Extra traction under tough conditions
As soon as the new Sprinter series had been launched by Mercedes-Benz, work got underway to develop an all-wheel-drive system for the range. JARLATH SWEENEY went to the Arctic to test it!
The new Sprinter 4×4 is a van for a broad selection of commercial users that work on construction sites and dirt tracks, as well as in the mountains, snow-prone regions and muddy fields.
Its all-wheel-drive system could not be simpler to operate. It can be engaged at the press of a button and the 4ETS (Electronic Traction System) then takes over. All the driver has to do is accelerate and steer carefully and let the technology take care of the rest. The all-wheel drive is integrated into the standard-fit Electronic Stability Program (ESP) and complements the safety systems provided.
Four-wheel drive can be engaged using a switch on the instrument panel when the engine is running and the vehicle is stationary, or when travelling at low speeds of up to 10 km/h. An indicator lamp in the switch informs the driver that the all-wheel drive is engaged.
In contrast to other systems of this type, the Sprinter’s all-wheel drive does not provide a rigid through-drive. The power is transmitted variably; all the components of the standard-fit ADAPTIVE ESP remain operational when all-wheel drive is selected.
When all-wheel drive is engaged, the drive power of the Sprinter 4×4 is split in a ratio of 33 to 67 percent between the front and rear wheels in normal operation, ensuring handling performance practically on a par with the Sprinter’s usual rear-wheel drive in everyday operation.
The Sprinter 4×4 model’s all-wheel-drive system works with the 4ETS instead of with mechanical differential locks: should one or more of the wheels lose traction, 4ETS brakes the spinning wheels automatically with short pulses, and increases the drive torque at the wheels by the same amount, thereby offering good traction.
Automatic brake application, by means of 4ETS, has the same effect as up to three differential locks: the inter-axle lock, the rear axle lock and the front axle lock. The engineering employs the same basic principle as the all-wheel drive on the new Vito 4×4. In view of the fact that the Sprinter 4×4 is usually deployed in rougher applications, however, it does without the finer touches such as the pre-loaded multi-disc clutch between the front and rear axle.
For off-road use, the optional “Low Range” reduction gear is additionally available. Engaged at the push of a button – when the vehicle is stationary, the 4×4 drive activated and the clutch and brake pedals pressed – the ratio is shortened by a factor of 1,42, or 42 percent. The maximum vehicle speed obtainable in the individual gears is reduced accordingly, while tractive power is increased by the same factor.
In addition, the Sprinter 4×4 is available with the option of Downhill Speed Regulation (DSR), which ensures that a preselected speed is maintained constantly when driving downhill. Again, DSR is activated using a button in the cockpit. The speed is then controlled using either the accelerator and brake or the stalk for the cruise control.
The 4ETS is fully integrated in the Adaptive Electronic Stability Program (ESP). The control characteristics have been adapted for all-wheel drive and all of the Adaptive ESP functions are retained when the all-wheel drive is engaged.
One particularly important aspect of the many Sprinter body variants and attachments is the load and centre-of-gravity detection feature; Load Adaptive Control (LAC). In the case of special-purpose bodies, for example, Adaptive ESP detects the position of the centre of gravity, based on the vehicle’s movements, and adapts the control characteristics accordingly.
Although the Sprinter 4×4 is not an off-roader, it has a raised body (by 110 mm at the front and by 80 mm at the rear) to provide adequate ground clearance.
Depending on the specific model version, the all-wheel drive in the Sprinter 4×4 results in a weight penalty of just 115 to 135 kg. This comparatively low increase is down to the 4ETS all-wheel-drive technology that does without heavy mechanical differential locks.
Two power outputs of 96 kW (129 hp)/305 Nm and 121 kW (163 hp)/360 Nm from the Mercedes-Benz Euro-6, 2,15-litre, BlueTec diesels are the main options for the 3,5- and 5,5-t 4×4 Sprinter – be it panel van, bus or chassis/cab.
For those seeking even more power, the 3.0 CDI, with 141 kW (190 hp) and 440 Nm, is also offered. These engines are mated to a six-speed manual or five-speed automatic transmission.
On the drives undertaken along selected routes surrounding Arvidsjaur, Sweden, the surefootedness provided by the excellent traction from the four driven wheels, and the fact that only winter tyres (not snow tyres with studded caps) were used, impressed most.
As regular readers of FOCUS know, this magazine has been appointed an associate member of the International Truck of the Year (IToY)! FOCUS is the sole South African magazine to have joined this prestigious body. One of the advantages of this association is access to exclusive articles, specially written for FOCUS by ITOY jury members. This is one such article.