PROBLEM TO BE SOLVED: To solve problems in which the conveyance speed of a feed chain to a threshing device is optimized by shifting gears on the basis of a conveyance speed of the reaped grain culm of a reaping device, and therefore a transmission for exclusive use of the feed chain is necessary and a manufacturing cost is increased.SOLUTION: A feed chain (13) is configured to be driven by the transmission path of two systems of a gear shift rotary transmission path (D) for transmitting gear shift synchronization rotation transmitted to a reaping device (4) and a constant speed rotation transmission path (T) transmitted to a threshing device (3) at a fixed gear ratio. Two shafts of a starting end side shaft (31) of a starting-edge side gear (30) with the feed chain (13) wound therearound and a terminal side shaft (33) of a terminal side gear (32) are made the input shafts of the feed chain (13), respectively. The rotational power from the constant speed rotation transmission path (T) is input in any one of the starting end side shaft (31) and the terminal side shaft (33), and the rotational power from the gear shift rotary transmission path (D) is input in any other side of the starting end side shaft (31) and the terminal side shaft (33).SELECTED DRAWING: Figure 2
