Peterbilt 348 2017 - Page 176

OPERATINGTHEBRAKESYSTEM
WARNING!
Thebrakesystemisacriticalvehicle
safetysystem.Forthesafetyofyou
andothersaroundyou,havetheve-
hiclesubmittedforperiodicpreven-
tivemaintenancechecksaswellas
havinganysuspectedproblemsim-
mediatelycheckedbyanAuthorized
ServiceCenter.Failuretoproperly
maintainyourbrakesystemcanlead
toseriousinjuryaccidents.
BrakeComponents
Thefollowingisabriefdescription
ofthehydraulicbrakesystem.Itis
intendedtosupplyyouwithgeneral
informationonhowthesystemworks.
Forcompleteinformationseethe
PeterbiltMediumDutyMaintenance
Manual.
Anti-LockBrakeSystem(ABS)
ModulatorValveBody:adjustsbrake
uidowbetweenthemastercylinder
andthewheelcaliperstoavoidwheel
lockup.
ABSWarningLamp:lightswhenthe
ABScontrollerdetectswheellock-up
whiledrivingandactivatestheABS.
LightsalsowhenafaultintheABSis
detected.
BrakeFluidReservoir:storesbrake
uidandoffersaplacetoreplenish
whenneeded.
BrakeMasterCylinder:translates
brakepedalforceintohydraulicuid
pressureintheprimaryandsecondary
circuits.
BrakePedal:appliesactuationforce
fromoperator'sfoottothemaster
cylinderpistons.
BrakeWarningLamp:illuminates
wheneitherpowersteeringuidow
isinterruptedorwhenapressure
differentialispresentintheprimary
andsecondarybrakeuidpressure.
Eithercaseadverselyaffectsbraking
operation.
DifferentialSwitch:measuresthe
hydraulicuidpressuredifference
betweentheprimaryandsecondary
circuits.
ElectrohydraulicPump:The
Electrohydraulic(EH)pumpisusedas
abackupboostpump.TheEHpump
turnsonandprovidesuidpressure
4-36Y53-6060-1C1(03/17)
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