Vibrating Screen Components

Jul 15, 2020

Vibrating screens consist mainly of: screen body (vibrating basket / live frame), vibrator

assembly (vibrating unit), screening media, supporting frame and drive unit. Above figure
shows components of a typical vibrating screen.
Screen Body
The side plates of screen body are reinforced with plates and angles or channels. The side
plates are connected to each other by the screen deck (bucker-up-frame or trays)
constructed of transversal tubular or channel beams, heavy duty angles and flats; by the
feed box; the discharge lip and by the tube of vibrator assembly. The side plates and beams
may be protected from abrasion by covering them with wear resistant material. Together
these parts form the screen body. The screen body is generally of bolted construction.
The screen deck supports the screening media. Vibrating screens of most types can be
manufactured with more than one screening deck. On multiple-deck systems, the feed is
introduced to the top coarse screen; the undersize falling through to the lower screen decks,
thus producing a range of sized fractions from a single screen. The screen shown in above
figure has two decks.
Screening media (cloth or wire screen) is held in place by tension bars, which are attached
to the side plates tensioning the screening media over the screen deck.
The tensioning bar on side tension screens also serves as wear protection. Other screen
parts exposed to wear are also protected by wear plates / liners.
Screening Media
Separation of material is accomplished by means of screening media, commonly referred to
as decks, which act like a filter. Screening media are made of wire, woven wire cloth,

perforated plates, grizzly bar set, rubber or polyurethane.

Vibrator Assembly (Exciter)
The vibrations are given to a screen deck by vibrator assembly consisting of unbalanced
masses. The vibrator assembly shown in above figure is made up of eccentric shaft
contained in the shaft casing. The shaft is supported on two vibration screen duty selfaligning double row spherical roller bearings. The assembly is bolted to the two side plates.
The stroke length of vibration can be adjusted by rotating the counterweights installed at the
ends of the eccentric shaft. Instead of rotating the counterweights, some design provide
arrangement to change mass of the counterweights.
Generally, power is transmitted from the drive motor to the vibrator assembly by V-belt
transmission. The speed of the vibrating screen (vibration frequency) can be adjusted by
changing the ratio of V-belt sheaves. The eccentrically-bored screen sheave offsets the
stroke, so that drive centers do not change during operation. Instead of V-belt transmission,
drive motor with cardan/propeller shaft (universal coupling) is also used to drive the vibrator
assembly.
Screen Support Assemblies
The screen is supported on all four corners by either steel springs (as shown in above figure)
or molded rubber buffers (rubber springs), and it can either rest on the floor (as shown in
above figure) or be suspended by rods or chain. Rubber buffers provide longer life and less
maintenance than coil springs in wet applications. Marsh Mellow springs by Firestone are
rubber springs with fabric. Rubber buffers cannot break, trap particles, corrode, or bottomout. Bottoming-out under overload or surge load sends a large amount of stress to all of the
screen’s components. However, rubber buffers have an operating range. It is recommended
that shielding should be used to protect the rubber from exposure to hot metal, petroleum
base fluids (oil, grease), etc. These springs / rubber buffers absorb about 85% to 95%
vibration of the screen, isolating the screen from the supporting structure. Many times, if
screen is to rest on floor, the spring support brackets are bolted to the screen body by
turnable mounts, allowing the screen to be installed in alternative inclinations.

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