Allison Transmission Service Manuals
Allison Transmission History
Who in the realm of individuals remains unaware of the prominent American entity, Allison Transmission, established back in 1915? Spanning its extensive chronicle, the corporation has delved into realms such as motorsport and aviation. Presently, it stands as one of the globe's premier producers of automatic transmissions tailored for commercial vehicles. A surplus of 300 eminent Original Equipment Manufacturers (OEMs), specializing in buses, utility vehicles, firefighting apparatus, construction machinery, military conveyances, and various other vehicles, relies on the prowess of Allison's automatic transmission. Noteworthy is the fact that Allison Transmission was a subsidiary of General Motors from 1929 to 2007. However, in 2012, it metamorphosed into an independent publicly traded entity known as Allison Transmission Holdings Inc.
At the Szentgotthard plant, three distinct series of gearboxes find their culmination: the 3000 series, the 4000 series, and the Torqmatic. These transmissions, meticulously crafted, cater to a broad spectrum of commercial vehicles, ranging from long-haul trucks to construction behemoths, firefighting apparatus, utility vehicles, and other specialized automotive applications. The 3000 series caters to medium-duty vehicles featuring engines with a power output of up to 336 kW and torque levels reaching 1695 Nm. In contrast, the 4000 series is designed for heavy-duty machines equipped with engines boasting power up to 597 kW and a torque rating of up to 2644 Nm.
The gearbox configurations for both series encompass 6 or 7 gears, inclusive of overdrive and a secondary reverse. The transmission ranges are adaptable, tailored to the unique requisites of diverse technical applications. Additionally, all these gearboxes can be endowed with up to two power take-off shafts, accompanied by a retarder brake.
A hallmark of these transmissions is the cutting-edge 5th generation electronic control system, augmented by FuelSense technology. This innovative system not only enhances fuel efficiency but also offers adaptive capabilities to meet specific operational conditions. The FuelSense Package incorporates features such as an acceleration control system, a high-precision inclinometer for measuring road slope angles, EcoCal shift technology for maintaining optimal engine speed, Dynamic Shift Sensing for low engine speed gear shifts, and the Neutral at Stop option that lightens the engine load during halts, contributing to fuel economy and emission reduction.
Furthermore, FuelSense encompasses a smart control function that monitors power take-off (PTO) engagement, mitigating potential damage risks to components. Another notable feature inhibits gear engagement during the operation of specialized equipment until outriggers are retracted, cranes return to transport positioning, and doors are securely closed. The diagnostic function ensures timely maintenance alerts, averting premature oil and filter changes.
In essence, Allison's autom atic transmissions, adorned with these sophisticated design elements, demonstrate unparalleled efficiency across an array of machinery and operating conditions. These transmissions, especially those from Allison, provide a tangible solution to the scarcity of qualified drivers. The automated system inherently ensures seamless operation of engine and transmission components, thereby extending their service life. Moreover, Allison transmissions are programmable to impose speed and power limitations, such as during the truck's break-in period or to forestall traffic infractions, adding an extra layer of control and customization to meet diverse operational demands.
A BRIEF DESCRIPTION OF THE ALLISON 1000 AND
2000 SERIES TRANSMISSIONS
Allison Transmissions are fully automatic, torque-converter driven,
electronically controlled transmissions best suited for light-medium duty,
on-highway applications. Each transmission series (EVS, HS, MH, PTS, RDS,
SP, BUS, and INT) contains features which have been designed for specific
vocational needs.
• 1000 Series– This transmission is best suited for light duty on-highway
applications. The 1000 and 1350 transmissions have a park pawl.
• 2000 Series– These transmissions are best suited for single-axle
medium duty on-highway applications. The B220, 2200, 2350, and
2550 transmissions have a park pawl; the B210, 2100, 2300, and 2500
transmissions do not have park pawls.
The park pawl exists but cannot be engaged in some vehicle configurations
using 1000, 1350, 2200, 2350, and 2550 transmissions (e.g., some rear
engine vehicles with air brakes). For these configurations, the P (Park)
position is not used.
A provision to mount a PTO is available on all transmissions. The PTO drive
gear is optional.
All transmissions are capable of up to six forward ranges, dependent on
TCM calibration, and one reverse. All clutches are hydraulically-actuated,
spring-released, and have automatic compensation for wear. Gearing is
helical type, arranged in planetary sets. Electronic controls provide automatic
gear selection in each drive range and automatic engagement of the torque
converter (lockup) clutch.
ELECTRONIC CONTROL SYSTEM
The transmission control system consists of five major components connected
by customer-furnished wiring harnesses. The five major components are:
• Transmission Control Module (TCM)
• Engine Throttle Position Sensor (TPS) or direct electronic
communication of throttle information
• Engine, turbine, and output speed sensors
• Internal Mode Switch (IMS)
• Control valve body
The control valve body contains solenoids and a pressure switch manifold to
position and monitor control valve operation. The pressure switch manifold
also contains a thermistor to monitor sump fluid temperature. The TPS (engine-to-transmission communication link), speed sensors, pressure switch manifold, and internal mode switch communicate information to the TCM.
The TCM processes this information and then sends signals to actuate
specific solenoids located within the control valve body in the transmission.
These solenoids control both oncoming and off-going clutch pressures to provide closed-loop shift control by matching engine rpm during a shift to a previously established desired profile that is programmed into the TCM.
The transmission electronic control system has an “adaptive shifting”
feature. Adaptive shifting helps optimize shift quality by monitoring critical.
characteristics of clutch engagement and making on-going adjustments to improve subsequent shifts. The transmission shift calibration is based on several different types of shifts, e.g., full throttle, part throttle, closed throttle—upshifts, downshifts, etc. Each shift is associated with specific speed and throttle position parameters. In order to optimize each type of shift for normal driving, shift controls must experience operation and shifting in a wide variety of operating conditions.
A “drive in” period under varied driving conditions is required before the
adaptive controls can be expected to optimize each and every shift. In
general, shift quality will begin to converge to their “adapted” level following
several shifts of a particular shift type.
TORQUE CONVERTER
The torque converter consists of four elements – pump, turbine, stator,
and torque converter (lockup) clutch. The pump is the input element and is driven directly by the engine. The turbine is the output element and is hydraulically driven by the pump. The stator is the reaction (torque multiplying)
element. When the pump turns faster than the turbine, the torque converter is multiplying torque. When the turbine approaches the speed of the pump, the stator starts to rotate with the pump and turbine. When this occurs, torque multiplication stops and the torque converter functions as a fluid coupling.
Allison Transmission torque converters contain a torque converter
clutch. When engaged, this clutch causes the torque converter pump and turbine to be locked together, enabling them to rotate in unison at engine speed. This condition, commonly referred to as “torque converter clutch operation,” provides direct drive through the transmission. This type operation maximizes engine braking and enhances fuel economy. The torque converter (lockup) clutch is regulated by the shift controls to engage
automatically. The torque converter clutch releases at lower speeds or when the TCM detects conditions requiring it to be released. The torque converter clutch contains a damping mechanism which reduces the transmittal of engine-induced torsional vibrations into and beyond the transmission.
PLANETARY GEARS AND CLUTCHES
A series of three helical, constant mesh planetary gear sets and shafts
provides the mechanical gear ratios and direction of travel for the vehicle. Thenplanetary gear sets are controlled by five multiplate clutches that work in pairsnto produce up to five or six forward ranges, dependent on TCM calibration,nand one reverse speed. The clutches are applied and released hydraulicallyn in response to electronic signals from the TCM to the appropriate solenoids.
COOLER CIRCUIT
The transmission fluid is cooled by a remote-mounted oil cooler. The bottom of the transmission torque converter housing provides for the direct mounting of a control main filter and includes two ports to facilitate the attachment of the oil cooler lines.
PREVENT MAJOR PROBLEMS
Allison Transmission distributor or dealer when any of these conditions occur:
• Shifting feels abnormal.
• Transmission leaks fluid.
• Unusual transmission-related sounds (changes in sound caused by
normal engine thermostatic fan cycling, while climbing a long grade with
a heavy load, have been mistaken for transmission-related sounds).
• CHECK TRANS light or RANGE INHIBIT(ED) light comes on frequently.
• SERVICE TRANS light remains illuminated, if present.
TURNING THE VEHICLE ON/OFF
Before turning on or off the engine, the driver must verify that the service
brake is engaged and one of the following selector positions has been
selected and engaged:
• P (Park)
• PB (Auto-Apply Parking Brake)
• N (Neutral) if P (Park) or PB (Auto-Apply Parking Brake) is not available
NOTE: The vehicle should not start unless one of these selector
positions has been selected. If the vehicle starts in any other selector
position, seek service immediately.
Transmission operation at cold ambient temperatures may require preheatingmor the use of a lower viscosity transmission fluid.
Even when the engine is warm and capable of full-throttle output, the
transmission should not be taken out of P (Park), PB (Auto-Apply Parking Brake), or N (Neutral) for at least thirty seconds to allow for buildup of transmission fluid pressure.
ACCELERATOR CONTROL
WARNING: To help avoid injury or property damage caused by
sudden movement of the vehicle, do not make shifts from N (Neutral)
to a forward range or R (Reverse) when the throttle is open. The
vehicle will lurch forward or rearward and the transmission can be
damaged. Avoid this condition by making shifts from N (Neutral) to a
forward range or R (Reverse) only when the throttle is closed and
service brakes are applied.
The position of the accelerator pedal influences when automaticnshiftingnoccurs. When the pedal is fully depressed, upshifts will occur automatically atnhigher engine speeds. A partially depressed position of the pedal will causenupshifts to occur at lower engine speeds. An electronic throttle position signal tells the TCM how much the operator has pressed the pedal. Excessive throttle position may inhibit a directional shift.
PRIMARY/SECONDARY SHIFT SCHEDULES
SHIFT SCHEDULES.
The points at which shifts occur depend upon predetermined speeds and other operating conditions. A transmission “shift calibration” includes several sets of shift points which may be used according to current or anticipated operating conditions. Some shift schedules may be inhibited as a result of operating conditions, such as engine or transmission fluid temperature.
Shift schedules may be changed through selection of a remote (usually
dash-mounted) switch—which is typically associated with a change in
anticipated vehicle operation.
The TCM includes the capacity for two separate and distinct shift calibrations (customer-selectable), one for use in “Primary Mode” of operation and one in “Secondary Mode.”
• Primary—This shift schedule is typically used for all normal vehicle
operations.
• Secondary—This is an alternate shift schedule that the TCM uses
upon request. Not all vehicles will be equipped with a secondary shift
schedule. The request can be interlocked with a vehicle component, or
be operator-controlled via a dash-mounted switch.
Your vehicle may have a dash-mounted light that illuminates when the
secondary mode is active.
DYNAMIC SHIFT SENSING (DSS) (MH, BUS, HS, PTS, and RDS
Models).
NOTE: DSS was known as Load-Based Shift Scheduling (LBSS)
Vehicles equipped with DSS do not require the operator to change selection of primary and secondary shift schedules manually and no longer require a dash-mounted OEM-installed switch or Mode button for shift schedule selection. This is because DSS automatically selects the appropriate shift schedule based on vehicle load and operating conditions.
DSS selects between Economy and Performance shift schedules based on the vehicle's current estimated payload (determined by acceleration rate and requested power) and the grade on which the vehicle is operating.
This optimizes fuel economy while maintaining performance on vehicles so equipped.
DSS has been optimized to include a Super Economy Shift Schedule (SESS). This enhancement allows earlier up-shift under cruising conditions to further improve fuel economy. Cruise is defined as driving with low to no acceleration at a given road speed.
Fuel economy enhancement features available on some former models are improved with the current controls due to the use of an inclinometer (a device that senses road grade) contained in current TCMs.
ALLISON TRANSMISSION FuelSense®
Vehicles equipped with an Allison Transmission and a FuelSense®
package will save fuel when compared to vehicles without the package, depending on the duty cycle.
FuelSense®
2.0 is an initiative that groups software and calibration fuel
economy features into packages that can be easily selected when specifying a TCM calibration in the Allison Calibration Configuration Tool (ACCT).
With the introduction of FuelSense® packages, more descriptive feature designations have been created.
DIAGNOSTIC CODES
The red or amber RANGE
INHIBIT(ED) warning light is located on or near the shift selector. The purpose of this indicator is to alert the operator that transmission operation is being inhibited and that range shifts being requested by the operator may not occur.
When certain operating conditions are detected by the TCM, the controls will command the transmission to be locked in the range currently in use. If the torque converter clutch is applied when the condition is detected, the clutch will be disengaged concurrently with the activation of the RANGE INHIBIT(ED) light.
Each time the engine is started, the RANGE INHIBIT(ED) light will illuminate, then turn off after two seconds. If the light does not illuminate during ignition,
or if the light remains on after ignition, the transmission system should be checked immediately.
For the conditions under which shift inhibits occur, see the SHIFT SHIFT INHIBITS section in this manual.
NOTE: If the RANGE INHIBIT(ED) warning light flashes, it may
indicate that COTP is active.
CONVERTER OVER-TEMP TORQUE PROTECTION (COTP)
• Purpose
– Alerts the driver to a torque converter over-temperature condition.
– Limits the time that the torque converter can be stalled at full power
to prevent torque converter damage (if the vehicle is equipped to
limit engine rpm by SEM or LRTP) while maintaining an acceptable
level of driver control during normal operation.
Engine rpm cannot be controlled for non-SEM applications. Only
SEM or LRTP equipped vehicles will be able to offer torque limits.
On vehicles without SEM or LRTP, only the RANGE INHIBIT(ED)
light will be flashed.
• Functionality
– Converter slip speed is controlled via engine torque limiting to
regulate converter temperatures to acceptable levels.
– RANGE INHIBIT(ED) light flashes 1 second before and during
torque reduction.
• Criteria for activating COTP
– First level of COTP (RANGE INHIBIT(ED) light flashes)
• Difference of at least 1400 rpm or greater between engine
speed and transmission input speed
• 25% throttle or greater
• Less than 100 rpm transmission output speed
• All conditions above must be maintained for at least sixteen
seconds to activate first level of COTP (less if initial converter
temp predicted hot)
– Second level of COTP (Engine Speed will be limited to 900 rpm
and RANGE INHIBIT(ED) light flashes)
• Difference of at least 1400 rpm or greater between engine
speed and transmission input speed
• 25% throttle or greater
• Less than 100 rpm transmission output speed
• Twenty-three seconds total of throttle and output conditions
being met
Once you exit the COTP condition, a software counter will count back sixteen
seconds before full engine rpm is available.