Comprehensively tried and tested: Innovative testing systems ensure quality standards for Mercedes-Benz trucks

• Innovative testing systems for trucks in Wörth am Rhein
• Analysis of entire vehicles as well as individual components in a multi-stamp system and climate change chamber
• Vibration and resonance analyzes in the multi-stamp system
• Analysis of behavior under changing temperature and humidity conditions in the climate change chamber
• Testing under real conditions in hot and cold climates

Leinfelden-Echterdingen / Wörth am Rhein – Wörth am Rhein is not only home to Mercedes-Benz Trucks' largest truck production plant, but also the company's development and testing center (EVZ). The EVZ enables the concentrated bundling of tests with heavy trucks in one location on a total of six innovative indoor test stands and the drive-in lane in the directly connected outdoor area.

These testing and evaluation processes are the order of the day in the EVZ - regardless of the type of vehicle drive. However, the focus of activities is increasingly on specializing in testing procedures for battery-electric and hydrogen-based truck drive systems - and at the center of this is currently the battery-electric Mercedes-Benz eActros 600, which is being rapidly prepared for series production.

The newly developed and probably unique multi-stamp system for analyzing the vibration behavior of vehicles with regard to driver comfort and safety is located in test bench building 220 on the Wörth EVZ site. Also installed there is one of the most powerful climate change chambers in Europe, in which tests can be carried out at extremely cold and extremely hot temperatures. Both test systems were designed from the outset with trucks with alternative drives such as the Mercedes‑Benz eActros 600 in mind.

Road simulation and vehicle behavior in the multi-stamp system

Vibrations generated by different road surfaces are simulated in the multi-ram system. For this purpose, a collective of different real road surfaces is created and simulated based on specifically measured data stored in the system, ranging from motorway routes to country roads and pothole stretches to 100 percent bad road stretches. The vehicles are stimulated to vibrate in the vertical and longitudinal directions by excitation signals with a defined amplitude and frequency.

The developers' primary goal is to obtain validated measurement results and reproducible vibration and resonance analyzes of entire vehicles in the multi-stamp system. Regardless of the drive variant, the vibration and acceleration behavior of individual vehicle components and component groups can be checked and evaluated. The behavior of frames and bodies at different excitation frequencies and the effects on driving comfort are measured and evaluated. The stable assembly of bearings and dampers, for example, as well as the effects of their vibration behavior on other vehicle components are also part of the possible scope of testing in the multi-stamp system, as is the identification of bottlenecks and chafing points, for example in cable and pipe routing.

Depending on the scope, the investigation of the vibration and resonance behavior of the entire vehicle or individual components takes between eight and 14 days.

Structure and function of the multi-stamp system in Wörth

The multi-stamp system with its dimensions and unique testing options is unique due to its high performance. It forms a network of ten hydraulic cylinders installed longitudinally and ten vertically on an innovative oscillating foundation, which cause the clamped vehicle to vibrate in a targeted manner. One cylinder acting vertically and one cylinder acting in the longitudinal direction are installed per wheel and, in the case of axles with double tires, per pair of wheels.

The vibration foundation is mounted on a concrete foundation and is raised via air springs and decoupled from the environment before each vibration test begins. This prevents the oscillations and vibrations generated during the test process from being transmitted to the test bench building. The multi-stamp system is operated by a central hydraulic unit consisting of eight pumps with an oil pressure of 280 bar. Each cylinder has a load limit of eight tons.

The cylinders can be controlled individually. The multi-stamp system enables the measurement, examination and analysis of the vibration behavior of entire vehicles with up to five axles and a total length of a maximum of 20 meters. The track width is variable - it can be continuously adjusted from 1.77 meters to 2.06 meters. Vehicles can be tested in this facility together with semi-trailers or trailers up to a width of 2.50 meters, a maximum height of 5.30 meters, a wheel load of a maximum of eight tons and a maximum total weight of up to 60 tons.

Hot and cold: the high-performance climate change chamber

The high-performance climate change chamber in the Wörther EVZ was designed from the outset for use in electric and hydrogen vehicles. The advantage: In contrast to real on-site tests, for example in Finland or Spain, the simulated climate conditions can be flexibly represented in the climate change chamber under comparable conditions throughout the year.

The climate change chamber works in the temperature range from -40°C to +70°C. In addition to the temperature, it also has a humidity control, with which different humidity levels of up to 100 percent can be set as required within the physical possibilities. The temperature change coefficient for the temperature settings and humidity determinations is 1.0 Kelvin or one degree Celsius per minute, which allows the desired values ​​to be set precisely. This allows technical innovations as well as mechanical, electrical and comfort functions such as air conditioning systems for both conventional and alternative drives to be tested under arctic to subtropical climate conditions.

There is space for two tractor units in the climate change chamber. In it, the function of a wide variety of systems is comprehensively tested for their behavior in changing temperatures and humidity conditions. Optimizing the cold start behavior of combustion engines and electric vehicles is an important component. For electric trucks, the battery management and battery charge level (SoC) are primarily tested.

The cab air conditioning is checked in the climate change chamber, as is the condition and efficiency of the cold and heat insulation used. In addition, functional tests are carried out with mechanical and electrical components such as steering, tilt cylinders and front flap under different climatic conditions. Special truck equipment for use in Nordic countries is also subjected to intensive testing to ensure that it functions properly in arctic cold.

Protection and safety in extreme heat and cold

For test runs, the climate change chamber is equipped with an exhaust gas ventilation system as a safety feature and a gas warning system in the event of a release of carbon monoxide, hydrogen or methane. In the event of impending danger, optical and acoustic warning systems prompt you to leave the climate change chamber immediately in three stages. The warning system is also directly connected to the plant fire department.

The security measures also include that the control center must be manned during an ongoing test procedure when staff are in the chamber. Strict access regulations apply, and the interior of the climate change chamber is constantly monitored with cameras: no employee is allowed to stay in the chamber alone or without appropriate protective clothing. There are always two employees present; from -25°C, a stay is only possible with a medical clearance certificate. From +50°C, no employee is allowed to stay inside the climate change chamber.

Additional test procedures: Tests under real conditions

The test results obtained at the test facilities in Wörth under laboratory conditions are constantly checked and compared on site for reproducibility with the results that often last for weeks on outdoor test tracks across Europe under mostly extreme real conditions. The influence of factors such as road conditions that are icy or softened by heat, solar radiation as well as light and wind conditions, which cannot be represented under stationary test conditions, also come into play. These tests include, for example, test routes in regions such as Rovaniemi in the Arctic Circle in Finland, which is extremely cold in winter (winter tests) or the Sierra Nevada in Andalusia in southern Spain, which is extremely hot in summer (summer tests). The functions of the individual operating and battery systems are comprehensively tested, secured and optimized.

Mercedes-Benz Trucks successfully tested the battery-electric eActros 600 for long-distance transport last summer. For around five weeks, test engineers tested the electric truck with a total towing weight of 44 tonnes and a payload of around 22 tonnes at very high temperatures of up to +44°C in southern Spain. The range of tests ranged from the functionality of the air conditioning system in high heat, to the performance of the electric drive train and the battery thermal management, to measurements during charging processes at fast charging stations. After the tests were completed, a prototype completed the 2,000-kilometer route from Granada back to the Mercedes-Benz Trucks development and testing center in Wörth am Rhein on its own.

In Finland, Mercedes-Benz Trucks successfully completed the final winter testing of the Mercedes-Benz eActros 600 long-distance truck in March 2024 before its planned start of series production at the end of 2024. In ice, snow and temperatures down to -35°C, the further developed prototype generation of the eActros 600, which is intended for use in the important battery-electric transport segment on long international routes, had to prove its operational capability and long-distance transport range under extremely adverse conditions. In particular, the effects of extreme cold on handling, ergonomics and comfort were tested at the Rovaniemi test site. Criteria such as the starting behavior and cold protection of the drive components, thermal management, charging behavior and the robustness of the sensors were also checked.