Navistar Adds New Vocational Powertrain to Lineup

Navistar has launched the International S13 Integrated Powertrain for the vocational market. The S13 Integrated Powertrain, developed in collaboration with the Traton Group, expands on the current S13 Integrated Powertrain customer offering.

Navistar first introduced the S13 Integrated Powertrain for the on-highway market in August 2022, available in the International LT and RH Series models.

"The S13 Integrated Powertrain is the most advanced powertrain we've ever produced and the lightest vocational powertrain available on the market," said Mark Stasell, vice president, Vocational Truck Business. "The S13 Integrated will benefit vocational customers by achieving stellar performance, simplicity and serviceability, and superior operating economy."

According to the manufacturer, the S13 Integrated Powertrain was developed from a clean sheet design and consists of three distinct components – an engine, a transmission, and an aftertreatment system.

New Powertrain Specs

The 13.0L International S13 engine achieves advanced fuel efficiency and performance through a clean-burn combustion strategy and a reduction of friction and pumping losses. The S13 engine is Navistar's first engine designed with selective catalytic reduction (SCR) technology as the primary emissions reduction technology. 

Navistar noted the absence of an exhaust gas recirculation (EGR) cooler on this engine allows for nearly 100% of exhaust to flow to the fixed geometry turbocharger, equating to more power and improved engine performance. Additionally, the engine operates on low revolutions and high torque which equates to fewer fuel injections and less fuel consumption, delivering up to 515 horsepower and 1,850 lb.-ft. of torque.

The design of the Dual Stage Aftertreatment is purpose built, intended for easy access for serviceability, as well as improved emissions control and fuel efficiency. To keep temperatures at an optimal range and extend service intervals, the aftertreatment system includes a dual-stage SCR catalyst system in a one-box design.

Since an EGR cooler was eliminated from the combustion process, the manufacturer noted that it generates less soot and particulate matter. This cleaner combustion cycle allows for extended service intervals and eliminates the need for the diesel oxidation catalyst (DOC) and active regeneration.

"Vocational trucks often spend quite a bit of time idling on a job site which has historically required more frequent active regens," said Stasell. "The aftertreatment system of the S13 Integrated Powertrain, combined with the engine combustion strategy, vastly reduces the need for both active and parked regens."

Transmission & PTO Options For Vocational Fleets

The International T14 Transmission, a 14-speed automated manual transmission (AMT), combines the transmissions low range and six reverse gears through the use of a planetary gear set.

The T14 combines two deep crawler gears and a wide 26.7 overall ratio to provide slow-speed maneuverability, exceptional startability and enhanced performance running to and from the job site.

The T14 Transmission also features vocational-specific drive modes including:

• Off-road mode.
• Manual mode.
• Paver mode.

These drive modes, combined with other vocationally focused functionalities, such as split-shaft mode and rocking mode, which breaks the truck free when stuck, prove the T14 is ready for any job.

As part of the clean sheet design, shifting logic and integrated software controls maximize efficiency and performance resulting in gear shifting that is perfectly matched to engine revolutions. The T14 also uses an electronic clutch actuator with controls integrated with the engine to deliver faster, smoother shifting.

Multiple spec'ing options are available for various vocational customer applications including front-engine power take-off (FEPTO), rear-engine power take-off (REPTO) as well as single and dual output transmission PTOs.

All PTO options are factory-installed at Navistar's Integrated Powertrain Plant in Huntsville, Alabama, and carry the warranty of the T14 transmission.

The S13 Integrated Powertrain also takes advantage of Navistar's Diamond Logic electrical system, which the company noted provides both chassis upfitters and customers maximum flexibility, simplicity, and functionality.