General
Thissectionhasadescriptionandtherepairproceduresforthepartsofthehydraulicbrakesystem.These partsincludethebrakebooster,mastercylinder,andbrakeshoeassemblies.
DescriptionandOperation
Thebrakepedalisconnectedtothepushrodforthe brakebooster.Thebrakeboosterhelpsincreasethe forceonthemastercylinderbyusingvacuumfrom theengine.Thepistoninthemastercylinderforces oiltothewheelcylinderstoapplythebrakes.(The systemallowsbrakingwithoutvacuumfromtheengine.)
thepistonpushesfluidthroughthecheckvalve.A returnspringpushesthepistonbacktothestop platewhenthepedalisreleased.Fluidcanflow throughpassagesinthepistonandpasttheprimarycupasthepistonreturns.Fluidflowsacross thepistontopreventavacuumwhilefluidreturns throughthecheckvalve.Whenthepistonpasses thecompensatorport,excessfluidfromthesystem canreturntothereservoir.Thecheckvalvekeepsa verysmallamountofpressureinthebrakesystem. Thereservoirforbrakefluidhasasendingunitfor alowfluidlevelwarninglight.
SERVICEBRAKEASSEMBLY
Aservicebrakeassemblyisinstalledateachendof thehousingforthedriveaxle.Eachservicebrakeassemblyhasasingle-wheelcylinderatthetopofeach backplate.Thesupportplatehasananchorforeach shoe.Whenthewheelcylinderisactuatedbyfluid pressurefromthemastercylinder,theshoesexpand againstthedrum.Theprimaryshoestartstoturn withthedrum.Thisactionpushesthesecondary shoetightagainstthedrumandtheanchor.When thelifttruckistravelinginreverse,theprimaryshoe ispushedagainsttheanchorandthedrumbythe secondaryshoe.
BRAKEBOOSTERANDMASTER
CYLINDER
Thebrakeboosterandmastercylinderareassembledasaunit.Thebrakeboosterhasadiaphragm thatisactuatedbyenginevacuum.SeeFigure1. Thediaphragm,alongwiththeoperator’seffort, pushesonthepistoninthemastercylinder.Hydraulicpressureactuatesthewheelcylindersas
Theautomaticadjustinglinkageturnstheadjuster screwwheeltoadjusttheclearancebetweenthe brakeshoesandthebrakedrum.Thesecondary shoeandthelinksmovewiththedrumduringa stopwhenthetruckistravelinginreverse.The linkspermittheadjusterspringlevertorotatethe adjusterscrewwheel.Theadjusterscrewwheelonly canturnwhenthereisclearancebetweenthelining andthebrakedrum.Theadjusterscrewwheelcan beturnedmanuallythroughaslotinthebackplate.
PARKINGBRAKE
Theparkingbrakeusestheservicebrakeshoes. Additionallinkagepushestheshoesapartwhen thehandleverpullsthecables.Aswitchonthe right-handsideofthemountingbracketisactuated bythehandlever.Onallunits,theswitchenergizestheseatwarningcircuitwhenthehandlever
isreleased.OnunitswithaMONOTROL® pedal, thisswitchputsthetransmissionin NEUTRAL by de-energizingthedirectionsolenoids.Onunitswith aMONOTROLpedal,thereisalsoaswitchonthe left-handsideofthebracket.Thisswitchprevents theenginefromstartingunlesstheparkingbrakeis applied.
BrakeShoeAssembliesRepair
REMOVEANDDISASSEMBLE
WARNING
Brakeliningscancontaindangerousfibers. Breathingthedustfromthesebrakelinings isacancerorlungdiseasehazard.Donot createdust!Donotcleanbrakepartswith compressedairorbybrushing.Usevacuum equipmentapprovedforbrakedustorfollow thecleaningprocedureinthissection.When thebrakedrumsareremoved,donotcreate dust.
Donotsand,grind,chisel,hammer,orchange liningsinanywaythatwillcreatedust.Any changestoliningsmustbedoneinarestricted areawithspecialventilation.Protectiveclothingandarespiratormustbeused.
1. Tiltthemastback,andputblocksunderthe outermastweldment.Tiltthemastforwardto raisethetiresfromthefloor.
WARNING
Completelyremovetheairfromthetiresbeforeremovingthemfromthelifttruck.Air pressureinthetirescancausethetireand wheelpartstoexplode,causingseriousinjury ordeath.
2. Makesurethatyouremovealltheairpressure fromthetiresbeforeyouremovethewheels fromthehub.Removethewheelnuts;then removethewheels.Putcapscrews(16mm)in thethreadedholestopushthebrakedrumsfrom thehubs.SeeFigure2andFigure3.
3. Removethecapscrewsthattheholdtheaxle shafttothehub.Removetheaxleshaft.
4. Removethelocknut,lockplate,andbearingadjustmentnutfromtheaxlehousing.Removethe outerbearingcone.Removethehubfromthe axlehousing.Removetheinnersealsandbearingconefromthehub.
WARNING
Whenthebrakeshoesareremoved,donotcreatedustintheair.Seethecleaningprocedures inthissection.
5. Turntheadjusterscrewtoloosenthebrake shoes.Disconnectthelinkagefortheautomatic adjuster.
6. Usespringplierstoremovetheshoereturn springs.
7. Removetheholddownsprings.
CAUTION
Theadjusterscrewassembliesarenotthe same.Makesurethateachassemblyhasidentificationforinstallationonthecorrectsideof theaxle.
8. Removethebrakeshoesfromthewheelcylinder rods.Removetheadjusterscrewspring.Remove theadjusterscrewassembly.
9. Removetheparkingbrakecablefromthelever. Removetheleverfromthebrakeshoe.
10. Disconnectandputacaponthelinetothewheel cylinder.Removethebackplateandshield.Removethecapscrewsthatholdthewheelcylinder tothebackplate.Removethecableclampand pullthecablethroughthebackplate.
CLEAN
2. Useasolventapprovedforcleaningofbrake partstowetthebrakeliningdust.Followthe instructionsandcautionsofthemanufacturer fortheuseofthesolvent.Ifasolventsprayis used,donotcreatedustwiththespray.
CAUTION
Donotuseanoilsolventtocleanthewheel cylinder.Useasolventapprovedforcleaning ofbrakeparts.Donotpermitoilorgreasein thebrakefluidoronthebrakelinings.
3. Whenthedustiswet,cleantheparts.Putany clothortowelsinaplasticbagoranairtightcontainerwhiletheyarestillwet.PutaDANGEROUSFIBERSwarninglabelontheplasticbagor airtightcontainer.
NOTE: LEFT-HANDSIDESHOWN.
4. Anycleaningclothsthatwillbewashedmustbe cleanedsothatfibersarenotreleasedintothe air.
INSPECT
WARNING
Cleaningsolventscanbeflammableandtoxic andcancauseskinirritation.Whenusing cleaningsolvents,alwaysfollowtherecommendationsofthemanufacturer.
1. Cleanallmetalpartsexcepttheliningsandthe wheelcylinderwithsolvent.
2. Checktheboreofthewheelcylinderforholesor scratches.Replacethewheelcylinderifthereis anydamage.
3. Checkthereturnspringsfordamage.Inspectthe backplateforwearwherethebrakeshoestouch thebackplate.
4. Inspectthebrakeshoesforcracksordamage.If theliningsorshoesarewornordamaged,replace thebrakeshoes.Itisrecommendedthatbrake shoesbereplacedincompletesets.
5. Checktheadjusterscrewwheelforwear.Make suretheadjusterscrewturns.Checkforbentor brokenadjusterlinks.
WARNING
Thebrakeshoesonbothwheelsmustbereplacedifanyshoeisdamaged.Thebrakeperformanceonbothendsofanaxlemustbeequal orthelifttruckcanbedifficulttosteerwhen thebrakesareapplied.
NOTE: Ifthebrakedrumsrequiregrinding,donot grindmorethan1.5mm(0.060in.)fromthediameter.Themaximuminsidediameterofthebrake drum,includingwear,is319.5mm(12.58in.).If thebrakedrumislargerthanthis,replacethebrake drum.
6. Inspectthebrakedrumsforcracksordamage. Usesandpapertocleanthesurfaceforthebrake shoes.
ASSEMBLEANDINSTALL
1. Installthewheelcylinderonthebackplate.Push theparkingcablethroughthebackplateandfastentheclamp.SeeFigure2andFigure3.
2. Useasealant(HysterPartNo.264159)between thebackplateandtheaxlehanger.Installthe shieldandbackplate.Usingthesequenceshown inFigure4,tightenthecapscrewsto340to 375N•m(250to275lbfft).
Figure4.BackplateInstallation
3. Connectthebrakelinetothefittingonthewheel cylinder.
4. Installthelinkpivotontherearshoe.Install theparkingbrakeleveronthefrontshoe.Install theanchorpinsinthesupportflangesothatthey engagethebrakeshoes.
5. Lubricatethebackplatewithasmallamountof greasewherethebrakeshoestouch.Installthe brakeshoesontheanchorandengagethepush rodsofthewheelcylinder.Engagetheparking brakeleverintheslotintheparkingbrakecable asthebrakeshoesareinstalledonthebackplate.
6. Putananchorpinthatholdsthebrakeshoes throughthebackplate.Putaspringseat,spring, andretainerontheanchorpin.Pushtheretainer ontotheanchorpinandrotatetheretainer90 degrees.Makesuretheretainerisinthecorrect position.Installanotherretainerspringassembly.
7. Installthelink,parkingbrake,andspringbetweentheparkingbrakeleverandthebrake shoe.
8.H4.00XM-5.50XM(H100-120XM):Usingthe correcttools,installthereturnsprings.
9.H3.50-4.00XMS(H70-90XM):Installtheanchor guideontheanchor.Installthepivotplateonits anchor.
10.H3.50-4.00XMS(H70-90XM):Lubricatethe adjustercablewhereitslidesinthepivotplate groove.
11.H3.50-4.00XMS(H70-90XM):Fastenthelinkto theadjusterwheelactuatorandputthecable aroundthepivotplate.Raisetheadjusterwheel actuatoragainstthespringtensionandconnect thelinktotheanchor.
CAUTION
Besuretoinstallthewhitereturnspringfirst andthentheblackreturnspring.SeeFigure5. Improperassemblycanresultinbrakefailure and/orcomponentdamage.
12.H3.50-4.00XMS(H70-90XM):Usingthecorrect tools,installthereturnspringsasfollows:
a. Installthewhitespring.
b. Installtheblackspring.
13.H3.50-4.00XMS(H70-90XM):Verifythatthereturnspringsareproperlyinstalledasshownin Figure5.
14. Connectthecablefortheparkingbraketothe lever.
LegendforFigure5
NOTE: H3.50-4.00XMS(H70-90XM)RETURNSPRINGSSHOWN.
1.WHITESPRING
WARNING
Thethreadsoftheadjusterwheelarenotthe sameforeachside.Iftheadjusterassemblies areinstalledonthewrongside,thebrakeshoe clearancewillincreaseeachtimethebrakes areapplied.Theadjusterwheelfortheright brakehasright-handthreads.Theadjuster wheelfortheleftbrakehasleft-handthreads.
15. Lubricatetheadjusterscrewwithantiseizecompound.Turntheadjusterscrewinsothatthe brakeshoesretract.Installtheadjusterbetween theshoes.Aligntheadjusterscrewwheelwith theslotinthebackplate.Installtheadjuster springwiththelonghooktowardtheadjuster screwwheel.
CAUTION
Donotdamagethesealswhenyouinstallthe hubassembly.
17. Usenewoilseals.Installtheinnerseal,thebearingcups,andtheoutersealinthehub.Install theinnerbearingconeonthespindle.Lubricate theinnerbearingwithgrease.SeeFigure6.
18. Installthehubonthespindle.SeeFigure6.Lubricatetheouterbearingconewith80W-90oilfor gears.Installtheouterbearingconeandtheadjustmentnut.Tightentheadjustmentnutto200 to225N•m(148to166lbfft)whileyourotatethe hub.Loosenthenutuntilthehubrotatesfreely withNOendplay.Thetorquemustbelessthan 27N•m(20lbfft).Tightenthenutto34N•m (25lbfft)ortothefirstalignmentpositionafter 34N•m(25lbfft).Installthelockwashertohold thenut.Installthelocknutandtightenitto135 to150N•m(100to111lbfft).
19. Installthebrakedrumandadjustthebrake shoesasdescribedinBrakeShoesAdjustment.
2.BLACKSPRING
20. Applysealant(HysterPartNumber264159)to theflangeoftheaxleshaft.Installtheaxleshaft. Tightenthecapscrewsto225to250N•m(166to 184lbfft).SeeFigure7.
CAUTION
Whenthewheelshavebeeninstalled,check allwheelnutsafter2to5hoursofoperation. Tightenthenutstothecorrecttorque.When thenutsstaytightafteran8-hourcheck,the intervalforcheckingcanbeextendedto500 hours.
21. Installthewheel.Tightenthewheelnutsto610 to680N•m(450to500lbfft)onallunits.
22. Removetheairfromthebrakesystemandadjust thebrakes.SeeBrakeShoesAdjustmentinthis section.
BrakeBoosterandMasterCylinderRepair REMOVE
1. Disconnectthepushrodfromthebrakepedal. SeeFigure8.Disconnectthebrakelineatthe mastercylinder.Covertheendofthebrakeline. Disconnectthewiresatthereservoir.
2. Removethenutsthatholdthebrakeboosterto themount.
3. Removethebrakeboosterandmastercylinder.
DISASSEMBLE
NOTE: Donotdisassemblethebrakebooster.Repair partsarenotavailable.
1. Removethenutsthatholdthemastercylinderto thebrakebooster.SeeFigure9.
WARNING
Thereisacompressedspringbehindthepiston.Becarefulwhenremovingthesnapring andpiston.
2. Removethesnapringfromtheendofthemaster cylinder.Carefullyremovethepistonandspring fromthebore.
3. Removesealsfromthepiston.
CLEANANDINSPECT CAUTION
DONOTuseanoilsolventtocleanthemaster cylinder.Useasolventapprovedforcleaning ofbrakeparts.
Inspecttheboreofthemastercylinderforholesor scratches.Replacethemastercylinderassemblyif thereisdamage.
ASSEMBLE
NOTE: Lubricatethepartsofthemastercylinder withcleanbrakefluid.
1. Installthesealsonthepiston.Installtheseat, checkvalve,andspringinthebore.Installthe springandpiston.Installthesnapringinthe bore.SeeFigure9.
2. InstalltheO-ringandmastercylinderonthe brakebooster.
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INSTALL
1. Putthemastercylinderinpositiononthebrake boosterandinstallthenutsforthemastercylinder.Installthebrakeboosteronthemount.Installthenutsforthebrakebooster.Connectthe pushrodtothebrakepedal.SeeFigure8.
2. Connectthebrakelineatthemastercylinder. Connectthewiresatthereservoir.Fillthereservoirandremovetheairfromthebrakesystemas describedinBrakeSystemAirRemovalinthis section.
3. AdjustthebrakelinkageasdescribedinBrake PedalAdjustment.
BRAKEBOOSTERFILTER,REPLACE
1. Removethetwoclampsholdingtheoldfilter tothebrakevacuumlines.Removethebrake boosterfilter.SeeFigure9.
REMOVEANDDISASSEMBLE
2. Installnewfilterontobrakevacuumlines.Installthetwoclampstoholdbrakeboosterfilter ontobrakevacuumlines.