Post on 13-Apr-2018
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Chapter 20
Electronically
Automated StandardTransmissions
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Objectives (1 of 2)
Explain how a standard mechanical transmission isadapted for automated shifting in three-pedal andtwo-pedal systems.
Identify three different OEM automatedtransmissions and interpret the serial number codesof each.
Describe the hardware changes that differentiate astandard Roadranger twin-countershaft
transmission from its electronically automatedversion.
Outline the electronic circuit components that areused to manage AutoShift transmissions.
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Objectives (2 of 2)
Outline the main box and auxiliary section actuator
components required for AutoShift electronically
automated, standard transmissions.
Describe how the electronic circuit componentswork together to perform the system functions.
Perform some basic diagnostic troubleshooting on
automated transmission electronics.
Describe the ZF Meritor SureShift and FreedomLinetransmissions and the Mercedes Benz AGS
transmissions.
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Transmission Identification
The best way of identifying transmission
specifications on a vehicle is by accessing
the chassis data bus, specifically the 130
MID for generic ESTs.
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AutoShift (1 of 2)
Serial Number: RTAO14710 B AS
R Roadranger
T Twin countershaft
A Automated
O Overdrive (X)100 + 50 = nominal torque capacity
7 Design level (5 = spur gear, 6 = multimesh gearing,7 = multimesh front, helical auxiliary gearing)
10 Number of forward speeds
B Ratio set designation (C) AS AutoShift
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AutoShift (2 of 2)
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UltraShift
Serial number: RTO - 14 9 10 B - DM 2
R Roadranger
T Twin countershaft
O Overdrive 14 Torque capacity
9 Design level
10 Forward speeds
B Ratio category DM UltraShift with DM clutch
2 Automation level/Gen II electronics
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Freedomline
Serial Number: M O16 Z 10 C - A 18
M ZF Meritor
O Overdrive (no letter = direct drive)
16 Input torque rating: 1,600 lb./ft. Z Design platform: Z = FreedomLine F = 9 speed
G = 10 speed
10 Number of forward gears
C Ratio A Automated (S = shift by wire, M = manual)
18 Highest torque in top 2 gears = 1800 lb./ft.
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Mercedes Benz AGS
Serial Number: MBT560 S - 6 O
MBT Mercedes-Benz Transmission
560 Input torque rating 560 lb./ft.
6 Number of forward ratios
O Overdrive (D 5 direct drive)
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UltraShift Two-pedal
Automated Transmission
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Mercedes-Benz AGS
Two-pedal Automated Transmission
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AutoShift Components
The Eaton Fuller Roadranger AutoShift automatedtransmission is a two-module system.
The System Manager (ECU) does the thinking.
A second module, the transmission controller (ECU),
converts that thinking into action by performing theswitching functions of the transmission.
AutoShift transmission components can be groupedas follows:
Base standard gearbox Transmission automation components
Vehicle automation components
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Base Transmission
The AutoShift transmission is based on a Roadranger twin-countershaft platform.
A Fuller 10-speed transmission has a 5-speed main or frontcase, with a 2-speed auxiliary section.
Although the base transmission has a similar appearance tonon-automated versions, the following changes are required:
Main box. Two screw bosses have been added to the case sothe transmission controller can be mounted to the side.
Range cylinder cover. The range cylinder cover is altered tohouse the range shift control mechanism.
Shift bar housing. The shift bar housing has been machined toaccept the speed sensors.
Shift yokes. The shift yokes have been hardened at the forkpads to improve durability during shifts.
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Automation Components
The transmission automation components
include:
XY shifter
Speed sensors
Power module
Transmission harness
Range valve Reverse switch
Transmission controller
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Electric Shifter Assemblies
The shift shaft is a squaresection shaft.
The shift finger rides on theshift shaft.
This permits the shift finger tobe moved along the rail.
The shift shaft has a machinedarea on the end to enable it torotate the position sensor.
The gear select yoke alsorides on the shift shaft. Theyoke is driven by the gearselect ball screw, whichrotates the shift shaft for gearselection.
The gear select sensorprovides position data to thetransmission controller.
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Ball Screw Assemblies (1 of 2)
The shift finger position is located by a pair of
ball screws.
One ball screw is used for the lateral (left to
right) movement that is required to select thecorrect rail.
The other ball screw is used for the forward
or backward positioning required to select agear.
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Ball Screw Assemblies (2 of 2)
The ball screw assembly ismade up of a worm gear,ball screw nut, and ballbearings.
When the worm gear
rotates, the ball bearingsride in the grooves of theworm threads.
When a ball reaches theend of a ball screw block, it
is forced into a tube to bereturned to the beginning ofthe worm threads in the ballscrew block.
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Rail Select Ball Screw
The gear select ball screw nut has a pair of
tabs, one on either side.
These tabs drive the gear select yoke, which
is located on the shift shaft with the shiftfinger.
When gear selection is commanded, the ball
screw block moves the gear select yoke,which in turn moves the shift shaft.
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Electric Motors
The motors use apermanent magnetoperating principle and arecapable of forward orreverse rotation.
The rail select motor ispinned directly to the railselect ball screw and thegear select motor is pinneddirectly to the gear select
ball screw. The electric motors used in
each ball screw assemblyare not interchangeable.
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Position Sensors (1 of 2)
Position sensors convert amechanical position to asignaled voltage value that isthen returned to the ECU.
AutoShift position sensors arethree-wire voltage dividers.
They are supplied a referencevoltage of 5V, modulated bythe ECU.
There is a resistor betweenthe 5V input terminal and theground connection.
A wiper contacts the resistorand, depending on itsmechanical location,determines the signal voltagevalue returned to the ECU.
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Position Sensors (2 of 2)
The rail select sensor is connected to the rail select
ball screw. The position sensor yoke arm fits over a
pin on the side of the rail select screw block. Its
signal allows the transmission controller to
determine whether the shift finger is located over
the correct rail before effecting a shift.
The gear select sensor monitors shift finger position
during gear selection. The signal returned to thetransmission controller confirms whether a shift has
been successfully effected.
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Shop Talk
Current versions of AutoShift are designed to
break driveline torque when a predetermined
driveline (road) speed is sensed.
This prevents driveline component stalldamage to the engine.
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Range Valve Operation (1 of 2)
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Range Valve Operation (2 of 2)
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Speed Sensors (1 of 4)
Three speed sensors are usedin the transmission. Theymeasure and report: Input shaft speed
Mainshaft speed
Output shaft speed
When the teeth of the pulsewheel cut through themagnetic field in the sensor,an AC voltage is induced inpulses.
The AC voltage value and
frequency produced will rise inproportion to the increase inrotational speed.
These sensors can be testedby measuring voltage output.
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Speed Sensors (2 of 4)
The input shaft speed sensoris located at the right frontcorner of the shift rail housing.
The speed sensor magnet andcoil produce pulses from the
upper countershaft PTO gear. The AC voltage and frequency
rise proportionally with shaftspeed.
The ECU measures thefrequency of the pulses, notthe actual voltage generated.
Input shaft speed is calculatedby multiplying countershaftspeed by the head set ratio.
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Speed Sensors (3 of 4)
The mainshaft speed sensor is located at theleft rear corner of the shift rail housing at theauxiliary countershaft drive gear.
A pulse generator principle is used; the ACvoltage and frequency produced and sent tothe ECU increase proportionally with shaftrotational speed.
The auxiliary countershaft drive gear ismeshed to the mainshaft through theauxiliary drive gear and is driven at the samespeed.
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Speed Sensors (4 of 4)
The output shaft speed sensor picks up pulses
produced by a tone ring located on the output shaft.
This tailshaft-located sensor inputs road speed data
to the AutoShift transmission controller and to other
chassis electronic systems.
Road speed is determined by factoring the output
shaft speed with the drive axle carrier ratio and the
rolling radius dimension of the tires. A standard 16-tooth pulse wheel is used.
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Function of the Speed Sensors
Shift synchronization Input shaft speed and mainshaft speed data is used by
the transmission controller for synchronizing shifts inthe transmission main box.
Verifies range engagement The data generated by the mainshaft and output shaft
speed sensors is used by the transmission controller toverify range engagement.
Reports road speed data The output or tailshaft speed sensor data may also beshared with other chassis electronic systems as vehicleroad speed data.
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Power Module (1 of 2)
The power module is locatedon the transmission controllernext to the electric shifter unit.It incorporates the followingcomponents: Cycling circuit breakers
Reverse voltage diode Reverse voltage Zener diode
The power module connectsthe vehicle electrical systemwith the transmission electricaland electronic systems and
protects the transmissionelectrical system from currentoverloads with cycling-typecircuit breakers.
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Power Module (2 of 2)
The AutoShift power modulecontains two SAE #1 cyclingcircuit breakers:
One rated at 25 amps. The25-amp breaker protects
the circuit supplying theelectric shifter motors andthe logic battery powerfrom current overloads.
The other at 10 amps. The10-amp breaker is locatedin series in the circuitsupplying logic batterypower following the 25-amp breaker.
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Reverse Voltage Diode
The reverse voltage diode is located just past the
25-amp circuit breaker. The diode permits current
flow in one direction only. In the event of a reversepolarity condition, the reverse voltage diode blocks
current flow into the transmission electrical circuit.
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Reverse Voltage Zener Diode
The reverse voltage zener diode is located between the negativeterminal on the reverse voltage diode and battery ground.
The zener diode functions as a normal diode but acts to regulate
voltage should it exceed a specified level. The reverse voltage zener diode used in the AutoShift power
module will permit current flow, although it will not permit thevoltage value to exceed 32V.
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Power Module Functions
Motor Power. Connected to the vehicle cranking motor, the circuit passes throughthe 25-amp circuit breaker and the reverse voltage diode and connects to themotor terminals.
Motor ground. The motor is direct grounded through the power module by means
of a wire to the cranking motor ground terminal. Logic power. Logic power refers to the electric feed required to power up the
system ECUs. It is routed from the vehicle cranking motor battery terminal throughboth the 25-amp and 10-amp circuit breakers.
Logic ground. The logic ground is routed direct from the cranking motor groundterminal through the power module and out to the logic power connector.
T i i C ll
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Transmission Controller
It has some limited processingcapability but is mainlyresponsible for managing theswitching requirements of thesystem.
The transmission controller
ECU is multiplexed. It is connected to the system
electrical/electronic circuit bymeans of a dedicated harnessknown as the transmissionharness.
All of the input and outputcircuits are connected to thetransmission controller bymeans of this harness,including the data link to thesystem manager.
I ti B k
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Inertia Brake
The inertia brake system onan AutoShift transmissionhelps stop the countershaftson initial engagements whenthe clutch is either out ofadjustment or defective.
The inertia brake is mountedat the 6- or 8-bolt PTO.
The inertia brake consists of asolenoid and brake.
The solenoid controls theinertia brake by switching
regulated air pressure to theinertia brake piston to applythe friction and reaction discs,which brakes the countershaft.
C ti
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Caution
When removing the inertia brake solenoid,ensure that system air pressure is completely
relieved and the air/filter regulator is
removed.
Vehicle Automation
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Vehicle Automation
Components
The vehicle automation components connect thetransmission electrical and electronic circuits with
those of the vehicle. This group of components
includes:
System manager
Gear display
Shift lever
Power connect relay
Start enable relay
Vehicle harnesses
S t M
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System Manager
The system manager ECU is a secondmicroprocessor module with the dual functions of
interfacing with the rest of the vehicle and overall
management of the transmission systems.
Controlling logic power
Managing shifting
Processing fault conditions
Processing shift lever commands
Controlling Service and Wait lights
Providing information to lever digital display
C ti
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Caution
The shifter module must be calibrated beforea vehicle is placed in operation.
Data Retention
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Data Retention
The system manager stores fault code datain its nonvolatile RAM before turning off the
power connect relay during each shutdown.
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Service light
The service light displays
fault information to thedriver or technician.
A flashing or continuous
illumination of the service
light indicates that a fault
code has been logged. Logged fault codes can
then be pulse displayed
by flashing numeric codes
on the service light.
Wait light
The wait light was only
used on the earliest
versions of
AutoSelect/AutoShift.
On those transmissions
using a wait light, it is
illuminated on power-upwhen the system manager
and transmission controller
perform a self-check
sequence.
If the transmission checksokay, the wait light turns off.
S k Detents
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Speaker
The speaker tone is
used to alert the driverto break torque on the
driveline so that a shift
can be effected.
The tone signal is
output by the system
manager.
Detents
The detent mechanism
locates the
transmission shift lever
in the correct location
in each range select
position.
It provides an elementof gearshift feel to the
driver when shifting
from one gear to
another.
Gear Display
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Gear Display
When a shift is initiated, thetarget gear is displayedcontinuously.
When the transmission shiftsto neutral, the target gearbegins to flash.
When the shift sequence iscompleted, the display ceasesto flash and the range status isdisplayed.
Up arrows indicate the inputshaft speed must be increased
until it matches main shaftspeed.
Down arrows indicate theinput shaft speed must bedecreased to match the mainshaft speed.
Vehicle Harnesses (1 f 2)
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Vehicle Harnesses (1 of 2)
Vehicle Harnesses (2 of 2)
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Vehicle Harnesses (2 of 2)
Tower Harness Service Port
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Tower Harness Service Port
The service port is located inthe tower harness. It is used toaccess circuits for voltagechecks. The circuits can bechecked without separatingharness connectors.
Pin A: ignition power
Pin B: dummy
Pin C: measures voltage atthe power connect relay
Pin D: ground
Pin E: start enable relay coil Pin F: dummy
Pin G: power connect relaycoil; output from the systemmanager
Fallback Modes
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Fallback Modes
When a fault code is logged, the transmissionelectronics are designed to assess all
remaining functionality and then default to a
limited operational mode. Five-speed fallback
One-speed fallback
In-place fallback
Downshift fallback
Fault Code Status
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Fault Code Status
An active code indicates a problem active at thetime of reading the system.
An inactive code (historic code) indicates theoccurrence of a fault that has either occurred in thepast or is not detected at the moment of reading the
system. The presence of an inactive code may indicate that
the vehicle has not been driven in the propermanner.
AutoShift system troubleshooting should beperformed using the AutoShift service literature thatcontains step-by-step troubleshooting guides.
Pretests
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Pretests
Transmission pretests should be performedbefore progressing to specific fault codeisolation.
Pre-checks require that electrical inputs andpneumatic supply to the transmission befunctioning properly.
The pretests eliminate obvious high-level
problems immediately before progressing toa detailed, sequentially stepped diagnosticprocedure.
Symptom-driven Diagnostics
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Symptom driven Diagnostics
No fault codeA transmission is, above all, a mechanical
device, and problems will occur in which
active or inactive electronic codes are notlogged.
Mechanical faults
Never assume that every fault must be
electronically monitored.
CEEMAT
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CEEMAT
This was an early, not too successful effortby Eaton at an automated transmission
system.
The acronym stands for converter enhanced,electronically managed, automated
transmission.
You do see a few CEEMAT automated
transmissions around, but more likely in a
college or teaching environment rather than
on the highway.
Engine SynchroShift (ESS)
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Engine SynchroShift (ESS)
Rockwell Meritor introduced Engine SynchroShift (ESS) in 1997just before their merger with the German company ZF.
ESS is a three-pedal system designed to synchronize enginerpm automatically to road speed during any shift sequence.
The ESS transmission had no independent processing capabilityand relied upon multiplexing to the engine electronics to operate.
The end result was to make the shifting of a non-synchronizedmanual transmission as easy as shifting a fully synchronizedtransmission. As a three-pedal system, the main function of the clutch was to
break driveline torque at stall; that is, for starting and stoppingthe vehicle.
Auxiliary range shifts were automatic, reducing driver effort andsynchronizer damage.
ESS featured a break torque switch that enabled the driver topower upshift and downshift.
SureShift
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SureShift
SureShift is a ZF Meritor three-pedal automatedtransmission that uses joystick initiated shifts.
The clutch pedal is used only to break driveline
torque at stall (starting and stopping).
SureShift is currently available in 9- and 10-speed
transmissions.
The electronics are J1939 networked to the chassis
data bus. The system is essentially a later versionof the ESS system.
FreedomLine
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FreedomLine
The ZF Meritor FreedomLine transmission was thefirst two-pedal system automated transmissionavailable for trucks.
The driver can select either automatic or manual
modes of operation, but he has no direct controlover clutching.
A self-adjusting system-actuated clutch is built intothe FreedomLine automated transmission.
It is available in 12- and 16-speed versions. FreedomLine transmissions are networked into the
chassis data bus via a J1939 data link.
Mercedes-Benz AGS
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The automated transmission is an adaptation of the Mercedes-Benz six-speed, medium-duty, mechanical transmission that hasbeen around for a number of years.
It is packaged into an aluminum housing and uses a two-pedalsystem with a manual option mode.
When operated in manual mode, the management electronicsprevent the driver from making a shift that could result indriveline damage.
It is networked to the J1939 data bus so that shift algorithms arebased in what is happening elsewhere in the engine anddrivetrain.
Troubleshooting is accomplished using Freightliner ServiceProsoftware.
UltraShift
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The UltraShift automated transmission wasintroduced by Eaton Fuller Roadranger in 2003 asa two-pedal system. The initial release was a 10-speed unit with an inertia brake.
UltraShift uses a modular automation design that is
said to simplify service repair work. The clutch usedis a 15.5 inch, two-plate, ceramic button type withcoaxial springs.
In common with all current automatedtransmissions, the driver can option manual shifting.
The Eaton Gen II software is programmed withalgorithms that prevent the driver from making ashift that could result in driveline damage.
Urge to Move
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g
The latest innovation from Eaton Fuller is the addition of a fullyautomated wet clutch to their six-speed AutoShift transmissionused in medium-duty applications.
This converts their automated transmission into a two-pedalsystem that handles similarly to an equivalent Allison automatictransmission.
To make the wet clutch perform much like an automatic with atorque converter, Eatons wet clutch uses a creep feature knownas Urge-to-Move.
Urge-to-Move loads a continuous 45 pounds-feet of torque to thetransmission through the wet-clutch pack so that the driversenses engagement at any time the shift lever is in the driveposition.
This system requires a cooler for the transmission fluid.
Summary (1 of 6)
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y ( )
Automated standard transmissions use electroniccontrols to adapt a standard mechanicaltransmission for either semi-automated or fullyautomated shifting. This technology allows thedriver to keep both hands on the steering wheelduring shifting and significantly reduces driverfatigue.
Automated transmissions can be divided into three-pedal systems that use a clutch pedal and two-
pedal systems that eliminate the clutch pedal. Allautomated transmissions use a clutch, but theclutch is controlled by the system electronic controlunit (ECU).
Summary (2 of 6)
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y
The Eaton Fuller AutoShift transmission is based ona standard Roadranger twin countershaftmechanical transmission platform. AutoShiftelectronics use two ECUs to perform logicprocessing and output switching operations
required by the system. The AutoShift system manager ECU performs most
of the processing. It manages transmission functions and information,
interfaces with the chassis data bus, controls shifting
through its handshake connection with the transmissioncontroller, acts on driver command signals, performsdiagnostic self-checks, and logs fault codes.
Summary (3 of 6)
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y
The AutoShift transmission controller managesshifting based on command signals received fromthe system manager, monitors the input circuitcomponents physically located within thetransmission, exchanges speed and gear ratiostatus data with the system manager, and providesthe system manager with diagnostic information.
The AutoShift system manager ECU is located inthe shift tower assembly.
The transmission controller ECU is located on theleft side of the transmission.
Summary (4 of 6)
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Shifts are effected by an electric shifter assembly that replacesthe gear shift lever in a standard Roadranger transmission. Apair of reversing electric motors actuated by the transmissioncontroller precisely locates a shift finger in the shift blockrecesses in the shift rails.
The rail select motor is used to move the shift finger transversely(side to side) with the objective of locating it precisely in the shiftrecess of one of the three shift rails.
The gear select motor moves forward and backward. After theshift finger has been positioned over the correct shift rail, thegear select motor is energized to move the rail into gear.
Summary (5 of 6)
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The means used by automated transmissions toselect gears is identical to that in a standardtransmission: shift finger movement first selects oneof the three shift rails, then slides that rail fore or aft.
AutoShift transmissions perform self-diagnostic
tests and log fault codes when performanceparameters of any electronically monitoredcomponent or system are out of specification.Faults are broadcast over the chassis data bus.
Fault codes can be displayed by the AutoShiftdiagnostic (service) lights, or by either using ahandheld diagnostic EST or a PC with theappropriate software.
Summary (6 of 6)
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The electronics are SAE J1939 compatible,which permits multiplexing with other chassis
electronics systems.
Most of the automated transmissions thatcompete with the AutoShift system are
similar in terms of their principles of
operation.