A field thrasher (10) includes a housing assembly (22) and a thrashing assembly (24). The housing assembly (22) includes an upper, thrashing enclosure (32) with a mouth opening (34) and a chaffe discharge opening (38). A lower, collection enclosure (33) is mounted below the thrashing enclosure (32) and includes a grain discharge opening (36), an air discharge opening (80) and a chaffe discharge opening (38). A spout (46) is mounted on the thrashing enclosure (32) in communication with the mouth opening (34). The thrashing assembly (24) includes a flail subassembly (50) comprising a rotor shaft (106) rotatably mounted in the thrashing enclosure (32) and tines (64) extending outwardly from the rotor shaft (106). A drive subassembly (40) includes a motor (42) drivingly coupled to the rotor shaft (106) and mounted on top of the thrashing enclosure (32). A fan subassembly (103) is mounted in a fan compartment (41) at an upper end of the thrashing enclosure (32) and provides an airflow through the housing (22).