Can the selective use of technology improve driving ability?
PowerTorque has been closely following the MAN TGX, since it was effectively relaunched at the end of last year with the inclusion of the Euro 6, 15.2-litre D38 engine under the cab floor. What also adds to the interest is the first availability in our market of the ZF TraXon automated manual transmission, the next generation AMT that follows on from the popularity of the AS Tronic.
At 560 hp (412 kW) and with 2700 Nm of torque, this six-cylinder engine is part of a three-option power and torque rating in Europe that offers the operator 520 hp and 2500 Nm, 560 hp and 2700 Nm or 640 hp and 3000 Nm, all derived from the same D38 engine with MAN’s two-stage turbos, EGR and SCR+CRT.
With the 12-speed ZF TraXon AMT (called by MAN the TipMatic TX), and the latest generation Intarder with a braking force of 3500 Nm, the driveline is well matched and available with a choice of three diff ratios – 3.7, 3.36 and 3.08:1.
At the permitted maximum of 100 km/h, the 15-litre turns over at 1230 rpm with the 3.08 version, moves a little faster at 1340 rpm with the 3.36, and then fairly romps along at 1470 with the 3.7:1 ratio, albeit this is aimed at maximum GCMs of 120 tonnes.
In the TGX D38 prime mover under evaluation we ran with 3.36:1 diff ratios hauling a B-double set loaded to within a good breakfast of hitting the 62.5 tonnes mark. The Intarder was also highly impressive. At peak weights on the hills over the route it could hold the rig without applying the service brakes.
Being a demonstration unit, it came with lane departure assist, adaptive cruise control, sat/nav and Bluetooth connectivity, emergency braking assist and emergency stopping signalling, an underbunk, slide-out fridge unit and an extremely comfortable twin bunk set-up that is fitted with an Aussie-supplied interior sprung mattress.
There was no problem in terms of keeping front axle weights within legal requirements, and, even with a relatively set-back pin position, the ride and directional stability of the prime mover was really impressive. There was never a need to chase the front end down the highway, or any evidence of the back end trying to influence the front.
AdBlue use on the Euro 6 engines is minimal, and at around 2.0-2.5 percent it’s a big change from the early Euro 5 competitors that could use more than double that figure.
In our earlier coverage of the TGX with the D38, PowerTorque covered the more detailed technical bits and pieces of the engine and transmission, and for those wanting greater insight into the TraXon gearbox we’d recommend checking out the editorial feature on pages 58-60 in this issue.
The CRT filter system is something that you don’t experience when sitting in the cab at a truck show, so we’ll explain that bit as being a Continuously Regenerating Trap (hence CRT), that comprises an oxidising catalytic converter and a closed diesel particulate filter, located upstream of the SCR injector.
The particulate filter removes up to 99 percent of all soot particulates from the exhaust gas during normal vehicle operation by the passive regeneration process.
It’s a compact unit that forms part of the Euro 6 silencer pack and doesn’t require driver input, unless you intend to complete a regen’ burn inside a warehouse. In that scenario the high temp of the exhaust gas during a regen’ could ignite combustible materials left lying around. The solution is to just press a cancel button and defer the regen’ until you are back in the open air.
Out on the road the MAN is extremely quiet in the cabin, and with good visibility and a very comfortable driver’s air suspended seat it’s easy to quickly feel very much at home.
All the lighting and engine checks can be completed from the dashboard, and the onboard computer gives the driver a comprehensive read-out of function and attitude, in respect of average speeds and fuel economy.
Unlike the DAF XF105, with which the TGX is obviously going to draw comparison, the rear suspension is fitted with ECAS, making a quick and easy rear end lift or dump through the airbags when coupling or decoupling.
My drive consisted of leaving Newcastle and heading south on the freeway for Sydney, scooting around the skinny lanes of Pennant Hills Road and then joining the M2/M7 for the run to the Hume Freeway and southbound to Melbourne.
It’s an almost continuous climb up to Sydney from the Hawkesbury River, and then yet more climbing up into the NSW Southern Highlands.
As this was the first experience I’d had with the new ZF, I gave into my curiosity and let it work things out for itself, rather than intervening either to hold a specific ratio before cresting a hill, or downshifting earlier to maintain momentum up an incline.
As yet, the ZF in our market isn’t offered with the link to predictive mapping to follow the topography of the route. But it works well, with quick and snappy shifting, especially for swapping ratios back and forth between 10-11-12.
These top three changes are faster than any others in the box and could not be beaten by even the best of manual cog swappers. It shows its ability on long climbs behind other laden B-doubles where momentum is lost by the vehicle ahead with every gear change, while the ZF is so quick that you can close the gap during the climb.
I have driven with adaptive cruise control (ACC) in passenger cars, but never for a long period in a truck application. My natural curiosity proved to be my downfall, as, with ACC engaged, every time I came up behind a vehicle, or had a vehicle cut into my lane ahead of me, the ACC system reduced speed to maintain the selected distance between the vehicle in front, and the rig lost momentum.
It’s no problem in a passenger car with ACC because a return to the previous speed is almost immediate. But, with ACC in a truck, the driver is continuously losing momentum and having to regain that by harder acceleration. That’s takes time and uses more fuel.
Prior to playing with ACC, I was running at 1.75 km/l with an average speed of 75.4 km/h, and by Sutton Forest this had dropped back to around 1.64 km/l.
By the time we arrived at Holbrook things had improved to 1.8 km/l with an overall average speed of 77.61 km/h. From Holbrook through to Derrimut in Melbourne the data recorder was showing an actual fuel use of 2.14 km/l over 386.2 km, with an average speed of 87.92 km/h. For the total distance of 1071.3 km the figures came in at an average speed of 82.76 with actual fuel use of 1.97 km/litre.
We are always learning in this industry, and, in hindsight, and without using ACC, I am comfortable that even with an engine showing under 4000 km at the start of the run, in normal driving, and without ACC operating, it’s fair to expect fuel consumption in the region of 2.25 to be easily achievable on this specific run.
Well, I have learnt my lesson on that one, as it’s now a feature I shall only use on level running around the Western Ring Road at the end of a long day and with time to spare. The rest of the time I’ll rely on human intervention and maintain momentum to avoid having to make up lost speed on the inclines.
Having learnt by my experience with ACC, it will now be interesting to put Dave Whyte behind the wheel, and then suffer the consequences of his performance as he will undoubtedly score a better result on both journey time and fuel economy.
Technology is a wonderful thing, but it needs to be applied to suit the circumstances and not taken as providing a perfect solution.
MAN looks like it has the right product at the right time. If you want to try one for yourself, give Penske Truck Rental a call and see if you become a Euro 6 convert.