Mercedes-Benz
Unimog U 4023 and U 5023
The
toughest sections of the off-road course south of Berlin really highlight the
familiar strengths of the legendary short-nosed Unimog: its outstanding
handling characteristics in difficult terrain. In the new generation, these
have been improved even further, thanks to the altered position of the engine.
In
2013, Mercedes-Benz introduced diesel engines for the entire commercial vehicle
range which conformed to the Euro VI emissions standard well ahead of the norm
coming into enforcement. At the same time, the extreme off-road version of the
Unimog also underwent a complete redevelopment to feature a mid-engine design.
The engine has been shifted a metre to the rear, which helps not only
accommodate the assemblies that Euro VI made necessary, but also enables direct
power take-off from the engine. This means that devices can work independently
of the vehicle being driven. Transmission power take-off also remains possible.
The
Euro VI diesel engine is the heart of the new mid-engine concept. The engine
used here is the new high-torque OM 934 BlueTec 6 engine; a four-cylinder unit
with an output of 170 kW (231 hp) and a displacement of 5.1 l. Exceptionally
efficient, the assembly provides a higher torque of 900 Nm, which is available
consistently over the entirety of the principal driving range from 1200 rpm to
1600 rpm. The technical top speed of 90 km/h is quite adequate for longer
journeys and motorway driving.
Despite
the added engineering complexity required to meet the Euro VI criteria, the new
all-terrain Unimog combines low fuel consumption with reduced emissions, great
reliability, a long life expectancy and long maintenance intervals. Alongside
cooled exhaust gas recirculation within the engine, emission control features a
successively switched system comprising a closed particulate filter, AdBlue
injection and an SCR catalytic converter. A particularly positive aspect: for
the new Unimog with Euro VI engines, fuel consumption has been reduced by up to
three percent. This means that the engines, which already produce up to 90
percent less emissions and particulate matter than the previous models, are
even more environmentally friendly.
The
transmission of the Unimog has been optimised and uprated, resulting in shorter
shift times whilst also extending its service life. The transmission is
operated via a steering-column lever, which is also used to control the
electronic quick reverse (EQR) function. As in the previous version, eight
forward and six reverse gears are available and there is also an optional
off-road group for off-road use in the speed range between 2.5 and 35 km/h.
Safety
has also been improved: the new engine brake is a double-speed decompression
brake which, in the case of the OM 934, develops braking power of up to 180 kW.
Each cylinder in the engine has its own engine brake unit. The high braking
efficiency considerably reduces wear and tear on the wheel brake systems, thus
greatly improving the overall economy. Offroad ABS comes as standard.
As
with all Mercedes-Benz commercial vehicles, the new model designations of the
big Unimog include the horse power number: 230 in this case. The first two
digits of the designation stand for the vehicle type. The biggest differences
between the two models come in the form of the axles and frames, which thus
affect the axle loads and gross vehicle weight. In the case of the U 4023, this
is a maximum of 10.3 t, for the U 5023 a maximum of 14.5 t.
This
cab is a classic – it has been instrumental in defining the appearance of the
Unimog since 1974 – today it shapes the appearance of the Unimog extreme
off-roader. The standard-production version of the cab is now 120 mm longer
than its predecessor and it is also slightly higher. Together with the
relocation of the transmission controls from the centre console to the
steering-column lever, this results in substantially more generous space
conditions inside the cab. Inside, the Unimog benefits from a new range of
equipment including a multifunction steering wheel, adjustable steering column,
steering-column lever, multifunction buttons, instrument cluster with a large
display, and an upgraded heating and ventilation system, all of which create
optimum conditions for the driver. The changed position of many controls in the
overhead console makes it much easier to move across from the driver's to the
co-driver's seat. Also, the seat position in the low-vibration area behind the
front axle together with the new cab mounting concept make for comfortable
driving, particularly off-road. All in all, the driver and passengers can enjoy
real truck comfort in the new Unimog, which is not something to be taken for
granted in a specialist vehicle of this type.
The
Tirecontrol plus tyre pressure control system has been completely redesigned.
The preconfigured tyre pressure for the type of deployment can now be set
simply and conveniently on the display by selecting the appropriate programmes.
"Road", "Sand" and "Rough Terrain" modes are
preset. On the outside, the dynamically designed radiator grille and the new
bumpers featuring state-of-the-art lights clearly indicate that a new Unimog
generation is in operation here. The lamps not only look good, they also
provide better vision, thanks to a broader light cone, increased range and
daytime running lamps. If desired, a new camera monitoring system can also
optimise all-round vision, particularly in the region directly in front of the
vehicle – a particular plus, for example, when operating a winch or connecting
front implements.
The
cab access concept has also been fully revised and the cab is now accessed
safely and comfortably via two or three steps, depending on the customer's
requirements. The Unimog cab can be tipped to simplify maintenance and repair
tasks. In the new model series, the Unimog extreme off-roader remains available
ex-factory with the characteristic crewcab which offers space for up to seven
people.
The
great advantage of the Unimog extreme off-roader – its outstanding handling in
heavy terrain – remains unimpaired. Indeed, in some respects its strengths have
been further extended. The fact that the frame and the tubular cross-member of
the Unimog is welded guarantees its exceptional robustness and torsional
flexibility of up to 600 mm when driving off-road. The axle articulation of up
to 30 degrees is made possible by the use of torque tube technology in
conjunction with coil springs, whereby the torque tube and the torque ball are
used to connect the axles to the transmission. Portal axles, the low centre of
gravity and extremely good angles of approach and departure (44 degrees at the
front, 51 degrees at the rear), as well as the ramp angle (34 degrees) and its
slope-climbing ability (45 degrees) all add up to make the Unimog extreme
off-roader a true off-road professional. In addition to this there is the
maximum fording depth of 1.20 m and a lateral inclination angle of up to 38
degrees. Driving in extreme situations with the all-wheel drive system engaged
is supported by the selectable differential locks and the tyre pressure control
system. Single tyres have always been part of the Unimog concept; the rear
wheels follow precisely in the tracks of the front wheels and are thus able to
take advantage of the firmer surface compacted by the front wheels.
The
Mercedes-Benz Unimog is a robust and reliable vehicle designed for a long
service life. The completely welded frame and the encapsulated chassis
components indicate that these vehicles are designed to cope with the highest
levels of stress and strain. The axles are reinforced and all key assemblies
are protected or are located in protected areas – and this is also true for the
fording ability up to the guaranteed depth of 1.20 m. And if things get too hot
in fire-fighting situations, the optionally available heat shielding provides
appropriate protection. It protects all of the important lines, the AdBlue
tank, catalytic converter, battery and the brake assemblies from high
temperatures.
All
this explains why the Unimog extreme off-roader enjoys such an excellent
reputation around the world. Off-road deployment in extreme conditions is the
order of the day for these vehicles. For clearing heavy snow, fighting forest
fires, disaster relief, crane operations, pipeline construction, on
expeditions, on rescue and recovery missions, and last but not least, in
passenger transport – the natural habitat of the U 4023 and U 5023 begins where
roads give way to rough tracks and open country. An array of equipment
developed by specialist equipment and body manufacturers means that the Unimog
can master difficult tasks, even in tough terrain.
Despite
the challenges posed by the Euro VI norm, the conceptual advantages of the new Unimog
extreme off-roader generation have not been hindered, in fact they have been
extended even further. Despite being a unique vehicle concept, the Unimog still
benefits from its proximity to the series-production Mercedes-Benz truck
models. As a result of concentration and being able to share the production
processes at the Wörth plant, the result is highly efficient manufacture,
guaranteed high quality and swift access to spare parts.
Around
the world, 650 service outlets in more than 130 countries stand ready to
provide maintenance and repair services. Special financial and other services
round off the overall package.
