Patent ID: 7104346

Claim:
A power wheelchair comprising: a. a frame; b. a seat supported by said frame; c. a pair of drive wheels positioned below a central portion of said seat on opposite sides of said frame and supported thereon, said drive wheels rotatable about transverse axes; d. drive means for causing rotation of said drive wheels; e. power means for supplying power to said drive means to move the wheelchair; f. control means for controlling the rotation of said drive wheels by said drive means; g. at least one idler wheel operatively connected to said frame and positioned behind said drive wheels and rearward of the back of said seat, said idler wheel mounted for rotation about a horizontal axis and supported for rotational movement about a vertical axis; h. at least one anti-tip idler wheel operatively connected to said frame and positioned forward of said drive wheels and said frame, said anti-tip idler wheel being independent of said drive means and being positioned off the ground when said drive wheels and said rear idler wheel are in their normal ground-engaging position on level ground; and i. a resilient suspension supporting said forward anti-tip idler wheel for resisting upward arcuate movement of said anti-tip idler wheel, said resilient suspension comprising a first assembly and a first member, said first assembly being operatively attached to said frame at a first location rearward of the front portion of said frame and said first member being pivotally attached to said frame at a second location, said first member comprising a substantially vertically oriented portion and a substantially horizontally oriented portion having an angle therebetween, said first assembly being pivotally attached to the substantially vertically oriented portion of said first member at a third location rearward of the front portion of said frame, and the substantially horizontally oriented portion of said first member being operatively attached to said anti-tip idler wheel.