The Mercedes Benz Unimog

An off-road institution

While the G-Class also cuts a striking figure as a lifestyle vehicle, the Mercedes-Benz Unimog is a real workhorse. It does duty as a forest fire-fighting vehicle in France, climbs Mount Etna in Sicily as a tourist shuttle and supports the German Maritime Search and Rescue Service as a sea rescue vehicle. In concert with more than 650 Unimog service outlets in over 130 countries, its off-road capabilities and reliability make it a loyal companion around the world. Readers of “Off Road” magazine voted it off-roader of the year in the category “Special-Purpose Vehicles” for what was already the 15th time in a row.

Dr Ralf Forcher, Head of Marketing, Sales and Service Mercedes-Benz Special Trucks: “In a certain sense, our Mercedes-Benz Unimog vehicles are a class by themselves, specialists for the exceptional jobs, with a diverse range of qualities for any conceivable mission. The superior handling of our legendary short-nose Unimogs only comes fully to the fore on the most demanding sections of an off-road route. Our all-round talent also delivers benchmarks in terms of efficiency, service life expectancy and maintenance costs”.

Hard times, unusual solutions – the zero hour of the Unimog

Daimler-Benz engineer Albert Friedrich designed the Unimog in 1946 together with Erhard & Söhne Company from Schwäbisch Gmünd, which originally supplied ashtrays for the Mercedes-Benz saloon cars. The new vehicle was conceived as a “motorized multi-purpose machine” for agriculture. Compared with the farm tractor technology at the time, it had numerous innovations on board. With a top speed of 50 km/h, it was twice as fast as a common agricultural vehicle. In addition, it was fitted with:

• Sprung and dampened axles
• All-wheel drive and front and rear locking differentials
• Brakes not only at the rear axle, but also at the front axle
• A two-seat enclosed cab with padded seats
• An auxiliary cargo bed above the rear axle with 1.0 t load-carrying capacity
• A static weight distribution of 2/3 on the front axle and 1/3 on the rear axle
• Implement attachment options at the front, middle and rear
• Power take-off operation at the front, middle and rear
• Power take-offs for implements

The response exceeded all expectations; series production at Maschinenfabrik Boehringer in Göppingen got the green light in 1949. That is also when the vehicle got its name: Unimog, an abbreviation for the German Universal-Motorgerät or Universal Motor Machine.

The home of the Unimog: Gaggenau in Baden

The demand for the universal genius soon outstripped the production capacities in Göppingen. Starting in June 1951, the Daimler-Benz truck plant in Gaggenau, Baden, became the new home of the Unimog. A fitting place: the first off-roader made in Gaggenau dated way back to 1907.

The first Unimog, the U 25, got along with just 25 hp: Under the bonnet of the vehicle that measures 3.57 metres in length was a four-cylinder engine with a displacement of 1.7 litres. 5846 units of the U 25 were built. The Unimog S marked the first major evolution in 1955. It is still the best-seller among the Unimog models until today. It was powered by a 2.2-litre petrol engine with six cylinders and 80 hp. This engine was also installed in the 220 S luxury saloon at the time. However, its petrol consumption was luxurious as well, which is why the subsequent model series 416 from the year 1965 was produced exclusively with diesel engines.

The Unimog models became a sales hit during the years of the economic miracle. In its 24 years of production, 45,336 units of the U 416 were sold – the Unimog model series with the second-highest sales after the Unimog S. It was used for an accordingly diverse range of applications: as an aid convoy vehicle, on the rails in road-rail specification or even as a patient transport ambulance. In addition, there were variants as a tractor unit or conversions to three-axle vehicles and tracked vehicles.

The 250,000th Unimog came off the assembly line already in 1984. By 2002, Gaggenau produced 320,748 units, with that number standing at over 350,000 units today. An exceptional number for a highly specialized vehicle such as the Unimog. Since 2002, the Unimog production is located at the world’s largest truck assembly plant in Wörth. Since 2006, a dedicated museum in Gaggenau has been exhibiting the fascination that is the Unimog, which can also be experienced there on an in-house test track with a gradient of 100 percent.

Nothing outperforms them in terrain: U 4023 and U 5023

In addition to the Unimog implement carrier, which is a familiar sight as an orange municipal vehicle, there are two variants of the Unimog with extreme off-road capabilities: the U 4023 with a gross vehicle weight rating of 10.3 t and the U 5023 with a gross vehicle weight rating of 14.3 t. In each case, the last two digits stand for the output of 231 hp (170 kW), which is produced by a 5.1-litre four-cylinder engine. Low in comparison to the G-Class at first glance. However, for commercial vehicles it is torque that is crucial. And that is where the Unimog delivers an impressive 900 Nm, which are on tap constantly across the entire main operating range of 1200 to 1600 rpm.

This power pack, the selectable all-wheel drive, the on-demand inter-axle and inter-wheel locks as well as eight forward and six reverse speeds with off-road reduction gear make the Unimog the ” master off the road”. It conquers gradients of up to 45 degrees or 100 percent. It can tilt by up to 38 degrees, which corresponds to a maximum tilt angle of 76 percent and it has a fording depth of up to 1.20 metres.

Such extreme operations are made possible by, amongst other things, the standard-fit portal axles, which result in an impressive ground clearance of 41 cm. Coil springs with their large spring travel allow an axle articulation of up to 30 degrees. That is why a Unimog can have the left front wheel on top of a rock and the right front wheel in a depression – and still maintain ground contact with all four wheels. Another off-road highlight is the “Tirecontrol plus” tyre pressure control system: The right tyre pressure for the particular surface is selected at the touch of a button (“Road”, “Sand” or “Rough Road”) and the Unimog always has the necessary grip as a result.

Around the world in the Unimog

These exceptional abilities also make the Unimog interesting as an expedition vehicle. One example is the U 4023 refined by Hellgeth engineering Spezialfahrzeugbau Company. Its gross vehicle weight rating is just 7.49 tonnes.

This is made possible thanks to systematic lightweight construction in building the box body and the cabinetry and by using lightweight aluminium for mounted parts and rims. As a result, the kerb weight including driver and fuel is just 6925 kilograms, making a dream of many globetrotters come true: They can drive a modern Unimog with camper body and extreme off-road capabilities holding the old “Class 3” driving licence.