Wednesday 22 September 2021

The new DAF trucks: our questions answered

Paccar subsidiary DAF is the first manufacturer to take advantage of relaxation of European weights and dimensions rules introduced in 2020 to launch a range of over-size truck cabs. The all-new XF, XG and XG+ trucks, unveiled last month, replace the existing XF range, and also incorporate weight-saving chassis innovations, and revised engines and gearboxes.

Their larger cabs offer improved aerodynamics, extra living space and enhanced passive and active safety.

DAF has followed its usual prac­tice of sticking with established and reliable technology when a new model is introduced: and the new trucks lack some of the electronic innovations to be found on established models from oth­er manufacturers. Nonetheless, the new trucks are said to be the biggest-ever product launch from DAF, and a new factory has been built in Westerlo, Belgium to handle cab construction and trimming.

The manufacturer is claiming an up to 10 per cent improvement in overall fuel efficiency and equivalent reduction in CO2 emissions, owing to both aerodynamic and driveline innovations.

All three cabs share a distinctive curved front with a 160mm elongation. Combined with a general aerodynamic clean-up of the front and sides of the cab, including a curved windscreen, improved sealing, and race-car style wheel-arches, these parabolic shapes reduce drag without the significant weight gain that would come had an aerodynamic ‘nose’ been added to the front of the cab.

The XG and XG+ create a new premium market segment, the firm says, with 330mm of extra cab length at the rear for increased space and comfort, and on the XG+, a roof that is 200 mm higher.

The new DAFs’ safety-enhancing features include the large windscreen and large side windows with ultra-low belt lines for improved direct vision. An optional kerb view window is available which, in combination with a foldable co-driver seat, provides an unobstructed view of pedestrians and cyclists next to the cab on the nearside.

The new DAF Digital Camera system can replace the main and wide-angle mirrors. Meanwhile a Corner View system, replacing kerb and front view mirrors, offers maximum visibility of the area around the cab’s A-pillar on the co-driver side.

Production of the new trucks starts in October in Eindhoven and Leyland.

While other manufacturers such as Mercedes-Benz have mapped out a post-fossil-fuel strategy dominated by hydrogen fuel cells and electric traction, DAF appears to be content to see how infrastructure and technology develop before making a commitment to a particular path.

Alternative drivelines were discussed during the launch, with a brief glimpse of a battery-electric tractor unit, and it was also revealed that a hydrogen-powered internal combustion engine was being developed. But DAF has long promoted the ability of synthetic diesel in the form of HVO to provide operators with a ‘fossil-free’ fuel for its trucks today if they desire it.

The virtual launch of the new DAF trucks did not provide the usual opportunities for face-to-face questions and answers. But Transport Operator later approached the manufacturer over some key issues which have been raised by British operators and drivers.

We asked why DAF was sticking with a mixture of exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) technologies to control NOx emissions, when other manufacturers were going an SCR-only route.

“We use indeed a mix of EGR and SCR to control emissions,” said DAF.

“Paccar’s philosophy is to develop and apply robust emission control systems for our customers. An important part of that concept is the combination of cooled EGR and high efficiency SCR system. Each supports the other.

“For example, under conditions where the SCR catalyst temperature is insufficient for max NOx conversion efficiency, Paccar applies a higher level of EGR to reduce NOx and make sure tail-pipe emissions are low. When all systems are at optimal operating temperatures, EGR flow can be lowered in favour of lower CO2 and PM emissions (and best fuel efficiency), making full use of high SCR efficiencies. This combined strategy has the added advantage of low AdBlue consumption, further contributing to low total cost of ownership.”

The claimed greater efficiencies of the new DAFs’ engines

have been achieved by increased internal pressures and revised fuel-injection and turbocharging strategies. We asked DAF how these had been achieved, and what was being done to reduce the need for PM filter maintenance.

DAF said the latest HE400 turbochargers used variable-geometry for maximum efficiency, and: “In the rare case an active regeneration is needed (most of the Paccar MX-11 and MX-13 engines use passive regeneration), an additional injector in the exhaust is used. Paccar has included this 7th injector since the launch of active regeneration DPF systems with Euro VI introduction for a clear reason; in-cylinder dosing for active regeneration of the DPF increases the risk of oil dilution and low oil change intervals.

“We designed a new cylinder block and head for both the Paccar MX-11 and MX-13 engine platforms.

“The material for the MX-11 in the New Generation DAF is upgraded to CGI500. Material choice for MX-13 is the same. Both engine blocks and cylinder heads are redesigned to accommodate the higher firing pressures of both engines (up to 265 bar). The sourcing of our materials will not be revealed, but the design changes indeed lead to the weight savings for both engines.”

DAF has also taken advantage of the latest developments in fuel-injection technology from its established supplier, Delphi, which became part of BorgWarner late last year.

“This updated system allows us to apply more injections per combustion at a higher precision and on a significant higher energetic level (which contributes to fuel savings),” said DAF.

The engines’ service intervals have also been extended. DAF explained: “Our current XF and CF series already allow up to 200,000 km service intervals for vehicles equipped with our ‘long drain’ or ‘Extended Service Interval’ option (which includes a bigger oil sump, larger filtration). [What’s] new is that long-haulage vehicles specified without the Extended Service Interval option now have service intervals up to 125,000 km, which means we now offer a once-a-year service interval option for all long-haulage applications.”

Unlike most of its competitors, DAF has no engine rated over 530 hp. Were there plans to change this in the future, perhaps by using an engine from an external supplier?

DAF responded: “No, there aren’t any plans in place, as in today’s transport business it is all about maximum fuel efficiency and there is hardly any demand for extremely high outputs. With our current output range up to 390 kW/530 hp we perfectly cover market requirements.

“The 390 kW/530 hp rating now has even more torque, up to 2,700 Nm, available and, importantly, that is available from 900 rpm, enabling maximum use of downspeeding to ensure the optimum combination of performance and fuel economy in the most demanding applications.”

On the importance of driver appeal in designing the new trucks, DAF said driver comfort was one of three strategic drivers for the development of the New Generation vehicles, alongside higher fuel efficiency/lower emissions and increased road safety.

“New Generation DAFs will help our customers to attract and retain the best drivers in the market, struggling with a substantial shortage of skilled drivers.”

Other manufacturers are high-lighting their efforts to develop semi-autonomous and self-dri-ving vehicles: we asked DAF for its take on this.

“We do not want to refer to the activities of our competitors, but here at DAF we adopt a healthy approach on new technologies: 1) We don’t bring them to the market unless they are fully reliable (and therefore can really benefit road safety and efficiency); and 2) we don’t add technologies which the market is not yet ready to embrace. Keep in mind that autonomous driving technologies are far from cost-free – and that costs would need to be borne by someone.

“Having said so: DAF is participating in several projects involving autonomous technologies, such as the UK platooning project and the European multi-brand-platooning project Ensemble.

“And in addition, within the Paccar organisation, we are working actively on the autonomous technologies of tomorrow. Nevertheless: it is still a long way before autonomous trucks will be a common sight on our roads.”

On whether the rollout of the new cab designs would extend ‘down-range’ to the LF and CF trucks, the manufacturer said: “The New Generation XF, XG and XG+ we have now revealed are designed primarily for long-distance applications. Other chassis variants will follow later. The ‘blue generation’ of the XF, CF and LF will continue in production.”

Although the clear and established market leader in the UK, there is a perception that DAF’s reputation has been marred to an extent by electrical niggles and warning lights illuminating for no reason. We asked what had been done to address this.

“Electrical wiring issues were addressed with the introduction of Euro VI and still resonate in the market. There is also a perception that DAF vehicles suffer from high numbers of electrical faults due to the number of warning lights that drivers can experience,” said the manufacturer.

“These issues have a solution and have hopefully been addressed on both existing and new vehicles, but it takes much longer to change the view of the market, who run vehicles that are not all brand new. The New Generation DAF trucks have been designed to further decrease the number of warnings to the driver dramatically.”

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