The vertical motion also minimizes blinding of screen by “near size” particles. The tangential component of motion is controlled by the angle of lead given to bottom weights with relation to top weight. Variation in lead angle controlled the spiral pattern of material travel over the screen cloth. Speed & flow pattern of material travel over the screen cloth can be set by the operator for maximum throughout & screening efficiency for any screen able product, wet or dry, coarse or fine, heavy or light, hot or cold. Typical material passes rapidly through the screen during its travel to the periphery. The oversize material get continuously discharged through a tangential outlet.