US Patent 7556109 Electric wheelchair suspension

An electric wheelchair suspension includes a supporting frame unit and two linkages. The supporting frame unit includes a bottom frame, two posts, and two main rods. Each of the linkages includes an upper link, a lower link, a front caster rod, a bottom link, and a rear link. The upper links are connected respectively and pivotally to the main rods. The lower links are connected respectively and pivotally to the posts. Each of the front caster rods is connected pivotally to the upper and lower links of a corresponding one of the linkages. The bottom links are connected pivotally to the bottom frame. Each of the rear links is connected pivotally to a corresponding one of the upper links and a corresponding one of the bottom links.