Patent ID: 7527551

Claim:
A heating, ventilation and air conditioning (HVAC) system comprising: a housing defining an air passage for directing air flow through said housing, an evaporator core and a heater core being supported in said housing for exchanging heat with air passing through said passage, a film having side edges and a plurality of elongated openings disposed in parallel relationship between said side edges and separated by strips of said film and supported by said housing to extend across said passage, a pair of racks attached to spaced ones of said strips and extending along said adjacent openings and having teeth disposed therealong, a pair of sprockets rotatably supported by said housing for rotation about an axis and engaging said teeth of said racks for moving said racks and said film linearly, a shaft extending between said sprockets, each of said racks including a strap spaced from and extending parallel to said rack teeth to define an elongated slot for overlapping and retaining said sprocket in engagement with said teeth, said slot presenting a bearing surface next adjacent to said rack teeth and said strap presenting an opposing and parallel bearing surface, a circular bearing member in each of said slots being circular and in rolling engagement with said bearing surfaces of the associated slot, each of said bearing members disposed in parallel and abutting engagement with one of said sprockets, each of said sprocket extending radially outwardly of the associated one of said circular bearing members, and each of said slots presenting a parallel abutment along said slot and disposed axially between said teeth of said adjacent sprocket and said associated bearing member for axially engaging said teeth of said sprocket to limit axial movement of said sprocket.