Test Driving the Mercedes-Benz Arocs
Trial drive with the Mercedes-Benz Arocs With or without all-wheel drive: The type of use determines the drive configuration
- Overview of PowerShift features
- High on payload: semitrailer/tractor combination with 4x2 tractor
- New: Hydraulic Auxiliary Drive
- As and when you need it: manually selectable all-wheel drive
- Off-road specialist: four-axle 8x8 with all-wheel drive
- All-purpose vehicle: 6x4 or 6x6 three-axle dumper
In order to assist the Arocs driver in the most diverse everyday situations, Mercedes PowerShift Offroad is equipped with a host of smart functions. Particularly useful features in off-road use are:
- offroad driving mode
- rocking-free mode
- four reverse gears
- fast forward-reverse shifting
- crawl function
- load-dependent rpm increase
In on-road use, assistance is provided by:
- cruise control with flexible hysteresis
- the EcoRoll function
- the crawl function
Drive configurations for off-road use
The multifunction display indicates when the various driving and operating aids are active or inactive.
Special operations call for special vehicles. On-road or off-road is one criterion, quantities and transport frequencies are others. Mixed usage of a vehicle model for diverse transport tasks on various routes imposes different requirements on the rolling stock in comparison to transportation of the same material on the same routes at all times.
When transporting large quantities of bulk materials such as gravel or sand on paved roads, for example, the prime requirement is payload capacity. Light-duty means of transport are called for here. The appropriate tractor vehicle is usually a semitrailer tractor from the Arocs family in standard 4x2 drive configuration.
The new "Hydraulic Auxiliary Drive" covers predominantly road-oriented use with an occasional requirement for increased traction. With this new all-wheel-drive variant, manually selectable, hydrodynamically driven wheel hub motors provide the drive power for the front axle, rather than mechanical propeller shafts. This saves weight and fuel – with weight savings to the tune of half a tonne in relation to permanent all-wheel drive for heavy-duty off-road use alone.
Manually selectable all-wheel drive as a good compromise
When the requirements regarding payload and fuel economy outweigh traction needs, manually selectable all-wheel drive without low-range gear is available as a second variant. Here the front axle is engaged via the transfer case while the vehicle is stationary. The cardan shafts are then connected to front and rear at a ratio of 1:1.
All-wheel drive makes sense for semitrailer tractors, too
When a semitrailer/tractor combination is to be used in more demanding terrain with a degree of regularity, a semitrailer tractor with permanent 4x4 drive should be considered. The classic all-wheel-drive Arocs fits the bill here in the commercial vehicles range from Mercedes-Benz. Permanent all-wheel drive – with inter-axle and inter-wheel differential locks as standard – enables this semitrailer tractor to cope more effectively with demanding terrain than the previously described tractors.
A popular alternative to the semitrailer/tractor combination – comprising a two-axle tractor and three-axle semitrailer – is the off-road-capable 6x4 tractor with a two-axle semitrailer in tow. The payload is slightly lower here, of course, but the degree of traction is substantially higher.
Upgrading the three-axle tractor to a 6x6 all-wheel-drive vehicle promises even better off-road performance. The driven front axle benefits cornering performance in particular. The new manually selectable all-wheel drive will come as standard, with permanent all-wheel drive available as an option.
Four-axle vehicles covering a diverse spectrum of operations
When transport tasks become even more difficult in yet more demanding terrain, a four-axle vehicle really is a must. While a single rigid vehicle is not the preferred option for on-road use only, on account of the lower payload, it has long been established as the no. 1 choice for mixed on and off-road use and in restricted space conditions. Reversing around various corners to the loading or unloading point is indisputably easier with a single vehicle than with an articulated combination.
The standard formula for four-axle vehicles in light to heavy-duty use is 8x4, while 8x8 is unbeatable for tough assignments. The 8x6 configuration is additionally available as a compromise.
A smaller but more versatile option is the classic three-axle vehicle. The classic three-way dump truck is in much more frequent use in this configuration than as a four-axle variant. It is in widespread service in many fleets as a 6x4 dumper. As a tractor – usually with a centre-axle tandem trailer in tow today, rather than the fifth-wheel trailer that used to be common – it provides a particularly economical means of transporting bulk materials or excavated soil from A to B by road before moving on to construction site C for off-road use without a trailer in tight operating conditions. Equally, this three-axle dumper is also at home pulling a medium-duty low-loader with an excavator lashed down on board. Or – upgraded to 6x6 – it can be used to overcome virtually insurmountable obstacles in difficult terrain.
In keeping with the previous model series, there is only one logical lock control here, in the form of the rotary switch which engages the inter-axle and inter-wheel lock in succession. Starting from the "Off" position with completely open differentials, the switch can be moved as necessary to position 1. The rotational speed compensation function hindering good traction is then deactivated, after which the rear inter-wheel locks are applied. When this is still not sufficient, the inter-wheel lock on the front axle is additionally applied in switch position 3. This enables the driver to work the vehicle free in the vast majority of cases – and straight wheels are recommended anyway in such precarious situations.