790/795/797 Series - Wanderlodge Owners Group Files/Jake Brake... · INSTALLLATION INSTRUCTIONS FOR 790/795/797 SERIES JACOBS ENGINE BRAKES ... two lengths, and original DDC stud

790/795/797 Series

Jacobs Engine Brake™

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� INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES™

Table of Contents

PageSection 1: Introduction 4-5HousingIdentification 4EngineIdentification 4SpecialTools 5RecommendedTorqueValues 5EngineCovers 5

Section 2: Engine Preparation 6-7Series 60 Engines with DDEC IV & VUndercoverWireHarnessInstallation(Retrofit) 6

Section 3: Brake Housing Installation 8-10SlavePistonAdjustment 10

Section 4: Engine Brake Controls 11

Section 5: Engine Brake Operational Check 12RockerCoverInstallation

Section 6: Engine Brake Maintenance 13-19TheoryofOperation 13ExhaustBlowdown 13PartIdentification 14ControlValve 15SlavePistonAdjustingScrew 16SolidScrew 16SolenoidValve 16MasterPiston 17-18SlavePiston 19

INSTALLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES™ 3

General Information

TheseinstructionsdescribetheinstallationoftheModel790/795/797SeriesJacobsEngineBrake™,designedfortheDetroitDieselSeries60®engine.Forspecificapplicationinformationandslavepistonclearancesettings,refertotheJacobsEngineBrakeforDetroitDieselEnginesApplicationGuide,P/N�4770,whichcanbefoundonwww.jakebrake.com.

Foradditionalinformationonthe790/795/797Seriesenginebrakes,refertotheSeries60EngineServiceManual,P/N6SE483.

UseOSHA-approvedcleaningsolventforcleaningparts.Originalpartstobereusedshouldbeinspectedforwearandreplacedasrequired.Besuretocoatpartswithcleanengineoilwhenreinstallingthem.

ThestandardJacobsVehicleSystemsWarrantyappliestotheinstallationofaJakeBrake®Kit.ThewarrantyisadministeredbyDetroitDieselCorporation.ForspecificwarrantycoveragespleasecontactDetroitDiesel.

Safety PrecautionsThefollowingsymbolsinthismanualsignalconditionspotentiallydangeroustothemechanicorequipment.Readthismanualcarefully.Knowwhentheseconditionscanexist.Thentakenecessarystepstoprotectpersonnelaswellasequipment.

THISSyMBOLWARNSOFPOSSIBLEPERSONALINJURy.

THISSyMBOLREFERSTOPOSSIBLEEqUIPMENTDAMAGE.

NOTE: INDICATESANOPERATION,PROCEDUREORINSTRUCTIONTHATISIMPORTANTFORCORRECTSERVICE.

Fuels,electricalequipment,exhaustgasesandmovingenginepartspresentpotentialhazardsthatcouldresultinpersonalinjury.Takecarewheninstallingequipmentorparts.Alwayswearsafetyglasses.Alwaysusecorrecttoolsandfollowproperproceduresasoutlinedinthismanual.

NOTE:

NOTE:

THEJACOBSENGINEBRAKEISAVEHICLESLOWINGDEVICE,NOTAVEHICLESTOP-PINGDEVICE.ITISNOTASUBSTITUTEFORTHESERVICEBRAKINGSySTEM.THEVEHI-CLE'SSERVICEBRAKESMUSTBEUSEDTOBRINGTHEVEHICLETOACOMPLETESTOP.

NEVERREMOVEORADJUSTANyENGINEBRAKEORCOMPONENTWITHTHEENGINERUNNING.

4 INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES™

Section 1: Introduction

HousingIdentificationThemodel,partnumber,serialnumber,andadjust-mentinformationarelocatedonthenameplateatthetopofeachhousing.(SeeFig.1andFig.�)

Fig1

Fig�

Fig3

EngineIdentificationEnginemodelidentification,serialnumberandmodelnumber,areonthenametaglocatedonthesideofthevalvecoverandstampedonthecylinderblockbeneaththeintakemanifold.(SeeFig.3)


SpecialTools

General18mm-1�pointSocket10mm-1�pointSocket6"Extension13mmWrenchRetainingRingPliers(.047"diameter,45˚)DiagonalWireCutter

KentMooreRockerShaftLiftingTool P/NJ-35966AStudTorqueSocket P/NJ-44706AMasterPistonAssemblyTool P/NJ-45976(Model797Only)

DetroitDieselSeries60EngineServiceManual

JacobsFeelerGage,0.0�0"(0.508mm) P/N017�78FeelerGage,0.0�6"(0.660mm) P/N017671FeelerGage,0.03�"(0.813mm) P/N030504ControlValveCoverRemovalTool P/N016978

RecommendedTorqueValues

HousingHold-down CapScrews 80lb.-ft.(108N-m)

(lubricatedwithengineoil)

RockerShaftHold-downStud 100lb.-ft.(136N-m)

SlavePistonAdjusting ScrewLocknut 336lb.-in.(38N-m)

SolenoidValve 110lb.-in.(1�.4N-m)

SlavePistonSpring ShoulderBolt �00lb.-in.(�3N-m)

EngineCoversTheenginebrakehasbeendesignedtofitontheSeries60enginewithnoadditionalvalvecovers.Onenginesequippedwithatwo-piecealuminumvalvecover,itisNOTnecessarytoremovethelowervalvecovertoinstalltheenginebrake.However,onestyleuppervalvecovermayrequiremodificationatthebreatherhousinglocation(inside)forenginebrakeclearance.

NOTE:

Fig4

IFINTERFERENCEEXISTSBETWEENTHEFRONTENGINEBRAKEHOUSINGANDTHEROCKERCOVERCAPATTHEBREATHERHOUSINGLOCATION,GRINDTHEUPPERCOVERTOPROVIDECLEARANCE.CLEANCOVERTHOROUGHLyAFTERGRINDING.


AccessEngineOverhead

1. DisconnectBattery

FAILURETODISCONNECTBATTERyMAyCAUSEECMDAMAGE.

�. Thoroughlycleanengine

3. Removevalvecoverandgasket.

NOTE: IFTHEENGINEHASATWO-PIECECOVER,THELOWERVALVECOVERBASEDOESNOTHAVETOBEREMOVED.

ExchangeWireHarness

1. Removeexistinginjectorharness&mountingclipsfromcylinderhead.

a.Separatewireharnessfromcylinderhead

retainingclips.b.Remove�harnessmountingboltsfromrear

ofcylinderheadatheadpassthroughholes.(SeeFig.5)

NOTE: FORADDITIONALACCESSTOREARCyLINDERHEADPASSTHROUGH,THEROCKERSHAFTSMAyBEREMOVEDUSINGKENTMOORETOOL#J35996A

Section 2: Engine PreparationSeries 60 Engines with DDEC IV & V

c.Disconnect10pinwiresocketlocatedonintakesideofcylinderblockbelownumbersix(6)intakeport.(SeeFig.6)

d.Removeharnessbymanipulatingharness throughcylinderheadpassthroughatrear

ofhead.

e.Removeharnessretainingclipsfrom threadedholesinheadanddiscardclips.

(SeeFig.7)

Fig5

Fig6

Fig7

REMOVEENTIRECLIPS,HOLESWILLBERE-USEDFORJACOBSSUPPLIEDHOUSINGHOLDDOWNBOLTS

NOTE:


Fig8

�. InstallnewharnessP/N�3536019foron-highwayapplicationsorP/N�3534�44foroff-highwayapplications

a.Manipulateharnessthroughrearheadpass

through.Routeharnessconsistentto previousharness.

TAKECARENOTTODAMAGEWIRINGORCONNECTORS

b.Connectnewharnesstoinjectors.

c.Connect10pinwiringsockettomainengineharnessandsecureharnesswithplasticwiretiesasnecessarytobrakespacertubes(referenceFig11inSection3forimage). d.Secureharnessatrearheadpassthroughwith�mountingbolts.

HARNESS IS NOW READY FOR JAKE BRAKE INSTALLATION


Section 3: Brake Housing Installation

InstallEngineBrakeHousings

1. RemoveRockerShaftAssembliesusing18mmSocketandKentmoore#J-35996A

NOTE:

WEARSAFETyGLASSESWHILEBLOWINGTHEOILFROMTHEBOLT

HOLES.

a.RemoverockerarmholddownboltsM1�x100mmlong(6).

b.Removerockerarmnutsatfrontandrearofhead(�).

c.Retorquerockershaftstudslocatedatfrontandrearofcylinderheadat100lb.-ft.(136N-m)withKentmooretool#J-44706A.(SeeFig.9)

�.SetRockerShaftAssembliesbackoncamcaps.

Fig9Fig11

3.Setfront&rearJakeBrakehousingsonrockershaftslocatingonretorquedstuds.Ensurethatmasterpistonpushrodswillengagewithpocketlocatedontopofinjectorrockerarm(seeFig.10).

4.PositionJakeBrakemountingspacertubesunderouterhousingmountinglegs.(SeeFig.11)

NOTE: TOPREVENTDAMAGETOWIREHARNESS,RUNWIRESINBOARDOFSPACERTUBESANDSECURETOTUBESUSINGPLASTICWIRETIES.

Fig10

REMOVINGTHEOILFROMTHEBOLTHOLESPREVENTSTHECyLINDERHEADFROMCRACKINGWHENBOLTSARETIGHTENED.ATTACHALENGTHOFTUBINGTOANAIRGUNNOZZLEANDBLOWOUTTHEOILFROMTHEROCKERSHAFTHOLD-DOWNBOLTHOLES.COVERTHEHOLESWITHHANDTOWELSTOMINIMIZEOILSPRAy


Fig15

5. InstallJacobssuppliedmountingbolts,twolengths,andoriginalDDCstudhexnutsremovedearlier.(SeeFig.1�)

A-M1�x140mm-usedontheexhaustsideoftheengine

B-M1�x170mm-usedonintakeside(solenoidside)ofengine

NOTE:

NOTE:

Fig1�

Fig13

Fig14

6. TorquedownbrakehousingpersequenceinFig.14at80lb.-ft.(108N-m).

7.VerifyexhaustandintakevalvelashisstillwithinDDCspecificationsforengine.Ifvalvelashisoutoftolerance,refertoDDCmanualforresettingprocedure.

8.Attachsolenoidwirestosolenoidandengagewiresinwireretainerclip.(SeeFig.15)

NOTE:

BEFORETORqUINGENSURETHATWIREHARNESSISINBOARDSOASTONOTINTERFEREWITHVALVECOVER

BEFORETIGHTENINGHOLDDOWNBOLTS,MOVETHEHOUSINGFROMSIDETOSIDEANDTHENLOCATEHOUSINGINCENTEROFTRAVEL.(SEEFIG.13)

A

B

797BAPPLICATIONSUTILIZEADDCWIREHARNESSTRAyWHICHISAT-TACHEDONTOTHEREARBRAKEHOUSING.

REFERENCETHEDDCSERIES60ENGINESERVICEMANUALP/N6SE483FORPROPERTRAyTORqUINGPRO-CEDURE


4. Rechecklashsettings.Iflashsettingisincorrect,repeatsteps(1)through(3)above

NOTE:

MODEL 795/797 SERIES

1. Backouttheadjustingscrewsontheslavepistonsuntiltheslavepistonsdonottouchtheexhaustrockerarmadjustingscrews.

�. Inserttheproperfeelergage(correctadjustmentisonhousingdatatag)betweentheslavepistonandtheexhaustrockeradjustingscrew.Usinga3/16"(inch)hexwrenchturnintheadjustingscrewuntiltheslavepistoncontactstheexhaustrockeradjustingscrewthroughthefeelergage,andadragisfeltonthegage.

3. Holdtheadjustingscrewinplaceandtorquethelocknutto38N•m(336lb-in).Rechecklashsettings.Iflashsettingisincorrect,repeatsteps(1)through(3)above.

Adjust Slave Piston Clearance

FAILURETOFOLLOWADJUSTMENTPROCEDURESCANRESULTINENGINEORENGINEBRAKEDAMAGE.

NOTE: MAKESLAVEPISTONADJUSTMENTWITHTHEENGINESTOPPEDANDCOLD.ADJUSTEACHCyLINDERWITHTHEEXHAUSTVALVESINTHECLOSEDPOSITION.

NOTE: REFERENCEJACOBSAPPLICATIONGUIDEP/N�4770FORPROPERENGINEANDBRAKESPECIFICLASHSETTINGS.

MODEL 790 SERIES

1.Backouttheadjustingscrewsontheslavepistonsuntiltheslavepistondoesnottouchtherockerarmadjustingscrew.

�. Inserttheproperfeelergage(correctadjustmentisonhousingdatatag)betweentheslavepistonandtheexhaustrockeradjustingscrew.Usinga3/16"(inch)hexwrench,turnintheadjustingscrewuntiltheslavepistoncontactstheexhaustrockeradjustingscrewthroughthefeelergage.Continueturningintheadjustingscrewuntilthevalvespringsbegintocompress,thenturninone(1)additionalturn.Waitatleast30secondsforoiltobepurgedfromtheJ-Lashadjustingscrew.

NOTE: ALLOILMUSTBEPURGEDFROMTHEJ-LASHADJUSTINGSCREW.IFOILISBELOW60°F,16°C,WAITATLEASTTWOMINUTESFOROILTOBEPURGEDFROMTHEJ-LASHADJUSTINGSCREW.

SERIOUSENGINEDAMAGEMAyOCCURFROMIMPROPERLASHSETTING.

3. Afterthetimeintervalspecifiedinstep(�),backouttheadjustingscrewONLyuntilalightdragisfeltonthefeelergage.Donotretractmore than required to obtain a light drag on the feeler gage. Hold the J-Lash adjusting screw inplaceandtorquethelocknutto38N•m(336lb-in).

NOTE: IFTHEJ-LASHADJUSTINGSCREWISBACKEDOUTUNTILITNOLONGERCOMPRESSESTHESLAVEPISTONSPRING,OILWILLENTERTHESCREWANDTHEADJUSTMENTWILLBEINCORRECT.IFTHISOCCURS,REPEATSTEPS(1)AND(�).

OVERTORqUEOFLOCKNUTWILLPROHIBITPROPERJ-LASHOPERATION

Fig16

ONCETHEENGINEBRAKEHASBEENRUNyOUWILLNOTBEABLETOCHECKTHEEN-GINEBRAKEADJUSTMENT.THISISBECAUSEOFOILRETAINEDINTHEJ-LASHADJUSTINGSCREW.IFUNSUREOFTHEADJUSTMENT,yOUMUSTREPEATSTEPS(1)THROUGH(4)ABOVE.


Section 4: Engine Brake Controls Series 60 Engines with DDEC IV & DDEC V

ONSERIES60ENGINESEqUIPPEDWITHDDECIVORV,THEENGINEBRAKEISCONTROLLEDByTHEDDECECM.USEOFAJACOBS'SUPPLIEDCONTROLMODULEISNOTREqUIRED.

CONTACTyOURVEHICLEOEMWITHyOURVEHICLESERIALNUMBERFORBILLOFMATERIALSNEEDEDFORINSTALLATION.

Jacobs Dash Switch (optional)

(mayuseinplaceofVOEMswitch)

1. Locateanareaonthedashforthedashswitchgroup,JacobsP/N0�0035,anddrilla�"hole.

�. PasstheloosewiresofthevehicleOEMwireharnessthroughthe�"holefromthebacktothefront

3. Attachthewireharnesstotheswitchterminalsontheswitchgroupp/n0�0035.

4. Installtheswitchassemblywiththebracket,lockwashersandwingnuts(seeFig.18).

DONOTOVERTIGHTENNUTS.SWITCHFAILURECOULDRESULT!

NOTE: CONTACTVEHICLEOEMFORINSTALLATIONDETAILSANDWIRINGDIAGRAMOFTHEWIRINGHARNESSANDINTERFACEWITHDASHCONTROLSWITCH.

Fig17

1� INSTALLLATIONINSTRUCTIONSFOR790/795/797SERIESJACOBSENGINEBRAKES™

Two-piece Rocker Cover Installation

1. Makesurethesealisinplaceintherockercoverbaseandsetthecoverinplaceonthecoverbase.

�. Installtheboltwithaflatwasher,isolatorandlimitingsleeveintothecoverholes.

3. Tightentheboltsto14N•m(10lb-ft)inthesequenceshowninFig.1.

4. Torquetheboltsto�7N•m(�0lb-ft).

Road Test the Vehicle.

1. Roadtestthevehicle.TheenginebrakeshouldcomeonwhentheswitchisintheONposition,theclutchisengagedandnothrottleisbeingapplied.

Section 5: Engine Brake Operational Check

Bleed the engine brake housings

1. Besurewiresareawayfrommovingparts.

�. Starttheengineandallowtorunforafewminutes.

3. Manuallyactivatethesolenoidvalveseveraltimestoallowthehousingtobefilledwithoil.

NOTE: THESOLENOIDVALVEISMANUALLyACTIVATEDByDEPRESSINGTHEARMATUREPINLOCATEDINTHECENTERONTOPOFTHESOLENOID.

Check for proper operation.

1. Manuallyactivatethesolenoidvalveandwatchthemasterpistonstobesuretheyaremovingdownintothepocketintheinjectorrockerarm.

�. Watchtheslavepistons.Theyshouldmovedowntocontacttheexhaustvalverockerarmadjustingscrews.

3. Checkeachhousingtobesureitisfunctioning.

4. Shutdownengine.

Rocker Cover Installation

One-piece Rocker Cover Installation

1. Installthesealintothegrooveinthecoverandsetthecoverinplaceonthecylinderhead.

�. Installthefourretainingboltswithisolatorsandwashers.

3. Startingwiththecenterboltsandworkingoutward,tightentheboltsto��N•m(16lb-ft).

4. Presstheprotectiveplugsintothetwocenterholes.

SERIES60ROCKERCOVER

Fig18


Section 6: Engine Brake Maintenance

TheoryofOperation

Energizingtheenginebrakeeffectivelyconvertsapower-producingdieselengineintoapower-absorbingaircompressor.Thisisaccomplishedthroughmotiontransferusingamaster-slavepistonarrangementwhichopenscylinderexhaustvalvesnearthetopofthenormalcompressionstroke,releasingthecompressedcylinderchargetoexhaust.

Theblowdownofcompressedairtoatmosphericpressurepreventsthereturnofenergytotheenginepistonontheexpansionstroke.Theeffectofthisactionisanetenergyloss,sincetheworkdoneincompressingthecylinderchargeisnotreturnedduringtheexpansionprocess.

ExhaustBlowdown

Referringtotheschematicdrawingbelow,exhaustblowdownoccursasfollows:

1. Theenergizedsolenoidvalve(A)permitsenginelubeoil(B)toflowunderpressurethroughthecontrolvalve(C)toboththemasterpiston(D)andtheslavepistons(E).

�. Oilpressurecausesthemasterpistontomovedown,comingtorestintheinjectorrockerarmrecess(pocket).

A

B CENGINE OIL IN

ENGINE OIL OUT

EE

FF

D

Fig19

3. Theinjectorrockerarmbeginsitstravelasinthenormalinjectioncycle,movingthemasterpistonupwardanddirectinghighpressureoiltotheslavepiston.Theballcheckvalveinthecontrolvalveimprisionshighpressureoilinthemaster-slavepistonsystem.

4. Highpressureoilcausestheslavepistonstomovedown,momentarilyopeningtheexhaustvalves(F),whiletheenginepistonisnearitstopdeadcenterposition,releasingcompressedairtotheexhaustmanifold.

5. Compressedairescapestotheatmosphere,completingacompressionbrakingcycle.


NEVERREMOVEANyENGINEBRAKECOMPONENTWITHENGINERUNNING.PERSONALINJURyMAyRESULT

TheJacobsEngineBrakeistypicallyatrouble-freedevice.However,inspectionsarenecessaryandsomemaintenanceisrequired.Usethefollowingprocedurestokeeptheenginebrakeintopcondition.

Thissectioncovershowtoproperlyremove,cleanandreinstallenginebrakecomponents.UseanOSHA-approvedcleaningsolventwhenwashingparts.Besuretocoatpartswithcleanengineoilwhenreinstallingthem.

Fig18

1SolenoidValve�Seal,SolenoidUpper3Seal,SolenoidCenter5MasterPiston6MasterPistonPushrod7MasterPistonSpring8MasterPistonRetainer9SpiroloxRing(797)9SnapRing(790/795)10AdjustingScrewLockNut11SolidScrew(795/797)11J-Lash(790)1�SlavePiston13SlavePistonSpringGroup17RetainingRing18Washer19InnerControlValveSpring�0OuterControlValveSpring�1ControlValve��PipePlug�3DriveScrew�4WireHarnessClip�5CapScrew�6CapScrew�7SpacerTube

PARTS LISTINGFig�0


ControlValve

REMOVECONTROLVALVECOVERSCAREFULLy.CONTROLVALVECOVERSAREUNDERLOADFROMTHECONTROLVALVESPRINGS.REMOVEWITHCARETOAVOIDPERSONALINJURy.

1. Pressdownoncontrolvalvewasherusingthecontrolvalvecoverremovaltool,Jacobsp/n16978torelievespringpressure(SeeFig.�1)

�. Removeretainingringusingretainingringpliers(SeeFig.�1).

3. Slowlyremovecoveruntilpressureceases,thenremovethetwocontrolvalvesprings.

4. Usingneedle-nosepliers,reachintotheboreandgraspthestemofthecontrolvalve.Removethecontrolvalve.

Fig�1

Fig��

Fig18

5. WashthecontrolvalveswithapprovedcleaningsolventPushawirethroughtheholeinthebottomofthevalvetoinsurethattheballcheckisfree(seeFig.��).Theballshouldliftwithlightpressureonthewire.Iftheballisstuckinthevalve,thecontrolvalveshouldbereplaced.Drythevalvewithcompressedairandwipecleanwithapapertowel.

6. Thoroughlycleanthecontrolvalveboreinthehousingusingcleanpapertowels.

7. Dipthecontrolvalvesincleanlubeoil.Holdingthevalvebythestem,guideitintotheborethenallowthevalvetodecendtothebottomoftheborebyitsownweight.Ifbindingoccurs,thecontrolvalveshouldbereplaced.Reassemblepartsreversingtheremovalprocedure.Besureretainingringearsarerotated90º(degrees)afterinstallationtoensurefullengagement.


SlavePistonAdjustingScrew

MODEl790SERIES

1. LoosentheslavepistonadjustingscrewlocknutandremovetheJ-Lashadjustingscrewfromthehousing.Cleaninapprovedcleaningsolvent.

�. InspecttheJ-Lashassemblytoassuretheplungerisretainedinthescrewbody,bypullingontheplungerwithfingers.Theplungershouldretractsmoothlyandcompletelyunderpressureifnotreplaceentireassembly.

NOTE:AMODERATETOHEAVySPRINGFORCEWILLBEPRESENTBEHINDTHEPLUNGERIFOILISSTILLTRAPPEDINTHEASSEMBLy.

3. PlacetheJ-Lashassemblyintotheslavepistonadjustingscrewboreandreplaceadjustingscrewlocknut.

NOTE:DONOTEXCEEDLOCKNUTTORqUE.THISWILLHINDERPLUNGERMOVEMENTANDCAUSEENGINEBRAKEPERFORMANCEPROBLEMS.

SolidScrew

MODEl795/797SERIES

1. Removethesolidscrews.

�.Cleanthesolidscrewsinapprovedcleaningsolvent.Inspectforexcessivewearordamage.Replaceifnecessary.

Fig�4

SolenoidValve

DONOTDISASSEMBLEORTAMPERWITHTHESOLENOIDVALVE.ENGINEDAMAGECOULDRESULT.

1. Disconnectsolenoidvalveharness.Using3/4"socketandextension,unscrewsolenoidvalve.

�. Removeanddiscardthetworubbersealrings.Iftheringsstayinthehousingbore,removewithapieceofwire.

3. Washoutthesolenoidvalvewithapprovedcleaningsolvent.Useabrushtocleantheoilscreen.Risethesolenoidvalveincleaningsolvent.

4. Cleanoutthesolenoidvalveboreinthehousing.Usecleanpapertowels.Neveruserags,astheymayleavelintandresiduewhichcanplugtheoilpassageways.

5.Coatnewsolenoidvalvesealringswithcleanlubeoil.Installthesealringsontothesolenoidvalvebody.Becarefulnottotwistthesealwhileinstalling.

6.Besurethesealsareseatedproperly.Carefullyscrewthesolenoidvalveintothehousingwithoutunseatingtheseals.Torquethevalveto110lb.-in.(1�.4N-m).

Fig�3


MasterPiston

MODEl790/795SERIES

1. Compressmasterpistonretainerandremovesnapringusingretainingringpliers(.047"diameter,45˚).(SeeFig.�5)

REMOVESNAPRINGCAREFULLy.MASTERPISTONISUNDERLOADFROMTHESPRING.REMOVEWITHCARETOAVOIDPERSONALINJURy.

�. Removemasterpistonpushrod,retainer,springandmasterpiston.

3. Cleanthemasterpistoninapprovedcleaningsolvent.Inspectforexcessivewearordamage.Replaceifnecessary.Inspectthemasterpistonbore.Somewearmarksarepermissible.Applycleanlubeoiltothepistonandinsertintobore.Masterpistonshouldmoveinandoutfreelywithnobinding.Ifbindingoccurs,replacemasterpistonand/orhousing.

5. Reassemblethemasterpiston,pushrod,spring,andretainerinhousing.Besuretorotatesnapring90º(degrees)afterinstallation.

NOTE:THESPRINGSHOULDHOLDTHEMASTERPISTONCOMPLETELyINTHEHOUSING.IFNOT,THESPRINGHASRELAXEDANDMUST

BEREPLACED.

NOTE:THESMALLERDIAMETERENDOFTHESPRINGENGAGESTOTHEMASTERPISTONPUSHRODBALLEND.SPRINGMUSTNOTEXPANDOVERBALLEND.

MODEl797SERIES

1. Usemechanic'spicktowedgescrewdriverbladebeneathspiroloxring(SeeFig.�6).

�.Rotatescrewdriverarounddiametertounwindspirolox.Removeanddiscardspiroloxring-itcannotbereused(SeeFig.�7).

REMOVESNAPRINGCAREFULLy.MASTERPISTONISUNDERLOADFROMTHESPRING.REMOVEWITHCARETOAVOIDPERSONALINJURy.

3.Removemasterpistonpushrod,retainer,springandmasterpiston.

4. Cleanthemasterpistoninapprovedcleaningsolvent.Inspectforexcessivewearordamage.Replaceifnecessary.Inspectthemasterpistonbore.Somewearmarksarepermissible.Applycleanlubeoiltothepistonandinsertintobore.Masterpistonshouldmoveinandoutfreelywithnobinding.Ifbindingoccurs,replacemasterpistonand/orhousing.

Fig�5

Fig�6

Fig�7


5.Reassemblemasterpiston,pushrod,spring,retainer,andspiroloxringinhousingusingmasterpistonassemblytoolJ-45976.(SeeFig.�8)

NOTE:WHENPLACINGRETAINERINTOBORE-PARTNUMBERSHOULDBEVISIBLE.

a.Loadspiroloxintotapperedring.(SeeFig.�9)

b.Engagemasterpistonassemblytoolintobore.Ridgewillengagewithborechamfer.

c.Pushdownonspiroloxuntilitsnapsintoplace.(SeeFig.31)

NOTE:THESPRINGSHOULDHOLDTHEMASTERPISTONCOMPLETELyINTHEHOUSING.IFNOT,THESPRINGHASRELAXEDANDMUST

BEREPLACED.

NOTE:THESMALLERDIAMETERENDOFTHESPRINGENGAGESTOTHEMASTERPISTONPUSHRODBALLEND.SPRINGMUSTNOTEXPANDOVERBALLEND.

Fig30

Fig�9

Fig�8Fig31


Fig30

SlavePistons

1. Removeslavepistonshoulderbolts.

NOTE:SPRINGPRESSUREWILLBERELEASEDASBOLTISREMOVED.THEREWILLBENOSPRINGPRESSUREREMAININGPRIORTOBOLTBEINGCOMPLETELyDISENGAGED.

�. Removesprings,bridge,andslavepistons.

3. Cleantheslavepistonsinapprovedcleaningsolvent.Inspectforexcessivewearordamage.Replaceifnecessary.

4.Ensureslavepistonborehasnoburrsorridges,ifsoremovewithamachinistdeburringtool.Donothonetheslavepistonbore.Removaloftoomuchmaterialwillreducebrakingperformance.

5. Reassemblecomponents.Torqueshoulderbolt�00lb.-in.(�3N-m).

OVERTORqUEWILLFRACTUREBOLT.

JacobsVehicleSystems��EastDudleyTownRoadBloomfield,CT0600�

VisitusontheInternet:www.JAKEBRAKE.COM

P/N�9901Rev.B ©�004JacobsVehicleSystems,Inc. PrintedinU.S.A. Rev.1�/06

790/795/797 Series - Wanderlodge Owners Group Files/Jake Brake... · INSTALLLATION INSTRUCTIONS FOR 790/795/797 SERIES JACOBS ENGINE BRAKES ... two lengths, and original DDC stud

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