Spacious cab with low entrance
Optimum, safe driving position between axles
Compact dimensions for slim profile
When it comes to the most difficult off-road applications - conditions for which the Mercedes-Benz Zetros has been specifically designed - the cab-behind-engine design emerges as the superior concept, thanks to the optimum driving position it offers, among other things. What use is a vehicle which technically is ideal for speed, but in fact the driver can no longer control it due to the demands of the terrain?
In the cab-behind-engine truck, the driver sits behind the front axle (similar to in a passenger car) rather than over it, and also occupies a lower position. As a result, in the cab-behind-engine truck he is subjected to significantly lower vertical and horizontal loads, and the speed limit at which the driver is still able to remain in control in his seat differs considerably between cab-over-engine and cab-behind-engine trucks. The cab-behind-engine design has a clear advantage in terms of a controlled, safe and ergonomic driving style.
In addition, the body of the Mercedes-Benz Zetros is mounted on the chassis on three points, rather than four points. Thanks to this three-point mounting technique, less distortion is transferred from the chassis to the driver's cab structure. The mounting point is located close to the vehicle's torsional axis which reduces so-called lateral distortion significantly.
Highest level of off-road efficiency and safety thanks to high degree of ride comfort
In practical terms this means that a driver at the wheel of a 4 x 4 cab-over-engine vehicle can only master the demands of a more challenging off-road course roughly half as quick and with some effort - and somewhat less composure - as a driver at the wheel of a 4 x 4 Zetros. In fact, the resulting benefit for the cab-behind-engine truck is generally more relaxed off-road handling, therefore leading in turn to greater driver-fitness reserves and also faster round trip times on longer routes. This also means that the Mercedes-Benz Zetros is always able to reach its destination particularly quickly and safely when this is the burning issue, in both the literal and metaphorical sense: in the case of urgent calls requiring the fire or emergency services, for example, as well as in difficult off-road locations on construction sites, in the energy sector and surface mining.
Furthermore, the cab-behind-engine design also benefits from a variety of other additional advantages which are specific to off-road use. For example, the longer wheelbase resulting from this design also means that overall the vehicle benefits from more favourable leverage ratios. This is noticeable not only in terms of less sliding over the front axle (especially in the case of the three-axle model), but also when driving up extremely steep hills in particular – the front axle of a cab-behind-engine truck is not so quick to lift off (especially when driving off).
And above all when driving down steep hills, through bushy, difficult-to-navigate terrain, or on slippery ground, the cab-behind-engine front end provides a sense of safety. It helps to keep the driver in his position away from trouble, and also provides a particularly ample crumple zone.
Another strong argument in favour of the bonnet relates to access to the windscreen and the engine compartment under the bonnet, which means that the position of the driver's cab does not need to be changed. In the case of applications in areas with extremely adverse weather conditions, among others, such as severe Siberian frost for example: the crew or at least some of its members can remain in the spacious cab, which can be heated by means of auxiliary heaters if necessary, while work which may be necessary on the engine or accessories is carried out, even in locations far from civilisation. Despite its light weight, the bonnet of the Mercedes-Benz Zetros can be fully walked on and therefore provides secure and convenient access for those tasks often typically required when driving off-road, such as cleaning the windscreen.
Maintenance and repair work made easy
Ease of service is unbeatable. In the case of the Mercedes-Benz Zetros, fewer steps are required to gain access to the engine and accessories. The bonnet can be tilted forward with considerable ease, and a torsion spring in the centre of the connection supports the bonnet whilst open.
If necessary, the bonnet can be fully removed simply by undoing a few screws as well as a connector. Cab access is also made easy thanks to a pull-out step on each side, enabling access to be gained to stepping surfaces built into the bumper. Furthermore, an additional platform inside the engine compartment provides a firm footing when carrying out maintenance or repair work.
The bonnet itself is made of glass fibre reinforced plastic, fabricated using the so-called long fibre injection process. A particular feature of this process is that tailor-made section thicknesses can be weight-optimised for specific loads better than when using the regular technique, such as for soaking mats or preforms. Just as with the steel bumper, the bonnet is made up of four parts.
The design of the entire front, in particular the elegant yet robust radiator grille, is based on the design used on Mercedes-Benz commercial vehicles. Echoes of the design of the GL and G models, which has always stood for legendary off-road capability, also underline the off-road credentials of the Mercedes-Benz Zetros from a visual aspect.
Form follows function
Even when it comes to the windscreen, form consistently follows function. The steep angle and moderate overall area guarantee that the driver's cab does not overheat excessively in hot countries.
All of the lights of the Zetros – down to the side indicators – are fitted with protective grilles. The steel bumper is composed of three parts.
The overall external contour of the body is stocky and compact. The total height of the driver's cab is just 2833 millimetres at nominal load and with standard 14.00 R20-size tyres. The maximum external width of the vehicle is 2530 millimetres, yet the bonnet and driver's cab have a significantly narrower appearance, measuring in at around 2300 millimetres in width. Altogether, both the low overall height and the slim body of the vehicle are a bonus for its off-road capability in cramped conditions – especially on hollowed-out trails, for example.
Last but not least, getting in and out in conditions with restricted side clearance is extremely easy in the case of the cab-behind-engine Zetros. The access steps are located behind the front axle, in a position which is as far away as possible from the door hinge assembly.
This means that a relatively narrow door opening angle is sufficient to provide enough room for getting into and out of the Mercedes-Benz Zetros. Its narrow body therefore goes one step further in enabling access in conditions which otherwise would pose a significant problem.
Convenient loading on trains or planes
Thanks to its low overall height, the Mercedes-Benz Zetros is generally highly suited to applications involving low headroom, such as silo loading bays for example. The profile of the driver's cab is also designed in such a way that the vehicle can be loaded for transportation via rail (on a rail goods wagon) and also via air freight. This makes the Mercedes-Benz Zetros a particularly interesting option for international disaster relief applications.
In addition, it supports the straightforward assembly of bodies which by their nature may be required to extend beyond the driver's cab.
Such items would otherwise either exceed the permissible overall height or only be mountable using a complicated folding design. Crane bodies are a typical example of such applications where a particularly low driver's cab is called for.
Convenient access, spacious cab
For driver and crew, the low cab not only provides for safe, convenient access when getting in and out, but also boasts a generous amount of interior space. The low engine tunnel does not impede through-cab access, and behind the seats there is more than ample space to meet a variety of different requirements. When used appropriately, the space from floor to ceiling behind the seats represents a storage volume of around 1400 litres.
The crew is accommodated in three full-size seats which are fitted with integrated safety belts and head restraints. As an optional extra, the Mercedes-Benz Zetros is also available with air-sprung seats. Both types of seats can be freely combined, and come in either a fabric or artificial leather finish. The cockpit with its operating instruments has been inherited from the Axor model series and adapted to meet the more compact installation conditions in the Zetros. The materials used in the interior are easy to clean, practical and typically robust for off-road conditions.
The instruments and switches are presented to the driver in a well-organised, practical and user-friendly manner. The instrument panel comprises a speedometer and rev counter, as well as a fuel/air pressure gauge and a central display. To the right of the steering wheel, and therefore to hand, is the mirror adjustment, the controls for the air conditioning system and also rotary switches for the differential locks and for engaging the off-road gear.
There is also a practical touch in the case of the switch for the differential locks: the driver engages the locks in ascending order as required, as the terrain becomes increasingly difficult. With the initial turn to the first setting, the interaxle differential lock is engaged; at the second setting the rear axle interwheel differential lock is also engaged; and the third setting finally adds the front axle interwheel differential lock to the mix for maximum traction.
Incorrect operation of the interwheel differential locks instead of the interaxle differential lock as the first off-road traction-enhancing measure - which under some circumstances can result in damage when cornering on a relatively high-grip surface - can therefore be totally avoided.
Four front DIN slots beneath the roof can be used to accommodate a variety of equipment, from a tachograph or regular radio, to an on-board two-way radio or similar. In the middle of the armrest support there is an open tray, with a non-slip finish and a raised edge, as well as two integrated cup holders. There is also a bottle holder in each of the door compartments.