Abstract: Classifying apparatus and methods are disclosed for the classification of extremely small solid particles of 18 mesh or less in which low frequency, high amplitude vibrations are imparted to a screen simultaneously with high frequency, low amplitude vibrations. The screen may be inclined at an angle of about 20.degree. from the horizontal and the screen mesh may be about 18 mesh or smaller and have openings which are approximately square in shape.

Abstract: An improved tensioning assembly for vibratory screens includes a rigid frame, at least one classifying screen in the frame, an anchor for anchoring one end of the screen, and a rotatable tensioning assembly at the other end of the screen for both anchoring the other end of the screen and tensioning the screen by rotation of the rotatable assembly. The anchor at the one end of the screen includes a plurality of threaded adjustment members spaced along the length of the anchor for flexing the anchor to selectively and incrementally further adjust the tension on the screen to compensate for tension variations across the width of the screen due to torque differentials in the rotatable tensioning assembly.

Abstract: An improved classifying apparatus and assembly for the tensioning of vibratory screens includes a rigid frame, a pair of classifying screens in the frame and means for tensioning the screens. The improvement in the means for tensioning the screens includes a stationary anchor at one end of the screens and elongate rotatable elements adjacent the other ends of the screens. Levers are mounted to the ends of the rotatable elements outside of the frame and a tensioning cable extends between the levers. A tensioning member is positioned in the cable which, when adjusted, rotates the rotatable elements to simultaneously and uniformly adjust the tension on the screens.

Abstract: Classifying apparatus and methods for the separation of solids of differing sizes includes a screening deck having an inclined frame and a screen in the frame on which the solids are deposited and moved downwardly. A plurality of beams extend beneath the screen transversely of the frame and the ends of the beam are mounted to the frame by a resilient mounting to isolate vibrations of the beam from the frame. A tappet assembly is fixed to each of the beams and contacts the underside of the screen and a vibrator motor is mounted to each of the beams to directly vibrate the beam, the tappet assembly of each beam, and the screen. Controls may be provided for independently operating each of the vibrators to vary one or both of the frequency or the amplitude of the vibrations of the screen over its length.