This hub is a double-width component installed in the drive system of a large square baler. It transmits torque from the gearbox to the flywheel or main drive shaft, synchronizing the plunger and knotter mechanisms. A worn hub introduces backlash, which causes timing drift between the plunger and the tying cycle, leading to missed knots or jammed twine. The original manufacturer machines the bore and keyway to the same tolerances as the original assembly, so no shimming or reaming is required during replacement. On reinstall, ensure the retaining bolt is torqued to specification and the key is seated fully in the shaft groove.