The cabover B-double prime mover market is still dominated by Kenworth and Volvo, with Freightliner losing ground, but the Scania, Benz and more recently MAN introductions and results have managed to change the paradigm in this market segment.
Diesel News test drove two of the new contenders to see just what they offer to the truck operator and driver and what it is about them which is cutting into the former market front runners’ lead in truck sales. In one of the tests Paul Matthei drove a Mercedes Benz from Brisbane to Melbourne, this is the first part of his story:
It was late on a Tuesday afternoon, warmed by the last golden rays of the winter sun, as I strapped down a load of steel products of various shapes and sizes and closed the curtains. I was looking forward to my first long distance drive of the new generation Mercedes-Benz 2658. In particular, I was curious to see the outcome of the bi-cultural mix of the Detroit-derived HDEP (Heavy-Duty Engine Platform) engine, known as OM473 in Benz parlance, in an MB chassis.
A visit to a weighbridge showed the combination was grossing 62.5 tonnes, a fairly typical weight for an interstate B-double. Then it was simply a matter of filling out the work diary and joining the evening procession southbound on the M1.
The first thing that struck me after reaching cruising speed was the relative quiet atmosphere inside the cab. It was almost eerie to be gliding along at 100 km/h with a 15.6 litre in-line six purring below, seemingly not making much more noise than a sewing machine and little if any sound of the air rushing past. It was certainly something I didn’t take long to settle into. As previously mentioned, there’s a definite link between a noisy environment and exacerbated fatigue, so full marks to the big Benz on this count.
Another significant reason for the quietness at cruising speed can be attributed to the exceptionally tall final drive ratio of 3.583:1 that sees the tacho registering just 1450rpm at 100km/h.
The powerplant itself is an engineering masterpiece, seamlessly delivering its 578hp (425kW) and 2800Nm (2065lbft) of torque via an equally impressive 12-speed PowerShift3 automated manual transmission (AMT). In experiencing this combination, I felt a sense of utter synergy between engine and transmission that I’ve not experienced in any previous Actros. Obviously, there’s no lumpy beat as was inherent with the previous V6 and V8 engines, but this OM473 straight-six seems to have its own brand of grit and determination that is far different from the V-bangers it replaced.
Interestingly, there’s also a very subtle, almost imperceptible, hint of diesel ‘knock’ or combustion ‘ping’ at certain points in the rev range, particularly at idle. For me this invoked a memory of the (much louder) signature sound of the venerable Detroit Diesel Series 60 in-line six, of which the OM473 is a direct descendant.
Another curious parallel is that the Series 60 also replaced V6 and V8 Detroit Diesel engines when it was introduced, but I digress. Suffice to say, it was pleasing to find that the engine hasn’t been overly ‘Benzified’ in its European setting and that all the desirable characteristics of the HDEP engine remain.
Back to the road, the pleasant driving environment was enhanced by a number of factors, not least the remarkably stable cab suspension that managed to soak up road anomalies without a hint of the wallow that plagued many a tall-cabbed European truck of the past.
Make no mistake, this is one high cab. Sitting in the seat the driver’s posterior is about two metres above ground zero while there’s around another two metres from there to the roof of the cab. This offers incredibly spacious room for an average height driver to stand up straight, change into jimjams and have a good arms-up stretch before retiring to the comfy innerspring mattress for a good night’s kip. But I wasn’t ready for that just yet, the night was but young and besides, I was busy negotiating the seemingly endless roadworks south of Ballina in northern NSW where you think the 80 speed limit will go on forever.
This did, however, provide a good chance to test out the adaptive cruise control (ACC) which performed faultlessly during the entire trip and proved particularly useful when travelling in a line of traffic such as through the roadworks. The ACC is part of an optional safety pack that includes autonomous braking, lane departure warning and a novel ‘Take a Break’ message that flashed up on the infotainment screen with increasing frequency as the night wore on. I don’t know how, but it seemed to pre-empt when I was feeling a bit doughy and provide the positive reinforcement needed to make me pull into the next available rest area for a breather.