Mack CSM 2010 - Descending a Grade

106OPERATION
DescendingaGrade
DANGER
TheMACKPowerLeash™Engine
Brakeassistsyouinestablishingfaster
downhilldescentspeedsthaninasimilarly
conguredandloadedvehiclewithout
anenginebrake;nevertheless,evenwith
anenginebrake,therearelimitstothe
maximumvehiclespeedatwhichyoucan
travelondownhillgradesandstillkeep
yourvehiclesafelyundercontrol.Always
approachthesesituationswithcaution,
andgaintheexperiencenecessaryforeach
gradeanddrivingconditiontodetermine
theappropriatedownhilldescentspeed.
Foracertainvehicleandloadcondition,a"controlspeed"maybeestablishedforagiven
descent.Thecontrolspeedisthevehiclespeedatwhichtheretardingforcesofairdrag,
rollingresistanceandenginebrakepowerareequallybalancedbythenaturalforceof
gravitythatcausesthevehicletoacceleratedownthehill,resultinginasteady,controlled
vehiclespeed.TheadditionalvehicleslowingpowerofferedbytheMACKPowerLeash™
EngineBrakeallowsthedrivertodescendthehillinahighergearthannormal(atafaster
controlspeed),withoutoverspeedingtheengine.
Forexample,considerthatyouaredescendingagradewithaspecicvehicleandan
assumedtotalvehicleweight.Youwillndthatwithoutanenginebrake,youmustdescend
thisgradeinthirdgeartomaintainasteady16kph(10mph)at2,000enginerpm,without
theneedtoapplytheservicebrakes.
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