| CPC A61G 5/026 (2013.01) [A61G 5/027 (2013.01); A61G 5/1005 (2013.01); A61G 5/125 (2016.11)] | 16 Claims |

|
1. Mechanical wheelchair drive comprising a rotatably mounted lever, a handle fastened to the lever and a force transfer unit configured to transfer a rotational motion of the lever to a wheelchair wheel, wherein the lever has a variable length and can be guided along a closed guide of a guide plate, which guide deviates from the circular form, so that a length variation of the lever takes place during the rotational motion, wherein the guide corresponds to a droplet-shaped closed curve having a wide end curve region and a narrow end curve region, wherein the end curve regions each have a vertex point and the narrow end curve region of the closed curve in a mounted state of the wheelchair drive points in a direction towards a backrest of a wheelchair in a mounted state of the wheelchair drive, a longitudinal axis running between the vertex points of the wide end curve region and the narrow end curve region is inclined by at least 5° but no more than 30° with respect to the horizontal, and wherein the curve can be described by the following mathematical equations:
![]() wherein θ corresponds to an angle, the coordinates X and Y describe the course of the guide in a Cartesian coordinate system, the parameter β is specified between −20° and 30°, the parameters A and B are specified between 0.01 m and 0.25 m and the parameter n is specified between 0.2 and 0.9.
|