Patent ID: 6857490

Claim:
A stair-climbing wheelchair having a seat, a frame supporting the seat, and a set of wheels on which the wheelchair can be propelled, the improvement comprising: a spaced-apart pair of elongate track assemblies mounted to said frame extending underneath said seat between said set of wheels in a front to back direction relative to the wheelchair, in an inoperative storage condition said track assemblies being spaced above a surface on which the wheelchair is supported by said set of wheels and in an operative drive condition said track assemblies engaging a surface on which the wheelchair is supported for purposes of transporting the wheelchair along a path of travel to thereby enable the wheelchair to descend and ascend an obstacle; each of said track assemblies including an elongate guide member carrying an endless belt, said guide member having front and rear end sections each supporting a roller over which said endless belt is mounted for rotation about said rollers, said guide member being upwardly arched between said end sections thereby permitting said endless belt to deflect upwardly between said rollers when said endless belt engages an obstacle; and said frame including a pair of X-shaped members that interconnect said set of wheels of the wheelchair to said seat of the wheelchair, each X-shaped member including a pair of legs that pivot at their interconnection in a scissors like motion to extend said set of wheel of the wheelchair below said track assemblies to place said track assemblies in said inoperative storage condition and to retract said set of wheels above said track assemblies to place said track assemblies in said operative drive condition.