ZF Premieres AxTrax 2 Electric Axle Platform at ACT Expo

The modular e-powertrain system employs in-house components scalable for medium- and heavy-duty commercial vehicles.

May 12, 2023

Ryan Gehm

Production of AxTrax 2 is planned to begin in Europe in late 2024 and in the U.S. in 2025. (ZF)

ZF unveiled its all-new AxTrax 2 electric axle platform at the Advanced Clean Transportation (ACT) Expo in Anaheim, California. The fully integrated and modular e-powertrain system for medium- and heavy-duty commercial vehicles (Class 3-8) is the fruit of the supplier’s sustained investment in research and development.

ZF’s Christian Feldhaus announced the world premiere of the AxTrax 2 e-powertrain system at the ACT Expo in Anaheim, California. (SAE/Ryan Gehm)

“We have fully invested in electrification,” Christian Feldhaus, director of Commercial Vehicle Driveline Systems, Americas, ZF Group, said during the product’s reveal. In 2022, ZF invested more than $3.7 billion in product innovation and technology – a large share of that for electrification in commercial vehicles and other applications, he said. ZF’s R&D expenditure was $2.75 billion in 2020.

The AxTrax 2 platform is a clean-sheet coaxial design offered in two variants: AxTrax 2 with one e-drive (which includes an oil-cooled hairpin e-motor, 800V silicon-carbide inverter and ECU), an e-actuator and a three-speed transmission, and AxTrax 2 dual with two integrated e-drives, two e-actuators and transmission. AxTrax 2 delivers 210 kW continuous power and provides 19,162 lb-ft (25,980 Nm) of peak torque. AxTrax 2 dual offers 380 kW continuous power and a peak 40,418 lb-ft (54,800 Nm). System weight (excluding brakes and suspension) is about 1,410 lbs. (640 kg) for AxTrax 2, and 1,969 lbs. (893 kg) for the dual version.

AxTrax 2 will cover Class 3-7 commercial vehicles with a single e-axle in a 4x2 or 6x2, or up to Class 8 with two e-axles in 6x4 or 8x4 configuration. “This product for 6x4 configurations will be offered in Asia and North American markets, and the dual-motor design will be offered mainly in the European market,” Feldhaus said. “The 6x4 configuration for this market with two of these axles [delivers] 420 kW, which is roughly 10 percent above a diesel.”

The fully integrated electric axle platform is a clean-sheet design for medium- and heavy-duty commercial vehicles. (ZF)

Both AxTrax 2 models are designed to replace the engine, transmission, driveshaft, differential and conventional axle to electrify a commercial vehicle. The “e-mobility kit” allows customers to electrify existing platforms and to develop purpose-built platforms. AxTrax 2 also can be fully synchronized with key vehicle functions such as braking, ADAS and automated-driving systems. It enables advanced digital and telematics systems via CAN bus to communicate and share e-axle system information.

In-house development

In-house-developed electric components for the new e-axle include the silicon-carbide inverter. (ZF)

The three-speed transmission is integrated into the product and comes with full neutral to allow the truck to be towed. It also allows the 6x4 configuration to have coasting capability for efficiency gains, Feldhaus said. Other integrated components include the oil cooler, e-pump, heat exchanger, brakes and wheel-end brake interface.

“In the initial [AxTrax] product we had e-components which we bought off-the-shelf from suppliers, like e-motors and inverters,” Feldhaus shared with SAE Media. “What we identified is that it’s not able to be the most efficient setup if we buy components off-the-shelf. We identified as a group both for passenger- and commercial-vehicle applications that we needed to develop those components in-house to get the maximum efficiency. That was the biggest lesson learned for us on the first generation.”

Approximately seven years ago ZF decided to develop SiC inverter technology and PSM (permanent synchronous magnet) hairpin e-motor technology. “Together with some of our partners, we developed core technology like the silicon-carbide semiconductors [that are] extremely important for the power efficiency gains,” Feldhaus said.

The modular design enables manufacturers to use ZF’s full e-powertrain systems or “mix and match” their own components. “Total cost of ownership has been the main driver to come up with this product development,” he said. “For end users to apply electric trucks in their fleets, we have to come up with a solution for their business case. So, efficiency has been in the forefront.”

Production of AxTrax 2 is planned to begin in Europe in late 2024 and in the U.S. in 2025. Feldhaus could not yet share OEM signoffs, “but this product will be readily available in this market on many OEM chassis,” he added.