Hyliion tandem's rear axle is a truck-type with a differential. Motor is ahead and is linked to the diff like a driveshaft. Photos: Tom Berg
Yours truly has driven the Hyliion electric drive tandem for trailers and I've found that it seems to do what its developers say: It helps propel a trailer on the level and while climbing hills, and holds it back on downgrades, capturing braking energy in the process.
First reported on TInfo last March, the tandem's hybrid action saves 10 to 20% in fuel while on the move, and another 10% or more when its batteries are tapped to become an auxiliary power unit, according to Hyliion Inc's CEO, Thomas Healy. He rode along to supervise the demonstration and to answer questions.
Hyliion engineer Morgan Culbertson, who wrote the control program, here controls the tandem with sliding toggles. Production models will be automatic and not linked to the tractor.
This was on freeways in Pittsburgh, Pa., one of the hillier areas in the country and therefore a good testing ground for the concept. I'll write a more complete driving report soon, but for now, can relate that I didn't have to push very hard on the accelerator or brake pedals of the tractor to maintain speed or keep speed in check while rolling downhill.
Healy says only enough power is used to help move the trailer, and “it never pushes the tractor.” Except for an on/off switch, it operates on its own and requires no link to the tractor. Thus any tractor of whatever age can pull a Hyliion-equipped trailer and be aided by it.
A readout in the tractor's sleeper showed fuel usage was cut substantially compared to when the tandem was purposely cut out. That and the company's test data, which indicate savings from 10 to 30% or more, suggest that fleets wanting to save fuel just have to consider the product. Many are, Healy says, and have requested units to test.
The powered tandem replaces a trailer's standard tandem slider, and a truck-type drive axle with differential replaces one of the "dead" axles. Hyliion technicians can do a swap in under an hour, he says. Non-slider assemblies will also be available.
Control box and battery pack are toward the tandem's front. They're protected from flying debris by the sloping shield.
Hyliion engineers -- one of them Healy himself -- have also designed a single-axle system for use in Europe, where it would replace one of the three axles under a semitrailer, a common configuration over there.
Healy plans initial assembly in Hyliion's facility later this year, and anticipates full production, probably by a contract manufacturer, by late winter or spring of 2017.
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