A New Hope

Some design tweaks combined with significant engineering advances make the Euro 6 DAF XF an exciting addition to PACCAR’s Australian offering.

Already a strong seller and multi-award winner in Europe where it topped the Heavy Duty market in 2018, DAF’s new Euro 6 XF exhibits the results of significant re-engineering of many of its systems and components to deliver a refined European truck with the ruggedness required to suit Australian applications. The DAF brand’s share of the local market has been steady in recent years but some sizable fleet sales of the new XF and CF models during the first half of 2020 have helped propel DAF into more positive territory despite a constricting overall market.

“The new models are the biggest thing to happen to DAF in its 21 years of history in Australia” says Felipe Rubio, General Manager of DAF Trucks Australia.

Felipe should feel comfortable with that quote as every major component, not to mention a few minor ones, have been examined and if any worthwhile improvement could be realised, has been, subsequently, revised. The PACCAR MX-13 engine powering the XF incorporates a number of changes and power output has been increased by 20hp to 530hp (390kW). Efficiencies have been gained by addressing a number of parasitic losses with the implementation of ‘smart’ oil, steering and water pumps to deliver output matched to the exact demands of the engine in any situation.

The Variable Geometry Turbocharger provides higher boost pressures at lower revs which is an important factor in achieving the maximum torque of 2,600 Nm in the 900-1,125rpm range. The increased torque at lower revs permits the use of faster rear axles which enable the XF to stay in higher gears for longer.

The engine has a new EGR system and thermal efficiency has been enhanced by developing a new combustion system, including new pistons and a higher compression ratio. The injectors and their management strategies have also been improved. The cooling system has been increased in size by 30 per cent and, in combination with improved air flow management, is able to dissipate the slightly increased heat generated by the Euro 6 engine. At the same time, it cuts engine fan operating times by half, contributing to fuel efficiency despite the increased horsepower rating.

The performance of the PACCAR Engine Brake has been improved over the Euro 5 engine. Maximum braking power of the MX-13 is now 360 kW and in the important 1,200 to 1,500 rpm range, engine braking power has increased up to 30 per cent.

The XF’s driveline applies the proven successful formula of having higher torque available at lower engine revolutions to maximise fuel efficiency. Add in factors such as ‘taller’ diff ratios and the latest generation of ZF’s TraXon automated 16-speed gearbox capable of skip shifting and the potential savings are evident in the XF. The TraXon’s lower internal friction losses and faster upshifts contribute to the low fuel consumption and driver comfort is also improved thanks to the TraXon’s quiet and smooth operation and precise clutch actuation. The TraXon also provides a wider ratio spread to capitalise on the down speeding of the engine. The TraXon has Eco Mode and Eco Roll functions as measures to further boost fuel efficiency, reduce emissions and lower operation costs. Eco Mode supports the driver in maximising economical operation yet, when required, more engine performance can be selected in an instant. The Eco Roll feature is similar to other modern truck transmissions, which disconnect the driveline and allow the vehicle to coast to make the most out of momentum and gravity. On the road the transition from coasting to positive drive is particularly smooth in the XF. The drive axles have low friction wheel bearings and relatively ‘tall’ 3.09 gearing as part of the fuel economy focus, which also includes the specification of a low friction lubricant.

Digital controls and monitoring devices provide several advantages over analogue systems including absolving the driver from having to constantly, or at the least frequently, watch vital gauges. The XF’s Battery Energy Monitoring System is a good example as it allows the driver to check the status of the batteries and provides warnings when electrical energy levels are critical. It also prevents overcharging which results in increased uptime due to longer battery life.

DAF’s active and passive safety systems are at least on par with anything else currently available in a heavy-duty truck and include all of the vital acronyms expected in a modern truck, particularly those manufactured in Europe.

Adaptive Cruise Control (ACC) automatically adjusts the truck’s speed to maintain a safe distance from the vehicle ahead. The settings are easily adjusted from the steering wheel controls.

Forward Collision Warning (FCW) generates an audible warning and a visual alert on the instrument panel, urging the driver to take action in order to prevent a collision. Should the driver be too slow in reacting the Advanced Emergency Braking System (AEBS) intervenes to slow the truck down in an emergency situation.

The Lane Departure Warning System (LDWS) warns the driver if the vehicle begins to move out of the lane owing to driver error, drowsiness or distraction. This particular type of technology is becoming more commonplace in heavy trucks as well as passenger vehicles.

Third party safety is addressed by the fitment of a camera covering the kerb side of the truck – an area typically inhabited by blind spots.

Naturally, there is a Vehicle Stability Control (VSC) system which for the new DAFs has been improved even further than on the previous models and is set to intervene to prevent jack-knifing and overturning. Driver and passenger airbags are standard as are pretension seat belts.

DAF has developed its Protective Cab Suspension Construction, a proprietary technology which is designed to absorb a significant part of collision energy by allowing a controlled rearwards movement of the cab along the chassis.

The HVAC system has also been completely re-imagined including the controls which now feature one-touch defrosting, park ventilation, park heating with timer, rest heat and automatic air recirculation and can also be operated using the rear wall control unit in the sleeper berth. The new ‘smart’ air-conditioning system consumes less energy by cooling the air down only as much as is needed to reach the desired interior temperature. Intelligent control of the evaporator is also used to avoid unnecessary air-cooling. The new fully automated HVAC system also uses residual heat from the engine for heating the cab during shorts breaks, further adding to fuel efficiency.

The XF cab comes in three configurations, all of them sleepers: the flat roof Comfort Cab, the mid-roof Space Cab and the imposing high roof Super Space Cab which has a roof to floor dimension of 2255mm. The exterior of the XF has been softened by incorporating larger radii on the corners of the cab delivering a more rounded and smoother overall shape which improves aerodynamics without intruding on the interior space. Combined with the new grille the cab has a completely different look from the Euro 5 XF. Revised side air deflectors mounted on the panels above the LED head lights serve to channel air around the sides of the cab. At the top, a new sun visor incorporates some of the same brushed aluminium look trim as found on the upper grille panel and makes its own contribution to the aero package and the exterior aesthetics. Similar alloy look trims can be found on the edges of the grille elements as well as on the top doorstep.

The XF’s interiors just ooze quality. In recent years the market has come to expect truck interiors to be stylish and comfortable while remaining practical, and DAF doesn’t disappoint by taking the XF’s interior to an almost sumptuous level without any flashy decadence to cheapen it. It is, after all, a work space, so why shouldn’t it have some style? The interior regularly functions as a rest and sleeping space as well, and here the XF certainly doesn’t disappoint with plenty of storage, a pull-out desk and an easily accessible under-bunk fridge.

The interior lighting has received a lot of attention from the designers with an innovative rotary switch control centrally located in the middle of the dashboard console, ensuring it is within easy reach. The driver can select different interior lighting modes for various driving and resting conditions, and there’s also a dimming function. For convenience, there’s a second control switch on the rear wall of the sleeper.

The windows are bigger and the mirrors have been located slightly rearward to provide a larger vision field at the A pillar. Note, the small quarter pillar on the previous XF has been eliminated.

The DAF XF has always been considered a “driver’s” truck, and the new Euro 6 model makes operating it even better, with the bonuses of significant fuel efficiencies and leading edge safety technologies.

Article reproduced courtesy of Prime Mover Magazine (July 2020)