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Aids for the Handicapped: A Stairs-Climbing Wheelchair

Client

National Inventors Council, Department of Commerce, Washington, D.C.

Problem

The National Inventors Council offered a reward of $5,000 to anyone who could successfully design a wheelchair that could climb stairs in 1959. A design was submitted by the author in 1962, the last year of the competition, but no prize was obtained. Later it was decided to build a model and find out whether the concept and the design were sound. The model worked as well as it was expected. It climbed and it was stable.

Solution

The approach consisted on a reclinable-seat wheelchair provided with retractalbe, spring-loaded spokes that comes out of the rims when the chair is tilted for climbing. The spokes in essence behave as compliant pinions against the stairs as a rack. As a result the wheels adapt to any type of stairs and will not slip because the static reactions are always vertical and have no tendency to slip, besides that, they are rubber-tipped at the spokes. The tilting frames is also provided with an additional fixed spokes wheel at the back side to facilitate climbing. A photograph of a 1/4 scale working model is shown in the act of climbing under its own power from a small electric motor. As will be noticed, one of the spokes has retracted as the axial component exceeded the frictional force, while another is receiving almost the full lateral load and lifting the chair.

None of the designs receiving the partial prize was successful commercially.

Picture of a Stairs-Climbing Wheelchair