Electric bus developments using in-wheel motors

Back in the late 1970s the Australian railway engineer who designed the first Tulloch double-deck railway carriages, had moved from the challenges of rail to road public transport.

Long before vehicle emissions laws and the recognition of climate change, Roy Leembruggen realised that there was a limited future role for the internal combustion engine in public transport.

He theorised that a battery-powered or overhead-powered electric bus was the future and, to prove it, he secured a government grant and designed and built the Townobile bus.

This futuristic bus was way ahead of its time, featuring monocoque construction that reduced weight. However, it relied on the only available deep-cycle batteries of the time – lead/acid traction batteries from forklift trucks – so it was heavy by modern battery-bus standards and range was severely limited.

Those factors, plus the resistance to change within State and Federal public transport departments, ensured that the Townobile project stalled.

Undaunted, Roy Leembruggen turned his attention to electric city cars and designed one that appeared at a technology conference in Sydney’s Darling Harbour, in 1988. I remember the event well, because I drove Roy’s machine to and from the conference.

Priced at a heady $25,000 in the late 1980s and with range limited by heavy lead/acid batteries it went nowhere, unfortunately.

The heart of both Townobile projects was an electric motor in each rear-wheel hub, minimising the space needed for motive power and allowing the full chassis length to be devoted to the battery pack.

Each hub motor slotted neatly into the ample space at the centre of a dual-tyred axle. (Yes, Roy’s electric car had centrally located dual tyres up front that steered motorcycle style.)

The advent of air-operated disc brakes solved Roy’s problem of rear brake packaging, allowing the brake disc and calliper to be mounted inboard of the wheel-motor casing.

The Townobile lesson wasn’t lost on overseas engineers, even if it typically went nowhere Down Under, where our leaders seem happy to have Australia remain a mine site.

Several electric bus wheel-motor innovations have happened overseas and the latest was exhibited at the recent Busworld Conference in Brussels. Ziehl-Abegg SE released the ZAwheel and independent rear suspension package, designed for rear-fitting to existing buses.

The assembly replaces the diesel engine, transmission, rear axle and suspension of a conventional bus with two electric wheel motors, air suspension and disc brakes.

Ziehl-Abegg is targeting town bus fleets that have vehicles due for refurbishment and repowering. Rather than investing in a new diesel powertrain, these companies have the option of electrifying their older buses, for a fraction of the cost of a new electric bus.

The transition is being done by a dedicated company, “I See Electric Busses(sic)” and takes place at one of six locations in Germany.

Each conversion takes a week and I See Electric Busses has done 400 conversions to date.

Ziehl-Abegg is expecting to widen the international appeal of its ZAwheel assemblies and Australia will hopefully be a target. We’ll keep abreast of this development.

Another European motor-in-wheel initiative is the swivelling wheel motor and suspension kit developed by Protean Electric.

“Transport-as-a-Service urban mobility is gaining momentum, and with it the need for a new class of urban transport vehicles,” explained KY Chan, CEO of Protean Electric, a former UK company recently taken over by Swedish company, NEVS/Evergrande.

The Protean360+ corner module was designed for next-generation urban vehicles. The Protean360+ corner module is aimed at small buses and combines a wheel motor with a suspension strut that allows the wheel to rotate a full 180-degrees in each direction.

This production-ready innovation will allow small buses to move sideways into parking places and turn within their own overall length.

Whether this technology will come here is a moot point but if the big European companies adopt it, you can bet we'll see it.