Allison Transmission T 270 User Manual

Table4–7.TypesofRetarderControl(cont'd)
TypeDescription
AmountofApplication
Singlepressure
switch
Offor“FullOn”(basedonbrake
pressure)
BrakePressureApply
**
Threepressure
switches
1/3,2/3,or“FullOn”(basedon
brakepressure)
PedalPosition
**
Specialbrakepedal1/3,2/3,or“FullOn”(basedon
brakepressure)
SAEJ1939DataLinkDigitalmessagefrom
enginecontroller
ZerotoFullApply
Auto“half-on”plus
pressureswitch
*
Halfcapacityatclosedthrottleor
“FullOn”withbrakepressure
Auto“1/3on”plustwo
pressureswitches
*
1/3capacityatclosedthrottle
or2/3and“FullOn”withbrake
pressure
Handleverplus
pressureswitch
*
6levelsofmodulationwithlever,
or“FullOn”withbrakepressure
Footpedalplus
pressureswitch
Fullmodulationwithseparate
pedal,or“FullOn”withbrake
pressure
Combinationsofthe
abovesystems
**
Handleverplus
interfaceforspecial
pedal
*
6levelsofmodulationwithlever,
or3levelsofmodulationbased
onpedalposition
*
Thesecontrolsystemsmayapplytheretarderathighspeedongradeswhenthevehiclehas
roadspeedlimitingandtheretarderisenabled.
**
Forretarderapplysystemsintegratedwiththeservicebrakesystem,theretarderismost
effectivewhenappliedwithlightbrakepedalpressurefor1–2secondstoallowtheretarderto
fullycharge.Addedpedalpressurecanbeappliedwhenmoreaggressivebrakingisdesired.
4.3.1RETARDERCAPACITYREDUCTION.
NOTE:Intheeventofexcessivelyhightemperaturesinthe
transmissionuidand/orenginecoolantduringretarderoperation,
themaximumavailableretardercapacitymaybereduced,affecting
vehicleoperation.
Retardercapacityisreducedifthetransmissionretarder-outortransmission
sumptemperatureexceedsspeciedlimits,asdetectedbytemperature
sensorswhichareintegraltothetransmission.Inaddition,retardercapacityis
reducedintheeventofelevatedenginewatertemperaturebasedon:
76

Allison Transmission T 270 Specifications

General

Brand	Allison Transmission
Model	T 270
Category	Controller
Language	English