Navistar International LT Series - Page 219

Operation
AdvancedStabilityFunctions(ESP):Thisfunctionenhances
stabilitybysensingactualvehicledynamics.ESP-equipped
vehiclesaddyawcontroltothebasicrollstabilityfeature.
VehicleStabilityControlSpeedReduction:Inthecaseofa
potentialrollevent,thestabilitysystemwillremovethethrottle
andquicklyapplybrakepressuretoslowthevehiclecombination
belowthethreshold.
SteeringAngleSensor(ESPonly):Thissensorenables
theadvancedstabilitysystemtocapturethedriver’ssteering
inputandinterveneifayawcorrectionisneeded.Thesensor
alsoprovidestheearliestindicationofanincreaseinlateral
accelerationthatmightcauseapotentialrollevent.Asteering
anglesensorprovidesagreaterstabilitymarginthanavehicle
thatisnotequippedwiththissensor.
BrakeDemandSensors:Thestabilitycontrolsystem
(RSPandESP)wasdesignedtosupplementthedriver’s
actions.Bydirectlymeasuringdriverbrakedemand,the
systemcantransitionseamlesslybetweendriver-intendedand
system-intendedbrakingpressure.Forexample,ifinacertain
maneuver,thesystemcalculates40psi(276kPa)isneeded
andthedriverisonlyapplying20psi(138kPa),thesystem
compensatesautomaticallytodelivertheneeded40psi(276
kPa).If,however,duringthesamemaneuver,thedriversteps
onthebrakepedalquicklytoapplyahigher(above40psi
[276kPa])brakinglevel,thedriver’sbrakinginputoverridesthe
temporarychangemadebythesystem.
ABS/StabilitySystemInteraction:WiththeABSbased
stabilitycontrolsystem,theABSisgivenpriorityatthewheel
endstomanagewheelslipforoptimalbraking.TheABS
functionssimilarlywhetherthestabilitysystemorthedriver
appliesthebrakes.
TomaximizetheeffectivenessofESP:
•Ensureloadsareproperlysecuredatalltimes.
•Exerciseexcessivecautionbyavoidingsharpturns,
suddensteeringinputs,orabruptlanechangesathigh
speeds.
ESPeffectivenessmaybereducedgreatlyif:
•Theloadshiftsduetoimproperretention,accident
damage,orthemobilenatureofsomeloads.
•Thevehiclehasanunusuallyhighoroff-setcenterof
gravity.
•Onesideofthevehicledropsoffthepavementandthe
dropistoolargetobecounteractedbyareductionin
speed.
•Thevehicleisusedtohauldoubleortripletrailer
combinations.
•Veryrapidsteeringinputsareusedathighspeeds.
•Therearemechanicalproblemswithsuspensionleveling
ofthetractorortrailerresultinginunevenloads.
•Gustywindsarestrongenoughtocausesignicantside
forcesonavehicle.
208