Thin wheelchair

September 2005

This wheelchair was the final degree project of the Product Design Engineering degree I finished in 2005. This project was sponsored by the Red Cross

Their proposal was to create a personal wheelchair that could be adapted for its use in the beach. The Red Cross has some wheelchairs that can be borrowed but there are not many and they need two or three people to help the users.

—
Marta de Bergua and Jordi Parra

Testing the wheelchair

During a couple of days, the guys from the Red Cross let us check by ourselves how hard was to push the wheelchair on the beach sand.

At the same time, people part of the Institute for People with Disabilities of Barcelona also joined the discussions during the whole project to give us feedback about the actual equipment and help us decide what do they think is best for them.

The frame

Saline water was the biggest problem. For that reason we designed a simple frame made of carbon fiber with no soldered parts.

The seat is first laminated with different layers of carbon fiber, a poliurethane foam is milled and attached to the seat and another set of layers of carbon fiber are laminated on it to create the legs that support the wheels.

In the front part, titanium tubes are curved and slided on the carbon fiber part. The titanium tubulars are assembled with poliamide removable joints on the carbon fiber part.

From the street to the beach

The main problem moving the wheelchair in the beach was the size of its wheels. It needed a big surface of contact for not getting stuck on the sand. Even the big wheels the wheelchairs we tested had were not enough.

After a lot of discussion, what started as a joke became phisically the best solution. A big wheel containing the wheelchair would be the biggest wheel size and surface of contact we could get and the volume of it would keep it floating in the water.

Final proposal

The big wheel was made of different carbon fiber modules that could be assembled and stored by the Red Cross in their storage rooms at the beach.

All the calculations proved that this system improved the performance of the actual wheelchairs. The force needed to move it was drastically minimized and the user could also move it by himself by pushing inside the wheel.

The grade of this project was 10/10 and, as you can imagine, we were really happy after all the hours of work we spent on it!