Unimog meets Mörtlbauer: From hydrogen project to work assignment

Driving and working emission-free is the goal on the road to CO2 neutrality. Not only fully electric vehicles but also other alternative drive systems can help achieve this. A two-year project sponsored by the German Federal Ministry of Economics and Climate Protection has now come to an end.

Mercedes-Benz Special Trucks and Mörtlbauer presented their duo of Unimog and Mörtlbauer. A hydrogen combustion engine is at work in both vehicle prototypes. Both are already hard at work.

Gallery: Unimog meets Mörtlbauer: Successful development project for hydrogen combustion engine

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Source: Mercedes-Benz Trucks

"After numerous test runs, exhaust gas measurements and technical fine-tuning, we are convinced that hydrogen combustion is sensible, practicable and very low in emissions for work machines with high power requirements for driving and for driving the auxiliary drives," says Franziska Cusumano, Head of Mercedes-Benz Special Trucks.

The Unimog implement carrier has already been in use with this drive system for over a year in various tests, while the dump truck crawler has been working in initial application-specific trials since spring 2024. For the presentation, the Unimog towed the Mörtlbauer on a low-loader. A short test drive with the use of equipment has now been undertaken on the Mörtlbauer factory premises and the refuelling process presented to the public.

With minor modifications, the hydrogen combustion engine can be used in a similar way to today's diesel engines. Both models are powered by a medium-duty engine that the engineers have converted to run on hydrogen. All that was needed were adapted pistons, a hydrogen-compatible intake system and an optimised ignition system. The water produced during combustion was released into the atmosphere via the exhaust system.

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Four 700-bar high-pressure tanks in the Unimog can hold a total of around 13 kilograms of gaseous hydrogen. 290 hydrogen PS and a torque of 1,000 Nm are therefore roughly comparable with a 300 PS diesel version. This must be able to ensure that all auxiliary equipment can also be operated without any problems. The dump truck Mörtlbauer holds 14.5 kilograms of hydrogen at 700 bar. This allows the workhorse to move up to 16 cubic metres of content at 30 tonnes.

Other Unimogs with different fields of work:

Unimog TenereX from Hellgeth: Ready for the next expedition

New Mercedes-Benz Unimog corners like it's on rails

Mercedes Unimog gets even cooler with railroad-ready model

Seriously cool Mercedes-Benz Unimog is ready to battle blazes

"The fact that our Mörtlbauer and the Unimog from Mercedes-Benz Special Trucks can be refuelled with gaseous hydrogen without any problems and also work reliably when using the equipment is the result of the excellent partnership work in the research network," Armin Mörtlbauer, Managing Director of Mörtlbauer Baumaschinen Vertriebs GmbH, adds: "However, we still have further to go before we can use them in series production. When politics and society set the course in the direction of hydrogen combustion engines, we will be in the starting blocks." 

The two vehicle prototypes show how low-emission driving and working with constantly high engine power can remain possible in the future alongside purely electrically powered vehicles. The development project for hydrogen combustion engines (WaVe) started in July 2021 together with 18 partners from industry and science.

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