|Direct from the development shop at the Benteler facility in The Netherlands, the prototype MAN Metropolis hybrid 6x2 chassis emerges into daylight for the first time|
Truck and bus manufacturer, MAN has a global reputation. The company has a good market share in most sectors of the truck market - with the exception of waste and recycling, perhaps. So when our collection and transport correspondent heard about a new hybrid concept vehicle specifically designed to meet operational demands in an urban environment, he had to be the first to take a look.
by Malcolm Bates
Before we start, I should explain that the history of automotive engineering is littered with 'concept vehicles' that never made it into production. There have also been those that deserved to succeed, only to be killed-off by corporate politics, a change in regulations, or even something completely unexpected, like a melt-down of the global financial system.
On the other hand, there are also designs that made it without the benefit of any visionary thinking whatsoever. I say this in order to illustrate that even in today's high-tech computer-driven age, the balance between success or failure can still come down to something as intangible as 'brand image', 'customer perception', or even the personalities tasked with seeing it through to production.
So how then shall we judge the new MAN 'Metropolis'? We need to start by observing that several other truck manufacturers have already staked a claim in this highly specialised niche including Volvo, Renault and Mercedes Benz - manufacturers which, it could be argued, have a much higher profile in waste and recycling than MAN.
|Cab interior - and of course exterior - is the same as standard diesel-fuelled MAN TGS - only gearshift and other minor controls differ|
We also need to observe that while truck manufacturers, environmental campaigners and yes, even technical journalists, are keen to talk about new 'environmentally friendly' products (like hybrids), designed to save our planet, the reality is likely to be something different. While a true 'zero emission' refuse collection truck might be technically possible - it isn't at present as the true environmental costs of battery production are usually ignored. And while many so-called 'hybrid' solutions work fine, they nearly always fall short in some way.
Current diesel trucks are economical and reliable to run, are light in weight (leaving plenty of margin for payload) and even on tough refuse collection operations, should be capable of working hard in an urban environment for at least eight years. Did I mention price? Whatever environmental campaigners may say, everything has a price. And unless unfairly discriminating legislation skews the market, the benchmark price for the world's best zero-emissions vehicle is always going to be a standard diesel truck. Sadly, every 'environmental solution' I've seen to date compares badly on all, or several of those criteria.
WORTH THE WAIT?
So, finally, welcome to the MAN Metropolis. My longer-than-average introduction helps illustrate that this truck has been a long-time making - two years of planning and computer modelling by the technological wizz-kids at Benteler Engineering Services in the Netherlands, working with the product planners at MAN in Munich, in fact. If successful, the prize for MAN could be massive - Metropolis could raise the profile of the brand in the waste and recycling sector in one mighty leap and bring with it increased sales of more conventional diesel truck chassis as well.
The prototype is scheduled to be officially unveiled at the IAA exhibition in Hanover in September, then shown in conjunction with contractor Suez (a potential first customer) at Pollutec, Lyon, in November. 'Real life' testing is due to start in early 2013 and production is unlikely to start for another six months at the earliest. My mission? To get in first and see if Metropolis is worth the wait. The project stands on three fundamental principals;- No loss of payload (compared to a diesel chassis), ability to operate throughout the night thanks to significant noise reduction, and finally, to achieve the maximum reduction in emissions, while being environmentally sustainable. "We are claiming this is the first hybrid solution that can actually carry more payload than a diesel truck and offer wider utilisation," suggests Patrick Op deBeecke, vice president global projects. That is some claim.
|Look no engine! Under the cab sit three battery packs. A 3 litre Audi diesel is used to charge 'boost'. This, and electric drive motor, are located within chassis rails under a faun compaction body|
After an hour-long presentation at the impressive Benteler facility in Helmond, I'm fully briefed. The key requirement of the Metropolis project has been to design a truck chassis for the urban environment that looks forward well into the next decade - the 2020s - but also answers the operational demands that we are all facing right now. In other words, it should be technically possible for a fleet of MAN Metropolis refuse collection vehicles (RCVs) to be put into service, just as soon as the MAN management board signs it off for production. This project doesn't have to wait for new technology to be developed, diesel to become more expensive, or future legislation banning diesel trucks from downtown areas in order to become viable.
LESS IS MORE
More significantly, it doesn't ask 'the customer' - you, the operator - to accept an operational 'penalty' in the shape of reduced payload due to the extra weight of the hybrid transmission, or reduced operational shift availability due to the range of the battery packs. In fact the Metropolis really can claim to be the first hybrid truck that offers significantly more payload - up to 14 tonnes is available at a design weight of 26 tonnes GVW within a 6x2 rearsteer format - and increased 'on station' service levels thanks to impressive noise level reductions, compared to what you're currently using.
|Payload is greater than a diesel truck down to the weight saved by fitting a much smaller fuel tank. Audi diesel runs at constant low revs giving maximum torque, so only needs tiny 120 litre fuel tank!|
Offering more payload AND technology in one truck sounds unlikely, but I can confirm, it is true. Clearly such a claim would be negated if the actual 'performance' (that is acceleration, tractability and braking) compared to a standard diesel truck was reduced. I can't entirely confirm how it drives in service at this point because actual service trials - collecting waste - have yet to take place. But from what I can judge by pulling the prototype out of the experimental shop, the Metropolis hybrid should perform as well, if not better, than a 300/400hp diesel truck with automatic transmission.
So you'll be amazed when I tell you that the 'power unit' is the same V6 Turbo diesel engine normally found in a standard Audi automobile, then? I certainly was. How can such a small unit (of just 3 litres) power a 26 tonne truck? The answer is 'easily'. Unlike some other hybrids, the Metropolis uses a single internal combustion engine - not two as some do, or 'none' as with battery electrics. But this isn't used to directly drive the wheels. While a conventional truck driveline is retained (a prop shaft and axle differentials, rather than wheelmotors) the Audi diesel simply generates power to boost charge the three-part battery pack. It is the battery packs - via a sophisticated management system - that put the power into the electric motor that powers the drivetrain and other automotive systems. It is also electricity that powers the compaction system, binlifters and indeed, all the other functions that are normally powered by an engine-driven PTO on a conventional RCV..
The clever part? It looks just like any other MAN diesel truck. The cab, most of the controls, the chassis and running gear are all the same as a 'TGS' model truck. The key difference is that under the floor of the tilt cab there is 'only' the battery pack (3x35kW modules giving 105kW/hr) and a cooling system to keep them at optimum working temperature, rather than a big heavy diesel power unit. So where is the diesel engine? Amazingly, the 150kW V6 fits behind the cab under the compaction body floor, together with the 203kW (283kW peak) Remy electric motor, within the chassis rails. There are no complex components or battery packs located between cab and body - so a longer wheelbase (or shorter body length) is not required.
WHY HYDRAULICS HAD TO GO
There are no hydraulic systems on the Metropolis - all the automotive functions such as power steering and cab tilt are electrically-powered. Service brakes remain 'air' via a compressor - to help retain a drivability standard comparable to a conventional diesel truck - although a 'regen' braking capability kicks-in first. The level of retardation is adjustable to suit operating conditions, but unlike systems that use supercaps or other accumulator systems, there is no need for sharp levels of braking on the collection round (route) in order to recharge the system for the next 'launch'. In fact, it is the quiet, gentle nature of the Metropolis that is at the heart of Patrick Op deBeeck's claim of dramatically increased utilisation.
How so? Typically, a fleet of conventional diesel-fuelled RCVs with hydraulic compaction systems and binlifters will start work at 6 or 7 am and work a single shift of around forty hours a week. In contrast, a typical line-haul truck/trailer (costing much less to purchase) delivering products to supermarkets or retail locations in the same urban environment will almost certainly be double shifted, running 16 or more hours out of 24.
"While the Metropolis hybrid is expected to cost around 80% more than a conventional MAN diesel RCV chassis due to the cost of the battery packs, we are confident that our high standards of quality will enable it to work a double shift pattern every 24 hours," Patrick Op deBeeck explains. "Which, when fuel cost savings and a significant reduction in brake and driveline wear are taken into account, will make Metropolis a financially viable option," he adds.
"Remember, in contrast to a payload reduction that comes with other hybrid systems, there is an actual payload bonus with Metropolis (it's 30 kg), but by also eliminating the hydraulics, we can use intelligent electronic systems that only use the power they actually need." This reduces fuel consumption and emissions by up to 60% compared to a diesel chassis, Patrick suggests. But the real bonus is a reduction in operational and drive-by noise levels. "We are getting levels as low as 65dBA," he adds. Yes, Metropolis really is that quiet.
As Klaus Feldmann, the project manager at Benteler explains, the driving force behind Metropolis has been to deliver more than a conventional diesel truck, not less. "Any hybrid system is going to cost more initially," he confirms bluntly, but honestly. "The focus on this project has been to develop a solution that is quiet enough to make the collection of garbage and recyclable materials throughout the night in downtown areas viable (when there is less traffic congestion), without residents objecting. Then go out again later the same day and work another shift well into the evening." On that basis, one Metropolis could do the work of at least two comparable diesel trucks - more when fitted with a demountable body system.
The adoption of what is in effect a 'diesel generator' means the Metropolis will not run out of battery power. The diesel engine runs at constant revs during transit mode to and from the collection zone. This is enough to allow the fitting of compact battery pack modules which allow for up to 15 km - around 4 hours of work - in pure battery-only mode at any one time, with the diesel engine completely shut down," Klaus Feldmann explains. That's working on a mileage of around 150 km per 24 hours. When not working, a simple 'plug-in' cable is used to give a top-up charge.
|This graphic shows the layoput of the various hybrid systems as used in the Metropolis hybrid truck chassis. Significantly most components are located well away from the dangers of everyday urban oprations|
So what happens when the Metropolis reaches the downtown 'work zone'? "The driver has two options," Klaus explains. "The diesel engine is so quiet, that where zero exhaust emissions is not a priority, it can remain running. But working in downtown areas at night, or early in the morning, all the functions including bin lifters can be used entirely in battery electric mode, with the diesel engine shut down. If the batteries reach a critical level of discharge, the power unit will automatically cut-in, much as it does on a Prius hybrid car," he adds.
So how does the Metropolis drive to the tip site, or back to the depot? "While a conventional axle and prop shaft is used, it takes advantage of the constant torque of electric motor drive. The Metropolis has a two-speed transmission, in much the same way that a full hydrostatic system might," Klaus Feldmann explains. "Low range is primarily for use during the collection process and is limited to 30 kph. High range has been designed for transit mode to the worksite at a normal truck-limited 89 kph." he adds.
A bonus of the system is that looking to the future - when diesel fuel is even more expensive - it is possible for the battery management system to advise the driver of how much range is left towards the end of each shift. As it is likely to be cheaper to recharge the depleted Kockum nickel/manganese/cobalt batteries, than top up the diesel fuel tank, the battery management system allows the driver to drive back to base in high range on battery power alone.
You have to admit it, that makes Metropolis one clever truck!
WMW will soon be putting the MAN Metropolis to the test in real life service conditions. Although any brand of compaction REL, sideloader, or hooklift body can be fitted to production chassis, initial trial units feature a 22 m2 Faun 'Variopress' compaction body with Zoeller 'E-Rotary Z Delta' electric binlifters.
We'll bring you the story of how well Metropolis works in a real urban environment in a future issue.
Malcolm Bates is Waste Management World's collection and transport correspondent
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