In the world of freight transport, the humble trailer is finally getting a tech-savvy upgrade. Across Australia, a quiet innovation is gaining traction: electric trailer axles.
They are not just adding horsepower—they are changing the rules of road efficiency and sustainability.
Before Australian highways caught wind of the idea, Europe was already paving the way.
The TRANSFORMERS project in the EU was a forward-thinking initiative aimed at making freight transport more energy-efficient and sustainable.
It focused on redesigning trucks and trailers to reduce fuel consumption and CO₂ emissions — hopefully, without needing to change existing EU regulations.
Apart from experimenting with adaptive aerodynamics, it did include a trailer-mounted electric system that recovers energy during braking and provides extra power when needed.
The TRANSFORMERS project involved 13 partners from six European countries and took place between 2013-2017. Electric trailer axles integrate electric motors directly into the axle assembly, allowing trailers to become active participants in propulsion and energy management.
Unlike traditional passive trailers, e-axle-equipped trailers can:
- Recover energy through regenerative braking
- Provide supplemental torque to assist the prime mover
- Power auxiliary systems like refrigeration units.
There are two main types: Recuperating e-axles: Converting kinetic energy to electrical during motion.
- Drive and retarding e-axles: Provide propulsion and braking support. E-axles vary in design and complexity:
- Motor types: Synchronous motors are simpler but less efficient; asynchronous motors offer variable speed and better energy use; Switched Reluctance Motors (SRMs), as used on TRAKr, are more compact and cost effective.
- Cooling systems: Options include water, air, or oil cooling, each with trade-offs in weight, cost, and efficiency.
- Drive styles: Single-motor setups require gearboxes; dual-motor systems allow direct drive to each side.
Australia’s transport industry is experimenting with new electric axles on trailers.
While fully electric prime movers remain a long-term prospect, electric trailer axles (e-axles) have emerged as a viable transitional technology that delivers measurable efficiency gains without requiring full vehicle electrification.
Core benefits for fleet operators are:
- Improved fuel efficiency: Reduced load strain on prime movers translates to lower diesel consumption.
- Reduced emissions: reduced carbon footprint.
- Regenerative Braking: Captures energy on descents and during braking; acting as additional ‘retarder’. Retardation from the rear offers stability benefits by reducing trailer ‘over-run’.
- Refrigeration Support: Enables self-powered cooling units without diesel generators.
- Accessories power: Batteries could provide energy for any electric accessory (e.g. tailgate, forklift, air blower, heating element, etc.).
However, there are impediments to the trailer electrification. To name some:
- Regulatory Boundaries: There is no current heavy vehicle registration category for a driven trailer. The ADRs define a trailer as a pulled vehicle. Yet, recent pilot programs are exploring rule amendments and broader utility (e.g. HVIA initiative).
- Overseas developed technology: The European designs are mainly available in wide-single tyres (often called ‘super-singles’).
Despite obvious benefits, Australian regulations limit the allowable axle mass for wide single tyres, making them a tough sell for operators.
Fleet managers and advocacy groups are now pushing for updated laws — ones that reflect modern tyre technology, not legacy assumptions.
At least in urban areas.
Some notable Australian early adopters should be applauded: Primary Connect, Woolworths’ logistics arm, already has 25 refrigerated trailers fitted with SAF-Holland’s TRAKr e-axles.
These units power refrigeration van cooling systems independently, cutting diesel use and emissions in chilled freight.
A partnership between QTRS, an Australian supplier of transport refrigeration equipment and services, SolarEdge e-Mobility, a European provider of e-motors and TMC, Australian axles and suspensions supplier, has resulted in Australia’s first solar-powered e-axle trailer being trialled on Queensland roads.
In Western Australia, companies like Ace Off-Grid Electrics and Mobile Audio Engineering are retrofitting traditional trailers with electric braking systems, regenerative capabilities, and auxiliary battery setups.
The future of smart trailers in Australia looks bright—and electric. Industry giants like BPW, ZF, and SAF-Holland are doubling down on R&D, while regulatory bodies consider modernising laws that unlock wider adoption.
This will result in:
- More hybrid-electric fleets, using trailers to boost efficiency and lower emissions.
- Integrated data systems, turning trailers into rolling sensors and energy hubs.
- Semi-autonomous trailers, leveraging AI to optimise braking, weight distribution, and energy flow.
As one insider quipped, “The trailer used to be a drag. Now, it’s intelligent, responsive and electric.”
ARTSA-Institute Life Member, Nemanja Miletic is the Product, Engineering and Technical Manager of SAF-Holland Australia.
