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Daimler Trucks North America, Detroit deliver next-level fuel efficiency

June 1, 2020
New DT12 transmission series now ready to order; redesigned DD15 Gen 5 engine available for January 2021 builds

Daimler Trucks North America (DTNA) says recent enhancements to the Detroit DD15 engine and an expanded lineup of the Detroit DT12 automated manual transmission will deliver better fuel economy, performance and durability for Freightliner Cascadia customers.

The DT12 transmission has evolved into the DT12 On-Highway Series to offer three purpose-built options to meet the unique needs of various on-highway applications, all of which are now available to order. Engineered with fuel efficiency and performance in mind, the all-new DT12-HE debuts with enhanced features and capability, DTNA said.

The DD15 Gen 5 engine was updated and engineered to deliver efficiency the market expects. It will be available with January 2021 truck builds. The Gen 5 advances the legacy of Detroit’s heavy-duty engine platform (HDEP), the most popular Class 8 heavy-duty engine platform sold in North America for the past five years, according to data from IHS Markit.  

“The addition of the DD15 Gen 5 and DT12 On-Highway Series to the Detroit portfolio is sure to add to the momentum we have built by delivering the most robust and fuel-efficient powertrain on the market,” said Kelly Gedert, vice president of on-highway market development for DTNA. “With a rich heritage of innovative engineering, world-class manufacturing facilities, and access to a global toolkit of cutting-edge technologies, our customers demand Detroit solutions because they are the best in the industry.”

The DT12 On-Highway Series pioneers new features for the DT12 transmission line, DTNA said.

The trifecta-topping Detroit DT12-HE transmission is an all-new DT12 option unleashing ultimate performance, capability and efficiency. Customer adoption is growing for downspeeding with faster rear axles ratios to achieve maximum powertrain fuel efficiency. In answer to this increasing demand, the transmission boasts higher overall ratios for improved downspeeding and an improved oil system design, both contributing to increased efficiency. The DT12-HE debuts with Cascadia production beginning in early 2021 and additional model applications will be announced soon.

Also included in the DT12 On-Highway Series, is the DT12-HL transmission, a lightweight carry-over option offering comparable efficiency and durability to the rest of the portfolio and intended for weight-sensitive applications. Lastly, the DT12-H, a revised designation for the stalwart of the portfolio, retains the same characteristics that made the DT12 a favorite of fleets small and large. Both the DT12-H and DT12-HL are currently available for order in Cascadia builds.

The new DD15 Gen 5 engine advances the legacy of the DD15 to bring enhanced performance, durability and fuel economy for the Cascadia, DTNA maintained. A rethink of the engine, and the application of precision engineering principles, combine to provide cutting-edge improvements for 2021, including increased downspeeding, better combustion and a new swirl piston design. With nearly 50% new componentry for the DD15 and finetuning by the global team of Detroit engineers, the DD15 Gen 5 brings up to a 3% improvement in fuel efficiency from propulsion alone. As an additional benefit of more efficient operation, the engine also stands to reduce carbon dioxide emissions.

A new ball bearing simple geometry turbocharger reduces friction and allows peak power and torque to be reached faster in the Cascadia. Peak horsepower is reached at lower engine RPMs of 1,500 RPM versus the prior generation’s 1,625 RPM, and peak torque is achieved at 900 RPM vs a previously rated 1,075 RPM. Modified inlet ports in engine cylinders and a new piston bowl shape combine to create a swirl effect that creates a fuel spray pattern for better atomization. Along with an ultra-high compression ratio, the new swirl design piston makes combustion cleaner and more efficient than the previous generation of the DD15.

The durability of many key components is improved thanks to reduced design complexity and increased robustness, DTNA added. A new EPA GHG21-compliant aftertreatment system for the DD15 Gen 5 debuts a smaller unit design to reduce weight by more than 60 pounds while increasing nitrous oxide conversion and, dependent on duty cycle, allowing increased diesel particulate filter service intervals.

The DD15 Gen 5 also debuts ThermoCoasting, a new feature that prevents aftertreatment cool down during a driving regen to keep the system at the optimum temperature. To accomplish this, ThermoCoasting will engage engine brakes when necessary between 900 and 1,500 RPM while the engine mimics coasting by maintaining zero torque at the flywheel to balance power delivery. Powertrain noise levels during ThermoCoasting are unobtrusive and parallel the decibel levels observed when in low engine brake setting. ThermoCoasting stands to benefit aftertreatment performance and is just one of many thermal management improvements made to the DD15 Gen 5, which also includes improved cooling circuitry and temperature distribution across cylinder heads.

A fully integrated powertrain from Detroit enables a technologically and data-driven experience for asset operation. The benefits of Detroit integration include the addition of Detroit Assurance 5.0, which introduces the industry’s only full SAE Level 2 collision mitigation system. Detroit Assurance 5.0 offers features such as Active Lane Assist to help keep a vehicle in its lane, Side Guard Assist with full trailer sweep to allow a driver to “see” into their blind spot and receive auditory and visual warnings of obscured vehicles, pedestrians or objects, and Active Brake Assist that includes the industry exclusive feature of full braking on moving pedestrian and Adaptive Cruise Control down to zero miles per hour to either avoid rear-end collisions or lessen their severity. Combined, the system offers the most advanced driver assistance features available on the road today to increase driver comfort, improve the driver experience and add peace of mind for fleets.

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