US Patent 7090240 Tiltable seating apparatus for wheelchair

A tiltable seating frame (10) for selectively positioning seating in a wheelchair, in which a seat platform (12) has opposing sides (18) that each extend to an arcuate distal edge (20) and each side defines an arcuate slot (22) parallel to the distal edge. A base (14) has opposing sides (70) that receive pairs of front and rear rollers (72, 74) on which the distal edges (20) travel. Each side (70) also receives a guide roller (76) attached intermediate and vertically spaced relative to the front and rear rollers (72, 74). The guide rollers (76) extend through the respective arcuate slot (22) of the seat platform (12), to guide the movement of the seat platform (12) relative to the base (14).