Allison Transmission 3000 HS

sameWOTupshiftsasthecorrespondingS1throughS4schedules.However,
theS5throughS8partthrottleshiftscheduleshavebeenmodied.
4.2.6DYNAMICSHIFTSENSING(DSS)(N/AforOFSModels).
NOTE:DSSwasknownasLoad-BasedShiftScheduling(LBSS)
priortoJuly2014.
TheDSSshiftingstrategyoptioncombinestheadvantagesofboth
performanceandeconomyshiftschedules.Thecontrolsautomaticallyselect
theeconomyshiftschedulewhenanunloadedstateofthevehicleisdetected
(basedoncapabilityofthevehicletoacceleratequickly),thenautomatically
switchtoperformanceshiftpointswhenthevehicleisloadedanditsability
toaccelerateisreduced.Theresultingoperationcancontinuouslymodify
transmissionshiftingtokeeptheenginenearitsmoreefcientspeeds,which
canproduceimprovedoverallvehiclefueleconomywhilestillenablinghigh
productivityduringloadedconditions.DSSisavailableforalltransmission
models,excepttheOFS.DSSrequiresthatthePrimaryandSecondaryshift
scheduleshavethesamenumberofforwardgearranges.
DSSisimplementedtwodifferentwaysdependingonwhetherthevehicle
hasEngineManagementIntegrationbetweentheengineandtransmission
controlstheDSSisimplementedtwodifferentways:
•Torque-BasedDSS:Invehicleswheretheengineandtransmission
haveEngineManagementintegration,theDSSalgorithmwillusethe
SAEJ1939enginetorquemessagestoestimatethevehicleload.
Torque-basedDSSincludesanadditionalshiftmodewhichisamore
aggressiveeconomyshiftschedule.TheSuperEconomyShiftSchedule
(SESS)worksinthebackgroundoftheselectedEconomyand
Performanceshiftschedules.SESSallowsthevehicletocruiseatthe
lowestpossibleenginespeedwithoutluggingtheengine.DSSwillshift
basedontheSESSwhenthevehiclemeetsthefollowingconditions:
–Constantthrottleposition
–Verylowtractiveeffort
–Steadycruiseoperation
Anysuddenchangeinthrottlepositionortractiveeffortwillcause
theTCMtoexitSESSandreturntothebasicEconomyand
Performanceshiftschedules.SESSisstandardinalltorque-based
DSS-activecalibrations.
•Acceleration-BasedDSS:InvehicleswithoutEngineManagement
Integrationbetweentheengineandtransmission,theDSSalgorithm
usesthrottlepositionandoutputaccelerationtoestimatethevehicle
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