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Shaftless Screw Conveyor – Spirac

Spirac shaftless screw conveyors with horizontal, inclined and vertical orientation with no intermediate or end bearings, low rpm and low power usage is a space-saving, extremely reliable conveying option. Maintenance is significantly reduced when compared to traditional conveying methods. The elimination of a central shaft allows a much higher fill rate resulting in lower rpm’s; more efficient conveying and consequently less wear and power usage.

Click here for sample SPIRAC Shaftless Conveyor Specification in Word

Click below for video clip for a shaftless conveyor in action for screening, grit and sludge handling:

 See video clip (2 minute) for handling a number of applications such as sludge dewatering, large objects, screening,
  • No intermediate or end bearings – reduce major maintenance work
  • Duoflo liner –
    • Doubles life expectancy to regular lines (UHMW-PE) with integral lubricatn and added hardeners
    • Built-in wear indicator
      • Yellow Indicator shows once the liner has worn out by 80%
      • Liner change-out simple and quick (10 to 15 minutes per piece) with a snap-in, snap-out.
      • Screw: Excessive wear on the screw shall be indicated by loss of more than 50% of the height of the main outer screw section over 30% of the total length of the screw. If excessive screw wear is found the conveyor supplier shall provide new screw to replace the screw in the conveyor that has excessive wear.
      • Liner Spec Language:
        • The inside trough surfaces of the conveyros shall be lined with a layer of ultra high molecular weight polyethylene UHMW-PE. The wear liner shall be SPIRAC Duraflo SPX or Xylethon by Durawear.  The liner shall be a single piece, formed and bonded with two (2) layers of the same material, each of a different color, to provide a visible indication when the liner is nearing the end of its useful life.  Liners using layers of different material shall not be accepted. The liner shall be supplied in maximum 3.3 foot long sections to provide ease of replacement.  The liner shall be held in place with stainless steel clips; no fasteners will be allowed.  Liner thickness shall be at a minimum ½” thick.  Liners less than the specified minimum thickness, molecular weight, wear strips and steel or hardened steel shall not be acceptable.The liner material shall have the following physical properties, as a minimum:


                  Value/Unit Testing Method
          Density 61.2 lbs/ft3 DIN53479
          Molecular Weight 9.2×106 g/mol Margolies
          Ball Indentation Hardness 5,946 lbs/in2 DIN53456
          Shore Hardness D 64 DIN53505
          Crystalline Melting Range 278º F  
          Dynamic Coefficient of friction 0.1-0.12 ratio

          of tension/load

          Plastic to steel


        • Spec Language: Screw & Liner WarrantyThe shaftless screw liner and spiral shall be warranted for a period of three years from factory start-up against wear.Liner: For a wear indicator (two color) liner, excessive wear shall be indicated by appearance of the bottom indicator layer (second color) along more than 30% of the conveyor length during the first three years of service.  If these wear indications occur the conveyor supplier shall provide new formed and banded liner to replace all the liner in the conveyor that has excessive wear.If a one color liner is used the excessive wear shall be indicated if the thickness of the liner, at three points over a 30% long section of the conveyor, is a ¼” thick or less at the thinnest point of the liner, during the first three years of service.  Since one color liners prohibit a simple visual inspection confirmation for the liner thickness status at the spiral-liner contact point, the conveyor manufacturer shall supply a field technician to the jobsite on the annual acceptance date for three consecutive years, to remove a minimum 30% of all liners and demonstrate to the owner that at a minimum of ¼” of liner is remaining.  If excessive liner wear is found the conveyor supplier shall provide new formed and banded liner to replace all the liner in the conveyor that has excessive wear.

 Spirac DURAFLOW liner with built in wear indicatior


  • Direct Drive – allows a clean and efficient transmission without the maintenance required with belt and chain drives.

Spirac Direct Drive shaftless


  • Shaftless Spiral – made out of special high tensile micro-alloy steel. Conveyors are designed for the  transport of otherwise difficult to handle materials, such as municipal dewatered sludge, wastewater
    screenings, grit, industrial sludges and other sticky, viscous, stringy materials.

Spirac sizes

  • Inclined Shaftless Conveyor

Spirac shaftless conveyor loss of rotation sensor

  • Steep Inclined Conveyors – Octagonal Shape for steep inclines or vertical applications

Spirac Octagonal Shape steep incline or vertical

  • Vertical Conveyors

Spirac vertical conveyor











  • Drainage Options
Spirac drainage options perforated screen Wedgewire or Open Drain
  • Slide Gates
Spirac Slide Gate Options
Spirac slidge gates discharge in truck or dumpster
spirac conveyor feeding rolloff container with electric actuators
Spirac bin filling simple no gates
  • Centrifuge Start-up Diverter Gate – redirects slop from centrifuge startup
Spirac Centrifuge startup Diverter Gate redirect Slop


  • Grit Conveyor – Grit Chambers
Spirac grit chamber shaftless screw


  • Hinged Lid – Anti-lift pad
Spirac hinged lid anti-lift pad shafless conveyor


  • Inlets & Outlets

Spirac inlets


  • Complete Sludge Solutions – Live Bottoms, Storage Bins

Spirac complete sludge storage bins live hoppers


  • Enclosed Container – sludge, screenings, grit

Spirac enclosed container sludge screenings grit odor

  • Container filling System

Spirac container filling system