This concept enriches the user of a manual wheelchair by offering an ergonomic alternative to the present method of grasping & pushing a cold slippery hand rim.
The concept answers the need of the wheelchair-bound who have reduced hand & arm capacity or prehension problems.
The Propulsor is designed to be manufactured by common processes such as injection molding or die casting.
The add-on Propulsion unit requires no modifications to the chair and can be retrofitted to fifty year old wheelchairs or installed by the inexperienced user with only a screw driver as tool.
The princeple is simple. Three rollers allow the unit to travel the circumference of the hand rim. To absorb the imperfections of the hand rim two of said rollers are spring loaded. The rocker on which the handle is fixed houses a rubber pad at each extremity. This rocker shares the same pivot bolt as the top roller and is balanced on a leaf spring that keeps the rubbers in a neutral position. When the user pushes the handle the rocker pivots causing the front rubber to crimp against the hand rim.The reverse action allows the opposit rubber to crimp and propel the chair backwards. When not in use the unit sits in a clamp thus allowing the chair to be pushed without the rubbers crimping the hand rim.
To brake the chair, a side mounted rubber sheet mounted on the unit frictions against the tire when the user pulls the handles laterally inwards.
Prototypes of said concept exist and have met my expectations during road tests.
The Propulsor unit should retail at $3-400.00
The only existing products that offer similar technical aide
are the Wijit that retails a +-$4,800.00 and the Geared Hubs that are priced at $2-3,000.00.