Patent ID: 7311329

Claim:
A wheelchair comprising: a frame; a first anti-tip wheel supported by the frame for rotation about an axis of rotation and having an outer portion adapted for rolling contact with a supporting surface and having a first side; and at least a first housing supported by the frame, the first housing partially surrounds the anti-tip wheel, at least a portion of the housing extends laterally beyond the first side, the first housing having a convex outer surface with a vertex positioned at a first height and an outer perimeter proximate the wheel outer portion, and a portion of the convex outer surface proximate the outer perimeter defines a tangent line to both the portion of the outer surface and an outer extent of the wheel such that when the first housing contacts an obstacle at a height less than the first height, interaction of the outer surface with the obstacle facilitates movement of the wheel over the obstacle, and further comprising a second housing supported by the frame and the first anti-tip wheel having a second side, wherein the second housing partially surrounds the anti-tip wheel, at least a portion of the second housing extends laterally beyond the second side, the second housing includes a convex outer surface with a vertex positioned at the first height and an outer perimeter proximate the wheel outer portion, and a portion of the outer surface proximate the outer perimeter defines a tangent line tangent to both the portion of the outer surface and an outer extent of the wheel such that when the second housing contacts an obstacle at a height less than the first height, interaction of the outer surface with the obstacle facilitates movement of the wheel over the obstacle.