One of the most versatile commercial vehicles Mercedes-Benz has ever produced is the Unimog. Tests and measurements have now been carried out on a section of highway to see if the vehicle would function reliably in practical use when fueled with liquid hydrogen, at low temperatures, and in challenging topography.
The measurement data was collected during mowing a grass verge, acceleration tests, and refueling at a public pump, in order to be used for further vehicle development. This is an important step in the ongoing "WaVe" development project, in which 18 partners are collaborating on the drive concept of the hydrogen combustion engine.
Franziska Cusumano, Head of Mercedes-Benz Special Trucks and Custom Tailored Trucks: “After a project duration of just over two years, we are now conducting practical testing with a first operational prototype. The tests with employees of Autobahn GmbH are particularly valuable for us because we can directly incorporate important feedback from practical experience into our development.”
The test vehicle is based on the Unimog U 430 implement carrier. For its alternative hydrogen propulsion system, it features a specially converted gas engine with integrated tank, safety, monitoring, and measurement systems. During hydrogen combustion in the engine compartment, water is produced, which is released as hot steam through the exhaust. The wheelbase and platform length are designed to allow the hydrogen tanks to be mounted behind the driver's cab. The four TÜV-certified 700-bar high-pressure tanks hold a total of approximately 14 kg of gaseous hydrogen. They are grouped into two double tanks, each operated independently by its own tank control unit. In the next development phase, the tank capacity will be increased to cover a typical workday. The engine delivers approximately 290 hp / 1000 Nm and is noticeably quieter than its diesel-powered counterpart. The prototype was equipped with a front-mounted mower with two cutting heads to gather further insights during operation.
The development of the test vehicle with ahydrogencombustionengine is taking place within the framework of the publicly funded project "WaVe". This project, funded by the Federal Ministry for Economic Affairs and Climate Action, is being jointly implemented by 18 partners from industry and science and began in July 2021. The aim of the WaVe project is to examine the extent to which the conventional diesel engine, as a multi-energy distributor for the drive system and all auxiliary drives, can be replaced by a hydrogen-powered combustion engine.
Photos: Daimler Truck
Especially for the Unimog, this variant could prove to be a viable drive system for the future, given its limited installation space and the high performance required in operational applications. Following the initial successful field test, the development team has a remaining project duration of six months to implement further adjustments and improvements. Günter Pitz, Head of Powertrain Development at Mercedes-Benz Special Trucks, believes continuing the project is worthwhile: “The hydrogen combustion drive concept can serve as a blueprint for high-performance applications in the special-purpose vehicle sector. It could enable very low-emission driving and operation on construction sites, in municipal services, or in agriculture. To achieve series production readiness for such vehicles, continued financial predictability is essential.”
