Detroit DT12 Automatic Manual Transmission (AMT) Now Standard
The Detroit DT12 AMT is now the standard transmission choice across all Daimler heavy-duty models worldwide and will also be the primary transmission option for the Western Star X Series. However, it’s worth noting that this brand will still offer a manual transmission option.
In the Australian market, the Eaton RoadRanger remains available, but the Detroit DT12 AMT is considered the default choice. Within the Western Star X-Series, there are two variants of the new AMT, both falling under the DT12 family and featuring overdrive gearboxes. The DT12 is suitable for applications up to 72.5 tons GCM, while the extreme-duty OVX variant is designed for loads exceeding 150 tons.
The inclusion of ‘V’ in the model designation indicates that these transmissions are intended for vocational use, capable of handling scenarios such as off-highway operations. They come equipped with a comprehensive feature set, including functions like a rocking mode designed to assist the truck in freeing itself when stuck in challenging terrain like gravel.
Two versions of the new AMT are on offer, both named DT12 and originating from the same family. The OV represents the overdrive variant of the transmission, while the HE is tailored for high efficiency. Opting for the HE AMT maximizes fuel economy, making it ideal for linehaul operations where getting the most out of each liter of fuel is crucial.
The OV variant of this transmission is selected when the AMT is expected to handle scenarios such as off-highway tasks. It comes equipped with a comprehensive feature set, including functions like a rocking mode designed to assist the truck in freeing itself when stuck in gravel or similar situations.
Within the OV transmission category, two versions are offered: the OV and the OVX. The primary distinction between the two lies in their capacity, with the OV being suitable for GCMs up to 62.5 tonnes, while the OVX has no weight limit.
Detroit’s road train testing has demonstrated the AMT’s impressive performance, even with only 12 gears, as opposed to the conventional 18. The take-off feature has proven its effectiveness when compared to a manual clutch, thanks to the automated manual’s precise control. It carefully manages heat distribution within the clutch and differential, releasing takeoff power at an optimal rate to minimize potential risks.
A feature known as Powerlaunch allows you to increase engine revs to well above 90% of engine torque before engaging the clutch at the precise speed required for a smooth start from a standstill. Activating this feature is simple, with no switches to fumble with—drivers just push the accelerator pedal all the way down, and the control system takes care of the rest.
In Australia, all Western Star trucks equipped with the AMT utilize the control stalk to switch between various driving modes. These modes are diverse and customizable, allowing end customers to specify their preferred modes and determine how the AMT will function when ordering the truck.
Some fleet customers may prefer the truck to automatically default to economy mode after it’s turned off, while others may opt for the AMT to retain the selected mode until the next time the truck is started.
Some operators might select the option to allow manual gear changes at lower speeds but restrict this feature at highway speeds to improve fuel efficiency during long-distance, high-speed trips, while still granting drivers the flexibility for low-speed maneuvering.
