Universal joint

A universal joint is a joint in a rigid rod that allows the rod to bend in any direction. It consists of a pair of ordinary hinges located close together, but oriented at 90° relative to each other.

Universal joints are common wherever a drive shaft[?] needs to turn a corner; a drive shaft with a universal joint can freely rotate through the universal joint, and no gears are required to couple the two ends. The most obvious example of this application of a universal joint is in the drive shaft of automobiles.