This V-belt transmits power from the combine engine to the header drive system. It sits on the pulley set that drives the cutterbar, reel, and auger, synchronizing their operation with ground speed. A worn or slipping belt causes uneven header speed, leading to material bunching or stalling at the feed intake. The belt is constructed to match the original cross-section and length, which keeps the tension within the design range of the automatic tensioner. On installation, verify the belt sits fully in each pulley groove and adjust the tensioner to the specified deflection.