gyratory

Gyratory refers to motion around an axis characterized by circular or conical paths, and to devices that produce such motion. The word comes from Greek gyros, meaning circle.

In physics and engineering, gyration describes the circular motion of a body or particle about an axis. It is a general term used to describe how objects move in rotating frames, including the behavior of gyroscopes and precession phenomena.

The best known is the gyratory crusher, used in mining and aggregate industries to reduce ore or rock size. A gyratory crusher has a concave surface and a conical head that gyrates within it; the shaft is mounted eccentrically, causing the mantle to describe a continuous, crushing motion.

Another application is the gyratory sifter, a screening device that uses an eccentric drive to impart a gyratory motion to a stack of screens, enabling separation of particles by size in food, pharmaceutical, and chemical processing.

Gyratory motion also appears in laboratory equipment and instruments that require controlled circular movement, and the term is used more broadly to describe any circular motion about an axis.