Thanks to ZF's close-to-the-wheel electric drives, heavyweight vehicles can be operated with zero emissions in city traffic. The benefit: cleaner air and reduced noise levels.

Numbering roughly four billion, more than half of the world’s population lives in cities, making urbanization a global megatrend that is on the rise. Metropolitan cities like London have to bear the consequences. Air pollution caused by exhaust emissions has become such a problem in some areas that city administrators have to place limits on large diesel-powered vehicles. Even in smaller cities, residents are moaning about the heavy increase in commuter and truck traffic on the roads. They simply long for cleaner air and less noise. In addressing these issues, e-mobility is one of the buzzwords. As an example of e-mobility technology, electric drives not only reduce harmful pollutants, but they are also quieter than conventional combustion engines. They represent a particularly interesting alternative for operating large commercial vehicles in city centers. Compared to long-distance traffic, distances for city buses and local delivery trucks are manageable. These vehicles can be recharged at charging stations when they are not in operation or parked overnight in the terminal or bus depot.

Several electromobility solutions are available for heavy vehicles. They range from diesel engines combined with hybrid transmissions to all-electric, close-to-the-wheel or central drives. In the latter two options, the position of the engine on the vehicle’s axle provides for different performance features. “For us, it is important to pursue all these developments and always be out in front. This way, we are able to offer commercial vehicle manufacturers a broad range of electric drives that meet all needs,” explains Andreas Moser, head of the Axle & Transmission Systems for Buses & Coaches Business Unit at ZF. "We realized that our close-to-the-wheel electric drive is a particularly versatile and attractive option for very powerful applications".

An electric all-rounder

This concept involves two compact electric motors installed directly on each wheel that provide the necessary power to operate fully loaded city buses or large delivery trucks. At 125 kW each, these motors are extremely powerful. With two times 11,000 newton meters on the wheels, there is enough output torque to get a 26-ton vehicle up steep hills with only one drive axle. Another major benefit is that this system is compatible with a multitude of drive technologies. It can be operated fully electrically, powered by a battery, fuel cell or even an overhead line as well as a serial hybrid combined with a combustion engine.

Driving emission-free through the city

It all started with the AVE 130. Now, it is a standard feature in low-floor buses.

Increasingly strict emission standards in cities are becoming a major problem for public transport authorities. For this reason, the close-to-the-wheel electric drive has been used in the AVE 130, a low-floor portal axle for city buses, since 2012. Thanks to the AVE 130, the public transport authorities were suddenly able to operate city buses fully electrically and without any emissions for a longer period of time. Public transport authorities also understand the value of compatibility with different drive technologies. They can choose the variant that best matches the local infrastructure needs and the required ranges. Since its introduction, more than 300 city buses in Europe and Asia have been equipped with the AVE 130 and logged over 14 million kilometers.

E-mobility for heavyweight delivery vehicles

Other types of commercial vehicles can also benefit from this tried and trusted technology. One potential target group is heavy delivery trucks for which previous electric drives were not powerful enough. The automotive industry also recognizes this trend and is always launching new and, in some cases, very sophisticated prototypes and concept vehicles. One example is the recently introduced Mercedes-Benz Urban eTruck, an all-electric truck with a gross vehicle weight of 26 tons. Its motor concept which was custom-designed by ZF engineers has two close-to-the-wheel electric motors on the drive axle, similar to the AVE 130. It can transport goods to supermarkets in major cities reliably, quietly and emission-free.

More power for agricultural machinery

Thanks to the close-to-the-wheel electric drive in the trailer, the Innovation Tractor 2016 can effortlessly take on gradients of up to 30 percent.

Food for growing urban populations not only has to be distributed and delivered, it also has to be produced. For farms to be more efficient, they require more powerful machinery to pull heavily loaded trailers over bumpy terrain. The close-to-the-wheel electric drive again plays off its strengths in the ZF Innovation Tractor 2016. Its trailer is fitted with a customized version of two electric wheel heads designed especially for agricultural and construction machinery. These wheel heads are powered by a generator module in the tractor. They deliver additional power for crossing terrain that a conventional tractor-trailer would have a difficult time with. The Innovation Tractor can move over wet or loose ground just as easily as it can climb gradients of up to 30 percent. An additional benefit is that thanks to the additional power from the trailer, the tractor or tractor engine can be smaller. This is ideal for farmers who only opt for large engines in their tractors just so they can pull fully loaded trailers when needed.

Ready for the mobility of the future

“In view of today’s global megatrends, we have paved the way early on for electromobility,” says Moser. “The close-to-the-wheel electric drive is only one example of our e-mobility solutions. Our commercial vehicle portfolio also includes technologies for lighter-weight vehicles intended for short and long distance driving.” These include all-electric options for city driving such as a central drive for buses or mid-sized delivery trucks and a passenger car central axle drive adapted for lightweight delivery trucks. With the TraXon Hybrid transmission, 40-ton trucks and buses can also benefit from the advantages of a hybrid drive when it comes to long-distance driving. Furthermore, at ZF the right software ensures that drive systems think independently and work efficiently. After all, energy management in the vehicle decides on the actual realistic ranges. This pays off. Buses equipped with the AVE 130 have, in the meantime, been hauling in the awards. The Urbino 12 electric from the Polish bus manufacturer Solaris was named "Bus of the Year 2017" in August. For Moser, it is only a question of time until electromobility for commercial vehicles will enjoy broad success on the market.

The Urbino 12 electric from Polish manufacturer Solaris won the title "Bus of the Year 2017". The all-electric city bus is powered by the AVE 130 electric portal axle from ZF.

Picture: Solaris Bus & Coach S.A.

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