The most powerful tool for vibrational screening is gyratory vibration, which is used by a VIBRO SCREEN. It produces 100% rotary motion, which causes dispersion stirring and stratification of the sifted material. The feed material continuously flows horizontally through the vibro screen surface in a loop pattern. Vibro screens are operated by a unique vertically mounted motor with eccentrics at both the upper and lower shaft ends. In the horizontal plane, rotation of the out of equilibrium top weight induces friction, while rotation of the lower weight causes tilt and vibrations in the vertical plane.