Allison Transmission T 270 User Manual

4.2SHIFTSCHEDULESANDAUTOMATICRANGESHIFTS
Eachtransmissionshiftcalibrationincludesmultipleshiftscheduleswhich
areusedtocontroltransmissionshiftsinvariousoperatingconditions.The
shiftschedulesaffectthetimingofshiftsbetweengears.Theactualnumber
offorwardgearsisdeterminedbasedonthetransmissionmodelandthe
selectedrangepositionoftheshiftselector.
Vehicleperformancemaybeaffectedwhenshiftscheduleschange.The
transitionbetweenshiftschedulescanbeinitiatedbyseveraldifferentactions.
ThetransmissioninitiallyattainsrstrangewhenD(Drive)isselected(except
forthoseunitsprogrammedtostartin2(SecondRange).Asvehiclespeed
increases,thetransmissionautomaticallyupshiftsthrougheachrange.Asthe
vehicleorequipmentslowsdown,thetransmissionautomaticallydownshifts
tothecorrectrange.TheSELECTdisplayshowsthehighestrangeavailable
inD(Drive).
NOTE:ThevehicleOEMorbodybuilderisresponsibleforevaluating
thedriveabilityofshiftschedulesintheintendedvehicleandduty
cycle.Foradditionaldetailsregardingtheseshiftschedulesand/or
otheroptionsforprimaryandsecondaryshiftschedules,contacta
qualiedAllisonTransmissionserviceoutletforfurtherinformation.
4.2.1UPSHIFTING.AslongastheTCMcalculatesthatthereisenough
vehiclepowerandvehicleaccelerationavailabletograntandkeepthe
nextupshift,thentherearenootherlimitationsimposedonupshiftinguntil
thevehicleattainsitstoprangedisplayedintheSELECTdisplayonthe
selector.Vehiclepowerandaccelerationcharacteristicsaremonitoredbythe
transmissioncontrolstoattempttoeliminateshiftcycling.Shiftcyclingisan
upshiftfollowedcloselybyadownshift,whichisthenfollowedbyanother
upshift,andsoon.
NOTE:Ifshiftcyclingisnoted,usethealternateshiftscheduleby
pressingtheMODEbutton.Theoperatorcanalsomanuallyselect
thenextlowerrange(usingtheshiftselector)toholdthatlower
rangeuntilconditionsaremettogranttheupshiftpointagainwithout
shiftcycling.
4.2.1.1HOLDSCHEDULEFORUPSHIFTS
Asastandardfeatureofeachshiftcalibration,thetransmissioncontrols
incorporatea"holdupshift"shiftschedule,whichtheoperatormayselectif
thetransmissionisnotoperatinginitshighestrange.Whenthisscheduleis
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Allison Transmission T 270 Specifications

General

Brand	Allison Transmission
Model	T 270
Category	Controller
Language	English