US Patent 7841931 Airflow controlled combine shoe

A combine harvester having a frame and a crop harvesting header supported by the frame to gather crop material. A threshing and separating mechanism connected to the frame that receives the crop material from the header to thresh and separate the grain. A shoe assembly positioned beneath the threshing and separating mechanism to receive the threshed grain connected to a drive that affects fore-and-aft reciprocating movement of the shoe assembly which conveys grain rearward. A flexible seal attached to the underside of the shoe assembly across the width of the shoe to obstruct air from flowing under the shoe assembly.