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Everything you need to know about centrifuge belt length calculations

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When it comes to decanter centrifuges, using the right calculations to determine the system's belt length will help you achieve more precise results.

Here's everything you need to know about belt length calculations.

Centrifuge motor and rotor sheaves

Centrifuges are composed of a rotating assembly driven by an electric motor.  The electric motor is mounted on a foundation frame and bolted to the ground.

The rotating assembly entails two main components:

  • Outer bowl
  • Screw conveyor

When the centrifuge unit is operated, the primary (main drive) motor turns the outer bowl. Similarly, a secondary motor is connected to the screw conveyor through a cyclo-gearbox.  The operation of both motors creates a differential speed between the outer bowl and the screw conveyor.  This allows operators to control conveying action inside the rotating assembly.

While the centrifuge unit is running, sludge (or material mixture) is pumped into the unit (assisted by an external pump) through a feed tube.  The effect of the centrifugal forces (generated by the bowl and the screw conveyor) causes the solids to move towards the outermost section of the bowl, in result separating the solids from liquids.

The conveying movement (generated by the screw conveyor) contributes to moving the solids towards the steep section of the bowl and ejected through discharge ports.

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two pulley systems in centrifuges

Both components, the outer bowl, and screw conveyor are driven by an electric motor.  The electric motor drives the components through a belt connected between the motor's sheave and the component's (bowl or conveyor) rotor.

The motor sheave and rotor sheave create a two-pulley system.

Two pulley systems can be found almost everywhere today, from clock mechanisms to construction sites and elevators.  Ultimately, these systems are used to transmit torque (or power) across axles to provide mechanical advance.

Belt sizing calculations

Belt sizing may be calculated in situations when the motor sheave, rotor's sheave, and the "center-to-center" distance (between the two) are known.

Formulas in Inches:

Belt length = ((DM * π) / 2) + ((DR * π) / 2) + (L * 2)


  • DM is the diameter of the motor's sheave
  • DR is the diameter of the rotor's sheave
  • L is the distance between the center of both

Scheme of a two-pulley system joined by a belt

The Vision Machine belt sizing Calculator

Too much math? No problem, we've got you covered. We've got great calculators for you!

Use our Belt Sizing Calculator to calculate the belt sizes for specific motor and rotor sheave diameters.

Centrifuge Belt Sizing Calculator


Belt Length Calculator - https://www.omnicalculator.com/physics/belt-length

The Haus Decanter Centrifuge -  https://centri-force.co.uk/case-studies/haus-decanter-centrifuge-how-it-works/

About Vision Machine

Vision Machine Inc. specializes in the manufacturing and repair of horizontal decanter centrifuges and has been doing so since 2004. We offer centrifuge manufacturing, custom centrifuge manufacturing, centrifuge repair, centrifuge replacement parts, and centrifuge controls from leading manufacturers.

From centrifuges that remove high-value solids from liquids, refining processes, or waste minimization, Vision Machine Inc. has a separation system to Vision Machine works with a variety of industries within the oil and gas sector, as well as other industries that require the use of centrifuges meet your needs. 

Vision Machine works with a variety of industries within the oil and gas sector, as well as other industries including refining/petrochemical, dairy, municipal, rendering, food & beverage, dredging, and fracking.  

At Vision Machine, Inc., we pride ourselves on providing our customers with the highest value, the lowest total cost of ownership and easiest to operate separation systems available. All proudly made in America at our Spring, TX facility.