An assembly (200) for loosening or tightening mechanical nuts includes a socket arm (40) defining a socket (42) at its distal end for engaging a mechanical nut (102); a crank (30) connected or connectable at its first end transversely to a proximate end of the socket arm (40); a sliding hammer (20) connected or connectable to a second end of the crank (30), thereby being operable to impart a rotational impact on the socket arm (40) via the crank (30); and a support structure (250) connected or connectable at its proximate end to one of the socket arm (40), crank (30), or sliding hammer (20) and defining at its remote end a support surface (260) operable to bear against an external structure (100) thereby to support the assembly (200) in use.