Mercedes Actros 1845 Semi Truck – Video
The pair of Actros quickly left behind the approach road from Faro to the A22 motorway. With PPC set to standard mode with a hysteresis of -5/+4 km/h, the red and white duo followed the signs for “España” to the east and headed for the first measuring point on the Algarve motorway: the co-drivers started their stopwatches at kilometre stone 78, precisely logging the driving time and fuel consumption meter reading at two-kilometre intervals.
On the test route located on the Algarve in the south of Portugal, there are around 35 transitions between hill and valley over precisely 200 measured kilometres. These were tackled by two very special Actros 1845 vehicles, which took to the A22 motorway simultaneously. Traffic is relatively light along this route, which runs parallel to the coast and increasingly fills up with tourists during the spring.
They could not know that, despite their identical model designation, these two test trucks are very different by nature. The red 1845 represents the state of the art prior to the introduction of the 2nd generation powertrain in 2015 and 2016 respectively. Its fellow, in white, is equipped with all aspects of the 2nd generation powertrain. The idea now is to prove that it can outperform its predecessor.
On the outside, it is hardly possible to distinguish between the two vehicles. Only someone paying very close attention would notice the slight difference in the side lip of the rear spoiler. The principle is clear: even after 2600 hours which the new Actros spent in the wind tunnel prior to its launch in 2011, there are always ways of improving the aerodynamics based on the current state of the art.
The majority of measures which make up the 2nd generation powertrain, and which result in a further reduction in the consumption of the Actros, are not apparent at first glance. The list of these improvements is long. The engine, for example, is generally more efficient due to the reduced exhaust gas recirculation rate and is more powerful at the lower end of the engine speed range than ever. The transmission and drive axles also generate less internal friction. Intelligent auxiliaries such as the new alternator and electronically controlled power-steering pump contribute to reduced consumption – like the refined switching strategy for the PowerShift automatic transmission, too.
Fuel savings of up to 6.5 percent are promised. Now, though, it is time to show what the vehicles can do on an undulating motorway where Predictive Powertrain Control (PPC), the cruise control system fitted on both trucks, will handle the topography. Yet from the outset a small but subtle difference is evident between the current version of the Actros and its predecessor: when accelerating the white Actros 1845 makes more intense use of the lower end of the rpm range than the red Actros 1845, and that is definitive. The previous technology for the transmission typically operates on a 2-5-8-10-11-12 gearshift pattern. Oriented for exceptionally low speeds, the white Actros with 2nd generation powertrain uses a 2-5-7-9-10-11-12 pattern, moving up gear by gear to the highest switching stage.
Both Actros models cope masterfully with the hilly terrain until the turning point at Tavira. Maximum torque of 2200 Nm, increased to 2400 Nm with Top Torque if required, speaks for itself: the engines remain in the engine speed range between 1000 and 1100 rpm and negotiate the numerous gradients easily in the top gear. This does not involve a lot of loss of speed, yet the new rear axle ratio of i = 2.533 means that the engine only has an rpm of just under 1200 rpm at the cruising speed of 85 km/h.
It is only necessary to downshift once and that demonstrates another difference between the Actros with 2nd generation powertrain and the preceding model: In the white Actros, which is the latest version, PPC switches the transmission into eleventh gear at the foot of the gradient, while the red Actros proceeds differently. It approaches the climb in twelfth gear to then subsequently shift into tenth. The demand of the developers will confirme: it is one of the typical features of the new switching strategy that such double gear steps on hills are significantly reduced with the latest Actros compared to the previous version.
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