Prater Industry’s patented Rota-Sieve® is a centrifugal rotary sieve – also known as a rotary sifter – designed to sieve amalgamated substances, bulk raw materials, and finished products. Its simple design and lightweight components remove foreign objects like insects, plastics, or string from material during production, while also scalping and sifting. Used in chemical, food processing, mineral handling, powder coating, and other industries, the Rota-Sieve® handles various agglomerates, granules, powders, and other materials that flow freely.

Some key features and benefits of the Prater Rota-Sieve® (RS include:

  • Capable of extremely high throughputs
  • Can be customized to comply with FDA, USDA, BISSC, 3-A, and other regulatory authorities in the US and Europe
  • Completely enclosed design eliminates issues from dust
  • Features a fully-adjustable 4-paddle rotor
  • Internal components are easily accessible
  • Lightweight rotor assembly can be removed without tools (Rota-Sieve® RS1500 model only)
  • Options include materials of construction, finishes, various hoppers and stands, process designation, and many others
  • Rota-Sieve® RS1500 model allows for easy removal of internal components for cleaning without the need for tools
  • Utilizes a shaft supported by three bearings and drilled to enable the purging of air

Maintenance & Servicing for Rota-Sieve® 1500

Now let’s take a look at different aspects of servicing and maintaining Prater’s easy-to-clean rotary sieve, specifically the RS1500 model known as the Rota-Sieve®. Below, you can find links to videos that show just how easy it is to assemble and disassemble, explained succinctly by one of Prater’s expert technicians.

Removing Rotor & Screen Frame Assemblies 

First, let’s examine how to access the rotor assembly from the rotary sieve.


  • Unclamp three clamps at the end of the rotary sieve to allow the door to open.
  • Open the door and pull the rotor assembly out.
  • Engage latch to keep the rotor assembly from sliding forward.
  • Next to the latch is a lever. This can be pulled to allow the rotor assembly to pivot.
  • A switch at the end of the assembly will lock it into place.
  • The screen can then be removed from the rotary sieve’s assembly.

Next, how to maintain the rotary sieve’s screen frame assembly.

  • Loosen and remove three hex bolts.
  • Lift off the outer ring.
  • Remove screen from the screen frame assembly.
  • Install a new screen.
  • Put the outer ring back on.
  • Replace and tighten three hex bolts until the screen bottoms out.

Limit Switches

Taking a brief break from lists, here’s how limit switches work on the Rota-Sieve® 1500. Equipped with three limit switches, this rotary sieve features one on each side door and another on top of the door through which the rotor assembly is accessed. Limit switches shut off power if any door is open while the motor is running. This ensures no one can access the rotating components, thus preventing injuries. The tongue actuators for the Rota-Sieve® 1500 are also positioned on each door so they’ll engage when the doors shut, allowing the motor to restart.

Lining Up the Auger With the Stub Shaft

It’s important to understand how to put everything back together. Here’s how to correctly reinstall the auger assembly in the Rota-Sieve® 1500.

  • Slide auger assembly into bearing housing to reinstall.
  • Make sure the female square lines up with the square stub shaft.
  • Carefully mate the female square at the end of the auger assembly with the square stub shaft inside the bearing housing.
  • If the auger assembly doesn’t slide in all the way, remove the rotor slightly and rotate the shaft assembly until it lines up.
  • Once properly lined up, the female square will fit with the stub shaft, allowing the unit to close.
  • There is tongue on the bottom of the housing and groove on the bottom of the screen frame assembly. This is for ease of reinserting and aligning screen frame assembly.

Reinstalling the Rotor & Screen Frame Assemblies 

Now let’s look at how the rotor and screen frame assemblies are reinstalled.

  • Lift latch to allow the assembly to rotate.
  • Pivot the entire assembly square to the machine.
  • Once in position, the latch will engage.
  • Remove the quick clamp holding assembly in place.
  • Push screen frame assembly back into the machine slowly.
  • Once the door shuts, reattach quick clamps to secure the door.
  • A positive click from the limit switch ensures the door is closed properly, allowing the rotary sieve to start.

Accessing the Drive Components

Occasionally, maintenance is required on a rotary sieve’s drive components. Here’s how to access those in the Rota-Sieve® 1500.

  • Remove fasteners around OSHA safety guard assembly.
  • This allows access to the pullies and belts inside to enable replacement.
  • Should bearings require replacing, remove entire guarding assembly.
  • Take belt drive components off to access bearings.
  • Inboard and outboard bearings can be replaced without removing the inlet from the machine.
  • Replace fasteners around the safety guard to return rotary sieve to operational readiness.

Removing & Reinstalling the Screen Frame

Removing the screen frame from the rotor assembly is necessary for maintenance or cleaning. Here’s how to remove the Rota-Sieve® 1500’s screen frame, which takes two people to do safely so as not to damage it.

  • Make certain that the rotor’s locked back.
  • First-person should start pulling the rotor assembly off.
  • When it’s close to the end, a second person should help support the weight of the screen frame.
  • Once the screen frame is removed, it allows the screen to be removed and the rotor to be cleaned and inspected.
  • To reinstall the screen frame assembly, both people should lift it up.
  • With help from the second person to get the screen frame assembly in place, position and lock it onto the two rods that secure it.
  • Push screen frame on.
  • Engage front two rods.
  • Machine can now be put back together.

Rotary Sieves by Prater

Prater can customize any of our rotary sieves to fit the specifications necessary for your application. Utilizing our testing facilities, we can work any special features you may need into the design of our standard rotary sieves to develop an ideal solution. To find out about our Rota-Sieve® line, we encourage you to contact us for more information.