Hyster E004 (S4.00XM) Forklift Service Repair Manual

S3.50XM S4.00XM S4.50XM S5.50XM [E004

Description

Gearpumpshaveseveralsectionsandaremadewith asingleset(singlestage)ofgearsorwithmultiple sets(tandem)ofgears.SeeFigure1.Asingle-stage pumphastwocoversandthegearhousingwiththe gears.Sealsareusedtopreventleaksbetweenthe sections.Tandempumpshaveagearhousingfor eachsetofgears.Mosttandempumpsalsohavea centersectionforthebearings.Theinletandoutlet portsarenormallyonthegearhousingorrearcover. Thefrontcoverhasthesealfortheinputshaft.The inputshaftisconnectedtoadrivensprocket,coupling,orgearbysplinesorakey.

Allthegearpumpshavedevicesthatkeepthe thrustclearanceataminimumwhenthepressure increases.Whenthepressureislow,theclearance increasestopreventwear.Topreventleakagewhen thepressureishigh,theoilfromtheoutletside ofthepumpistransferredtoawearplate.The oilpushesthewearplateagainstthegears.Some pumpshavebearingblocksthatmoveclosertothe gearswhenthepressureincreases.

Figure1.TypesofGearPumps

Operation

Gearpumpshavetheteethofthegearsengagedin thecenterofthepump.Whentheinputshaftis turned,thedrivegearturnsthedrivengear.SeeFigure2.Theoilintheinletchamberismovedoutfrom thecenterbytheteethofrotatinggears.SeeFigure3.Theoilbetweentheteethismovedaround thepumpingchambertotheoutletchamber.Theoil ispushedfromtheoutletchamberbythegearteeth thatarebeginningtoengage.

Whenthepressureincreasestothespringsetting, theballmovesfromitsseatandoilflowstotheinlet chamber.

Thegearsandbearingsarelubricatedbyoilfromthe outletsideofthepump.Asmallamountofoilflows pastthegearsandintothebearingsandtothefront sealcavity.Acheckballandspringareinstalledin somepumpstokeeppressureontheoilinthispassage.Theoilpressurepreventsairleaksthroughthe frontsealandmakessurethereisoiltothebearings.

1.OILENTERSGROOVESINBUSHINGS

2.OILENTERSINLETCHAMBER

FLOWCONTROLVALVE

Someofthepumpshaveaflowcontrolvalveinthe rearcover.SeeFigure4.Theflowcontrolvalvehas eithera pistonandspring,oracartridgewithapistonandspring.Thepistonhasanorificethatpermitsaconstantvolumeofoiltoflowtothecontrolled flowport.Whenthepumpspeedincreases,thepistonmovestopartlyopenthepassagetothemaincontrolvalve.Thisactionkeepsconstantthepressure differenceacrosstheorifice.Aconstantpressuredifferencebetweenbothsidesofanorificecausesaconstant flowthroughtheorifice.

1.INLET 2.OUTLET

3.SEALMADEBY GEARTEETH

Figure2.GearPumpOperation

Figure3. CheckValve

RELIEFVALVE

Somepumpshaveareliefvalveinstalledinacartridgeorinaboreintherearcover.SeeFigure4. Reliefvalvesinthepumppreventthepressurein thecontrolledflowsystemfromincreasingbeyond thespecifications.Thereliefvalveinthecartridge hasapoppetandspring,withtheseatforthepoppetinthecartridge.Thereliefvalveandflowcontrol valveonsomepumpsareinstalledinthesamecartridge.Someofthereliefvalvesthatareinstalledin thepumpsareadjustableonlywithshims.Replace thecartridgeifthereliefvalvehasaproblem.

NOTE: Wornordamagedsealsarethemostcommon causeofpumpfailure.Thepumpbearings,gears, andshaftsalsowear.Manyservicepersonsdonot repairawornpumpbecausethecostofrepairscan begreaterthanthecostofanewpump.Theseals canbereplacedinthehydraulicpump.Ifthepump willberebuilt,thefollowinggeneralproceduresare forrepairinggearpumps.

REMOVE

WARNING

Makesurethecarriageisloweredbeforedisconnectinganypartsofthehydraulicsystem.

1. Ifthelifttruckisequippedwithavalveonthe tank,thevalvemustbeclosedbeforeremoving thepump.Ifthereisnovalveonthetank,removebreatherandinstallaplug.Thisaction

1.INPUTSHAFT

2.BEARINGBLOCKS

3.REARCOVER

4.DRIVEGEAR

5.CARTRIDGE,FLOWCONTROLANDRELIEF VALVE

6.DRIVENGEAR

7.FRONTCOVER

preventsthetankfromdrainingtoofastwhen theinletlineisdisconnected.

2. Disconnecthosesfrompump.Putcapsonallfittings.Becarefulsoinlethoseisnotdamaged duringremoval.

3. Ifthepumpisdrivenbyadriveshaft,disconnect driveshaftatpump.

WARNING

Someofthehydraulicpumpsareveryheavy. Usealiftingdevicewhenremovingorinstallingthepump.

4. Removecapscrewsholdingpumphousingtothe mount.

5. Removepumpfromlifttruck.

Figure4.GearPumpBasicParts

DISASSEMBLE

NOTE: SeeFigure6,Figure7,Figure8,orFigure9 fortheillustrationthatissimilartothepumpbeing repaired.Theillustrationcanhavepartsthatare differentthanthoseintheactualpumpthatisbeing repaired.

1. Removegearorsprocketfrominputshaft.If equipped,removepulleyfrominputshaft.See Figure5.

passagesinthehousingsections.Theoilpassagefor thethrustplatesisintheoutletchamber.

Makesureyoumakecarefulnotesofthelocationand orientationofthepartsandsealsduringdisassembly.Someofthepartsaresimilar,butnotexactly thesameanditcanbedifficulttomakeanidentificationiftheyaremixed.

3. Removecapscrewsornutsthatholdhousingstogether.Useaplastichammertoseparatehousings.Donotdamagemachinedsurfaces.

4. Removegearsandthrustplates(ifused).Make anoteofthepositionsofthethrustplates,seals, andgaskets.Donotuseapunchtomarkthe parts.Removeanyspringsandcheckvalves.

5. Removebearingswithapuller.Insomepumps, thebearingblocksorplatesmustbereplaced withthebearings.

6. Removefrontseal.

CLEAN

WARNING

NOTE: NOTALLLIFTTRUCKMODELSHAVEAPULLEYASSEMBLYONTHEGEARPUMP.

Cleaningsolventscanbeflammableandtoxic andcancauseskinirritation.Whenusing cleaningsolvents,alwaysfollowthesolvent manufacturer’srecommendedsafetyprecautions.

WARNING

2. Beforedisassemblingthepump,makealignment marksonallhousings.Somehousingscanbeassembledinthewrongpositions,whichwillcause failureorincreasedwear.Carefullycleanthe outsideofthepump.

NOTE: Theinletportsinmostgearpumpsarelarger thantheoutletports.

NOTE: Ifthepumpisheldinavisefordisassembly, makesurethevisedoesnotholdthepumptootightly andcausedistortionofthepumpbody.

NOTE: Thepositionofthesealsisimportant.Insome pumpsthedirectionofpumprotationischanged bychangingthepositionofthesealsandhousings. Theholesinthesealsmustbealignedwiththeoil

Compressedaircanmoveparticlessothey causeinjurytotheuserortootherpersonnel. Makesurethepathofthecompressedairis awayfromallpersonnel.Wearprotectivegogglesorafaceshieldtopreventinjurytothe eyes.

CAUTION

Anydirtthatentersthehydraulicsystemcan causedamagetotheparts.

Cleanallpartsofthepumpwithsolvent.Usecompressedairtodrytheparts.Donotuseaclothtodry theparts.Piecesoftheclothcancauserestrictionsin thehydraulicsystem.Makesuretheworkareaand toolsareveryclean.

Figure5.PulleyAssemblyonGearPumps

NOTE: THERECANBEAVARIATIONOFINTERNALPARTSONDIFFERENTMODELSOFLIFTTRUCKS.

INSPECT

1. Inspectoutsideedgesofgearteethforgrooves orscratches.Iftheedgesofthegearteethare sharp,useemeryclothtobreaktheedges.Replacegearsiftherearedeepgroovesonthegears.

Wearonthesealareaoftheshaftindicatesthere isdirtintheoilorahardseal.Inspectsealto seeifithasbeentoohot.Lookforsmallcracksin sealsurfaces.Ifthesealwastoohotorthewrong oilwasused,thesealwillbetoohardortoosoft. Inspectsplinesorkeygroovefordamage.

Figure6.HydraulicGearPumpSingle-Stage

2. Ifthegearshaftshavegroovesorarewornmore than0.05mm(0.002in.),theymustbereplaced.

NOTE:

NOTE: Somepumpbodieswillshowgearmarks wherethegearsrotatebecauseofthesmallclearancesbetweentheparts.Thesegearmarksdonot indicateawornordamagedpumpunlessthepump willnotsupplythevolumeandpressureshownin thespecifications.

3. Inspectgearhousingforwearorgrooves.Most wearoccursontheinletsideofthegearchamber.Putastraightedgeacrosstheinletsideof thegearchamber.Ifa0.13mm(0.005in.)thicknessgaugefitsbetweenthestraightedgeand thehousing,thegearhousingmustbereplaced. Ifthegearhousingisworn,inspectbearingsfor wear.Ifthesystempressureistoohigh,thegear housingswillwearquickly.Groovesinthegear

chamberindicatedirtisintheoil.Smallholesin theoutletsideofthegearchamberindicatethat cavitationhasoccurred.Makesureinlethose, fittings,andtankhavenorestrictions.Cavitationcanalsooccurwhentheenginespeedistoo high.

Ifthesurfacesofthegearchamberorgearteeth havebluemarks,thepumpwastoohot.Heat damageinthepumpcanbecausedbyhotoilor lackofoil.Checkfrontsealsurfacetoseeifair wasenteringthepumpthroughthefrontseal. Makesuretheoilisthecorrectviscosity.The wrongviscosityoilcanincreaseleakagewithin thepump.Leakageinsidethepumpincreases theoiltemperature.

THERECANBEAVARIATIONOFINTERNALPARTSONDIFFERENTMODELSOFLIFTTRUCKS.

Figure7.HydraulicGearPumpSingle-Stage

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NOTE: THERECANBEAVARIATIONOFINTERNALPARTSONDIFFERENTMODELSOFLIFTTRUCKS.

4. Checkthrustplatesforwearorgrooves.If thethrustplateiswornmorethan0.05mm (0.002in.),itmustbereplaced.Replacethrust plateifithasgroovesorholes.Dirtyoilcauses thethrustplatetowearnearwherethegears engage.Smallholesontheoutletsidethethrust platearecausedbycavitation.Lackofoilcan alsocausesmallholesinthethrustplates.Ifthe colorofthethrustplateshaschanged,thepump wastoohot.

5. Inspectallmachinedsurfacesforscratchesor damage.Removewithemeryclothanymetal thatisabovetheflatsurface.Checksurfaces withastraightedge.Inspectgroovesforthe sealsfordirtorscratches.

6. Inspectbearingsforwearordamage.Replace bearingsifthereisanysmallholeonthebearing surface.Replacebushingifitisnotround.

Figure8.HydraulicGearPumpTandem

7. Lookfordamageonseals.Replaceallsealsand O-rings,eveniftheyareingoodcondition.Look forcutsorchangesinshapethatcancausedamage.Findoutwhatdamagecausedthepump tofail.Adamagedsealforthethrustplatecan causetheshaftsealtoleak.Adamagedshaft sealcancauseairtoenterthehydraulicsystem.

8. Inspectflowcontrolvalveandreliefvalvefordirt orscratches.Makesurepistonmovesfreelyin thebore.Lookatpoppetandseatfordamage. Thespringsmustnotbebrokenorbent.Inspect O-ringsfordamage.Makesureorificesareopen.

CAUTION

Donotpermitdirtyoiltoenterthegearpump.

10. Inspectinlethosetothegearpump.Usealamp tolookinsidethehose.Lookforpiecesofrubber thatareseparatingfromthehose.Inspecthose forrestrictionsatbends.Checkforloosefittings ordamagedO-rings.

ASSEMBLE

CAUTION

Makesurenodirtentersthepumpduringassembly.

1. Lubricateallpartswithhydraulicoilbeforethey areinstalledintothepump.

2. PutLoctite290® sealantaroundoutsideoffront seal.Installsealinfrontcover.Makesureseal isinstalledstraight.Ifpumphasaballbearing fortheshaft,installitinthefrontcover.Install snaprings.

Figure9.HydraulicGearPumpTandem

9. Ifanypartsofthepumphavedamagefromdirt intheoil,inspecthydraulictank.Draintank, cleanscreenandtank,andreplacefilter.

3. Installneedlebearingsintofrontandrearcovers. Useapresstopushbearingsintoposition.Push onendofbearingsthathaswriting.Ifthepump hascheckvalves,installthemincover.

CAUTION

Makesuretheholesinthegasketsandsealsare alignedwiththeholeintheoutputsideofthe pump.Thepumpwillnotoperatecorrectlyif theoilfromtheoutletchambercannotflowto thethrustplate.

4. Installsealsforthrustplate.Installrubberseal withlipsawayfromgears.Installpapergasket againsttherubberseal.Theplasticgasketisinstalledbetweenthepapergasketandthethrust plate.Installthrustplatewiththebronzeside towardthegears.

Somepumpshavethrustplateswithsmall groovesfortheseals.Thesealsmustbecut tothecorrectlength.Cuttwostripsthatare 5.5mm(0.22in.)longfromsealstrip.Put greaseonsealsandinstallthemingroovesin centerofthrustplate.Cutthrustplateonfront cover.Hitthrustplatewithaplastichammer to0.8mm(0.031in.)frommachinedsurface. Cutfourstrips6mm(0.24in.)fromsealstrip. Pushstripsintoslotsinthrustplate.Lightlyhit thrustplateagainstthemachinedsurface.Use asharpbladetocutthesealsevenwiththeedge ofthethrustplate.

InstallsealthathasaWshapeandspacerin grooveinfrontcover.Donotbendmetalseal. Installsealinoutergrooveinfrontcover.Install bearingblocksinthesamepositionsfromwhich theywereremoved.

5. Installgearsandbearingblocksinpumpchamberhousing.Makesuregearhousingisinstalled inthecorrectposition.Thesmallholeinsome housingsmustbeintheoutletchamber.The largechannelsintheinletandoutletchambers mustbetowardtherearcover.Thearrowindicatingthedirectionofrotationonthegearhousingmustbetowardthefrontcover.Alignmarks ongearhousingwithmarksoncovers.

6. Putconnectingshaftindrivegearshaftonthe pumpswithtwopumpchambers.Installthrust platesandseals.Putgearsandpumpchamberhousingoncenterbearinghousingwiththe marksaligned.

7. Installsealandrearcover.Useaplastichammer tojointhesections.ApplyasmallmountofLoctite290® sealanttothreadsofcapscrewsorstuds. Installcapscrewsorstudsandtightenwithyour fingers.Rotatedriveshafttomakesurepumpis assembledcorrectly.Tightencapscrewsornuts tothespecificationusingan"X"sequence.

8. Useasoft,blunttooltoinstallO-ringsinbore oftheflowandreliefcartridge.SeeFigure10. Installreliefvalveandflowcontrolvalve.Install fittingswithnewO-rings.

9. Ifapulleywasremoved,installpulleyonshaft andtightennutto72N•m(53lbfft).SeeFigure5.

Figure10.FlowControlandReliefValve Cartridge

INSTALL CAUTION

Beforethegearpumpisinstalled,loosenthe locknutontheadjustmentscrewfortherelief valve.Loosentheadjustmentscrewuntilthe springisnotcompressed.Ifthereliefvalvewas adjustedforawornpump,thesettingwillnot becorrectforanewpump.Damagetothehydraulicsystemcanoccurifthesettingofthe reliefvalveistoohigh.

Alwaysinstallanewfilterwhenrepairsare madetothehydraulicsystem.Drainandreplacethehydraulicoiliftheoilisdirtyor burned.

1. InstallnewgasketorO-ringonfrontcoverof pump.PutathinlayerofNever-Seez® onsplines ofdriveshaft.Fillinletportofthepumpwith hydraulicoil.Turndriveshaftinthedirectionof rotationuntiloilcomesoutoftheoutletport.

WARNING

Someofthepumpsareveryheavy.Usealifting devicetohelpinstallthepump.

2. Installpumpinlifttruck.

3. Installandtightencapscrews.Removecapsfrom fittings.Connecthoses.

CAUTION

Donotpermithotoiltoenteracoldpump. Makesurethereliefvalveineachsystemisat thelowestsetting.

4. Removeplugfrombreatherontank.Install breather.Openvalveontank.Filltankwith cleanhydraulicoil.

5. Installa0to20MPa(0to3000psi)pressure gaugetoateefittingatthepumpoutletport. Startengineandrunitatidlespeedfor3minutes.

CAUTION

Donotoperateanyvalveuntilthepumphas runfor3minutesatlowpressureandlow speed.

6. Touchpumpwithyourhand.Ifpumpishot,it hasaproblem.Ifpumpisnothot,thenincrease enginespeedtohighlimit.Momentarilyincrease pressureto reliefsetting.Repeatthisprocedure for3minutes.

7. Lookatpressuregaugeandadjustreliefvalve. SeeChecks andAdjustmentsforthelifttruckfor whichyouaremakingrepairs.

PumpOutputCheck

Twomethodsaregivenforcheckingthevolumeof flowfromthehydraulicpump.Thefirstmethoduses aflowmeter,apressuregauge,andaneedlevalve. Thesecondmethodusesaneedlevalve,apressure gauge,acontainer,andatimer.

NOTE: Ifthepumphastwooutletports,doseparate flowtests.Addtheresultsofbothteststofindthe totaloutputrate.

METHODNO.1

WARNING

Hydraulicoilcanbehot.Donottouchtheoil duringthetests.

SeeFigure11.Thepressuregaugemustbebetweentheneedlevalveandthepump.Makea separatecheckforeachsystemifpumpistandemorifflowregulatorispartofpump.When thehydraulicoilisatoperatingtemperature,run engineat2800RPMwithnoloadonhydraulic system.Notethereadingoftheflowmeter.Compareoutputrateofpumpwithspecificationfound inthe CapacitiesandSpecifications section ofthe ServiceManual foryourlifttruck.

2. Runengineathighlimit.Slowlycloseneedle valveuntilgaugeindicatespressurejustbelow specificationforreliefvalvesetting.Thepump outputathighorpressuremustbewithin25% oftheoutputwithnoload.Iftheoutputathigh pressureislessthan75%ofthelowpressureoutput,thepumphasaproblem.

1. Iftheflowmeterisavailable,installflowmeter betweenneedlevalveandoutletportofpump.

METHODNO.2

WARNING

Hydraulicoilcanbehot.Donottouchtheoil duringthetests.

1. Anothermethodofcheckingthepumpoutputis tomeasuretheamountofoilmovedinagiven amountoftime.SeeFigure12.Runengineuntil oilis55to65 C(131to149 F).Disconnectline fromoutletportofpump.Installa0to20MPa (0to3000psi)pressuregaugeonateefitting connectedtoahosefromtheoutletport.Install needlevalveonendofhose.Connectanother hosetoneedlevalve.Puttheotherendofthe hoseinacontainerwitha18liter(5gal)capacity. Makesurereservoirisfull.

CAUTION

Thistestmustbedonequicklytopreventthe hydraulictankfrombecomingempty.Donot

operatetheenginewhenthereisnooilinthe hydraulictank.

2. Theneedlevalvemustbefullyopen.Startengineandrunengineatitsgovernedrpmfor5seconds.Stopengine.Measurevolumeofoilthat enteredcontainerin5seconds.Multiplyquantityincontainerby12tofindoutputperminute. Comparepumpoutputratewiththespecificationsfoundinthe CapacitiesandSpecifications sectionofthe ServiceManual foryourlift truck.Thepumpoutputratemustbewithin20% ofthespecifications.

3. Startengineandrunengineatitsgovernedrpm. Closeneedlevalveuntilpressureincreasesto justbelowreliefvalvesetting.Measurethevolumeoffluidthepumpmovesin5seconds.Comparethisquantitywiththeresultsfromthetest ofthepumpoutputatlowpressure.Theoutput ofthepumpathighpressuremustbewithin25% ofthevolumeofoilflowatlowpressure.

Figure11.HydraulicPumpOutputCheckwithFlowMeter

Ifthepumpmakesnoiseordoesnotmovethecorrectamountofoil,checkforairinthesystem.Run theengineuntiltheoiliswarm.Removethefilter headandlookintothetank.Iftherearebubblesin theoil,airisinthehydraulicsystem.Themostcommonplaceofentryoftheairisintheinlethoseto

thepump.Checkforairleaksbypouringoilover thefittingsandhosewhentheengineisrunning.If thenoisedecreases,theleakisinthatarea.Seethe Troubleshootingsectionforothercausesofairinthe hydraulicsystem.

Figure12.HydraulicPumpOutputCheck HydraulicSystemAirCheck