StringChair is a lever drive system for wheelchairs which can be installed to almost any wheelchairs on the market. It consists of a hub (in the middle of the wheel with the spokes), a rope drum near the hub, the driving string and the levers with adjustable stroke force. The drive system is symmetrical, the two sides are mirroring each other. The levering strenght can be adjusted manually in a standing position.
How it works: The user of the wheelchair can drive the chair by pushing the „rods” forward. The two sides are independent so
the driving rhythm can be alternating or synchronised. By pulling the levers backwards the user operates the brakes. Steering is
made by pushing one lever forward and pulling the other to braking position. This movement offers an easy maneuverability
or even a 180/360° turn around one wheel. The user keeps the standard handrim driving mode of the wheelchair, so the backward travelling.
Benefits: The problem with the current wheelchairs is that the arms are making a twisted (elbows above the shoulders), strenuous, jerky, pulsating movement. It can cause unusual stress to the muscles of the upper body and the arm, and what is
more important it can cause irreversible joint degradation to the shoulder. For people living with specific diseases or in an elderly age this kind of movement/drive is impossible.
Stringchair puts the arms backs to a healthier, more ergonomic position, tested by human evolution. It offers a consistent,
balanced, smooth movement and force load instead of the high force peaks during the classical hand rim drive.