Duct damper for transverse fan

Claim 1

A combine having a straw separation area including straw racks and a grain cleaning area beneath said straw separation area including grain cleaning pans; a transverse fan for producing wide and uniform air streams for use in said separating and cleaning areas; means for driving said fan at a substantially constant speed; a casing enclosing said fan and including an air intake opening, a main cut off for air moved by said fan, a first air outlet duct directing air to said straw separation area and a second air outlet duct directing air to said grain cleaning area; a transversely extending choke means pivotally mounted on said combine in said air intake opening adjacent to said cutoff and coextensive with said fan on an axis parallel to the axis of said fan, said choke means being adjustable between a choke position blocking part of said opening and an open position freeing said opening; a first baffle having perforations therethrough pivotally mounted on said combine in cooperative relation with said first duct for selective pivotal adjustment between an open position wherein said first duct is not obstructed thereby and a closed position wherein first baffle is in blocking relation to said first duct; and a second baffle having perforations therethrough disposed in said second duct and pivotally mounted on said combine for selective movement between an open position in which it does not obstruct said second duct to a closed position wherein it is in blocking relation to said second duct, said perforations in said baffles permitting partial flow through the associated ducts when said baffles are in their closed position, said first and second baffles being spaced from said fan a sufficient distance so as not to adversely affect the position of the fan vortex.