Allison 1000/2000/3000/4000 Product Familiarization

Allison 1000/2000/3000/4000 Fleets Training

Allison 1000, 2000, 3000 and 4000 Transmissions are found in a wide variety of vehicles around the world.

• These four Transmission offerings are grouped as Product Families – the 1000/2000 Product Family and the 3000/4000 Product Family.
• Both Product Families share some key features and can be found in similar applications, the biggest difference being 3000/4000 Product Family Transmissions are typically found in larger vehicles and more heavy-duty applications than 1000/2000 Product Family Transmissions.

A). The Transmission's Role in the Vehicle

The transmission’s primary role is to convert the Engine’s rotational power into a wide range of output speeds.

• The Transmission is located behind the Engine.
• The Engine crankshaft connects to and drives the Transmission input.
• The Transmission develops output rotation which is typically supplied to the vehicle’s final drive or axle by a driveshaft or driveline.

Without a Transmission, the vehicle would be limited to a single gear ratio making the vehicle very inflexible.

• Modern vehicles require the ability to accelerate from a stop, handle a load, and attain normal road speeds.
• A single gear ratio typically provides either good low speed performance or good high speed performance – not both.

• A single gear ratio vehicle designed for low speed and load handling performance will not perform well at road speed.
• A single gear ratio vehicle designed for road speed performance will not handle loads or accelerate well from a stop.

Manual Transmissions typically rely on the operator physically moving gears, using a manual shift selector, to manually select Transmission ranges.

• In a basic Manual Transmission, gear ratios are based on the number of teeth on two gears – the drive gear and the driven gear.
• When the operator manually shifts the Transmission, the drive-to-driven gear tooth count changes and various ratios are created.
• A clutch is typically required to disconnect and engage Engine power to the Transmission.
• Disengaging the clutch (foot pushing the clutch pedal), removes the Engine power from the Transmission.

• This allows the operator to make manual shifts and allows the Engine to idle with the vehicle stopped and the transmission in range.
• Engaging the clutch (foot off the clutch pedal), mechanically connects the Engine and Transmission input.
• The power from the Engine can be used by the Transmission to create output when a moving range has been selected.

Allison Automatic Transmissions upshift and downshift automatically and don’t require an operator-controlled clutch.

• The Allison Torque Converter connects the Engine to the Transmission input.
• At a stop, Engine power is not transferred through the Torque Converter to the Transmission input.
• When Engine rpms increase, the Torque Converter drives the Transmission input.
• The Transmission Electronic Control and hydraulic systems work together to automatically control shifts.

B). Basic Allison Transmission Operating Principles - Planetary Gear Sets

Allison Transmissions are constructed with planetary gear sets.

• Planetary gear sets consist of a Ring gear, Sun gear and a Carrier assembly which includes Pinion gears.

• Various output ratios are created by holding and driving components.
• To decrease input speed (and increase torque) the Ring gear is held, the Sun gear is driven, and the Carrier becomes the output mechanism.

• To increase input speed (and decrease torque) the Ring gear is held, the Carrier is driven, and the Sun gear becomes the output mechanism.
• A 1:1 ratio is achieved when no components are held and two components are driven at the same speed.
• Reverse is created by holding the Carrier and driving either the Sun gear or Ring gear.

Most 1000/2000/3000/4000 Transmissions utilize three Planetary gear sets.

• The gear sets work together to create the necessary output ranges, often using created output from one gear set to drive components in other gear sets.

C). Basic Allison Transmission Operating Principles - Clutches 

Clutches are used to hold, connect and sometimes drive Planetary components.

• Allison Transmission clutch assemblies are multi-disc, consisting of an alternating stack of fiber "friction" and steel "reaction" plates.

• Clutches are applied by compressing the plates together using a piston forced by hydraulic pressure.
• Clutches are released by spring pressure when the hydraulic pressure against the piston is exhausted.
• "Stationary" clutches hold planetary components or shafts.
• Rotating clutches lock rotating components or shafts together.

Most 1000/2000/3000/4000 Transmission gear packs utilize three stationary clutches and two rotating clutches.

D). Basic Allison Transmission Operating Principles - Range Shifts

Clutches are applied in various combinations to create different output ranges.

• The Transmission Electronic Control and hydraulic systems work together to apply and release clutches.

• The Electronic Control monitors and adapts shifts to match driving conditions.

• The Electronic Control also monitors inputs from vehicle systems to enable optional operational features – for example, if programmed, the Electronic Control may prevent shifts out of Neutral unless a signal is received indicating the operator has depressed the brake pedal.

• A variety of optional features are available depending on the Transmission configuration and intended use (also referred to as the Vocational Model).

E). Vocational Models

Allison uses Vocational Model designations to specify how Transmissions are used and which optional component and programming features are available.

• For example, the HS (or "Highway Series") Vocational Model is specific to vehicles which will only be operated in "on road" conditions (not used off-road).

• The HS Vocational Model includes 1000, 2000, 3000 and 4000 Transmissions to satisfy a variety of Vehicle and Engine sizes.
• Electronic programming features and options are grouped into logical packages for the various on-highway applications.
• And external feature availability is matched to the vehicle’s intended use; for example, RDS Transmissions are available with Power Take-Off (or "PTO") provisions because applications utilizing these Transmissions typically require a PTO to power various Vehicle features.

Allison Tech Data (available online for Allison Service Channel partners, including authorized Distributors, Distributor Branches and Dealers) maintains the very latest product information, including Transmission specifications, Vocational Model information and much more.

The latest version of the Vocational Model Guide (available through the Allison Transmission Publications website) is another resource that compiles Vocational Model, specification and Input/Output Package information.

F). 1000/2000 Product Family Designation Codes

#1000/2000 Product Family Non-Bus Transmissions:

• The first number indicates whether the Transmission is a 1000 or 2000.
• The second number identifies the Transmission gearing as either close or wide ratio, plus indicates whether the Transmission includes a park pawl.
• A "5" in the third field indicates a Transmission with a higher park pawl rating.
• The fourth field is reserved for future designation use – it is currently "0" for all 1000/2000 Product Family Transmissions.
• The Vocational Model identifier appears at the end of the Transmission designation code.

#1000/2000 Product Family Bus Transmissions:

• The "B" indicates the Bus vocation.
• "2" identifies the Transmission as a 2000.
• "1" or "2" is used to identify whether the Transmission includes a park pawl.
• 1000/2000 Transmissions used in buses outside North America utilize designations described here, but can be accompanied by a "T" prefix.

G). 3000 Product Family Designation Codes

#Early 3000 Non-Bus designations:

• Include the two-letter prefix "MD".
• The number "3" identifies the transmission as a 3000.
• The second number field is either "0" or "5" to indicate close or wide ratio, respectively.
• The next field indicates the number for forward ranges.
• The fourth numeric field is reserved to indicate any major revisions.
• Suffixes can include P for PTO, R for retarder, and RM to indicate the Transmission is an Allison Remanufactured unit.

#Current 3000 Non-Bus designations:

• The first number in the designation, "3" identifies the Transmission as a 3000.
• The second numeric field can indicate wide or close ratio, or can indicate that the Transmission is capable of 7 forward ranges.
• The remaining two numeric fields are reserved for differentiators related to ratings, features or major revisions.
• The Vocational Model identifier appears at the end of the Transmission designation code.

#3000 Bus Transmission designations:

• "B" in the first field indicates the Transmission is a Bus Vocational Model; and a "T" in that same field indicates a Bus model that will be used outside of North America only.
• "300" or "400" identifies the Transmission as a 3000; "200" or "300" used with the "T" designator indicates the Transmission is a 3000 used outside North America.
• Suffixes can include "P" for PTO, "R" for retarder, and "RM" to indicate the Transmission is an Allison Remanufactured unit.

#B 3400 xFE:

• The B 3400 xFE is a Bus Transmission that departs from the standard designation code convention.
• The B 3400 xFE is based on the B 300/400 but with modifications for city and Transit Bus applications.

H). 4000 Product Family Designation Codes

#Early 4000 Non-Bus designations:

• Include the two-letter prefix "HD".
• The number "4" identifies the Transmission as a 4000.
• The second field is either "0" or "5" to indicate close or wide ratio.
• The next field indicates the number of forward ranges.
• The fourth number is reserved as an indicator for major revisions.
• Suffixes can include "P" for PTO, "R" for retarder, and "RM" to indicate the Transmission is an Allison Remanufactured unit.

#Current 4000 Non-Bus designations:

• The first number, "4" identifies the Transmission as a 4000.
• The second field can indicate wide ratio, close ratio, or indicate that the Transmission is capable of 7 forward ranges.
• The remaining two numeric fields are reserved for differentiators related to ratings, features or major revisions.
• The Vocational Model identifier appears at the end of the Transmission designation code.

#4000 Bus Transmission designations:

• "B" indicates the Transmission is a Bus Vocational Model; "T" is used to designate Bus Vocational Models outside North America.
• "500" indicates the Transmission is a 4000; "400" when used with the T designator indicates the Transmission is a 4000 used outside North America.
• Suffixes can include "P" for PTO, "R" for retarder, and "RM" to indicate the Transmission is an Allison Remanufactured unit.

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