Jump to: Developing the fully electric sweeper, Technical credentials, What next?.
Johnston Sweepers won Bodywork Innovation of the Year at the CM awards last year. This is the vehicle that allowed it to make a clean sweep in what was a hotly contested category.
Johnston Sweepers’ VE651 – or eVie (electric vehicle intelligent electronics) – is said to be Europe’s first fully electric truck-mounted sweeper.
“It is against this background of seeking alternative fuels that Johnston’s design team made the strategic decision to develop what many thought was impossible – a fully electric truck-mounted sweeper.” reads the company’s awards entry.
Johnston, like a handful of other manufacturers, already offered a zero emission compact (2cu m) sweeper, but a larger fully electric truck capable of operating for a full work shift with routine overnight charging was widely considered unachievable due to the size and weight of the batteries. Undeterred, the company set about designing just such a sweeper, primarily to assess the feasibility of such a vehicle and to gauge market interest.
Developing the fully electric sweeper
Clive Offley, who heads up Johnston’s engineering team, outlines the complexity of the task. “We initially looked at electrifying just the bodywork – the sweeper – but it didn’t make sense to mount it onto a diesel chassis, or to create a hybrid. Municipals are working towards banning diesel entirely, so to remain ahead of the market we set about designing a fully electric machine.” To do so, Johnston worked in collaboration with Dutch electric vehicle specialist Emoss.
Once Johnston had sourced the battery (see below), it knew it would offset the weight of the two engines and two sets of transmission used in a standard diesel machine, meaning the overall weight and payload of the sweeper would remain the same.
“A special system was developed to mount them behind the cab where the now-redundant exhaust and air cleaner are located. We also needed to develop electric drives for the suction fan, and all of the hydraulics and sweeper functions.” explains Offley. This proved to be more than a year’s work for Johnston’s R&D team.
“The project required us to find solutions for numerous highly complex technical challenges, but the outcome is that we have been able to produce a zero emission full-size sweeper with a 6-tonne payload, similar to a diesel machine, that is capable of a full sweeping shift, proving our theory,” adds Offley. “All of the automotive functions of the VE651 are electrically powered, as well as the sweeper fan, brushes and Supawash system, requiring no additional power input. And it is this aspect of the design which we believe makes the machine the first of its kind in Europe.”
Technical credentials
The Johnston eVie makes use of a modified 16-tonne DAF LF chassis. A 200kWh lithium ion phosphate (LiFePO4) battery pack, which was chosen for its balance of weight, power density, charge rate and lower operating temperature (because it requires no liquid cooling), powers a high performance 350kW electric motor.
The truck is fitted with a pair of 22kW on-board chargers giving a charging capacity of 44kW, leaving the fastest possible charging time at four to five hours. It can be charged from various standard 415V AC 3-phase industrial sockets or from a supplied charging post. The AC charging connector is a Type 2, which can charge from any supply, such as those at motorway services and street-side chargers. The battery is good for 3,000 full charging cycles and an on-board battery management system constantly monitors and maintains the temperature and health of all battery cells. The truck’s driving range is 200km at mid-load on a single charge, meaning it operates at less than 1kWh per km.
What next?
The Johnston eVie produces zero-exhaust and dust, and is virtually noise-free. The only sound comes from the airflow and the brushes on the road surface, making it ideal for municipal sweeping, working around pedestrians and residential streets without polluting the local environment in any way.
The machine has been put through extensive engineering development testing, and independent industry tests are under way in preparation for taking it to full production. A first production batch of machines is being built at Johnston’s manufacturing facility in Dorking, Surrey. The company says there has been “enormous interest in the sweeper from major UK cities, [elsewhere in] Europe, and worldwide”.
