热门搜索:

  • /?7
  • 下载费用:8 金币 ?

brake06 PARKING BRAKE.pdf

关?键?词:
BRAKE06 PARKING BRAKE
资源描述:
58 LEXUS Technical Training 1. Describethepurposeoftheparkingbrakesystem. 2. Explaintheclutchspringandsleevenutfunctioninmaintaining theadjustmentofthecaliperparkingbrake. 3. Describetheproceduretoreseatthepistonofthecaliperparking brakeduringpadreplacement. 4. Explaintheoperationoftheexclusiveparkingbrakeassembly. Section 6 PARKING BRAKE Lesson ObjectivesParking Brake Theparkingbrakesystemisasecondarybrakingsystemusedtoholda parkedcarinposition.Theyareappliedindependentlyoftheservice brakes.Sincethereisnoinertiatoovercome,lessbrakingpoweris requiredtoholdthevehiclestationaryandlessforceisrequiredto apply.Theapplicationofonlytwoofthefourbrakeassembliesare requiredtoholdthevehicle. Therearethreestylesofrearparkingbrakesystems.Twotypesuse theservicebrakeandtheotherisanexclusiveparkingbrakedesign. Theservicetypeparkingbrakeusespartoftheordinaryservicebrake mechanismandoperatestheshoeorpistonmechanically. Theparkingbrakeleverislocatednearthedriver’sseat.Pullingthe parkingbrakeleverbyhandorpressingthepedalwiththefoot, operatesthebrakeviaacableconnectedtotheparkingbrakeleverof thebrakeassembly. Thereareanumberofdifferenttypesofparkingbrakelevers,as shownbelow.Applicationdependsuponthedesignofthedriver’sseat andthedesiredoperatingeffort. Theparkingbrakeleverisprovidedwitharatchetlockingmechanismto maintaintheleveratthepositiontowhichitwasset,untilreleased.Some parkinglevershaveanadjustingscrewnearthebrakeleversotheamount ofbrakelevertravelcanbeeasilyadjusted.Travelisdeterminedbythe numberofclicksoftheratchetmechanismfoundintheRepairManual. Parking Brake Levers A ratchet locking mechanism holds the lever in position when set. Parking Brake MechanismsSection 6 60 LEXUS Technical Training Theparkingbrakecabletransmitsthelevermovementthrougha typicalseriesofcomponents,asshownbelow,tothebrakedrum subassembly.TheIntermediateLevermultipliestheoperatingforceto theEqualizer.TheEqualizerdividestheleveroperatingforcetobrake assembliesatbothwheels.Thetwomajorpartsmayvaryindesign however,theirfunctionremainsthesame. Linkage Components The intermediate lever multiplies the operating force to the equalizer. The equalizer divides the force to brake assemblies at both wheels. Onallmodelsusingdrumbrakesontherear,thecablepullsthe parkingbrakelever.Thelever is attachedtothesecondaryshoeatthe topandtransferstheleveractiontotheprimaryshoethroughtheshoe strut.Whenreleased,thebrakeshoespringsreturntheshoestotheir retractedposition. Drum Type Parking Brake Components The cable pulls the parking brake lever and transfers the lever action to the primary shoe through the shoe strut. Parking Brake Linkage Drum Parking BrakeParking Brake Therearetwotypesofrearwheelparkingbrakesystemsfordisc brakes.Thefirstusesthebrakecaliperassemblytomechanicallyapply pressuretothedisc.Thesecondtypeisanexclusivedrumbrake assemblythatappliespressuretoaninsidedrum,whichisanintegral partofthediscrotor. Theparkingbrakeisbuiltintothecaliperhousingandisprovided withanautomaticadjustingmechanismtocompensateforpiston movementasthebrakepadswear. Caliper Parking Brake Assembly The piston is mechanically forced to engage the pads to the rotor. Theautomaticadjustingmechanismmaintainstheoperatingclearance betweenthepadsandtherotorasthepadsweardownwithuse.The primaryassemblywhichmakesthispossibleistheSleeveNutand AdjustingBolt.TheSleeveNutisheldbytheClutchSpringwhich allowsittoturninonedirectiononly.ThediameteroftheClutch Springisslightlysmallerthanthediameterofthesleevenutand allowsittoturnintheunwinddirectiononly.Theclutchspringisheld stationarywithoneendattachedtothepiston. Whenthebrakepedalisdepressed,hydraulicpressureforcesthe pistontomovetotheleft.ThemovementofthePistonexertspressure ontheThrustPlateandThrustBearingagainsttheSleeveNut causingittobescrewedoutfromthestationaryAdjustingBolt.The SleeveNutcanbeeasilyscrewedoutbecausetheClutchSpring unwindsandthereforedoesnotpreventtheSleeveNutfromrotating. ThedistancethattheSleeveNutscrewsoutfromtheAdjustingBoltis equaltotheamountofpadwear. Disc Parking Brakes Caliper Parking Brake Automatic Adjusting MechanismSection 6 62 LEXUS Technical Training Thepistonheadisprovidedwithtworecesses,oneofwhichengages withapinthatprotrudesfromthebackingplateofthebrakepad.This pinpreventsthepistonfrombeingrotatedbytheautomaticadjuster. Theadjustingboltstopperpreventstheadjustingboltfromrotating. Theonlypartallowedtoturnisthesleevenut. Piston Head Design The pin on the brake pad is indexed to the recess of the piston head to prevent the piston from rotating. Whenbrakepadsarereplaced,thepistonwiththesleevenutmustbe forciblyrotatedintothecylinderwiththeSpecialServiceToolshown below(SST09719-00020). Rear Caliper Pad Replacement The piston must be forcibly screwed into the cylinder with the SST. Afterpadreplacement,theparkingbrakelevertraveladjustment shouldbeperformed.Depressthebrakepedalseveraltimestoactivate theautomaticadjustmentwithinthecaliper.Thenadjustthecablefor thepropernumberofclicksofthehandbrakelever.Parking Brake Whentheparkingbrakeisapplied,thecableattachedtotheparking brakeleverrotatesthecranklevercounterclockwise.Thecrankpin thenpushesthestruttotheleft.Thestrutmovestheadjustingbolt, sleevenut,andpistontowardtheleft.Asthestrutmovestotheleft,it alsocompressestheadjustingboltreturnspring.Theassemblymoves untilitpressesthepadsagainstthediscrotor. Parking Brake Operation The crank pin pushes the strut and adjusting bolt, sleeve nut and piston toward the disc rotor. Whentheparkingbrakeleverisreleased,thecompressedReturn SpringpushestheAdjustingBoltandPistonbacktotheirprevious positions.Asaresult,theparkingbrakeisreleased. Duringthisoperation,theClutchSpringpreventstherotationofthe SleeveNutsothattheforceoftheparkingbrakeleveristransferredto thePistonviatheAdjustingBolt. Parking Brake OperationSection 6 64 LEXUS Technical Training TheexclusiveparkingbrakeisfoundontheLandCruiser,Supra, Celica,Previa,AvalonandCamry.Asillustratedbelow,adrumbrake iscastintothediscrotor.Theshoesandothercomponentsaresimilar toaconventionaldual-servodrumbrakesystembutsmallerandwith nowheelcylinder. Exclusive Parking Brake Assembly A pair of brake shoes are mounted to the backing plate and a brake drum is cast into the disc rotor. Activatingtheparkingbrakeissimilartoapplyingtheparkingbrake onconventionaldrumbrakes.Adjustmenttotheexclusiveparking brakeisdonemanuallyattheShoeAdjustingScrewSet(StarWheel) andmustbedoneperiodically. Exclusive Parking Brake Components Manual adjustment is made at the Shoe Adjusting Screw Set. Exclusive Parking Brake
? 汽车智库所有资源均是用户自行上传分享,仅供网友学习交流,未经上传用户书面授权,请勿作他用。
0条评论

还可以输入200字符

暂无评论,赶快抢占沙发吧。

关于本文
本文标题:brake06 PARKING BRAKE.pdf
链接地址:http://www.autoekb.com/p-2791.html
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服客服 - 联系我们

copyright@ 2008-2018 mywenku网站版权所有
经营许可证编号:京ICP备12026657号-3?

收起
展开