A simple idea, a brilliant execution.
During the Second World War, Albert Friedrich was head of aero engine design at Daimler-Benz, but also found time to research another project, unbeknown to his bosses. Friedrich was interested in developing a versatile agricultural vehicle that combined the best features of a tractor and a truck. He described his then nameless concept as an “engine-powered, universally applicable machine for agriculture.” The vehicle would in due course become a valuable tool for many occupations far beyond its originally intended application.
Late 1945 saw Friedrich seeking permission from the occupying US Army to obtain a production licence. This was duly granted, so Friedrich and fellow engineer, Heinrich Rößler, a former colleague at Daimler-Benz, commissioned Eberhard & Söhne in Schwäbisch Gmünd, a city in the eastern part of the German state of Baden-Württemberg, to help them develop and productionise their concept. Eberhard & Söhne was a manufacturer of items in silver and gold, so seemed an unlikely choice for this work, but the project progressed rapidly, thanks to the clarity of the specification.
The vehicle Friedrich and Rößler had designed had switchable rear or four-wheel drive, with differential locks on both axles and equally large tractor-style wheels and tyres all round. A flexible ladder chassis mounted above the axle line and long-travel coil springs gave it exceptional ground clearance and manoeuvrability off-road. Unlike a conventional tractor, it had a forward-mounted cab with a canvas top, behind which was a short integral load deck. There was a built-in tow-hitch at the rear and power take-off points at the front, centre and rear to drive farm machinery. A six-speed gearbox gave it a top speed of 50km/h (31mph), making it more suitable for on-road use than a traditional tractor.
The summer of 1946 saw the first prototypes begin exhaustive trials under the supervision of Christian Dietrich, the engineer appointed to lead the test programme. Dietrich clocked up many miles on public roads and also used a prototype to showcase the vehicle’s abilities to farmers, its initial target market. Another engineer, Hans Zabel, is credited with christening the new vehicle Unimog. This was simply a contraction of Universelle Motor Gerät (Universal Motor Device), which was the name used to label the engineering drawings. In November 1946, Unimog was confirmed as the name the vehicle would carry in production.
Two significant issues now needed to be addressed: sourcing an engine supplier and finding a company to mass-produce the Unimog. Eberhard & Söhne did not have the capacity to undertake series production and built just six pre-production test vehicles, so Goppingen-based machine tool manufacturer, Gebrüder Boehringer, was engaged. The early Unimog vehicles manufactured by Boehringer carried a distinctive painted badge featuring an Ox’s head with U-shaped horns.
Regarding the engine, prototype Unimogs used the Mercedes-Benz M136 petrol engine, but the company’s OM636 diesel unit, at that time under development, would be much more suitable and was used from 1948 onwards in the production vehicles, which carried the model suffix 70200.
As Boehringer was not perceived to be an automobile manufacturer, Friedrich and his team had not only to continue development, but advertise and sell the Unimog themselves. After approximately 600 had been made (150 orders alone arising from the Unimog’s appearance at the 1948 Frankfurt agricultural show), Friedrich realised that demand was such that production needed to be scaled up considerably. Seeking further capital to fund this expansion, Friedrich made contact with his former colleagues at Daimler-Benz, who were very receptive. In early 1951, production of the Unimog was transferred to the Daimler-Benz truck factory at Gaggenau, Baden-Württemberg, where it would remain for the next fifty-one years.
Changes from the Boehringer Unimog were minimal and included a name change to Unimog 2010(1). The Ox head motif remained the sole branding until 1953 when Daimler’s three-pointed star was placed on the grille below it. Three years later, the Ox head badge was deleted. Outputs increased; 1,005 for 1951 rising to 3,799 a year later. In addition to its agricultural target market, the Unimog was increasingly finding public service and military customers.
Under Daimler control, development work hastened changes, which included wider tracks, longer wheelbases, synchromesh transmissions and higher payloads. In 1953 the 2010 was succeeded by the 401 and 402 models. The 401 shared the original’s wheelbase of 1,720mm (67¾”) while the 402 had a 400mm (15¾”) stretch to 2,120mm (83½”). For the first time, an enclosed cab with more rounded bodywork became available. This was outsourced to a company called Westfalia(2) and was nicknamed ‘Froschauge’ (frog eye). A total of 16,250 401/402 models were produced over three years.
1955 saw the launch of what would become a ubiquitous and long-lived version, the 404/404S. This had a more conventional truck profile with a large open or enclosed load bay behind the cab and a carrying capacity of 1.5 tonnes (3,307 lbs). This version found favour with a wide variety of users, including the military, fire service, forestry and utility companies. It would remain in production in a number of different versions for a quarter of a century.
Although never originally intended for military(3) use, the Unimog attracted attention from a number of nations’ armies. The Swiss took over 500, the French took 1,100 while the Bundeswehr took a barely believable 36,638 from a total of 62,242 404/404S versions produced. To improve its on-road performance, the French demanded petrol rather than diesel power and the M180 petrol engine would prove twice as fast as the lethargic diesel. Powered thus and carrying a dozen troops, the Unimog could barrel along at 90km/h on decent surfaces, could pull over four tons of equipment, yet was still able to crawl around on terrain a seasoned fell runner may baulk at.
Adaptations were mainly performed by the end user to make the Unimog suitable for their specific requirements, from ambulance to agriculture, municipal work to mobile workshop. From 1957, wider cabs were offered. Single cabs were made at Gaggenau while double cabs were contracted out to Wackenhut in Nagold.
Diverse demands and requirements became the norm regarding the Unimog, leading to a veritable labyrinth of three-digit model numbers beginning with a ‘4’. By 1966, 100,000 Unimogs had been produced, that figure having doubled in eleven years. 1968 saw production of the Unimog commence in Gonzalez Catán, Argentina, which continued until 1983.
1974 heralded the arrival of a new design of Heavy (SBU) Unimog models with an entirely new, squarer style. The existing rounded-cab versions were given the moniker Light (LBU). In 1977, Unimog production passed the 200,000 mark. A period of stability lasted until the mid-1980s when a full series renewal occurred, introducing new Light and Medium series models to the range. These offered more efficient engines and a variety of heavier payloads.
1992 saw lighter, narrower versions launched with very angular bodywork and an asymmetric bonnet, lower on the driver’s side to enhance visibility. New features included anti-skid electronics, driver operated tyre pressure adjustment and a ‘Servolock’ system for hydraulic attachments front and rear.
Realising Unimog had become quite the cult vehicle outside its natural environments, Mercedes opted for a little humour, exhibiting the Funmog at the 1994 Off-Road Exhibition in Cologne. Based on a 408 and available in pitch black or metallic red, for your DM150,000, the Funmog came with chrome trim, leather seats and…carpets! Most headed to Japan, where the Funmog was advertised as the perfect vehicle in which to pull up outside your favourite nightclub.
With ageing equipment and ongoing vehicle development, time was eventually called on the Gaggenau plant in 2002 after the production of over 320,000 Unimogs. A huge send-off party ensued. The excellent Unimog museum remained close by, but production headed to newer and larger facilities at Wörth am Rhein, where figures are now closing in on half a million.
One final and unique Unimog advantage has been available for twenty years: Variopilot gives the driver the ability to swap the steering wheel and pedals from left to right at the push of a lever; handy for close-quarters manoeuvring in confined spaces or near cliff-edges, I imagine. As to the Unimog’s abilities, the Bundeswehr has a saying, “If a Unimog can’t go there, neither can a Panther Tank.”
Over its lifetime, the Unimog has evolved immeasurably but, in terms of its fundamental fitness for purpose, it hasn’t changed at all. You’ll still find it in a field of potatoes, a forest, quarry or mine, equipped as an ambulance or fire truck, or shifting snow and maintaining the verge, and a thousand more roles. Now in its seventy-fifth year of faithful service, it is showing no signs of slowing down. Happy birthday, Unimog!
(1) This was, apparently, the serial number carried by the Unimog’s technical drawings.
(2) Westfalia would later achieve fame for its camper van conversions of the VW Type 2 Transporter.
(3) Requesting a production licence for a new German military vehicle in 1945 would probably not have been the brightest idea!
Data sources: aoonauto.com, Daimler archives, Unimog-magazine.de