Abstract: A screening machine of the moving base type has an oscillating force reducer and a single counterbalance drive, with the weight of the drive counterbalance sized to underbalance the longitudinal reaction force exerted by the deck on the drive shaft, but to substantially overbalance the lateral reaction force exerted by the deck on the drive shaft. The weight of the force reducer, the spring constant of the spring which oscillates the force reducer, and overall cost are surprisingly reduced.

Abstract: The screening efficiency of a gyratory screening machine, of the type having a moving base, is significantly increased by mounting to the base a spring/mass system which is tuned so that operation of the machine drive produces amplified movement of the mass along at least one of two perpendicular axes on which the base moves. Movement of the mass reduces the net force on the base along the axis on which the mass oscillates. The reaction force of the machine drive on the base along the other of the two perpendicular axes may be offset by a rotary counterbalance operated by the drive. Movement of the base relative to the ground is thereby reduced, and movement of the screen deck relative to ground is increased. This both increases the effectiveness of the screening motion and decreases the total reaction force transmitted through the base.

Abstract: Disclosed is a clamp for securing the top cover of a screening machine. Clamping is not subject to galling or seizing and the force exerted is not temperature or displacement dependent. The clamp is air pressure operated, with super-atmospheric pressure being applied for clamping and venting to atmosphere or sub-atmospheric pressure being applied to release the clamp. The clamp is mounted for easy swing away movement when not in use so as to permit the top cover to be removed. Multiple clamps may be simultaneously operated from a common manifold.

Abstract: Disclosed is a ball cleaner for a screening machine in which the ball cages are presented by a molded plastic insert having integral intersecting longitudinal walls and cross walls. The weight of material being screened on the screen which overlies the insert is not carried by the insert but rather by a separate support beneath it. The support comprises a peripheral frame and joists within the frame which directly underlie at least the longitudinal walls of the insert. The insert completely isolates the frame from the erosive action of the cleaning balls and can be replaced separately from the frame.

Abstract: A screen deck having spaced, canted parallel slats which present screening slots between them, wherein the slats are mounted on pedestals that are positioned and aligned by parallel rods which extend transversely through the pedestals. The pedestals are spaced apart by spacers between them, the spacers being held in place by the rods. Slat mounting is facilitated and slot width uniformity is improved by use of the pedestals.

Abstract: A flexible connector for screening machines comprises an assembly of a plurality of generally cylindrical, flexible collars. Each collar has an annular endwise bead on a first circumferential end and an annular endwise opening groove within an endwise surface of a second circumferential end. The collars are connected by applying force in an axial direction to adjacent and aligned collars to seat and secure the bead of one collar into the groove of an adjacent collar to form a tube along an axis of connection between a particle chute and a movable screen frame.

Abstract: A machine and method for separating chip-like particles according to thickness which provides low blinding and high efficiency at high throughput in sustained operation. The machine has a sloping deck mounting a series of spaced flexible louvers or slats which extend parallel to the direction of chip flow down the deck. The slats are canted transversely to the direction of flow, and present unobstructed full length slot-like chip openings between them. The deck is driven with a horizontal gyratory motion such that during the upstream half of each cycle of movement, each slot moves toward chips on the adjacent slat which slopes toward it, and moves away from such chips during the downstream half of the cycle. The path of screening movement is uniform over the entire deck, that is, the motion of the lower or discharge end of the deck matches that of the upper or feed end.

Abstract: An apparatus for automatic screen analysis of a granular material in which the material is screened from a polygonal drum which is divided crosswise into at least two chambers by a transverse partition. A first chamber has progressively coarser screens on each of its faces except one, which has a downward slanting ramp for transferring the sample into a second chamber. Particles are transferred or chuted into the second chamber after they have been screened on all the screens of the first chamber. The second chamber has screens progressively coarser than those in the first chamber, for making more cuts. This construction increases the number of graded screening surfaces available without requiring greater drum length or more sides.

Abstract: A screening machine having an improved seal operable between the stationary inlet and outlet conduits of the machine and the movable inlet and outlet ports of the screen enclosure. The improved seal comprises a low friction slideable ring movable relative to a slide surface on one or the other of the conduit or the screen enclosure.

Abstract: In a multiple deck screening machine, the feed material is divided into separate equal fractions as it falls into parallel vertical channels. Each channel serves a particular screen deck via a chute which diverts the respective fraction from the channel onto the screen. The lower chutes include widened portions that extend laterally from their respective channels into areas which are masked or closed above by overlying upper chutes, in order to provide flow areas onto the respective screens which are wider than the channels that feed them, and thereby provide better flow distribution onto the screens.

Abstract: A method and apparatus for improving the distribution of a stream of incoming feed material onto the screen of a screening machine. The distributor apparatus includes a rotating, dished or cupped thrower surrounded by a fixed shroud. The shroud is of a cross-sectional area substantially larger than that of the thrower but substantially less than the surface area of the screening machine's top screen. The incoming material is discharged into the cup of the thrower, the rotation of which slings the material outwardly over the rim of the cup and against the shroud, in a more symmetrical angular distribution. A roof having directional vanes on it is interposed above the screening machine's top screen, and below the thrower and shroud. The infed material drops from the shroud onto the vaned roof, and the vanes direct it outwardly in a predetermined pattern toward the peripheral edges of the screening machine's top screen.

Abstract: The screening motion of a screening machine is changed by adding ballast, while the machine is in operation, to selected closed compartments moving with the vibrating assembly. In the preferred embodiment, the ballast is added through flexible tubing which is inserted through ports that close with spring loaded oil hole caps. When the tubing is pulled from the ports, the caps snap closed to capture the ballast in the selected compartments.