Eager to extend the capability of the new DAF XG range especially in high productivity applications, Ross Cureton, Director of Product Planning, offers firsthand insights into the involved process undertaken by PACCAR as it sought to determine observable step changes in performance, fuel economy and durability across the new powertrain.
Prime Mover: When was your first involvement with the XG project?
Ross Cureton: My first contact with this truck was in 2017-18 when it was still in the styling studio. It was still lumps of clay. It was great to be invited into the inner sanctum of DAF from the very beginning.
PM: Were changes to European regulations covering cab size a catalyst?
RC: The current EU legislation which allows larger cabs was not in place when DAF began designing this next generation. The keys really were the corner radius and the taper of the cab. When you look at the truck now you see a lot of attention to detail in the way gaps are dealt with particularly around the headlamp and step areas. These days with computer simulation you can get a much better understanding of where every gram of metal has to go. This is a complete ground-up new cab and spec for the finished truck is only 20kgs heavier than the XF, despite being bigger.
PM: Was a total redesign really necessary?
RC: There’s two big things there, aerodynamics and direct vision. There was a real need to redesign the cab from scratch because if you want an improvement in direct vision, among other things you need to push the windscreen lower and to do that something’s got to give. There’s a cooling system underneath the tunnel, plus a heater/ventilation system inside the cab, and they’re all getting squished, so you really do need to design all the sheet metal from scratch. The whole point of making the cabs deeper from front to rear was to make them more aerodynamic. All the OEMs did studies about what would that look like and the front of the cab going forward let them increase the corner radius of the cab without impinging on the driver’s space. The objectives were to get fuel efficiency and increase safety. Safety is not much talked about in Europe because it’s now a given and is legislated. Safety now tends to mean safety of people outside the truck, not inside the truck as much. So, avoiding the collision or avoiding the pedestrian those sort of things are really what safety is now about.
PM: What was some of the reasoning in integrating a 15-litre engine into this model?
RC: We know that the 15-litre cabover market is strong in Australia and getting stronger, and we haven’t had an entrant in that for DAF. 15-litre trucks haul the bulk of freight in Australia, they’re highly utilised and selling in quite respectable numbers. So, this is obviously where we want to be. There’s some really good trucks out there and people buy them for good reasons. DAF’s product has always been as good as them, but they simply didn’t have a 15-litre. The new cab coincided with a new platform of engine product that Cummins was developing and you don’t usually choose to develop and validate an engine at the same time as doing a new truck because it’s a massive undertaking. This new engine, we felt, had promise. It was Euro VI compliant without EGR. It’s very compact and light and broadly the same size and weight as the MX-13 which means it’s going to go in the same hole. Take an MX-13 which has EGR out and put in a 15-litre that doesn’t, and you’ve got a cooling system that will cope. This engine is designed for really high peak cylinder pressures which give high torque and high torque gives good fuel consumption because you can downspeed the engine further than before. Not every engine has maximum torque at 900 revs, yet this one does. It has a robust stiff block, four engine mounting points and its gear train is at the back of the engine which suits cabover applications. It’s got a 50-litre sump so 80,000km oil drain intervals are standard.
PM: Are you happy with the result?
RC: Putting a 15-litre into this truck would have been some achievement but it would have been a waste of time if it didn’t fit the combinations that customers utilise. It does. Now we’ve got a bigger cab, that’s not heavier with a powerful engine, that’s not heavier. In Australia, trying to get European trucks to be viable on front axle mass has always been a challenge, so we felt this was going to be a good thing.
PM: What about the rest of the driveline?
RC: The engine’s 3200Nm of torque required a different gearbox and the ZF Traxon 16-speed used is rated for that and is a different unit from the Traxon used behind the 13-litre. Most European trucks don’t have 16-speeds but the smaller ratio steps mean the 660hp can stay in its sweet spot more often. We’ve specified 46,000lbs Meritor axles and Air Glide suspension. The rear frame cut off accommodates drop deck trailers and the XG has the same trailer compatibility as a Kenworth. Weight distribution can be the enemy of European trucks but we’ve managed to include 1,150-litre fuel capacity which is allowing validation customers to comfortably run Melbourne to Brisbane at B-double weights without refuelling.
PM: What’s the reasoning behind referring to the engine as a PX-15 rather than a Cummins?
RC: We’re not hiding the fact of who made the metal, but the integration is a big part of it and the truck needs to work, feel and operate like a DAF. And our dealers are across all of that too. Between PACCAR and Cummins there are a lot of dots on the map. If we put the world’s best truck in the market but can’t support it, it will count for nothing.
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