Universal Joint

A universal joint, also called a universal coupling or U-joint, is a joint connecting rigid shafts whose axes are inclined to each other, consisting of a pair of hinges set at 90 degrees to one another and linked by a cross shaft, used to transmit rotary motion between misaligned shafts. The English scientist Robert Hooke recorded the first known use of the term 'universal joint' in his 1676 book on helioscopes, building on a coupling design generally credited to the 16th-century Italian mathematician Gerolamo Cardano. The device remained a specialist mechanism until the American engineer Clarence Spicer and his Spicer Manufacturing Company popularized it for automotive and industrial drivetrains in the 20th century, and it is now a standard component wherever rotating power must cross an angle.