Mercedes-Benz History: An In-Depth Look at the Mercedes Unimog

Words Jim Davis | September 14, 2010
An in-depth history and model range of the legendary Mercedes-Benz Unimog complete with photos
Words Jim Davis September 14, 2010

There are quite a number of automotive legends – most of them already covered by the dust of history, not so the Mercedes-Benz Unimog. Launched during the hard times immediately after the end of World War II, the indestructible Unimog has long since become one of the living legends in automotive engineering. The Unimog holds its ground in the face of assignments under the most arduous conditions, changing economic settings and changing customer groups. Small wonder: the Unimog copes with extremely difficult ground, pulls complete goods trains, can be used as a road/railer and features attachment points for a large variety of implements.

Hard-working jack-of-all-trades right from the start

The Unimog has proved itself as a hard-working jack-of-all-trades anywhere in the world for many decades. What has remained is its basic design concept: enormous versatility for assignments of virtually all kinds, superior off-road mobility thanks to its all-wheel drive, portal gear axles and differential locks front and rear, a compact cab, outstanding robustness and the possibility of attaching a multitude of working implements.

First drafts as early as 1945

The first drafts of an agricultural vehicle, made by Albert Friedrich who had previously been Head of Aeroengine Design at Daimler-Benz, date back to the autumn of 1945. Friedrich assembled a committed team of development engineers and won over Messrs. Erhard & Sons in Göppingen, Germany, as development partners. Large-scale production began in 1948 at the mechanical engineering factory of Messrs. Boehringer in Schwäbisch Gmünd. Since high investments had to be made to reach economically viable production volumes, the project was taken over by Daimler-Benz in the autumn of 1950 – production in the Gaggenau plant started in 1951.

From 1953, the Unimog was decorated with the Mercedes star; in the same year, a fully enclosed cab complemented the previous version with folding top. Two years later, the Unimog S set out on its impressive career: it was soon highly popular among armed forces and, later on, also among civilian users, particularly among globetrotters and members of expedition. Produced until 1980, it became the bestseller in Unimog history.

Additional series to meet rising demands

As requirements became more demanding and diversified, Daimler-Benz expanded the Unimog range by the larger 406 series from 1963. In 1972, Daimler-Benz resumed the original idea of an agricultural vehicle – and for many years, the Unimog was joined by the MB-trac agricultural tractor. Only two years later, the first units from the 425 series – heavy-duty Unimogs for particularly demanding tractor work – came off the assembly lines.

From 1985, Daimler-Benz replaced the entire Unimog range in several steps. A few years later, the top-of-the-range Unimog U 2450 L 6×6 was launched, a three-axle vehicle with an impressive engine output of 177 kW (240 hp). From 1992, the company offered the new lightweight and medium-duty 408 and 419 series, which were particularly suitable for municipal work. Shortly afterwards, the Funmog – a conspicuously designed and elegantly equipped Unimog, which also cut a fine figure outside the disco in the evening – assumed the status of a cult vehicle. The small UX 100, a compact implement carrier, predominantly appealed to municipal authorities from 1996.

Into the future with the new U 300 – U 500 series

The new Unimog U 300, U 400 und U 500 available since 2000 are also tailored to municipal work. The vehicles combine spectacular looks with a practical as well as attractively designed cab made of fibre composite materials, a driver’s workplace called VarioPilot that can be moved from left to right and back again within seconds, a new VarioPower high-performance hydraulic system and engines with output ratings up to 205 kW (280 hp) – the new Unimog for the new millennium can do even more than any of its predecessors and meets the most diverse demands of a heterogeneous clientele.

Complete Unimog range

  • 1963: Unimog 406, start of the medium-duty series
  • 1966: New range structure
  • 1972: MB-trac – new approach to agricultural tractors
  • 1974: The U 120 introduces the heavy-duty series
  • 1976: Range expansion and new designations
  • 1985: Start of the new 407 – 437 series
  • 1992: The new 408/418 series
  • 1993: Funmog – going to the disco by Unimog
  • 1996: UX 100, the little one for municipal authorities
  • 2000: New U 300 – U 500 Unimog generation

In the early sixties, the small basic Unimog alone was no longer capable of meeting the growing demands and covering the ever more diversified range of assignments. The Unimog S, first and foremost a military vehicle, was not always the right alternative for civilian applications, even though it was available in finishes other than olive green. Therefore, the company launched a medium-duty series with the designation 406 in 1963. The wheelbase of this new, additional Mercedes-Benz Unimog was 2380 millimetres long.

Opening up new dimensions: the 406 series

At the same time, larger diesel engines were for the first time installed under the Unimog’s short bonnet: 65 hp generated from four cylinders and a little later even from the legendary, large-volume OM 312 six-cylinder diesel engine with a displacement of 5.7 litres – setting a new standard in performance. With reference to its hp rating, the new Unimog became known as the U 65. With the additional 406 series, Daimler-Benz complemented the Unimog range by a genuine jack-of-all-trades for use on and off the road, permitting completely new applications, for instance as a versatile tractor.

406 series rapidly joined by additional model series

In 1966, the company restructured the Unimog range. The small Mercedes-Benz Unimog U 34 was joined by the medium-duty 406 series with the U 70 model, which, at a later stage, developed into the U 80 and U 84 as engine output increased – figures relating to engine output in hp in each case. Parallel to this, Daimler-Benz introduced the 416 series with 2900 millimetre wheelbase corresponding to the Unimog S. The series initially consisted of the U 80 which developed over the years into U 90, U 100 and finally into the powerful U 110.

In addition, Daimler-Benz introduced the lightweight 421/403 series, complemented at a later stage by the 413 series, to fill the gap between the original Unimog and the medium-duty series. These new series differed in terms of their wheelbase lengths and their engines, which were adopted from the car range (421 series/U 40 with 2.2 litre displacement) as well as from the commercial vehicle range (403 series/U 54 with 3.8 litre displacement). The output ratings of these models, too, rose continuously until the renewal of the range in 1977.

Unimog complemented by a specialist farm tractor: the MB-trac

This rapid progress in model policy, which may not have been easily comprehensible at all times, resulted in another anniversary: production of the 100,000th Unimog in May 1966. During its career over almost 20 years, the Unimog had developed magnificently ever since the days the first chassis prototype had been completed. It had long since acquired a legendary offroader reputation throughout the world. As successful as the Unimog may have been, it was only rarely used in agriculture. To cover this market segment, Daimler-Benz therefore launched an additional vehicle in 1972: the MB-trac.

The new agricultural tractor combined Unimog engineering, including all-wheel drive and power transmission to four equal-sized wheels, with the looks of a tractor: a long and very narrow bonnet and behind it an angular, high-rising driver’s cab. Contrary to conventional tractors, however, the cab was located between the axles and fully enclosed.

Within just a few years, the initial MB-trac 65 and MB-trac 70 (later 700) models developed into a broad series right up to the extremely powerful MB-trac 1500. In spite of this, the MB-trac failed to become a great hit. Daimler-Benz eventually integrated the MB-trac in a joint venture with the agricultural machinery unit of Deutz. Production of the MB-trac was discontinued in 1991.

425 series: the new, big Unimog

The next new Unimog series emerged in 1974, two years after the MB-trac. Large-scale production began in 1975: the U 120 from the 425 series was the heavy-duty top model in the range of versatile tractors and working machines from Daimler-Benz. Its conspicuous features included a new, angular cab and a large bonnet set at a flat angle. The latter ended in a large-surfaced, black radiator grille. This cab design has basically remained unchanged for the last 25 years.

The 425 series initially included a 120 hp model (boosted shortly afterwards to 125 hp in the U 125) with 2810 millimetre wheelbase and a permissible gross weight of nine tonnes. Also in 1975, production of the 435 series as the successor to the Unimog S began for the German armed forces; these vehicles had wheelbase lengths of 3250, 3700 or even 3850 millimetres. From 1976, the 424 series fitted into the range somewhat further down below.

New model designations to create a clear structure

At about the same time, Daimler-Benz introduced new model designations. The models with the rounded, meanwhile classic shapes were the Mercedes-Benz Unimog U 600/L, U 800/L, U 900 and U 1100/L. New angular shapes were the hallmark of the Unimog U 1000, U 1300/L, U 1500 and the flagship, the U 1700/L with 124 kW (168 hp) engine. The letter “L” indicated the long-wheelbase version – the majority of models were meanwhile available in two wheelbase lengths.

The Unimogs with rounded cabs belonged to the lightweight series, the new models with angular cabs made up the medium-duty and heavy-duty series, the division being made on the grounds of permissible gross weight. Several engines were available for different series – the Unimog designation system was not easy to understand. And finally, the range was still complemented, though in declining numbers, by the tried-and-tested Unimog S, the only one with a petrol engine.

Disc brakes in Unimogs long before their introduction in trucks

Clearly more easily understandable were the technical highlights: with the exception of the bottom-of-the-range model, all Mercedes-Benz Unimogs were fitted with disc brakes all round at the time the new model designations were introduced – long before this safety equipment became state of the art in trucks. The efforts of the Unimog people to give every customer the model he or she needed paid off in the form of another record figure: in 1977, the 200,000th Unimog was produced.

Complete renewal with the 407, 417 and 427 series

In the following years, the Unimog range remained largely constant. But then, between 1985 and 1988, new models were again launched one after the other: Daimler-Benz completely replaced the entire range by the 407, 417, 427 and 437 series. The cab from the medium-duty and heavy-duty series was now also used for the lightweight models. New wheelbase lengths, dimensions, weights, chassis and engines under the cabs’ sheet metal skins resulted in completely new vehicles.

After this renewal, the range was larger than ever before, extending from the lightweight, particularly easily manoeuvrable Mercedes-Benz Unimog U 600 with an output of 44 kW (60 hp) and a gross weight of 4.5 tonnes via countless versions – the result of further expansion in the early nineties – to the three-axle U 2400. Its engine developed a new record output of 177 kW (240 hp) from a displacement of six litres. The two-axle version’s permissible gross weight was 14 tonnes.

Output increased almost tenfold since the beginning

From 1993, the range was rounded off at the top end by the Unimog U 2450 L 6×6, a three-axle unit with all-wheel drive. The people who had developed the first Unimog more than 40 years earlier would certainly not have dared dreaming of such models – if anything, a comparison of engine output is worth its while: from the first Unimog to the new top model, it had increased almost tenfold.

Completely new series for new customers

Shortly after the renewal of the Unimog range between 1985 and 1988, Daimler-Benz started a new innovation drive in 1992. New lightweight and medium-duty series, the 408 (U 90) and 418 (U 110, U 140), replaced their still rather youthful predecessors. Their most conspicuous feature was the completely redesigned cab, with a front section set at a very steep angle to provide the driver with an excellent view of the area ahead of the vehicle. On request, the bonnet even featured an asymmetrical cutaway section on the driver’s side, permitting the best possible view of connections and mounted implements. The Unimog’s handling and ride were improved by a new frame and progressively acting coil springs.

The tried-and-tested ladder-type frame was retained, with tubular cross members welded into the longitudinal members. This design of frame allowed for extreme torsion, yet the ensemble as a whole was remarkably rigid. In conjunction with the suspension, therefore, it offered excellent offroad wheel-load distribution. At the same time, whether laden or unladen, the progressively acting coil springs provided constant and optimally adjusted suspension quality. In addition, the rear telescopic shock absorbers operated using a load- and path-dependent characteristic curve, resulting in reduced damping of the vehicle when empty.

Clearly more space, comfort and practicality

The completely redesigned cab with its raised roof provided substantially more space than before, clearly laid out controls and, not least, an appealing working environment. The new Mercedes-Benz Unimog’s special technical features included a tyre pressure control system that could be operated on the move, the anti-lock braking system, new engines from the car range for the lightweight U 90 as well as Servolock, a unit for hydraulically locking working implements. The new Unimog generation not only expressed individuality and great practicality in its looks, with its diversified range of applications, it also recommended itself for an ever more important group of buyers: municipal authorities.

Pulling up outside the disco in the Funmog

A very different group of customers emerged temporarily: the Mercedes-Benz Unimog had been discovered as a disco-mobile in Japan – the old battlehorse with its advanced engineering, a died-in-the-wool commercial vehicle, was all of a sudden a big hit among youngsters. Daimler-Benz reacted by launching Funmogs, an impressive, pitch-black Unimog from the heavy-duty series and a red-metallic one from the new medium-duty series. Both featured plenty of chrome trim. The attractive Funmogs promptly won the “Offroader of the Year” award in the spring of 1994. The indestructible nature of the evergreen from Gaggenau was also reflected by the production figures: in the same year, Unimog production exceeded the 300,000 mark – a very high figure for a special-purpose vehicle.

UX100 – the little one for municipal authorities

Two years later, in 1996, Daimler-Benz 1996 expanded the range by the addition of an implement carrier for municipal authorities, the UX100. This small Unimog was a slim and easily manoeuvrable vehicle, suitable for work on walkways and in parks. However, the Unimog’s little brother did not generate big business. Within the framework of its concentration on core competencies, Daimler-Benz transferred the smart UX100 to Hako, a company specialising on vehicles of this type and size. Nevertheless, the Unimog engineers adopted quite a few ideas from the UX100 project for future vehicles.

Spectacular: Unimog U 300, U 400 and U 500

The company had meanwhile been preparing for another renewal of the Mercedes-Benz Unimog range. In the spring of the spectacular year 2000, the company presented new, equally spectacular Unimog models: the U 300, U 400 and, a little later, the U 500 (408/418 series) replaced the previous medium-duty and heavy-duty series. With this model replacement, the Unimog received more advanced technology in one go than ever before in its long career. A particularly conspicuous feature is the highly advanced, practical and at the same time extremely appealing cab made of fibre composites. The huge windscreen extends far down, permitting a perfect view of all connections and implements – the latter can now be mounted effortlessly in one-man operation.

Engine fitted between the axles

The bonnet is extremely short because the engine has been moved backwards to a location between the axles. You could say that this Unimog incorporates an idea of its inventor, Albert Friedrich, who had sketched in the engine in a similar position in one of his first drawings in 1946.

VarioPilot: moving the driver’s place to the other side

The all-new cab incorporates not only plenty of space and highly comfortable appointments but also an idea the engineers adopted from the UX100 project and refined it: the driver’s workplace, complete with steering wheel, gauges and pedals can be moved from the left to the right-hand side and back in next to no time. What sells under the name VarioPilot proves to be an extremely practical feature for the different applications in municipal work. A broad range with wheelbase lengths between 3080 and 3900 millimetres and permissible gross weights from 7.5 to 15.5 tonnes underlines the Unimog’s flexibility and performance more than ever before. For special applications, for instance tractor operation, the Mercedes-Benz Unimog is available with special equipment, including a torque converter and clutch unit or remote control with cable.

New emphasis: implement carrier for municipal work

Both the design of the new Mercedes-Benz Unimog and its features underline that it is clearly oriented to the spectrum of the 408/418 series. It is still a near-perfect offroader, but its emphasis is on implement carrier work. Other features of the new Unimog: permanent all-wheel drive, electro-pneumatic Telligent gearshift, the new VarioPower high-performance hydraulic system and new, extremely powerful engines with output ratings between 110 kW (150 hp) and 205 kW (280 hp) and complying with the EURO 3 emission standards. And those still looking for a classic Mercedes-Benz Unimog with a focus on extreme off-road capabilities will continue to be served for the time being by current model series.