Navistar ProStar+ - Page 199

Operation
ThePARKINGBRAKEvalveknob(YELLOW)shouldbepushed
inrst,aftersufcientairpressureisbuiltup(applyfootbraketo
preventvehiclefromrolling).TheTRAILERAIRSUPPLYvalve
knobmaythenbepushedin.
TheTRAILERAIRSUPPLYvalveknob(RED)andPARKING
BRAKEvalveknobwillautomaticallypopoutifthesystem
pressure(bothfrontandrearcircuits)dropsto20-40psi(138-
276kPa).Thetractorprotectionvalvewillthenclose,thetractor
springbrakeswillapply,andthetraileremergencysystemwill
beactivated.
Onvehiclesequippedwiththestandardtwo-valvesystem,
theoperationofonevalvetogetherwiththeotherpermitsthe
operatortoselectthedesiredfunctionsdescribedbelow:
RedValve
(TrailerAirSupply)
YellowValve
(ParkingBrake)
Function(Mode)
OutOutSystemPark
InOutTrailerCharge
InInNormalRunning
OutInBobtail/SlidingFifth
WheelAdjustment
/SlidingTrailer
TandemsAdjustment
ThePARKINGBRAKEvalve(YELLOWknob)controlsthespring
brakesonthetractorandwhenpulledoutsimultaneouslycauses
thetrailersupplyvalvetopopout,thusapplyingbothtractorand
trailerparkingbrakes.Thetrailerbrakesmaybeindependently
releasedbypushingonlytheTRAILERAIRSUPPLYvalve(red
control)in.
TheTRAILERAIRSUPPLYvalve(REDvalve)deliversairto
thetrailersupplyandwillautomaticallypopout,shuttingoffthe
trailersupplyifpressureisdecreasedtoapproximately35psi
(241kPa).Forexactairpressureset-points,refertotheService
Manual.
NOTE:Whenattemptingtoreadjust/slidethepositionof
thetractorfthwheelorthetrailer’standemaxleswith
thetractorandtrailerfullyconnected,leavethetractor’s
PARKINGBRAKEpushedinandpulltheTRAILERAIR
SUPPLYout.Thiswillapplythetrailer’sparkingbrakes
andkeepitstationarywhilethetractorismovedforwardor
reverse.
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