Combine harvesters having reversible return systems, and related methods

A combine harvester comprising:

• a feederhouse configured to convey a crop material from a harvesting header;
• a threshing system configured to receive the crop material from the feederhouse and separate straw therefrom;
• a cleaning system below the threshing system and configured to separate grain from chaff of the crop material, the cleaning system comprising:
• a reversible return system configured to receive the crop material from the threshing system;
• a grain pan below the return system;
• at least one oscillating sieve configured to receive the crop material from the grain pan;
• and
• a blower configured to direct air rearward and upward through the at least one oscillating sieve;
• wherein the return system comprises a return pan configured to be tilted between a first orientation and a second orientation, wherein in the first orientation, a major upper surface of the return pan is sloped downward toward a forward end of the combine harvester, and wherein in the second orientation, the major upper surface of the return pan is sloped downward toward a rear end of the combine harvester, wherein the return system is operable to deliver the crop material to a forward end of the grain pan in a first operating mode, and wherein the return system is operable to deliver the crop material to a rearward end of the grain pan in a second operating mode.