There is a lot of room for improvement in the design of wheelchairs. This is demonstrated by the single-axle Hoss Mobility, which was developed on the basis of a Segway. The electric wheelchair from the Austrian company of the same name is agile and all-terrain. The team led by founder and electrical engineer Lukas Rigler installed structural dampers from ACE to ensure comfort for people with limited mobility on any surface.

Using Segways as the basis for the wheelchairs of the future seems paradoxical at first. After all, even people without disabilities receive instruction when using the recreational vehicle for the first time in order to avoid falling over or having an accident. The issue of safety is even more important for people who use wheelchairs to get around and want to get off the beaten track. The innovation from Lukas Rigler's team, who came up with the wheelchair idea more by chance, is aimed specifically at these people: "When I parted with my private Segway, I was surprised to find that a wheelchair user was the buyer. He wanted to convert it into a new type of wheelchair. It was only then that I realized the added value of single-axle technology." In the wheelchair sector, the handling and intuitive operation of a Segway are indeed revolutionary, and not just for designers like Lukas Rigler. The design, which he has perfected together with drive engineer Dominik Lorenz and delivered well over 200 times, makes it possible for the first time to turn on the spot while seated in a wheelchair, drive over hill and dale and even get safely through snowy terrain - all with compact dimensions. The larger wheels compared to the small wheels of commercially available models also prove to be an advantage. This became apparent when he helped the buyer of his old Segway to realize the conversion and develop the prototype of the Hoss Mobility. In order to exploit the full potential of the self-balancing Segway drive, the designer created a wheelchair from scratch.


Speeds and suitable damping as challenges

The special feature of his wheelchair, christened "Hoss", and the key to its intuitive handling is the ability of the single-axle vehicle to stabilize itself dynamically. To explain this, Lukas Rigler draws a comparison with the most familiar intuitive means of locomotion, our bodies: "If a person leans forward without moving their legs, they would fall on their nose. In order to prevent a fall, the brain tells you to move one leg forward at that moment. So if you lean forward, you inevitably move forward, one step at a time. Our hoss does the same, but with wheels instead of legs. Powerful processors and electric motors take over the function of the brain and muscles in our vehicle. And movement and tilt sensors protect against falling over." These have the task of constantly analysing the driving behaviour, whereby an independent mechanical support system stabilizes the wheelchair with wheels at the front and rear if necessary. A folding mechanism extends immediately in the event of system failure and brings the Hoss to a standstill. While a conventional electric wheelchair can usually be propelled at around 6 km/h, the Hoss Mobility can reach speeds of 15 km/h. According to drive specialist Dominik Lorenz, people with limited mobility want to be restricted as little as possible when enjoying their ride.

One of the challenges the team faced was the comparatively high speeds that a Hoss Mobility can achieve on level ground. In the long term, this puts a lot of strain on the rider's anatomy, especially on rough terrain. Lukas Rigler also came across this design-related task rather by chance during the development towards series production and notes "Interestingly, during research, for example at trade fair stands, hardly anyone in a wheelchair raised the issue of better cushioning with me. The impression was more that wheelchairs are the way they are and you have to get used to them. It was only when a prospective customer came to visit that I became aware of the cushioning. The gentleman had a manually powered wheelchair that looked as if Angus MacGyver had screwed it together, and one important modification that the user had built himself was its damping." While Lukas Rigler had thought about independent suspensions, shock absorbers and gas springs, the man gave him the idea of turning the seat as a whole into a damping and comfort zone. To overcome this challenge, he began an Internet search.

Solid-state damping in the form of the TUBUS from ACE as a solution

He quickly came across ACE Stoßdämpfer GmbH. The wide range of products and the well-structured website www.ace-ace.de were convincing. In addition, the existence of its own sales structure in Austria made the initial contact even easier. The collaboration on site proved to be as uncomplicated as it was goal-oriented. Although the design engineer had thought of a practical solution with hydraulic components, Hans-Jürgen Greindl, the responsible sales engineer at ACE Stoßdämpfer GmbH, surprised him with his own research and a much more cost-effective alternative proposal. "My contact at ACE suggested solid-state dampers as an intelligent choice for damping the seat surface. The ACE structural dampers he had in mind are less sensitive to dirt, have no guides or other sensitive parts and are therefore virtually indestructible. After a few ride tests, I was convinced," Lukas Rigler looks back. There was no question for the specialists at ACE that the TUBUS, which are called TUBUS because of their tube-like shape, would do their job, and not just because of the design. The engineers from Langenfeld in the Rhineland were also able to look back on experience from another application. TUBUS has already been used to successfully optimize the driving characteristics of electric scooters for pilots of different weights. In these tailor-made solutions, ACE's design engineers have used different structural dampers for different weight classes.
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From a large number of over 150 standard individual solutions, Hoss Mobility GmbH opted for the TR product family from ACE. This is characterized by soft deceleration. The compact design of these maneuverable wheelchairs is crucial in order to make the most of their advantages. The TR types have been specially developed for a maximum stroke of between 12 and 60 mm with a minimum overall height, whereby the energy absorption per stroke ranges from 1.2 Nm to 146 Nm. The dampers are available in formats with diameters from 29 mm to 100 mm. All of these maintenance-free, ready-to-install elements are made of co-polyester elastomer, which only heats up slightly and therefore ensures consistent damping. Compared to other components that decelerate inertial forces, such as rubber dampers or steel springs, TUBUS impresses with a service life of more than 1 million load strokes, making them suitable for continuous off-road operation and even theoretically suitable for inheritance from one generation of drivers to the next.


In this application, models of the TR63-43 type are installed. The first number stands for the diameter of the component, the second for the maximum stroke. This type is capable of reducing 12.0 Nm/stroke. For emergencies, even 17.0 Nm/stroke would be permissible. When they are not mounted on the revolutionary single-axis wheelchair, TUBUS of this series are suitable as end-position damping in linear axes, in toolmaking and machine tools, in hydraulic and pneumatic devices, handling devices and other applications. Since they can be fitted quickly and easily under the seat of any Hoss Mobility using a special screw, many people with disabilities are already benefiting from a significant improvement in their quality of life.