The problem with any auto box is that, unlike the
Page 37
Page 38
If you've noticed an error in this article please click here to report it so we can fix it.
driver, it cannot see the road ahead. What that means in practice is that EAS cannot judge whether a hill is becoming steeper—when a pre-emptory drop in gear may be necessary—or is easing off, when a change-down may be avoided.
To ensure that the driver retains total control, even when running in full auto mode, you can still make full or split shifts at any time using the regular EPS rocker lever. There is also a kick-down function on the throttle nedal should you want more get-upand-go. And if you want to do it all yourself you can even drive EAS as a clutch-less manual.
Apart from its EAS Telligent box and the MegaSpace cab's mind-blowing yellow and black optional leather interior trim, our r843LS is a typical 43ohp Actros 4x2. Like MAN's latest TG-A tractor, the Actros comes with an "interim" stage electronic tac_ho fitted in the headlining and an electronic speedo in the dash.
•
TEST PROCEDURE
We were determined to have a worthwhile comparison so, together with Merc's test engineers from the EAS project team at Gaggenau, we devised a straightforward test cycle. First, we would drive the Actros, loaded to 40 tonnes GCW, as an EPS manual, over a route we did not know. This would give us a worst-case baseline figure—namely an unfamiliar driver, driving an unfamiliar truck over an unfamiliar route.
Then, having become accustomed to the route, we would do it again, converting the 1843 (see panel, left) to run as a full auto, letting EAS do everything.
Finally, having become fully acquainted with the truck and route, we would do the last lap back in EPS manual mode to see if we could beat the auto.
Our T 52km test route took a little over two hours and was split 50:50 between busy undulating autobahns running from our start at Leonberg to Karlsruhe, before peeling off to Bruchsal where we switched to two-lane national routes for the return leg.
Ideally we would have liked to have run all three laps in one day but, in the event, we were forced to run the first two on day one and the final EPS on day two. However, the team from Gaggenau ran a second identically freighted 1853 "reference truck" with the same height MegaSpace cab some in minutes behind us with EAS on all three laps. This helped us calculate the differences across both days not least in terms of the weather—driving rain on the first two laps and only slighter better conditions on the second day. We also allowed for stopping times at lights in order to come up with a final definitive figure. Thus our test is as close as we can get to reality without becoming a laboratory experiment.
Time was when you could predict exactly how an old-fashioned auto would work. It changed up at X and changed down at Y. That usually meant when you had either revved the head off the engine or after the revs had fallen through the floor.
But today's auto boxes are far more sophisticated and flexible. There is no set pattern to FAS. It changes gear according to circumstances and terrain, and how fast you depress the throttle pedal—and it does it well. If we did notice any difference between EPS and EAS it is that the auto system is inclined to hold on to a gear a little longer than a driver by about roozoorpm and not let the engine lug for so long. As a result you tend to make
quicker progress—as the EAS lap average speed shows.
There was little else to choose between the two driving styles, although over the two-lane national route section we were always trying to hold 8hi in manual longer whereas EAS tended to drop half a cog.
EAS will remember your preferred start-off gear and will hold it throughout the journey. It also block shifts under its own steam, taking one-and-a-half or two gears at a time, whereas with EPS you have to wait until the dash display shows you that you have built up enough revs to take more than one cog.
The only other difference with EAS is when you are pulling away from rest, especially on a slope. As there is no clutch pedal you feel the biting point through your ears—and the seat of your pants—as opposed to your left foot. But it's no great challenge.
CM has driven EAS several times and each time it improves. Merc's engineers have been regularly updating its software—indeed, it has had an upgrade since Truck drove the 1840 in TET—so it is thinking quicker and smarter. But perhaps its greatest attribute is that, with nothing to distract you from braking and steering, you end up with a far less stressful drive. And that must affect economy.
SUMMARY
The Gaggenau team was pleased with the result, though dearly expecting it—even if we weren't. So, bruised egos notwithstanding, EAS was the winner on fuel, never mind driveability. By way of a sop Gaggenau's Anton Haitz told us: "The very good driver can be better than the auto because he can look forward—the auto can't see ahead. But if you take so drivers with 10 autos the consumption across the fleet would go up." According to Haitz, the average improvement is typically about 0.5 litres, though in our results it was more like a litre.
We took more comfort from the fact that
Merc's test driver Michael Merz, who piloted the reference truck, reckoned he could beat EAS for the first three hours only. That at least made us feel better. In time we probably could have beaten the auto. But we are not sure what it would have proved.
Overall, we're 99.9% persuaded by the fuel efficiency of EAS. Although just to be completely sure we would like to test an auto Actros around CM'S Scottish route at 44 tonnes. How about it DaimlerChrysler?
EAS still may not be able to see the road ahead like a driver. But its reactions are so fast, that's almost irrelevant now. And while some dyed-in-the-wool operators may feel that auto boxes will "de-skill" drivers we tend to see it another way. With all the congestion on the road, lunatic car drivers and hassles ofj ust-intime deliveries we think EAS will allow the driver to maximise those skills that really matter—steering and braking—leaving the electronically-managed driveline to take care of fuel economy.
Of course, consistent fuel economy across the fleet is not the only thing you are likely to find with EAS. According to DaimlerChrysler, UK EAS operators are already reporting better dutch life as the auto system protects against unintentional driveline abuse.
We reckon Truck was right. Autos are the future. The only question remaining is which truck maker will have the courage to make an auto box standard on a heavy tractor—and at no extra cost? But it's not a matter of if, only of when...