Lighter weight for the future of caravanning: The VARIO X lightweight chassis
With an innovative concept, the chassis specialist AL-KO VT is launching into the new camping season: Thanks to a clever design, the weight of the VARIO X lightweight chassis has been reduced by up to 30 percent compared to previous chassis – while maintaining the same high stability and load-bearing capacity. This creates extra capacity for payload and is the first step towards future mobility.
“The need for action became ever clearer,” says Eckle, whose ambition was sparked. “Not only my employer AL-KO VT, but I personally want to be a leader in innovation and to move the caravanning industry forward. That’s why I took another intensive look at the subject and, together with the entire team, completely rethought the existing lightweight construction concepts from the ground up.”
Volker Eckle, Head of Advanced Development Vehicle Engineering, and development engineer Maximilian Zimmermann were key members in the new construction. The two initiators were also supported by an interdisciplinary team made up of people from a wide variety of specialist fields, who drove the project forward with commitment and enthusiasm.
Not just during his own camping experiences with caravans and motorhomes, but also in conversations with body manufacturers and customers, Volker Eckle was repeatedly confronted with the key issue of weight and payload.
What would be the optimal solution if we had to start from scratch?
After the initial idea phase and a feasibility study, the goal was set: a new lightweight load-bearing structure concept with at least 20 percent less weight compared to the current standard – without sacrificing stiffness, load capacity or driving safety.
In line with the motto: “What would be the optimal solution if we had to start from scratch?” the team critically questioned not only the traditional designs but also every type of material. One thing was clear: as well as noticeably reducing weight, the new concept should address the important issue of sustainability and remain attractively priced for end customers.
The team took a closer look at various areas of action and questions, including
- Which materials are fundamentally suitable for chassis construction and are distinguished by lightness, durability and recyclability?
- What types of profiles and cross-sections can support such a structure?
- How will the product realistically be used later? What kind of stresses will the individual components be exposed to?
- Where are the previous design limits and how can these be shifted?
- Which manufacturing processes are available for the various solutions?
Inspired by nature
Volker Eckle drew inspiration from nature during the concept phase: “I enjoy being outdoors and, in light of my idea, I consciously looked at ‘constructions’ in the animal and plant worlds – after all, these are known to be both highly efficient and robust.”
They also considered using renewable raw materials like wood – but in the end, the experts once again chose proven steel as the load-bearing material. As Volker Eckle explains: “Every material has its strengths and weaknesses – and unfortunately, due to its structure, wood is simply not reliable enough for use in the underbody.” Steel, on the other hand, can easily be separated and, unlike other materials, is now efficiently and securely recyclable and can be returned to the raw materials cycle.
Interdisciplinary teamwork delivered the solution
With a smile, Maximilian Zimmermann adds: “That’s what distinguishes a good engineer: choosing the best materials for each application and combining them based on the latest state of the art!”
Once the team had determined the materials with the highest level of reliability and performance, the teamwork continued: discussions, calculations, simulations, tests, verification – after every stage of development, the process began again. Volker Eckle and Maximilian Zimmermann found it especially helpful to have a wide range of perspectives and expertise contributed by the various team members. “The best thing about this project was that there was no ‘old-school departmental thinking’, everyone truly supported the interdisciplinary approach,” Zimmermann recalls. “With engineering knowledge and practical experience, we kept coming up with new solutions that ultimately led to the optimal result.”
The result
- The steel frame of the chassis features a honeycomb structure created through material cut-outs; compared to its predecessors, this is significantly lighter but equally durable and load-bearing.
- Excess material was removed at several points (e.g. at the transition from the drawbar to the frame).
- The rear section was shortened by 1.5 metres.
- And a great side effect: the design is fresh and almost a little futuristic – it’s a shame that you can’t see it any longer once the body is assembled!
It took about three years from the initial idea to series production. Around half a million test kilometres were completed during this period. It’s a time Volker Eckle and Maximilian Zimmermann look back on fondly: “The VARIO X was a great challenge and a truly outstanding project for us, which could only grow through the interaction of different perspectives and skills. We're extremely happy that we were able to bring the chassis to market together with great colleagues – but that’s not the end. We will continue this path and see what the future brings in terms of new types of drive and materials. More ideas are already in the pipeline and just waiting to be implemented!”
