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OPER/MONS Euro-4: EGR vs SCR packaging the system for use
Page 64
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on a rigid,he says.-On an eight-wheeler, for example, you're looking at a minimum 5.1m wheelbase.That makes it a long truck, so space isn't really an issue."
Rigids can be fitted with smaller AdBlue tanks than tractor units because they are more likely to return to their home depot at night for a refill. "For example, we can provide eight-wheelers with a 36-litre tank that will hold enough AdBlue for a week's work on a single shift," says Smith.
However, Burnet says there is a risk of damage to the catalyst if SCR eightwheelers are crossing rough ground in quarries or construction sites.
"Damage is always a potential problem when you're working in that sort of environment," agrees Cussans.
Customer input "As for 7.5-tonners, a lot of them go to rental fleets.They already have to ask customers to fill their trucks with diesel before they bring them back. If they go down the SCR route, they'll have to ask them to fill up with AdBlue too.The reaction of many rental customers will be,'what's that?— he predicts. "If they know what it is, then they'll have to be warned not to pour it into the diesel tank. By contrast, EGR is established technology that requires them to do nothing."
However, counters Pain. FOR systems are also complex with their valve. coolers. and particulate traps. "What's more, they place more thermal stress on the radiator because they demand more cooling," he adds.
Is SCR likely to interfere with ancillary equipment mounted on chassis? Mercedes-Benz's UK truck marketing and sales engineering manager Nick Blake doubts this will be an issue. Nor does he anticipate heat dissipation difficulties with SCR.
-So far as equipment is concerned only bulk blowers on 6x2 tractor units are likely to cause problems," he says."I can't envisage any difficulties with power take-offs on rigids, and don't forget it's possible, up to a point, to reposition the SCR system on the vehicle. It's possible to move the catalyst, for instance, if you need to fit a leg stabiliser for a crane," But an EGR trap can get in the way of a stabiliser and may need repositioning,says Pain.
Cussans has doubts about SCR's spaceefficiency, arguing that anything extra that occupies space on the chassisand an AdBlue tank undoubtedly does is bound to cause difficulties for somebody fitting, say, a tipper body plus a grab.
"Body builders will, of course, have to ensure that operators can still access the AdBlue tank filler cap,says Smith.
So far as EGR being a better bet for city centre work is concerned,two or three wellknown operators have already expressed concern about the particulate traps clogging up, says Blake. Cussans contends that they need have no worries so far as MAN is concerned. pointi ng out that the manufacturer's PM-Kat trap is maintenance-free and sealed for the life of the engine. 'in the case of the D08 engine litted to our rigids that means it's good for at least one million km," he says.
Mercedes-Benz dealers will be able to offer both an SCR and an EGR solution at 7.5tonnes.While Atego is to be equipped with the former, Mitsubishi Fuso's Canter, which they also sell, will come with the latter, as will Isuzu's NOR.
So what do truck buyers make of the debate?
"For high-mileage applications SCR might be the way to go because of the fuel savings, hut for low-mileage work where fuel consumption is less of an issue we'd probably support FOR because its not as complicated," says David Barlow, chairman of 1,200-vehicle-strong contract hire specialist Prohire. However, he can understand customers running both high and low-mileage vehicles wanting to standardise on SCR to avoid the risk of employees assuming that trucks are fitted with EGR when they're equipped with SCR, and forgetting to pour in AdBlue.
"All Euro-4 trucks will have AdBlue gauges on their dashboards and I suspect drivers will get used to topping up the tank in the same way that they're used to topping up the screenwash," says Allison. Pouring in AdBlue will become especially vital after 1 October 2007 because the horsepower on new trucks will be reduced if levels are allowed to fall.
Residual values
"So far as residuals are concerned I suspect that 7.5-tonners with EGR may do better than those with SCR because people who buy such vehicles secondhand want something that's as simple as possible to operate,says Barlow.
"No matter whether it's EGR or SCR, the great difficulty we face is that we still don't know for certain how much Euro-4 chassis will cost.We understand that 7.5-tonner prices may rise by £2,000 to £4,000, and in the present climate we cannot expect our customers to shoulder that level of increase."
Over at MAN Cussans says: "We'll be charging £2,250 more for our Euro-4 7.5tonners, and £2.750 more for our Euro-4 18tonners. And while SCR systems are generally reckoned to cost nearer £4,000.Daf is levying roughly the same premiums for Euro-4 chassis as MAN ERF at those weights, says Pain.
Barlow. however, suspects that if registrations start to dip once Euro-3 trucks are no longer available, the premium prices manufacturers want to charge for Euro-4 chassis will also begin to fall as they fight to maintain sales levels."That's what happened when Euro-3 was introduced," he recalls. •