US Patent 7578355 Sway block of a three-point implement hitch

A sway block for a three-point hitch of an agricultural implement has a frame for supporting a tow hook; and the frame in turn has two substantially parallel right-angle plates. A respective pair of levers is hinged to each right-angle plate by pins; and each pair of levers is associated with a respective lock member operated from above by an operator using an actuating mechanism. The sway block performs the dual function of preventing sway and supporting a tow member.