Related: Hybrid Electric-Drive Trailer Tandem Promises Quick Payback
Electric Axle for Trucks Saves Up to 15% in Fuel, Hyliion Says
The Hyliion 6X4HE system, which includes an electric APU that saves another 12% in fuel, is being tested by three major fleets.

Green-painted Hyliion 6X4HE components include the motorized rear axle, lithium-ion battery pack, electronic controls, and electric APU.

An electric-powered axle for highway truck-tractors has been announced by Hyliion Inc., a startup technology company that has been developing a similar product for semitrailers. The truck version is now being tested by three major fleets, the company said.
Hyliion’s 6X4HE system generates electric power on downgrades or while coasting, and supplies supplemental power during launch and on upgrades, explained Thomas Healy, founder and CEO. He said the system delivers substantial fuel savings, lowers exhaust emissions, and eases work for the driver.
A Hyliion axle replaces a 6x2 truck’s non-driven dead axle or is added to a 4x2 truck, turning either into a 6x4. Existing 6x4 tractors can be converted by removing one mechanically driven axle and replacing it with a Hyliion axle.
The system includes a motorized axle, lithium-ion battery pack, and electronic controls. The battery pack also runs an auxiliary power unit during rest periods. It can be installed on a new or existing truck in about three hours.
Mesilla Valley Transportation, PAM Transport, and Ryder System all participated in testing and refining the 6X4HE, and each has one tractor running with it, Healy said.
Hyliion (pronounced HIGH-lee-on) first announced a powered trailer axle last year, but switched its focus to a truck system at the request of fleet executives. The axle’s hybrid action alone will save 15% in fuel, the company claimed.
“Fleets said they’d see a faster payback if it could be put on a truck because it would be used more often than on a trailer,” Healy told HDT. “We listened and focused our efforts to first deliver the 6X4HE System with an innovative APU” that uses the battery pack.
The APU includes an air conditioning compressor and blower to deliver 18,000 Btu’s for up to 10 hours to cool a sleeper in warm weather. This saves an additional 12% in fuel. Fleets are using a diesel fuel-fired heater to warm the sleeper, Healy said. In addition, two outlets provide electricity in the cab and sleeper. The system can also be plugged in to shore power.

The 6X4HE easily attaches to the truck frame and is self-contained, he said. PAM used a new Peterbilt 4x2 tractor, while MVT and Ryder converted in-service International and Freightliner 6x2 tractors, respectively. Systems operate autonomously with no driver involvement.
“Electrification is the talk of the industry,” said Scott Perry, chief technology and procurement officer for Ryder Fleet Management Solutions, in the Hyliion announcement. “Hyliion provides a creative solution for long-hau,l over-the-road trucking that we feel will be of interest to current diesel fleets that are looking for an advanced technology that they can pursue in the very near future.”
“We are excited to be a part of the testing process with Hyliion on a product that has the potential to be industry-changing,” said Paul Pettit, vice president, maintenance, at PAM Transport. “The Hyliion team is great to work with.”
“Innovation in fuel savings is nothing new to Mesilla Valley, but Hyliion’s system is the only thing we’ve seen that can make such a big impact,” said Royal Jones, MVT’s CEO.
Hyliion is currently taking orders for the 6X4HE with production starting next month. Pittsburgh-based Hyliion, founded in 2015, recently announced investment of $21 million from venture capitalists, and this will help fund the production, Healy said. More information is at http://www.hyliion.com.
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