Azure Dynamics enters into agreement to sell its patents
California Energy Commission awards nearly $2M to support alternative fuel production and vehicles

New Detroit DT12 transmission contributes to enhanced fuel efficiency and performance for heavy-duty trucks

Cutaway of the DT12. Click to enlarge.

Detroit Diesel Corporation, a Daimler company, is showcasing its DT12 automated manual transmission for heavy duty trucks. Part of the Detroit complete powertrain offering, the DT12 combines the operational ease of an automatic with the efficiency of a manual transmission, resulting in enhanced fuel economy, vehicle performance and safety.

The Detroit DT12 is a 12-speed, non-synchronized transmission with shorter gear steps, and was designed with a number of efficiency features to achieve optimal fuel economy. Adding to the transmission’s overall economy is its lightweight design, which offers additional payload because of its aluminum housing and single counter shaft. Available in the Freightliner Cascadia, the DT12 maximizes fuel efficiency for line-haul/long haul operations.

Detroit DT12 Quick Specs
Speeds 12
Maximum Input Torque 2,050 lb-ft (2,779 N·m)
Gear Ratios / Overall Ratio Direct Drive: 14.93 - 1 / 14.93
Over Drive: 11.67 - 0.78 / 14.96
GCW Direct Drive: 80,000 lb.
Over Drive: 97,000 lb. and up

The DT12 improves slow-speed maneuvering capabilities without compromising high road speed efficiency. The 12-speed, direct- or over-drive automated manual transmission combines a traditional manual gearbox with high-speed, computer-controlled shift and clutch actuators that automatically and seamlessly select the right shift pattern and clutch engagement for fuel economy and engine power. The DT12’s creep mode simulates a torque converter to improve low speed maneuverability for parking, docking, heavy traffic and other low speed situations.

Advanced technologies include:

  • Skip Shift. To increase shifting efficiency, the electronic powertrain controls automatically “skip” unnecessary gears, enabling the transmission to run through lower gears faster to achieve cruising speed sooner. This helps increase acceleration to achieve cruising speed quickly and smoothly. This also allows the driver to begin the acceleration in the appropriate “start gear” based on load and grade.

  • eCoast. eCoast allows the vehicle to ‘coast’ down grades with the engine operating at idle speeds while preserving vehicle momentum, maximizing fuel efficiency. The transmission automatically disengages when the vehicle is coasting. Sophisticated transmission electronics ensure safe operations in all driving conditions.

  • Powertrain Communication. A proprietary control module communicates with the entire powertrain, giving the transmission and engine the ability to share information and offer complimentary functions. For example, the engine can limit torque to protect against driveline damage and harsh shifts, while the transmission can optimize shifts to keep the engine in the sweet spot.

    The ability for the transmission and engine to share information fully leverages our integrated powertrain, providing a significant advantage to the driver.

    —Brad Williamson, manager, engine and component marketing for Daimler Trucks North America

  • Active Driveline Protection. The Transmission Control Module (TCM) calculates the torque wind-up in the driveline and regulates with engine torque control for enhanced driving comfort and less driveline wear. The TCM even limits torque in severe surface conditions, protecting the driveline.

  • Direct Drive. In top gear the transmission operates as a direct drive, sending engine input directly to the main shaft, eliminating parasitic gear mesh losses of power and fuel efficiency.

  • Oil Pump. An oil pump, powered by the countershaft, delivers oil directly to the gears. This is more precise and efficient than bathing all of the gears in oil.

Drivers will also appreciate comfort features such as helical gears and geometrical optimized gear-cut for noise reduction; pneumatic clutch and shift actuation for faster gear shifts; and a choice between eco or power-mode configuration. Additional advantages for the driver include a true two-pedal system for ease of operation; and a kick-down feature that improves vehicle acceleration when needed. Creep Mode improves low-speed maneuverability, making it easier to back up to a loading dock or in traffic.

The DT12 comes standard with a 5-year/750,000 mile warranty, with a 2-year/200,000 miles warranty on the clutch.

The DT12 is also equipped with Virtual Technician, the factory installed on-board diagnostics system. When a check transmission light illuminates, the fault is sent to a contact and the Detroit Customer Support Center (CSC) who can analyze the issue. The driver receives a service recommendation and the nearest authorized location with parts in stock.



If i were a big truck driver i would be interrested to buy.


If you were a driver, you'd probably be proud of your skills with a manual.

If you were a fleet owner, you'd prefer a transmission that protects itself and the driveline from damage and is harder for unskilled drivers to mess up.  You'd prefer being able to hire drivers with less experience.  This transmission is being sold to fleet owners.


As this is a non-synchronized transmission, they must be using some automated double clutching for shifting, adjusting engine rpm in the process. Probably the shift time is not quick (if it was, they'd have mentioned it).
Obviously there is a planetary gear stage (? on the left) that extends number of forward gears from 4 (3 constantly meshed plus a direct gear) to 12.
Just wonder how they implement the creep mode.


Creep mode is implemented with clutch slippage.  How do you think it would be done?

Henry Gibson

Linde built a small hydraulic hybrid vehicle decades ago. Artemis demonstrated high efficiency years ago in an automobile, and now develops them for wind turbines. United Parcel Service uses hydraulic hybrids in a few vehicles. INNAS NOAX has some special inventions for hydraulic hybrids including a free piston diesel engine.
Gains in efficiency has been shown by these developments and then there is the electric hybrid designs of Ian Wright and others. ..HG..


I know that it can be done that way. They might have used some more advanced solution, you can never know that something better wasn't invented. Perhaps here some hydraulic device with fast-acting digital valves.
I'm pretty sure that they'd use something else if creep mode was to be used some sigificant percentage of time, otherwise clutch wouldn't last long.


I'm a fan of electromagnetic drag for such applications, but an AMT is just a lay-shaft transmission with computer-controlled actuators instead of manual shifters and a clutch pedal.

The comments to this entry are closed.