Auniversal joint, (universal coupling,U-joint,Cardanjoint,Hardy-Spicerjoint, orHooke’s joint) is ajointorcouplingin a rigid rod that allows the rod to ‘bend’ in any direction, and is commonly used in shafts that transmitrotary motion. It consists of a pair ofhingeslocated close together, oriented at 90° to each other, connected by a cross shaft. The universal joint is not aconstant velocity joint.