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.

Though originally conceived as an truck/tractor hybrid, the Unimog's versatile design made it an attractive addition to military fleets. Images: Wiki Commons

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.

Though it didn't take long for the Unimog to become popular, the humble design of the original U25 left plenty of room for improvement. After all, the original Unimog could hardly reach 30 miles an hour on its 25-horsepower engine. In 1951, Mercedes-Benz stepped in and took over production, offering a closed-cab version. Images: Mercedes-Benz

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.

Though several engines have been offered in the Unimog throughout its nearly 70 years of production, a Mercedes-Benz four-cylinder diesel has been on the menu essentially throughout. Even today, a turbocharged 5.1-liter four-cylinder diesel motor is offered. It generates 231 horsepower and 664 pound-feet of torque – a far cry from the output of the original OM636. Image: Silodrome

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 interior of the early Unimogs show its tractor-like origins. Little concession was made to provide its occupants with luxury or style. That utilitarian approach would translate well to its use in military applications, as its simplicity would help keep the vehicle reliable and relatively easy to operate. Images: Vintage Mudder, C&C Equipment

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.

After the French army showed interest in the Unimog in 1950 and subsequently put in a large order of the vehicles for military use, Daimler-Benz decided to step in and take over Unimog production. DB bought not only the patents to the vehicle, but also hired development teams as well as sales and marketing people. In the next few years, Daimler would begin to expand the lineup, starting with long and short wheelbase variants before expanding into versions designed specifically for military use. Images: Silodrome, Wiki Commons

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.

Along with the versions outfitted for military use, the Unimog would also spawn off-shoot vehicles. One example was the ATF Dingo seen here. It was an infantry mobility vehicle based on the Unimog U 5000 chassis. It was designed to provide protection against landmines, small arms fire, artillery fragments and nuclear, biological, and chemical threats. Image: Wiki Commons

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.

The Unimog’s military use hasn’t been limited to just troop and cargo transport over the years. Here, we can see a CAESAR howitzer outfitted to a Unimog U2450 6×6 chassis. Along with combat applications, the Unimog has also been used by various militaries as an excavator in terrain deemed too harsh for traditional vehicles. It also serves as a transport for artillery rounds and other large pieces of ordnance. Image: Wiki Commons

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.

A Unimog U500 competing in the 2006 Dakar Rally. It’s said that on more than one occasion, Unimogs tasked as support vehicles for cars and motorcycles in the race have ended up unintentionally winning the truck class. Image: Wiki Commons

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.

Though the Unimog's utility has made it popular for military applications, it still remains available from Mercedes-Benz as a civilian vehicle as well. Though still focused on versatility and reliable operation in a wide variety of heavy-duty applications, the modern Unimog is a far more civil vehicle than the original models. This is likely due in some part to its growing popularity among affluent enthusiasts in the Middle East. Images: Mercedes-Benz

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.

About the author

Bradley Iger

Lover of noisy cars, noisy music, and noisy bulldogs, Brad can often be found flogging something expensive along the twisting tarmac of the Angeles Forest.
Read My Articles

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