Here's what I found at www.uspto.gov:

3430633     Conical Thresh. Assy   Mark, A.H.           Massey Ferguson                  March 4, 1969
3623302     Comb. Harvester          Schmitt, H            No company                           November 30, 1971
3848609     Axial Flow Type Harv   Roland-Hill, Edward  Clayson NV                      November 19, 1974       
4192322     Axial Flow Separator   Wilson, John E     Deere & Company                March 11, 1980
4136704     Rotor for a Combine     Dyke, Calvin J     Sperry Rand Corporation     January 30, 1979

Both the Clayson and Sperry Rand patents involved twin rotors.  Edward Roland-Hill, a co-inventor on the Clayson patent, has his address listed at Lancaster, PA - near New Holland, PA.

Calvin Dyke, however, has his address listed as Mt. Morris, IL.  So, it would lend some creedence to him being an IH engineer, leaving, and going to Sperry Rand.

The Deere patent shows an auger mechanism instead of a rattle chain for the feederhouse.  It is a single axial flow design.

The Massey Ferguson patent shows a mechanism very similar to the current Gleaner design, but with a cone shaped separator.

The Schmitt patent is from Germany, and although Claas isn't named, the designs appear to be very similar to the APS system used on the 400 series Lexions.