Haulers: The bigger the better?

Manufacturers report that demand for articulated dump trucks (ADTs) is growing, and new entrants to this market such as XCMG and Liebherr demonstrate that there is increasing interest in this type of hauler.

At last November’s Bauma China exhibition in Shanghai XCMG unveiled what it claimed was a 60 tonne ADT, the DAE60. The company also has 30 tonne and 45 tonne models in its portfolio.

The truck is said to offer a 45 km/h top speed and a maximum gradeability of 45o. Power comes from a Cummins QSK19 diesel engine driving a stepless AC drive – believed to be unique for any ADT on the market. The smaller models feature traditional six-speed transmissions.

By entering the 60 tonne weight range, XCMG’s machine is competing with the lower end of the rigid dump truck (RDT) market, but its six-wheel drive should give it a distinct off-road advantage over its rigid counter-parts.

This monster machine was certainly an eye-catcher, and followed on from John Deere’s launch of its largest ever ADT last year – the 46 tonne 460E. Indeed, several other manufacturers have also spoken about plans to launch larger ADT models in the future.

Ewen Gilchrist of Doosan ADT said, “It’s no secret that there is definitely a trend towards the larger unit, however the answer is the application – can ADTs compete on a traditional RDT application? No. But can they operate where RDTs cannot operate? Yes. Watch this space for the next model.”

And Marc Schürmann, managing director of Bell Equipment Europe, said the company was currently testing a new 50 tonne model, and was considering the production of a 60 tonne ADT in the future.
“But a 60 tonne truck will be a totally different configuration to the smaller models – it won’t be a 6X6 as we currently know it,” he cautioned.

Volvo Construction Equipment global director of hauler platforms Mats Karlsson also thought developing 50 or 60 tonne ADTs would be a challenge.

“When you look at ADTs there are some features that are very important,” he said. “The right gradeability of the machine, the right ground pressure and so on, so you get the right terrain manoeuvrability. As long as you can maintain these features, I don’t see a stopping point in terms of weight category for the concept as such. Then of course it’s availability of the components to support this – that would be a challenge.”

This is a consideration that Scott Pollock, product manager for trucks at Terex, agreed with. The largest ADT model that Terex manufactures is the 40 tonne class TA400 – part of its Generation 9 range that also includes the 30-tonne class TA300 and 25-tonne class TA250.

“We have no immediate plans to look at trucks of that size [60 tonne range]. Obviously these guys have done their homework and believe there is a market for them, but if you look at the kind of ground pressures these machines exert, the question is will they be true six wheel drive?” Mr Pollock said.

“Will the drivetrain systems reliable enough to allow a true six wheel drive machine to drive with a 60 tonne payload? Fuel efficiency is higher up the agenda as far as our customers are concerned,” he explained.

Saving diesel

Indeed, with the cost of diesel climbing ever higher and new exhaust emissions regulations in the US and Europe, fuel efficiency is also a major talking point for manufacturers throughout the construction equipment industry.

The changes in legislation to minimise diesel exhaust emissions has led ADT producers to re-design their trucks, with some going down the exhaust gas recirculation (EGR) and diesel particulate filter (DPF) route to reduce emissions, and others using selective catalytic reduction (SCR) to comply with the new US Tier 4 Interim/ EU Stage IIIB laws.

Both options result in reduced emissions, but in different ways. The EGR system re-circulates the exhaust gases and captures the soot in the DPF, burning it off at high temperatures. The SCR system is an after-burn treatment system whereby the exhaust gases are treated with a urea solution – marketed as AdBlue in many countries – prior to being emitted to the atmosphere.

The latest ADT from Liebherr – the 40 tonne class TA 240, which will be showcased for the first time at the Bauma show – sports a 350 kW engine, for instance. This uses the same SCR aftertreatment to meet the current Tier 4 Interim emissions laws as the first model launched by the manufacturer, the TA230.

Terex’s engines also feature SCR to meet the current US Tier 4 Interim/ EU Stage IIIB laws, and Mr Pollock said tests had produced up to 7% fuel savings compared with previous models.

“Ad Blue is new to the industry, and we have continually engaged with the customers through education and marketing programmes to help with the acceptance of this is a way forward to meet compliance,” Mr Pollock said, adding that the company also offered a Tier 2-compliant machine for less regulated markets.

Meanwhile, Doosan’s Mr Gilchrist said the company had experienced no push-back from customers in terms of the acceptance of the SCR emissions control system it used on its latest ADT range – the DA family, which consists of the 40 tonne class DA40, the 28 tonne class DA30 and the smaller DA25, which is coming soon and has no specific details as yet.

“Customers are extremely satisfied with the fuel and productivity gains on the new ADTs,” Mr Gilchrist said. “On a head to head test at a customer’s jobsite, we reduced fuel burn by -12% vs the previous model, and increased productivity by +15%. This is an excellent result.

“The beauty of the SCR system is it can be modified for export to high sulphur content areas which will also affect the resale price versus units with different technologies in the long-term,” Mr Gilchrist explained.

Meanwhile, Bell’s new E-Series ADTs will see their production launch at the Bauma show in Munich, Germany. The 30 tonne class B30E will be on show together with the smaller B25E – machines which, like all the models in the E-Series range, use SCR aftertreatment to comply with the current US Tier 4 Interim and EU Stage IIIB emissions legislation.

As well as boasting increased fuel efficiency, Bell said the new range was designed with a big enough space envelope to house the next wave of new engines that comply with future Tier 4 Final and Stage IV emissions requirements – laws which start to come into force next year.

On the other side of the coin, Volvo, Komatsu, Caterpillar and John Deere are some of the ADT manufacturers that opted to use the EGR/DPF method in their respective ADT engines to adhere to the current Tier 4 Interim/Stage IIIB emissions laws.

Volvo’s Mr Karlsson said the company took its environmental responsibility very seriously, and praised the EGR/DPF technology. “This emissions step has given us the most robust solution – in general customer feedback has been positive,” he said.

However, while manufacturers may be singing the praises of each separate aftertreatment technology at the moment, there is no getting away from the fact that a combination of both EGR and SCR solutions will likely be necessary on all engines in order to comply with the even stricter US Tier 4 Final/EU Stage IV laws that start coming into force from 2014.

Terex’s Mr Pollock confirmed that EGR would be a feature of the Tier 4 Final engine solution on its ADTs alongside the SCR.
“When we move forward to Tier 4 Final it will be an engine swap-out – the actual changes to the aesthetics of the machines will be very minimal,” he said.

Doosan’s Mr Gilchrist echoed this, stating, “We will continue with our current SCR technology with limited EGR for Tier 4 Final.”

Automation

But it’s not just engine developments and size classes that are occupying the minds of ADT manufacturers. Future developments are likely to hinge on increased automation – already a key feature of many new models.

Volvo is one of the manufacturers that includes an on-board weighing system as standard on its latest ADTs – technology that uses changes in hydraulic pressure to measure loads, warning operators if a machine is being over or under loaded as well as logging all transported loads and allowing this data to be accessed remotely, thanks to Volvo’s advanced CareTrack telematics system.

Volvo’s Mr Karlsson said the system was highly accurate. “We record +/- 1% accuracy when it comes to measuring the load. I truly believe that it does help the customer to make more money.”

Looking further ahead, Mr Karlsson said new developments in the ADT market would focus on efficiency. “We will continue working with fuel efficiency, securing that we have the right balance when it comes to overall costs per tonne moved and so on, but all the time maintaining the right terrain maneuverability of the machine,” he said.

Doosan’s Mr Gilchrist also said further reductions in the total cost of ownership were a target for his company’s future models.

“All efforts will be made by manufacturers to further reduce the customers’ cost for every tonne transported. So this must come in fuel gains, operator gains etc,” he said.

Terex’s Mr Pollock said automation was central. “We will be looking at automated differential locks and auto retardation systems so that the machines can be used by operators with different levels of abilities. Customers are also requesting production feedback, on-board weighing, telematics, fuel consumption figures –these are all under consideration.”

It is clear that ADT manufacturers have a lot on their minds
at the moment, and while size matters in this market, it is not the critical factor shaping the next wave of new launches.