This gear transmits drive from the reel motor to the reel shaft, synchronizing the rotation of the bat assembly with the machine's forward speed. It is the primary drive component in the reel driveline, meshing with the mating pinion on the motor output. A worn or damaged gear causes the reel to slip or stall, leading to uneven crop pickup and feeding. The original manufacturer's gear is cut to the same tooth profile and hardness as the factory-installed part, ensuring the correct backlash and load distribution across the tooth face. On replacement, inspect the mating pinion for wear and confirm the keyway alignment before securing the gear to the shaft.