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Tubular Drag Conveyors

Technical Details: The Basics

Cableflow, Chainflow or Dynaflow tubular drag conveyors for dry bulk materials.

What are they?

Tubular Drag Conveyors (TDCs) are mechanically driven conveyors that 'drag' material along the inside of a totally enclosed tube. They are designed to transfer a wide variety of bulk materials from a single or multiple in-feed points to a single or multiple discharge points through various configurations of totally enclosed tubing. TDCs use close-running discs connected by a cable or various styles of chain. They have been used successfully throughout a range of industries for over fifty years.

The cable drag conveyor disc is seated in the sprocket.

Cableflow cable & disc in sprocket

The drag conveyor disc and chain assembly moves through the sprocket.

Dynaflow chain & disc in sprocket

Chain drag conveyors move coal fines into a storage silo.

Dynaflow Chain Drag Conveyor moving coal fines

Cable drag conveyors are ideal for moving fragile products such as coffee beans.

Cableflow Cable Drag Conveyor moving coffee beans

How do they work?

A continuous loop of cable or chain with discs spaced along its length is pulled by a motor driven sprocket within an enclosed tube. Changes in direction are facilitated by bends in the tubing or by corner housings with drive or idler sprockets for tighter radii. Discharge of the product is through either tube outlets or housing outlet boxes. Cable or chain and casing are routed back to the in-feed point in an endless loop.

The disc and chain assembly is being fed into the conveyor pipe.

Dynaflow disc and chain being fed into pipe

Cable drag conveyors easily convey ground coffee.

Cableflow cable and disc in conveying tube with ground coffee

Drag conveyors can have 90 degree bends.

Dynaflow 90° bend in pipe

Sprockets are used for tighter bends in drag conveyor layouts.

Dynaflow sprocket for tighter bends

Bends & corner sprockets are used in drag conveyor layouts.

Cableflow tube bends & corner sprockets


By nature, a tubular drag conveyor absorbs all the reactions to its own conveying forces internally. The forces are transferred by compression of the flanged casing sections in the Dynaflow and Chainflow chain drag conveyors and by compression couplings in the Cableflow cable drag conveyor. As a result, the only external supports required are those necessary to support the weight of the conveyor and load of material being conveyed. The process of designing and installing supports for a TDC is identical to hanging pipe/tubing. Spiroflow engineers can recommend support locations.

These are typical circuits for drag conveyors.

Materials of Construction

Generally, the construction materials of a tubular conveyor are determined by the application and the product being handled. Materials that are corrosive or contaminable would normally dictate stainless steel construction on metallic material contact surfaces. In applications where corrosion or contamination is not a concern, carbon steel construction is a far more economical alternative. The most common materials of construction, in order of increasing costs, are carbon steel, 304 stainless steel, and 316 stainless steel. External components not in contact with the product are carbon steel unless specified otherwise. Other materials of construction can be quoted upon request.

This type of conveyor is also known as a:

Chain conveyor / Drag chain conveyor / Drag conveyor / Tube conveyor / Tube chain conveyor / Tubular conveyor / Drag link conveyor / Chain drag conveyor / Cable conveyor / Cable drag conveyor / Tubular drag conveyor / Tubular cable drag conveyor / Tubular chain drag conveyor / Cableflow tubular cable drag conveyor / Chainflow tubular chain drag conveyor / Dynaflow tubular chain drag conveyor / Coffee conveyor / Bulk coffee conveyor / Coffee bean conveyor / Puck conveyor / Hockey puck conveyor

This drag conveyor is used outside for a lime dosing application.

Chain drag conveyor used outside in lime dosing application


  • Totally enclosed, dust-free, contamination-free handling
  • Only mechanical conveyor that can operate in 3 planes which permit complex circuits eliminating transfer points and using only a single drive
  • Minimum horsepower and energy consumption particularly when compared to pneumatic conveying systems with equivalent rates
  • Can be meter or flood fed
  • Handles hot, cold, wet, dry, hygroscopic or temperature sensitive materials
  • May be fed at multiple points in a circuit
  • Minimum noise level
  • No need to mechanically separate product from the convey stream. Gravity is sufficient.
  • Gentle conveying action minimizes product degradation
  • Will not separate blends
  • Round construction minimizes residual accumulation and product build up
  • May operate under pressure differential or inert purge