Crushing and Screening Glossary

  • Aggregate
    • Sand, gravel, crushed stone and quarried rock used for construction purposes.  Any combination of crushed rock, gravel, sand or granular material suitable for the manufacture of hot mix asphalt, batch mix concrete or any other construction purpose. The term “aggregate”, as defined in many regulations, means gravel, sand, clay, earth, shale, stone, limestone, dolostone, sandstone, marble, granite, “rock” or other prescribed material. Note, the term “Earth” does not include topsoil and peat.
  • Baffle Plate
    • The spring-loaded plate that allows rocks to pass without harming the shredder blades.
  • Belt Scraper
    • Rubber or plastic piece used to scrape excess material off the return side (inside) of the conveyor belt.
  • Belt Tracking
    • The process of adjusting the conveyor belt to keep the belt centered on the idlers and the pulleys.
  • Belt Wipe (also called a belt cleaner)
    • Rubber or urethane component used to scrape excess material off the conveyor belt.
  • Bulk Density
    • A property used in reference to mineral components (soils, ores, aggregates, rock). It is defined as the mass of many particles of the material divided by the total volume they occupy. The total volume includes particle volume, inter-particle void volume, and internal pore volume.
  • Conversion Kit
    • Needed to convert engine power to hydraulic drive power for an additional stacking conveyor or other auxiliary equipment. Consists of a pump, filter, valve and all hosing.
  • Chute
    • A material deflector used to deflect material away from the shaker screen on to the ground or into the load hopper of a stacking conveyor. Typical options are short straight chute, short taper chute, long taper chute, fines deflector chutes, and fines collection chute.
  • CSS
    • Closed side setting.
  • Diesel Module
  • Dust Suppression
    • Water pipes and valves that are added to reduce dust generated by material processing.
  • Fines
    • The finished product that passes through all screens.
  • Finger Screens
    • A screen used when raw material contains lots of roots or other vegetation. Finger screens cascade on top of one another which prevents clogging.
  • Grade 80 Steel
    • A structural steel that is harder than mild steel which allows equipment to be built stronger with only moderate increases in weight.
  • Grizzly
    • The rough pre-screen portion of a screening plant that sits on top of the hopper.
  • Grizzly Screen
    • A heavy-duty screen used on the top deck for rough screening applications.
  • Hammermill
    • See shredder.
  • Harp Screen
    • A wire screen that resembles a harp, allowing the wires to vibrate slightly to reduce plugging in stickier material applications, such as dirt or damp sand. Often referred to as piano wire.
  • Independent Hydraulics
    • Refers to each function of a machine having its own hydraulic pump, valve and motor. This provides full power to all functions. This also enhances efficiency, making hydraulics more robust and easier to diagnose problems.
  • Idler
    • The rollers that support the conveyor belt.
  • Lagged Head Pulley
    • A rubber covered pulley used on the head or upper end of the conveyor to drive the conveyors. The rubber acts like a tread to drive the conveyor. The thicker the rubber lagging, the longer the pulley lasts.
  • Ore
    • A material that contains a metal in such quantities that it can be mined and worked commercially to extract that metal. The metal is usually contained in chemical combination with some other element in addition to various impurities.
  • Overs
    • Product that does not pass through a screen.
  • Pivot Plate
    • The plate on the lower end of the conveyor which the conveyor swivels or pivots on when it is making a radial stockpile.
  • Pulley
    • The large roller at the end of the conveyor which the belt wraps around.
  • Reduction Ratio
    • A 5:1 ratio means a 5” rock is crushed to a 1” rock.
  • Remote Control Tipping Grizzly
    • The grizzly can be cleared by use of a remote control by raising one side vertically, causing oversized material to dump off.
  • Return Idler
    • Idlers mounted underneath a conveyor to support the belt.
  • Rock
    • In the definition of aggregate the term “rock” excludes metallic ores and the non-metallic ores: andalusite, asbestos, barite, coal, diamond, graphite, gypsum, kaolin, kyanite, lepidolite, magnesite, mica, petalite, phosphate-rock, nepheline-syenite, salt, sillimanite, spodumene, talc, and wollastonite.
  • Rubber Disc Return Idler
    • A return idler that has multiple rubber discs instead of one solid steel can. This helps to prevent material buildup. When material builds up on return idlers, belts do not stay tracked (centered) and can even stop.
  • Self-Aligning Idlers
    • Idlers that track the conveyor belt automatically by floating on a bearing and constantly adjusting to the belt tracking.
  • Shaker Screen
    • A mechanical device that vibrates to sift materials into different sizes. Shaker screens can have either 2 or 3 decks of screens.
  • Shredder
    • A high-speed, flailed hammermill that pulverizes topsoil on screening machines.
  • Shredder Blades
    • The free-swinging part of the hammermill that breaks up dirt clumps.
  • Shredder Rods
    • The part that holds the blades in place on the hammermill.
  • Sod Deck
    • A rod type screen used as a top deck on screening plants in dirt applications. Sod decks reduce plugging due to sod clumps.
  • Spray Bars
    • Water pipes and valve that are added to shaker screens for washing applications. They are currently only offered in conventional screening plants.
  • Spyder
    • Self-contained machines that have all the elements of conventional machines with the addition of attached conveyors to move sized products away from the machine.
  • T-1 Steel
    • A type of hard steel for impact wear.
  • Troughing Idler
    • Idlers mounted on the top side of the belt which carries the material.
    • Screen Module
      • This is a screen on a stand used in conjunction with other stationary or semi stationary equipment.
  • Trommel Screen
    • A barrel type screen that rotates to tumble the material during sizing.
  • Weight Box
    • A heavy concrete block that holds down the end of stacking conveyors. On certain types of conveyors, a weight box version allows for a greater stockpiling capacity than a pivot plate version.
  • Wing Tail Pulley
    • A paddle type pulley used on the tail, or the lower end of the conveyors. These are better than drum pulleys because they clean the underside of the conveyor belt while keeping the belt running and centered. Additionally, these pulleys prevent rocks from getting between the pulley and conveyor belt which could damage the belt.
  • Wire Cloth
    • Square opening screen used to size material on any type of screening plant.