The ball system, particularly suitable for the tumbler screen, exploits the action of small balls, housed in a gap between the sieving mesh and the support mesh, connected for this purpose. Ball rebounding frees holes from any obstructions.

The kleener system, particularly suitable vibrating screens, exploits the scraping action of small cilinders, housed in a gap between the sieving mesh and a drilled sheet, installed to perform the operation. The cilinders vibrate and scrap the mesh holes, freeing them from any obstructions.

The brush system, it too suitable for vibrating screens, exploits the vibration to spin brush sets installed on a special frame, overlapping the mesh. The brushes spin and free holes from any obstructions.