If you’re a regular reader of Biglorryblog you’ll know that way back in November I gave you a tantalizing glimpse of the Mercedes’ Arocs, the new range of construction trucks from the German truck maker. Well it’s now been officially launched in all it’s ground-breaking glory for all those operators looking for a bullet-proof Euro-6 tipper, mixer or heavy-duty tractor. Yes that’s right you can get an Arocs as a two, three or four-axle rigid or tractor with no less than 16 power outputs to choose from starting at 238hp and going right up to a throbby 625hp provided by the all-new OM 473 in-line six, 15.6-litre big-banger which offers a maximum torque of up to 3,000Nm. It takes over from Merc’s previous V8 and has been developed to provide the kind of maximum power and durability needed in trucks operating on severe-duty cycles. How much power? According to Mercedes under full load the OM 473 can deliver around 2,500Nm at a little more than idle speed in all versions and it adds: “This is a higher level of torque than the maximum achieved by most truck engines.” The guys from Stuttgart go on to say: “On the test bench, the highest torque of all of the OM 473 variants is available at 1,100 rpm. In the real world, almost the entire tractive power is available across a wide range from around 900 to 1,400 rpm. Immediately thereafter, the engines reach their maximum output.” I can’t wait to have a go with it!
One of the special features of the new OM 473 engine is turbo-compound technology with a second blower connected in series after the exhaust gas turbocharger. Merc explains: “It also makes use of the available pressure of the exhaust after flowing through the exhaust gas turbocharger to further increase performance. This power is transferred to the engine's gear drive, and thereby directly to the crankshaft, via a shaft and hydrodynamic clutch. Turbo-compound technology increases the output of the OM 473 by around 50 kW (68 hp). The driver is able to feel the additional performance immediately via the already spontaneous response of the engine at low engine speeds.” Equally important is the fact that “At the same time, a reduction in fuel consumption of around 2% is achieved under high load. Depending on the version, consumption is between 0.5 and 1.5% lower than the preceding V8 OM 502 engine.”
The new OM 473 is available with three power/torque output:
Power output Maximum Torque
380 kW (517 hp) at 1,600 rpm 2,600 Nm at 1,100 rpm
425 kW (578 hp) at 1,600 rpm 2,800 Nm at 1,100 rpm
460 kW (625 hp) at 1,600 rpm 3,000 Nm at 1,100 rpm
However, if you’re looking for something a bit less roarty there’s always the 7.7-litre OM 936, the 10.7-litre OM 470 and the 12.8-litre OM 471 BlueTEC 6 diesels to put in your Arocs.
The OM 471 is available with four power output and torque ratings
Power output Maximum Torque
310 kW (421 hp) at 1,800 rpm 2,100 Nm at 1,100 rpm
330 kW (449 hp) at 1,800 rpm 2,200 Nm at 1,100 rpm
350 kW (476 hp) at 1,800 rpm 2,300 Nm at 1,100 rpm
375 kW (510 hp) at 1,800 rpm 2,500 Nm at 1,100 rpm
Four versions of the OM 470 are available in the Arocs
Power output Maximum Torque
240 kW (326 hp) at 1,800 rpm 1,700 Nm at 1,100 rpm
265 kW (360 hp) at 1,800 rpm 1,800 Nm at 1,100 rpm
290 kW (394 hp) at 1,800 rpm 1,900 Nm at 1,100 rpm
315 kW (428 hp) at 1,800 rpm 2,100 Nm at 1,100 rpm
Last but not least the OM 936 is available with five power/torque ratings
Power output Maximum Torque
175 kW (238 hp) at 2,200 rpm 1,000 Nm at 1,200 – 1,600 rpm
200 kW (272 hp) at 2,200 rpm 1,100 Nm at 1,200 – 1,600 rpm
220 kW (299 hp) at 2,200 rpm 1,200 Nm at 1,200 – 1,600 rpm
235 kW (320 hp) at 2,200 rpm 1,300 Nm at 1,200 – 1,600 rpm
260 kW (354 hp) at 2,200 rpm 1,400 Nm at 1,200 – 1,600 rpm
But whichever engine you go for all engines already comply with the Euro 6 emissions standard. They also feature Blue-Efficiency Power with common-rail injection, a closed particulate filter system and exhaust gas recirculation. Arocs will also be offered with two specific ‘mission-matched’ models called the ‘Loader’ and the ‘Grounder’ with the former line-up including “…payload-optimised 4x2 tractor units which are among the lightest vehicles in the construction sector, as well as 8x4/4 concrete mixers with the lowest possible kerbweight, able to transport the maximum amount of concrete on every trip.”
The Arocs Grounder is designed for operating in extremely difficult conditions, such as in quarries or on building sites and has been duly beefed up with 9mm thick main rails, and particularly high levels of stability and a high load carrying capacity. The Arocs rigid range starts at 18-tonnes and goes up to 41-tonne off-road eight-wheelers with a choice of diferent steel and air suspension packages.
New ‘ex-works’ there’s also a four-axle 8x4/4 ‘tridem’ with a single steer axle up front, and a double-drive bogie and trailing rear-steer axle at the back. Merc says: “Possible areas of application for it include trucks with a large rear mounted loading crane for example, which are required to operate on their own. A three-axle vehicle, or even a classic four-axle variant, would not be able to cope with the rear position of the loading crane due to the load distribution. Thanks to the triple solution at the rear, however, all axle loads can be handled without a problem.”
The transmission choice in all variants of the Arocs is the fully-automated, fast-acting Mercedes PowerShift 3 transmissions with eight, 12 or optionally 16 gears. They facilitate the work of the driver considerably, particularly with regard to tough manoeuvring or harsh off-road applications. As an option, regular manual transmissions with nine or 16-gears are available at extra cost. The latest PowerShift 3 auto has shorter shift times, which are up to 20% quicker compared with the previous PowerShift 2 box and even up to 50% compared with the old Telligent auto. With its sensitive shift sensor system, the Mercedes PowerShift 3 ensures a precise selection of gears suitable for the respective driving and load conditions.
Merc describes the PowerShift 3 auto as a “Smart sensor system for all situations. One feature is the ability to detect overrun mode on downhill gradients and as a result maintain the gear. The new crawl function (increased starting torque) with the integrated maneuvering mode enables particularly easy moving off and precise, defined maneuvering. In addition, different transmission modes and additional functions make driving in construction traffic simpler. The rocking-free mode, for example, enables vehicles which become stuck in muddy, boggy conditions to free themselves. The direct-shift mechanism which enables direct shifting from first to reverse – without having to shift via neutral – is yet another advantage. For quick reversing, for example when working on motorway construction, particularly ‘fast’ reverse gears are also available.”
Depending on the model Arocs comes with either an off-road or power transmission driving program, or as an option can also be ordered with the other respective driving program. Both driving programs each feature three transmission modes. Standard mode, including the standard eco-roll function, generally supports a particularly economical driving style for on-road use. Manual mode enables complete control of the Arocs in extreme off-road terrain. In the power driving program's "power mode", gear changes are carried out with an increase in engine speed of 100 rpm compared with standard eco-roll mode. Power mode is automatically deactivated when no corresponding torque is available to be called upon. The off-road driving program's ‘off-road mode’ is characterised by the Arocs permanently having increased torque at its disposal.
Particularly important for short-distance haulage and construction transport, with its high share of low-speed driving and maneuvering in restricted deployment locations, is the transmission's crawl mode: when start-off or reverse gears are selected, the driver can control the speed of the new Arocs by means of the brake pedal alone. A further support feature when maneuvering is the option to be able to shift directly from first gear into reverse.
Representing a world first in the commercial vehicle sector is the new Servotwin electro-hydraulic steering for four-axle vehicles. It features speed-sensitive power-assisted steering and active steering return. This newly developed technology, which is fitted as standard in heavy-duty vehicles and available as an optional extra in light-duty vehicles, opens up a world of previously unattainable steering comfort and maximum steering precision. Now throw in better ground clearance, new wheelbases, new axle positions and the latest 2.3m wide cab with a grille that mimics the teeth on an excavator bucket and you can see why Merc is so excited about its new construction kitten and when I’ve driven it I’ll let you know what I think of it.