Monthly Military: Mercedes-Benz Unimog

After World War II, Germany wanted to transform itself into an agricultural hub. Automaker Daimler-Benz saw a need for a specialized vehicle for such purposes. The result was the Unimog (UNIversal-MOtor-Gerät, the latter word being German for “machine”), designed in 1946.

In production for over 70 years and counting, the Unimog has become an institution. Serving in various military roles the world over, the vehicle also has its agricultural, search and rescue, firefighting, and other critical uses. All require a modular, heavy-duty truck with serious off-roading capability, and the Unimog fulfills the role.

Shortly after the first prototypes were revealed in 1948, Daimler realized the Unimog could do more than just serve the military. In the years since, the vehicle expanded into several variants with both civilian and military applications.

Now in use in more than 30 countries across the globe, the Unimog has evolved substantially from its humble origins. But the original concept of a simple, diesel-powered, off-road truck is still visible today.

Development

After receiving approval from the occupying Allied forces in the fall of 1945, engineer Albert Friedrich penned the original template for the Unimog. Finding a manufacturer with a working facility that could produce such a vehicle in post-World War II Germany proved difficult, though. The construction of the prototype vehicles was handled by Erhard and Sons, a silverware manufacturer with no prior experience building trucks or tractors.

Originally the Unimog was meant to have a power take-off for operating harvesting machines in crop fields and saws in forests. The general concept called for a vehicle that could take on a variety of tasks while remaining drivable on the street, so the general specification requirements included permanent four-wheel-drive, high ground clearance, self-locking differentials, power take-offs at both the front and rear of the vehicle, a cab that could accommodate two occupants, and highway cruising capability.

The initial prototype vehicles were powered by 1.7-liter, four-cylinder gasoline motors. The later development models were equipped with Daimler-Benz’s new OM636 diesel motor. It was a 25-horsepower, 70 lb-ft 1.7-liter OHV mill.

Riding on a 63.7-inch wheelbase and sporting a 4.2-foot track width and 18 inches of ground clearance, these prototypes could hit up to 30 mph on the road. They could also crawl along fields at 330 yards per hour thanks in part to the six-speed gearbox.

After extensive testing throughout 1947, the Unimog prototypes were shown publicly at the 1948 German Agricultural Society show in Frankfurt. As a result of the enthusiastic response they received, plans for production versions of the Unimog began to take shape. However, it was clear that Erhard & Sons didn’t have the capacity to build these vehicles in any significant numbers.

The task would eventually be handed to Boehringer Bros. in Göppingen. The company was a machine tool manufacturer whose factory was going to be dismantled, as its previous history included armament production for the Nazi war effort, so they were certainly motivated and their facilities were much better suited to the task.

By the middle of 1950, Boehringer had produced roughly 600 examples of the original Unimog. Military interest was beginning to develop as well, with the French Army ordering the first batch of Unimogs outfitted for non-civilian use.

After seeing this initial success, Daimler-Benz began to take serious interest. They would soon take over the Unimog project, buying the patents, hiring the development and sales team, and moving production to the company’s truck plant in Gaggenau, Badenia in 1951.

Generational Evolution

Not long after the ink had dried on the contracts, Damiler-Benz sought to expand the Unimog lineup. By 1953 the automaker was offering two different model options with the U401 and U402, with the latter offering an 83-inch wheelbase, while a closed cab version of the Unimog would become available that same year as well.

1955 brought the introduction of the 404S and 404 line of Unimog vehicles, an iteration that would see a 25-year production run with nearly 65,000 examples produced in total.

Similar to other Unimog designs both before and after it, the 404 featured a ladder frame, portal axles, and a coil spring and damper-style suspension system.

The initial primary customer for the 404S would be the newly-developed and NATO-aligned West German Armed Forces. As a result, the 404’s design would focus on cross-country mobility rather than specifically agricultural work.

Capable of fording up to 31 inches of water in stock form, the 404S weighed in at 6,400 pounds unloaded and could haul up to 3,300 pounds of cargo.

Motivation was provided by a choice of three different options: The M180 2.2-liter straight-six motor, M130 2.8-liter straight-six motor, or 2.2-liter OM615 four-cylinder diesel motor. All of them came with a transmission offering six forward gears and two reverse gears.

Development of the Unimog has remained ongoing throughout the subsequent decades. A wide array of variants has been produced for various military and civilian tasks. And it perhaps comes as little surprise that, due to its durability and modular design, the Unimog has also seen its fair share of off-road motorsport use.

Perhaps its most notable racing success has been in the Dakar Rally, a grueling 6000-mile event that takes participants from Paris, France, to Dakar, Senegal, where it has been used as both a race truck and a support vehicle and has won its class several times.

By 1993, the Unimog U 2450 L 6×6 made roughly ten times the power of the original Unimog. The following year saw the introduction of the Funmog, a limited-production luxury variant.

In 2003, Daimler-Benz moved Unimog construction to the Wörth am Rhein Mercedes-Benz-LKW-Montagewerk truck plant after more than half a century producing the vehicles at the Gaggenau factory. Production continues at the Wörth plant to this day. As of October 2016, roughly 400,000 examples of the Unimog have been sold among the nearly three dozen different model variants that have been available throughout the decades of production.