The Unimog is the ultimate automotive work tool. It usually takes a deep gulp of diesel as liquid food. But times are changing and turning against fossil fuels. Mercedes-Benz and its “Special Trucks” division want to be prepared for this. That is why a U430 Unimog implement carrier converted to hydrogen (H2) was put to the test.
Motorway test
The prototype equipped with a front mower had to prove itself by mowing a green strip of motorway, accelerating and refueling at a public petrol station. However, the practical use did not take place on public roads, but on a disused section of motorway in Upper Franconia, specifically between Bayreuth and Bamberg. The test was accompanied by employees of Autobahn GmbH.
A powerful workhorse: the hydrogen combustion engine develops 290 hp and 1,000 meters of torque. Daimler Truck
However, the hydrogen engine used for the tests is not a fuel cell, in which the refueled H2 is converted into electricity for an electric motor. Instead, the test Unimog uses a specially modified combustion engine that “simply” burns hydrogen instead of diesel. This process produces water that spurts out of the exhaust pipe as hot water vapor. Toyota also uses this process as an alternative to hydrogen Fuel Cell technology.
Driving and working with low pollutants
“We are very satisfied with the current state of development of the experimental vehicle,” says Franziska Cusumano, head of Mercedes-Benz Special Trucks. Günter Pitz, director of propulsion development, is also in favor of continuing the project. Certainly, the Trucks division continues to focus on battery-electric drives and hydrogen fuel cells. But according to Pitz, the concept of hydrogen combustion can “serve as a model for high-performance applications in the field of special vehicles”; on construction sites, in the municipal and agricultural sector, it offers the possibility of “driving and working with very few polluting emissions”. And relatively quiet, as tests have shown.
The prototype’s four 700 bar high-pressure tanks, tested by TÜV, contain a total of around 14 kilograms of hydrogen gas. In a next development stage, this volume will be increased so that the Unimog H2 can also complete a full working day.
Unimog potato planter
25 HP harvester: The track width of the Unimog was designed from the start so that two rows of potatoes could pass exactly between the wheels. This semi-automatic potato planter was used in the early years of the Unimog. Daimler truck
The history of the Unimog dates back to post-World War II. Albert Friedrich, at the time director of aircraft engine manufacturing at Daimler-Benz, developed the idea of an off-road vehicle which was initially intended for use in agriculture and which offered the advantage of a platform on which it was possible not only to bring in the harvest, but also to transport a large number of people to the fields. But the skills of the “universal motor vehicle”, or “Unimog”, were quickly recognized as being useful for other purposes. The Unimog is used in disasters, expeditions and municipal works, but is also in service with the army.
“WaVe” development project
The currently tested hydrogen prototype is part of the development project “WaVe” (hydrogen combustion engine), launched in July 2021, which is supported by the Federal Ministry of Economic Affairs and Climate Protection (BMWK) and for which a total of 18 partners from industry and science came together. The aim is to verify to what extent a combustion engine running on hydrogen can replace conventional diesel.