This hub is the central rotating element that carries the disc blade on a row-crop cultivator or disc harrow. It mounts between the blade and the support arm, allowing the disc to spin freely as it cuts through residue and soil. A worn hub introduces radial play, which causes the disc to wobble and leads to uneven working depth and accelerated blade wear. The hub is machined to the same bore and bearing-seat tolerances as the original assembly, so the disc runs true without shimming. On reinstall, ensure the bearing stack is fully seated and the retaining nut is torqued to specification.