

Figure1.TypicalSteeringSystem

DESCRIPTION

SteeringControlUnitAssembly

ThesteeringdiskisattachedtotheshaftoftheSCU. ThisshaftengagesthespooloftheSCU.TheSCUis aload-sensing,closed-center,rotary-typevalve.Duringthesteeringoperation,thesignalgeneratedis proportionaltotherotationofthesteeringdisk.The unitcontrolsboththedirectionandregulationofoil flowtooperatethehydraulicmotor.Ifthesteeringpumpfailstooperate,acheckvalveclosesin theSCU.TheSCUthenoperatesasahandpumpto makesteeringpossible.Thelifttruckisdifficultto steerwhenthepowersteeringisnotoperating.The SCUismountedtoabracketthatismountedtothe lifttruckframe.

REMOVE WARNING

Makesurethebrakepedalisreleasedand thebrakeisapplied.Putblocksonbothsides (frontandback)ofthedrive/steertireand

DESCRIPTION

thecasterwheelstopreventmovementofthe lifttruck.Putablockoneachside(frontand back)oftheloadwheelstopreventmovement ofthelifttruck.

1. Disconnectthebattery.Blockthedrive/steer tires,casterwheels,andloadwheelsonboth sidestopreventmovementofthelifttruck. Openthedriveunitcompartmentcover.Remove thebatterycompartmentcoverandthedrive unitcover.

2. Installlabelsonthehydrauliclinesforproperinstallationatassembly.Disconnectthehydraulic linesandinstallcapsonthelinesandfittings.

3. Removetheshoulderscrew,lockwasher,andnut thatholdthesteeringcontrolhandletotheSCU. Removethesteeringcontrolhandle.

4. Removethetwocapscrewsandlockwashersretainingthesteeringcontrolunittothemounting bracket,andremovethesteeringcontrolunit.

SteeringControlUnit

Thesteeringsystemisahydraulicsystemthatdoes nothaveamechanicalconnectionbetweenthesteeringdiskandthesteeringaxle.Thesteeringiscontrolledthroughahydrauliccircuit.

Ifthesteeringpumpfailstooperate,acheckvalve permitstheSteeringControlUnit(SCU)tooperate asahandpumpandtomakesteeringpossible.The lifttruckisdifficulttosteerwhenthehydraulic pumpisnotoperating,buttheSCUcanoperatethe hydraulicmotorandmakesteeringpossible.

OPERATION

TheSCUisarotaryvalvethatisoperatedbythe steeringdisk.Duringthesteeringoperation,the SCUcontrolsthedirectionofflowandamountof oilthatflowstothehydraulicmotor.Thehydraulic motoractuatesthesteeringchainorgeartoturnthe driveunit.Hydraulicoilreturnsfromthehydraulic motortotheSCUandthenreturnstothehydraulic tank.

Turningthesteeringdiskactuatesthreemainparts oftheSCU:(1)thespoolforthecontrolsection,(2) thesleeveforthecontrolsection,and(3)therotor inthemeteringsection.Whenthesteeringdiskis notmoving,thespoolandsleeveareheldintheneutral(center)positionbysprings.Duringthistime,oil flowsfreelythroughtheSCU.Theoildoesnotflow tothesteeringmotor.

Asthesteeringdiskisturned,thespooljustbeginsto rotate.Thespringstrytomovethesleevetokeepthe neutralpositionbetweenthespoolandsleeve.However,theforcenecessarytoturntherotorisgreater thanthepressureofthesprings.Thespringsbegin tocompress,lettingthespoolmoveasmallamount withinthesleeve.Thespoolstopsmovingwhenit touchesthecenterpin.Inthisposition,theholesin thesleeveandthespoolarealigned.Oilcominginto thecontrolunitflowstothemeteringsection.

Morerotationofthesteeringdiskcausesthespoolto rotatethepin.Thisactioncausestherotationofthe sleeveandtherotorinthemeteringsection.Theoil thenflowstoonesideofthesteeringcylinder.Hydraulicoilfromtheothersideofthesteeringmotor returnsthroughthecontrolsectionoftheSCU.

Whenthesteeringdiskstopsmoving,themetering actioninthemeteringsectionalsostops.Theneutralpositionspringsreturnthesleevetotheneutral position.Whenthisactionoccurs,thepressurestays inthesteeringmotortokeepthesteertireinposition.OilfromthepumpflowsthroughtheSCUto thetankorotherpartsofthesystem.Toreturnthe steertiretothestraightposition,thesteeringdisk mustberotatedintheoppositedirection.TheSCU willoperateasdescribed,butallpartswillrotatein theoppositedirection.

REMOVE

CleanaroundtheportsoftheSCUpriortoremoving thehydraulichoses.

1. Identifyandtagallhydraulichosesattachedto SCUforlaterinstallation.

2. RemoveallhydraulichosesattachedtoSCU,beingcarefulnottospillanyhydraulicoil.

3. Installacapontoeachhydraulichoseandinstall aplugintoeachportoftheSCU.Thisisdoneto preventoilfromspillinganddirtfromentering thesystem.

4. Removethecapscrewsandlockwashersthathold theSCUtothebracketandremovetheSCU.

5. PlaceSCUonacleanworkbench.Thework benchshouldhaveavisewithsoftjaws.

6. Wipeupanyspilledoil.

REPAIR

NOTE: CleanlinessisveryimportantwhenrepairingtheSCU.AlwaysrepairtheSCUinacleanwork area.Duringrepairs,alwaysprotectmachinedsurfaces.

NOTE: Beforedisassembly,draintheoil,plugthe portsandthoroughlycleantheexterioroftheSCU.

Putthecontrolunitinavisewithsoftjaws.See Figure2.

NOTE: WhenremovingO-ringscarefullycleanand inspectthegroovefortheO-ring.(Anydirt,burrs,or foreignmaterialinthegroovemaycausetheO-ring toleakhydraulicoil.)

AlwaysreplaceanyO-ringsthatareremovedduring repairoftheSCUwithnewO-rings.

1.STEERINGCONTROLUNIT

2.VISE

3.ALIGNMENT SCRIBE(MARK)

1. Scribe(mark)alineacrossthehousing,gerotor, andmountingcap.Thisisdonesotheunitcanbe reassembledbyaligningthemarks.Itiscritical toreassembletheSCUcorrectlybecausethere areholes drilledintothedifferentpartstoallow oiltocirculatethroughtheSCU.

NOTE: RefertoFigure3forthefollowinginstructions.

2. Removethecapscrewsthatholdthemounting capandremovethemountingcap.

3. Removedustseal,pressureseal,andO-ring(8) fromthe mountingcap.Carefullycleanandinspectallsurfacesofthemountingcap.

4. Removethrustraceandthrustbearingfromthe shaftof thespool.

5. Removethedrivepinbygentlypullingonthe shaftenoughtofreethedrivepinfromthegerotor.Removethedrivepinfromtheshaft.

6. Remove thegerotor.Carefullycleanandinspect allsurfacesofthegerotor.

7. Remove theO-ring(8)fromthehousing.Carefullycleanandinspectallsurfacesofthehousing.

Figure2.SteeringControlUnitinVise Disassemble(BeforeMay2002)

Disassemble(AfterMay2002)

1. Putthe controlunitinavisewithsoftjaws.See Figure 2.Scribe(mark)alineacrosshousing, gerotor,andendcap.Thisisdonesotheunit canbereassembledbyaligningthemarks.Itis criticaltoreassembletheSCUcorrectlybecause thereareholesdrilledintothedifferentpartsto allow oiltocirculatethroughtheSCU.

NOTE: RefertoFigure4forthefollowinginstructions

2. Removethecapscrewsthatholddowntheend capandremovetheendcap.

3. RemovebothO-rings,thespacer,andsealring fromtheendcap.Carefullycleanandinspectall surfacesoftheendcap.

4. Remove thegerotor.Carefullycleanandinspect allsurfacesofthegerotor.

5. Remove driveshaft.

6. Remove wearplateandO-ring.Carefullyclean andinspectallsurfacesofthewearplate.

7. Remove O-ringfromhousing.

NOTE: Themanualsteeringcheckvalvemaybea checkballoracheck/reliefvalve.

8. Remove theplugandmanualsteeringcheck valve.

9. Remove thespoolandsleevefromthehousing. SeeFigure5.

Figure3.SteeringControlUnit(BeforeMay2002)

Figure4.SteeringControlUnit(AfterMay2002)

CAUTION

Makesurenottodamagethedustsealwhen

CAUTION

Thecenteringspringsareundertension.Removetheretainingringcarefully.

15.

Clean WARNING

Cleaningsolventscanbeflammableandtoxic andcancauseskinirritation.Whenusing cleaningsolvents,alwaysfollowthesolvent manufacturer’srecommendedsafetyprecautions.

Clean allpartsinsolvent.Drythepartswithcompressedair.Donotdrythepartswithacloth.Make

Figure5.RemoveSpoolandSleeve

10. Removethrustracesandthrustbearing.

11. Removethequadseal.

removingit.

12. Removethedustsealusingasmallflatblade screwdriver.Carefullyprythedustsealfromthe housing.

13. Removethedrivepin.

14. Carefullyslidethespooloutofthesleeve.The springsandretainingringwillstaywiththe spoolasit’sremoved.

Removetheretainingringandsprings.

sureallsurfacesarefreeofscratchesandsharp edges.

Reassemble(BeforeMay2002)

NOTE: RefertoFigure3forthefollowinginstructions.

1. Installthegerotor.Carefullyalignthescribe (mark)onthegerotorandthehousing.

2. Installthedrivepin.

3. Installnewdustseal,pressureseal,andO-ring (8)onthemountingcap.Carefullyalignthe scribe(mark)onthemountingcapandthegerotor.

4. Installnewthrustracesandthrustbearingsinto thehousing.

5. RemovethetankplugonthebottomoftheSCU withaspannerwrench.RemovetheO-ring(11). Carefullycleanandinspectthegrooveinwhich theO-ringisseatedandinstallanewO-ring.

Reassemble(AfterMay2002)

NOTE: RefertoFigure4forthefollowinginstructions.

NOTE: Alwaysusenewsealswhenreassembling theSCU.Duringreassemblylubricatethenewseals withapetroleumjellysuchasVaseline™.Also lubricatemachinedsurfacesandbearingswithclean hydraulicfluid.

1. Installthequadseal:

• Installoneofthebearingracesandthesleeve intothehousing.

• Together,thehousingandbearingracecreate agrooveintowhichthequadsealwillbeinstalled.

• Holdthebearingracetightlyagainsttheinput endofthehousingbypushingonthegerotor endofthesleeve.

• Fitthequadsealintoitsseatthroughtheinput endofthehousing.Makesurethesealisnot twisted.

• Removethesleeveandbearingrace.

2. Lubricateandinstallthedustseal.

3. Installthecenteringspringsinthespool.Itis besttoinstallthetwoflatpiecesfirst.Next,installthecurvedpieces,threeatatime.

4. Fittheretainingringoverthecenteringsprings.

5. Applyalightcoatingofcleanhydraulicfluidto thespoolandslideitintothesleeve.Makesure thecenteringspringsfitintothenotchesinthe sleeve.

6. Installthedrivepin.

CAUTION

Donotdamagethedustandquadseals.

7. Applyalightcoatingofpetroleumjellytothe inneredgeofthedustandquadseals.

8. Installthethrustbearingandracesintothe housing.Thethrustbearingisinstalledbetween thetworaces.

9. Applyalightcoatingofcleanhydraulicfluidto thespoolandsleeveassemblyandslideitinto thehousing.

CAUTION

Donotdamagethehousingbyovertightening thevise.

10. ClampthehousinginaviseasshowninFigure2. Useonlyenoughclampingforcetoholdthehousingsecurely.

11. LubricateandinstallanewO-ringinthegroove inthehousing.

12. Installthewearplateandalignthescribe(mark) youmadeearlieronboththewearplateand housing.

13. Installthedriveshaft.Makesuretheslotinthe driveshaftengagesthepin.

14. LubricateandinstallanewO-ringinthegroove inthewearplate.

15. Installthegerotorandalignthescribe(mark) youmadeearlieronthewearplate,gerotor,and housing.

16. LubricateandinstallanewO-ringinthegroove inthegerotor.

17. LubricateandinstallanewO-ringinthegroove inthegerotorstar.

18. Installthespacer.

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19. Installtheendcapandalignthescribe(mark) youmadeearlieronthewearplate,gerotor,end cap,andhousing.

20. Installcapscrewsandtighteninacrisscrosspatternto16-18N•m(140-160lbfin)asshownin Figure6.

21. RemovetheSCUfromthevise.

22. Installthecheck/reliefvalveorcheckballand plug.UseanewO-ringandtightentheplugto 17N•m(150lbfin).

INSTALL WARNING

Ifthehosesareincorrectlyconnected,the steeringdiskcanmoverapidlywithhighforce whenthetruckisstarted.Donotplacethe handsnearthediskwhenstartingthelift truckafterconnectingthepump.

1. AligntheSCUwiththemountingbracketand installthecapscrewsandlockwashers.

2. Removethecapsfromthehydrauliclinesandthe plugsfromtheSCU.Installthehydrauliclines ontheSCU.

3. Replacethesteeringcontrolhandle.Replacethe shoulderscrew,lockwasher,andnutthathold thesteeringcontrolhandletotheSCU.

4. Installthedriveunitcoverandthebatterycompartmentcover.Removetheblocksfromthetires andwheels.Connectthebatteryandtestthe SCU.Checkforleaks.Closethedriveunitcompartmentcover.

SteeringPumpandMotorAssembly

DESCRIPTION

Thispumpandmotoralsosupplyoilfortheauxiliaryhydraulicfunctions.Thesteeringpumpand motorassemblyarefastenedtothelifttruckframe. Thesteeringpumpandmotoroperatewhenthekey switchis ON andtheoperatorhasboththebrake pedalandtheoperatorsensingswitchdepressed.

Thesteeringpumpisasmallgearpumpfastenedto apermanentmagnetDCmotor.Thesteeringpump hasabuilt-inpriorityvalvetoensurepriorityflowto thepowersteering.Whenboththepowersteering andauxiliaryfunctionsareusedatthesametime, thepriorityvalvewillensurethatfullflowisprovidedtothepowersteering.Theinlet(suctionport)

ofthepumpisconnectedtothehydraulictankwith ahydraulichose.

Thepumpoutlet(pressure)portsareconnectedto boththeSCUandthemaincontrolvalvewithhydraulichoses.Thehosetothemaincontrolvalveis theexcessflowline.Thehydraulicoilinthislinewill eitherbedirectedtotheauxiliaryfunctionsortoreturntheoiltothehydraulictankwhenthesteering diskisnotbeingrotatedortheauxiliaryfunctions arenotbeingused.TherearetwohosestotheSCU. OnehoseisthepriorityflowlinetotheSCU.The otherhosetotheSCUistheload-sensinghose.The load-sensinghoseisusedtodeterminetheamountof oilrequiredtooperatetheSCUforthepriorityvalve.

Figure6.TighteningSequence

PUMPANDMOTOR

RemoveandDisassemble

WARNING

Makesurethebrakepedalisreleased(inthe UPposition)andthebrakeisapplied.Put blocksonbothsides(frontandback)ofthe drive/steertireandthecasterwheels.Puta blockoneachside(frontandback)oftheload wheelstopreventmovementofthelifttruck.

NOTE: Therecommendedmaintenanceandrepairs forthesteeringpumpmotorarecoveredinthesection DCMotorMaintenance 620SRM294.

1. Disconnectthebattery.

2. Identifyandtagthepowercablesontheterminalsofthemotorforcorrectconnectionduring installation.Disconnectthecablesfromthemotor.

3. Identifyandtagthehydraulichosesatthepump forthecorrectconnectionduringinstallation. Disconnectthehoses,andinstallcapsonthe hosesandplugtheportstokeepdirtoutofthe system.

WARNING

Themotorandpumpassemblyhaveaweight ofapproximately27kg(60lb).Thesteering pumpmotorhasceramicpermanentmagnets. Donotletthemotorfall.Themagnetscanbe damaged.

4. Removethefourcapscrews,lockwashers,brackets,andrubberchannelmounts.SeeFigure7. Removethemotor,pump,andbracketfromthe lifttruckframe.

5. Checkthebrushes.Seethesections Periodic Maintenance 8000SRM970and DCMotor Repair 620SRM294foradditionalinformation forinspectionofthebrushesandcommutator.

6. Ifthemotormustbedisassembledforcleaningor repairs,removethepumpsoanewoilsealcan beinstalledinthemotor.Removethemountingbracketfromthemotor.Makematchmarks foralignmentonthepumpmountflangeandthe motorhousing.Makematchmarksforalignment ofthepartsofthemotorhousing.Thesemarks arenecessarytoassemblethemotorandpump

correctly.Removethecapscrewsandlockwashersretainingthepumptothemotor.

7.MOTORMOUNT

AssembleandInstall

1. Installanewsealinthemotorendhousing.

2. Putmultipurposegreaseonthesplinesofthe pumpshaft.Alignthepumpshaftwiththeopeninginthemotorandinstallthepumponthemotorusingthetwocapscrewsandlockwashers.

3. Installthemountingbracketonthemotor.

WARNING

Themotorandpumpassemblyhaveaweight ofapproximately27kg(60lb).Thesteering pumpmotorhasceramicpermanentmagnets. Donotletthemotorfall.Themagnetscanbe damaged.

4. Installthesteeringpumpandmotor.Usethe fourcapscrews,lockwashers,brackets,andrubberchannelmountstoretainthepumpandmotorassembly.

5. Connectthehydraulichosestothefittingsas identifiedduringremoval.

6. Connectthepowercablesonthemotor.

Figure7.TypicalSteeringPumpandMotor Mounting

WARNING

Ifthehosesare incorrectlyconnected,the diskwillmoverapidlywithhighforcewhen thetruckisstarted.Donotplacethehands nearthediskwhenstartingthelifttruckafter connectingthepump.

7. Checkthehydrauliclevelofthehydraulictank. Testoperate thesteeringpump.Connectthebattery.Checkforleaks.Installtheinstrument panelcover. Removetheblocksfrombothsides ofthedrive/steertire,casterwheels,andtheload wheels.

PUMP Remove

1. Disconnectthebattery.Blockthedrivetire, casterwheels,andloadwheelsonbothsidesto preventmovementofthelifttruck.

2. Installlabelsonthehydrauliclinesforproperinstallationatassembly.Disconnectthehydraulic linesandinstallcapsonthelinesandfittings.

3. Removethetwocapscrewsandlockwashersretainingthesteeringpumptothemotor.Remove thepumpfromthemotor.SeeFigure8.

Figure8.PowerSteeringPumpandMotor

Install

1. Alignthesplinedshaftofthepumpwiththemotorandinstallthepump.

2. Installthetwocapscrewsandlockwasherstoretainthepumptothemotor.

Disassemble

1. Disassemblethefittings,elbows,andO-rings fromthepumpbody.SeeFigure9.

WARNING

Becarefulwhenremovingorinstallingsnap rings.Thesesnapringscancomelooseduringremovalorinstallationwithenoughforce tocauseaninjury.Alwaysusethecorrectsnap ringpliersandweareyeandfaceprotection duringremovalandinstallation.

2. Useapairofsnapringpliersandremovethe snapringretainingtheshaftsealtothedrive gearshaft.Removetheshaftseal.

3. Marktheflange,pumpbody,andload-sensing valveassemblyfororientationduringassembly.

4. Removethefourcapscrewsfromthepumpbody. Separatethemountingflangeandtheendcover fromthepumpbody.Removethebackuprings, seals,bushings,andO-rings.

5. Removetheidlergearanddrivegear.

6. Inspectthedrivegear,idlergear,andthepump bodyfordamage.Ifanyofthesepartsaredamaged,thepumpmustbereplacedwithanew pump.Allseals,O-rings,backuprings,andsnap ringmustbereplacedifthepresentpumpisto beused.

NOTE: Themanufacturerdoesnotrecommendservicingtheindividualcomponentswithintheloadsensingvalveassembly.

Figure 9.PowerSteeringPump

Assemble

1. Applycleanhydraulicoiltoallthepumpcomponentsbeforeassembly.

2. Alignandinstalltheidlergearanddrivegearin thepumpbody.InstallnewO-ringsinthepump body.

3. Installbothbushingsontheshafts.Installthe sealsandbackupringsinthebodyofeachofthe bushings.

4. Aligntheload-sensingvalveassembly,pump body,andmountingflange.Installthefourcapscrews.Tightenthecapscrewsto68to74N•m (50to55lbfft).

5. Installanewshaftsealonthedrivegearshaft.

WARNING

Becarefulwhen removingorinstallingsnap rings.Thesesnapringscancomelooseduringremovalor installationwithenoughforce tocauseaninjury.Alwaysusethecorrectsnap ringpliers,andweareyeandfaceprotection duringremovalandinstallation.

6. Installanew snapring.

7. InstallnewO-ringsonthefittingsandelbows. Installthefittingsandelbowsinthepump.Installthepilotreliefvalveandload-sensingvalve inthepumpbody.Makesurethevalvesareproperlyadjusted.

8. Alignthesplinedshaftofthepumpwiththemotorandinserttheshaftinthemotor.Installthe twolockwashersandcapscrews.

AxleAssem blyRepair

GENERAL

Theaxleassemblyhasanarticulatedaxleweldment, whichisa mountforthemasterdriveunit(MDU), hydraulicsteeringmotor,andthecaster.ThetractionmotorfastenstothetopoftheMDUnearthe leftendoftheaxleweldment.TheMDUisfastened tothebottomoftheweldmentandrotatesonalarge bearing. Thetractionmotorsuppliesthepowerto turnthe drivewheelfortravel.ThehydraulicsteeringmotorrotatestheMDUforsteering.Thecaster supportstherightendoftheweldment.Thearticulatedaxleassemblyisfastenedtothelifttruckby ashaft andarticulates(tilts)ontheshaftforbetter tractionofthedrivetire.

TRACTIONMOTOR

Description

Thetractionmotorisnotpartofthesteeringsystem. ThemotorispartoftheMDUassemblyandmustbe removedtoremovetheaxlefromthelifttruck.

Remove

1. Disconnectthebattery.Openthedoortothe drive unitcompartment.

2. Putlabels onthepowercablesofthetractionmotorforcorrectidentificationduringinstallation. Themotor terminalsareidentifiedonthemotor asA1,A2, S1,orS2.

3. Taganddisconnectthewirestothebrakeswitch.

CAUTION

Brakefluiddamagespaint.Immediatelyremoveanybrakefluidthatisonapaintedsurface.

4. Positionacontainerundertheslavecylinderto catchthebrakefluidanddisconnectthehoseassembly.Capthehoseassembly.Allowthebrake fluidtodrainfromtheslavecylinder.

5. Makeamarkonthemotorhousingandtheaxle weldmentforcorrectmotoralignmentduringinstallation.RemovethesixM8capscrewsand lockwashersthatfastentheflangeofthetraction motortotheMDUbearinghousing.

WARNING

Thetractionmotorisheavy.Besurethatall liftingdevices(hoists,cables,chains,slings, etc.)aresuitableandofadequatecapacityto liftthetractionmotor.Thetractionmotorcan weighapproximately57kg(125lb).

6. Useaslingaroundthetractionmotorandan overheadcranetocarefullyliftthetractionmotor.Thecraneandslingmusthavealiftingcapacityofapproximately57kg(125lb).Donot damagethedrivegearonthemotorshaft.Donot damagethehornorbrakeassembly.Putthemotoronitssidesothegear,cableterminals,horn, brakeassembly,anddriptrayarenotdamaged.

Install

1. InstallanewO-ringonthetractionmotorhousing.UseO-ringlubricantontheO-ring.

WARNING

Thetractionmotorisheavy.Besureallliftingdevices(hoists,cables,chains,slings,etc.) aresuitableandofadequatecapacitytoliftthe tractionmotor.Thetractionmotorcanweigh approximately57kg(125lb).

2. Useanoverheadcraneandslingtocarefullylift thetractionmotorintothecorrectpositiononthe MDUhousing.Makesurethecraneandsling haveacapacityofapproximately57kg(125lb). Donotdamagethegear,motorterminals,horn, brakeassembly,ordriptray.MakesurethemotorandtheMDUgearsarealignedbeforecompletelyloweringthemotorontothegearhousing. Alignthemarksmadeduringremoval.

3. Installandtightenthesixcapscrewsandlockwashersinacrisscrosspatternto20N•m (15lbfft).

4. Connectthepowercablestothemotorterminals accordingtothelabelsmadeduringremoval.

5. Connectthewirestothebrakeswitch.

CAUTION

Brakefluiddamagespaint.Immediatelyremoveanybrakefluidthatisonapaintedsurface.

6. Removethecapfromthehoseassembly.Connectthehoseassemblytotheslavecylinder.

Addbrakefluidtothereservoirwiththerecommendedbrakefluid.Removetheairfromthe brakesystem.Seesection BrakeSystem 1800 SRM976and1800SRM983toremovetheair fromthebrakesystem.Donotoperatethelift truckwithoutremovingtheair.

7. Closethedriveunitcompartmentdoor.Connect thebattery.

MASTERDRIVEUNIT

Description

Themasterdriveunit(MDU)isturnedbythesteeringchain,orgearandhydraulicmotor.Thehousing forthesteeringbearingisfastenedtothebottomof theaxleweldment.Thetractionmotorisalsofastenedtothisbearinghousing.

RemoveChain-SteeredMDU

1. Turnthekeyswitch OFF,disconnectthebattery, andopenthedoorofthedriveunitcompartment.

2. Ifthetruckhasasteeringchain,usethesteering systemtomovethemasterdriveunitforaccess tothechainanchorofthesteeringchain.

3. Ifthetruckhasasteeringchain,removethe steeringchainfromthesprocketofthehydraulic motor.Toremovethechain,firstmakeamark onthechainanchorandtheMDUhousingatthe chainanchor.Removethecotterpinfromtheend ofoneoffsetlinkpinatthechainanchor.Remove thechainfromthesprocketofthehydraulicmotor.UsewiretofastenthechaintotheMDUso itdoesnotfall.

4. Puttherearofthelifttruckonblocksandremove thedrivetireasdescribedin PeriodicMaintenanceManual 8000SRM970.Makesurethe blocksareinalocationtopermitremovalofthe MDUfromtheleftside.

5. Positionacontainerunderthedrainplugand draintheoilfromtheMDU.Thecontainermust haveacapacityof4liter(1gal).Allowtimefor theoiltodrain;theoilmustdrainthroughthe bearings.Installthedrainplug.

6. Removethetractionmotor.SeeTractionMotor, Remove.