Overhaul hook ball

An overhaul hook ball, also known as an overhaul ball or headache ball, is a heavy weight that is attached to the end of a crane's cable, above the lifting hook. It is used to keep the cable under sufficient tension even when no load is attached.^[1][2][3] Although commonly spherical as the name suggests, overhaul balls may also be ellipsoidal or cylindrical.

A crane hook and overhaul ball assembly

Overhaul balls should be distinguished from wrecking balls, which although superficially similar looking, are different and serve a different purpose.