Mercedes-Benz has launched a new contender for harsh terrain and heavy loads. The all-new Zetros combines the off-road capability of a Unimog with the load capacity of a heavy-duty truck.

Mark Hopkins, MD for Mercedes-Benz Unimog, is in charge of introducing the chassis to the UK. “The Zetros' forte lies in its design as a cab-behind engine truck, allowing compact and low contours, easy entry and exit and simple servicing. “Additionally it offers notably improved control and significantly higher ride comfort than a cab-over-engine truck, particularly off-road and on poor-quality roads or tracks.”

The components of the Zetros consist amongst others of an in-line six cylinder with 7.2-litre displacement and 240 kW (326 hp) output, manual transmission and transfer case or the planetary axles with parabolic springs and drum brakes. The vehicle has been built especially for off-road use thanks to it's permanent all-wheel drive, three differential locks, single tyres and suspension which is specially tuned to meet the rigours of a demanding application.

This all-wheel-drive cab-behind-engine truck is available as a three-axle Zetros 2733,6x6 and a two-axle Zetros 1833, 4x4. The all-terrain Zetros enjoys a unique position in its segment, complementing the Mercedes-Benz Actros, Axor and Atego truck series.

The concept on which this new all-terrain, all-wheel-drive truck series is based has major advantages over the alternatives currently available on the market, says Mark.

“At the core of the new vehicle concept is the use of well-proven series-production components from the all-wheel-drive variants of the Axor/Actros series, used around the world and modified for off-road application. These are combined with an innovative cab module based on the “Global Cockpit” and the steering system of the Mercedes-Benz Axor. This design concept using these component groups transfers the acknowledged excellence of the ergonomics in the standard truck to an off-road vehicle. The new all-wheel-drive series particularly excels with respect to extreme agility and robustness, as well as outstanding reliability and cost-efficiency,” adds Mark.

The seating position ' behind the front axle ' provides car-like steering characteristics. In conjunction with cab features and controls adopted from large-scale series-production models. According to the manufacturer this enables the driver to be more in control.

The two and three-axle vehicles have a standardised cab that meets the highest safety and ergonomic expectations. In addition to three single seats, there is also room for luggage, kit and necessary tool and equipment.

Mark explains that the cab-behind-engine concept was implemented on this truck to create a greater freedom of movement and superior driving characteristics: “The advantages of a cab-behind-engine concept include a level cab floor with corresponding freedom of movement. Another comfort benefit ' especially off-road ' is the driver's seating position between the axles. The forward-tilting bonnet allows quick and convenient maintenance.”

High level of ergonomics

The Mercedes-Benz Zetros is configured for operations on very difficult terrain, and naturally has permanent all-wheel drive as standard. A two-stage transfer case with an off-road ratio of 1:1.69 increases pulling power by almost 70 % when conditions are extreme. There are also selectable, mechanical differential locks at the rear axle, between the axles and at the front axle. Standard-fit single 14.00 R 20 tyres provide another traction advantage when off-road, as the rear wheels follow the track of the front wheels. The Zetros has a standard fording depth iof 800mm, and optionally as much as 1100 mm with modifications.

The vehicle is powered by the OM 926 LA in-line six-cylinder engine. This compact and lightweight 7.2-litre turbodiesel develops an output of 240 kW (326 hp) and a maximum torque of 1,300 Nm at 1,200 - 1,600 rpm.

Power is transferred by the hydraulically shifted Mercedes-Benz G-131 transmission, which offers eight forward gears and a low-ratio crawler gear. A fully automated 6-speed transmission is also available. The front and rear axles are robust with the potential to carry axle loads of 7.5 tonnes (optionally 9 tonnes) for the front axle and 9 tonnes for the rear axle(s). The use of drum brakes and leaf springs all-round is in line with the tough operating conditions to be expected, and ensures ease of repair even in unfavourable circumstances.

“The concept underlying this new all-terrain, all-wheel-drive truck family from Mercedes-Benz has distinct advantages over other products already available in the market,” says Mark. “The new concept is based on the use of modified all-wheel-drive Actros chassis from series production, which are married to the new cab module. The use of components from large-scale series production ensures the global availability of replacement parts and service within the Mercedes-Benz Service organisation, which has nearly 5,000 outlets in160 countries of the world.”

Flexible concept: other configurations also possible

The Mercedes-Benz Zetros is available with a wheelbase of 4,800 mm (two-axle 4x4 models) or 6,200 mm (three-axle 6x6 models). The chassis weights are 8.6-tonnes and 10.5-tonnes respectively, with permissible gross vehicle weights of 16/18-tonnes for the 4x4 and 25/27-tonnes for the 6x6. The standard platform body has a length of 5.1-meters or 6.2-meters.

The new Zetros is produced at the Mercedes-Benz truck plant in Wörth, Germany.