Navistar ProStar+ - Engaging the Clutch

Operation
7.Double-clutchbetweenallupshiftsanddownshifts.
8.Afteryourshiftingabilityimproves,youmaywantto
skipsomeoftheratios.Thismaybedoneonlywhen
operatingconditionspermit,dependingontheload,
grade,androadspeed.Transmissionswithagreater
numberofspeedsareoptionallyavailable.Theymay
includetheuseofasplitterselectorswitchinaddition
totherangeselectorswitch.
EngagingtheClutch
•Alwaysstartinthepropergear:Anemptyvehicle
canbestartedinahighergearthanafullyloadedone.
Butstartinginageartoohighfortheloadcancause
toomuchclutchslippage,generatingexcessiveheat
andunnecessarywear.Agearthatwillstartthevehicle
movingwiththeengineatidlespeedisusuallycorrect.
Iftheenginemustberevveduptopreventstalling,the
gearselectionistoohigh.Astheclutchpedalisreleased
andtheclutchbeginstoengage,theenginespeedwill
dropslightly.Whenthishappens,fullyengagetheclutch
andincreasetheenginespeed.Increasingtheengine
speedbeforefullyengagingtheclutchcandamagethe
clutchanddrivetrain.
•Donotupshiftuntiltheenginehasreachedproper
speed.Upshiftingbeforethevehiclehasreachedthe
rightspeedwilllugtheengine.
•Whenapproachingahill,depressacceleratorsmoothly
tostarttheupgradeatfullpower,thendownshiftas
neededtomaintainvehiclespeed.
•Neverholdavehicleonahillwiththeclutch.To
holdonahillwiththeclutchrequiresthattheclutchbe
purposelyslipped.Bydoingthisenoughheatcanbe
generatedtoburnuptheclutch.
•Nevercoastwiththeclutchdisengaged.Thiscan
causeclutchfailurebytheveryhighRPMencountered
whencoastingingearwiththeclutchreleased.Inthis
situation,therearwheelsaredrivingthediscthrough
themultiplicationoftherearaxleandtransmissionratios.
Thiscanresultinover10,000RPM,whichisbeyondthe
burststrengthofthefacingmaterial.Somethingassimple
ascoastingdownanunloadingrampcanburstadriven
disc.
Reengagingaclutchaftercoastingcausestremendous
shocktotheclutchandthewholedrivetrain.Itcanresultin
internalenginedamageand/orclutchandywheelfailure.
Alwaysreportunusualclutchoperationpromptly.Proper
maintenance,performedontime,willgreatlyextendthelife
oftheclutch.Thedrivershouldreportanychangeinfree
pedal(freetravel)slippageoranystrangefeeltotheclutch
operation.
HelpfulHintstoOperateVehicleswithCeramicClutch
Facings
1.Drivermuststartvehicleinrst(low)gear.
2.Whileoperatingaceramicclutchthedriverhasto
engagetheclutchbeforegivingtheengineanyfuel(at
idle).
3.Thedrivershouldnottrytosliptheceramicclutch
byraisingengineRPMsandridingorfeathering
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