Saying ‘hi’ to hybrids: New Faun/Mercedes diesel electric ‘Dual Power’ hybrid trialled

WMW’s Malcolm Bates is the first journalist to have driven this interesting new hybrid by Faun and Mercedes – ‘interesting’ because this compaction-type prototype uses electrics rather than hydraulics.

WMW’s Malcolm Bates is the first journalist to have driven this interesting new hybrid by Faun and Mercedes ‘interesting’ because this compaction-type prototype uses electrics rather than hydraulics. So is electric the future? Malcolm travels to Germany, to find out.

by Malcolm Bates

If you’re ever asked to name three things for which the city of Aachen, Germany, is famous for, you might suggest ‘the world famous IKA Institute at Aachen University’ (for its work on advanced vehicle transmissions) and ‘the unique three-section articulated city buses’ (when others settle for two). But then you might get stuck thinking for a third.

Well, here it is the city of Aachen was selected by Faun GmbH as the location for 12 months of working trials with the new ‘Dual Power’ hybrid refuse collection vehicle (RCV). And best of all, I’ve been invited to try it.

If you were expecting a prototype, dripping with futuristic styling, then you will be disappointed because at first glance, the Dual Power hybrid looks just like any normal production ‘Rotopress’ one of the oldest designs in the current Faun product line. Was this really the basis of a design for the future?

Luckily, Georg Sandkuhler, head of R&D at Faun GmbH, is on hand to provide a guided tour round the vehicle along with an explanation. The prototype is indeed based on the rotating drum Rotopress principal, while the chassis looks like any other European-spec Mercedes ‘Econic’ low entry crew-cab 6x2. But, as Georg Sandkuhler explains, the whole project is based on finding the most fuel efficient and ‘environmentally friendly’ set of parameters which could be incorporated into a design of RCV and be in production within months, rather than a decade. And, the key thing to remember when designing anything for the future is, if it isn’t as practical as what is currently available, then the effort is going to be wasted. It has to perform as well, if not better than, a current machine.


The binlifters? They’re also electric, but unlike the prototype status of the rest of the vehicle, these are based on standard Ecoprocess electric lifters, already well-proven and available on existing RCVs. Click here to enlarge image

So, what does Georg Sandkuhler know? As an eager and slightly younger designer, he was responsible for the Faun ‘MSTS’ one-man operated, front-end loading, demountable refuse compaction and transportation ‘silo’ system. A design which even today hasn’t been beaten for its logical and practical approach. True, it isn’t in universal operation. But that is more to do with the politics behind its creation and the need for a specialized, very low-cabbed truck chassis which costs ever more to build. Unfortunately, this has wiped out many of the operational savings.

It’s interesting to note that while Sandkuhler is justifiably proud of his work on MSTS, he has also learned from it. ‘With the Dual Power concept, we realized that if a hybrid system suitable for garbage collection was to be a success, the new technology has to be fitted onto an otherwise standard truck chassis,’ he explains.

What he means is that while Faun could have gone for a really ‘futuristic’ concept, with hydrostatic drive, or some other diesel/gas/battery electric power pack combination, the end result would have to be built as a single product unlikely in an industry which still retains a distinctly separate chassis/cab and bodybuilder structure. And, there is very little point in a specialist bodybuilder becoming a chassis manufacturer in today’s global market. ‘When we started looking at a hybrid solution, we started from a position that Faun did not want to be a truck chassis builder, nor did we want to have every new truck chassis in our shops for time-consuming modifications, before we could mount the compaction equipment,’ Sandkuhler explains. That ruled out hydrostatic transmission.

Transit mode performance

The result of this thinking? A small diesel engine is located on the outside of the truck’s chassis rails and coupled to an electric generator to power all the compaction equipment. This also powers the vehicle when in ‘collection mode’. When being driven on the highway, the Dual Power truck’s existing engine and in this case, an Allison automatic gearbox enables it to perform like any conventional Euro-5 specification truck. Which is fine because a modern truck is at its most efficient when moving at normal highway speeds. It’s when something as large and potentially noisy as a three or four axle RCV hits congested city traffic, or stops in a residential neighbourhood to engage the hydraulic power take off (PTO) that the conflict starts. ‘That’s when an RCV starts to make an adverse impact on the environment,’ Sandkuhler confirms.

This scenario was the starting point for the project and with the involvement of the IKA Institute at Aachen University (which explains the Aachen connection), every aspect of noise, fuel efficiency, vibration and optimum performance curves were measured and compared. It was also where the ‘supercap’ (a sort of electronic accumulator) control technology was developed.

The bottom line? If we want a more efficient hybrid future, electric is the way to go. But isn’t there a problem of power loss in converting diesel power into electricity and then a further loss when you use electric motors to provide hydraulic pressure? Yes there is. Not to mention considerable added weight and heat build up all of which are detrimental to the size of the carbon footprint.

So how did the rotary action Rotopress evolve from being the oldest design in the Faun product catalogue into what could be the fittest in an evolutionary sense? The reason is very simple, as Sandkuhler explains: ‘A rotary action needs far less energy than that needed to power a hydraulic ram ‘in’ and ‘out’.’ So no rams, or hydraulic oil tanks (or leaks) results in less engine power needed, and weight savings in construction.

As a result of this, the whole concept is considerably quieter at 54dB(A) much less than a conventional hydraulic RCV that will be nearer 90dB(A). It is heavier the prototype is currently 1900 kg heavier, but on production versions the weight penalty will only be around 900 kg. We have already established it performs as well as any Euro-5 diesel truck at highway speeds something which can not be said for any pure battery electric or current generation gas-fuelled truck chassis. And, the Dual Power hybrid never suffers a flat battery because someone forgot to charge it up overnight.

So, if there are no hydraulics, then how do the binlifters work? The solution to this problem was to be found not in the Faun R&D department in Osterholz Scharmbeck, Germany, but in an office in Reykjavik, Iceland as well as a production facility in Nantes, France. As Sandkuhler explains, ‘Ecoprocess has been building electrically-powered binlifters for several years (five actually, according to Sandkuhler) and we were impressed by the concept, so we asked the company to be our partner in this project and we are very pleased with the end result.’ Binlifter problems solved then thanks to the Icelanders, they are also electric.

Going into hybrid mode

After a demonstration by Sandkuhler in the Aachenerstadbetrieb (the city council works department) depot yard, it’s time to head downtown and mix it with some real traffic, some residents and those articulated buses.


The Dual Power hybrid prototype at work in downtown Aachen. One of the city’s unique triple-section articulated buses passes by on the other side of the street. Click here to enlarge image

First impressions? At normal transit speeds, the prototype drives just like any other Econic. But on arrival at the collection round start point, the driver switches off the truck’s main diesel engine and starts the auxiliary which on this prototype is a 30kW Deutz unit, but on production machines will be a Volkswagen diesel as used in small vans. I’m now ready for launch from stationary to the next container pick-up. We’re now in hybrid mode. ‘When you’re ready, give it maximum acceleration,’ encourages Sandkuhler. The result is amazing as the 26 tonne gross weight, three-axle truck surges forward in almost complete silence. Is it as quick as 300 hp diesel truck with auto box? I suspect not, but Georg thinks it’s better. We time each option and he is right. The hybrid drive is faster, smoother and much quieter.

Dual Power does not require the driver to use the accelerator to start and brake pedal to stop. All I have to do is release my accelerator foot pressure and the truck comes to a computer-controlled stop (like a hydrostatic), feeding the scrubbed-off energy back into the system. The Supercaps are fully charged now, so next comes a real surprise with 175 kW available, the Faun hybrid can be driven without either engine running! This is especially useful when turning around in a tight cul-de-sac making it possible to hear the voice of the banksman. But equally, local residents would not have to listen to me revving the engine, the noise from the air brakes there is an anti-runback system in the hybrid drive or hydraulic rams.


Help with the hybrid concept and independent testing of the performance parameters was conducted by the IKA Institute, part of Aachen University. Here, the project team discusses the findings with Georg Sandkuhler (right). Click here to enlarge image

Does electric work? Yes it does. The company also claims it saves 30% in fuel and carbon emissions. But for me, the biggest advantage is the reduction in noise and vibration, because at these levels, it really does make the prospect of double shifting each vehicle a reality.

Modern RCVs are just too expensive an item of machinery to only work a single eight-hour shift in every 24. Thanks to reduced noise levels, the Faun hybrid RCV could do a normal morning and day shift, followed by an overnight shift downtown something which would make clear economic sense but should not upset residents in apartments.


‘And here’s how we did it,’ explains Faun R&D chief, Georg Sandkuhler. An auxiliary diesel engine mounted outboard of the main truck chassis rails, is coupled to an electric generator. Click here to enlarge image

The current price of around €60,000 (US$100,000) per vehicle, could, Faun claims, be clawed-back within five years of single-shift operation by fuel savings alone. So surely, double-shifting could make even greater savings, while reducing the size of RCV fleet?

Does this mean the future of domestic and trade waste collection is set to change dramatically? The race for hybrid solutions is certainly on, and I’d suggest that it’s something you need to consider before specifying your next generation fleet. The tough part is going to be making the choice between each different solution.


Company politics at work. Prototype is based on Mercedes ‘Econic’ chassis, but Mercedes is developing its own hybrid system for truck chassis, so the Faun hybrid carries a Kirchhoff Group logo, rather than a three-pointed star! Dual Power technology is likely to be available on more than one brand of truck chassis. Click here to enlarge image

All eyes on Aachen, then?

Malcolm Bates is Collection & Transport Correspondent for Waste Management World
e-mail: wmw@pennwell.com

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