This gear transfers drive from the inclined feeder drum to the feed chain or auger that moves crop material into the threshing cylinder. It meshes with the mating sprocket on the drum shaft and maintains the correct timing between the feeder and the cylinder. A worn gear produces irregular chain speed, causing material bunching at the cylinder entrance and reduced throughput. The manufacturer machines the tooth profile to match the original gear’s pitch and pressure angle, so the chain engages without backlash or skipping. On installation, verify that the retaining bolt is torqued to specification and that the chain tension is adjusted after the first hour of operation.