Vibratory screens on mobile machines have very specific design criteria. These include screen angle, G-forces and operating speed. Screen angles play a lesser role as you can adjust the angle based on the application at hand.

The screen operating speed is found to be one of the most common causes of screen inefficiency. Operating the screen at a lesser speed than designed for, usually has the following effects:

• Material carry over – improper stratification and separation
• Screening media (mesh) blinding
• Excessive screening media wear
• Screen box “banging” on the support structure
• Isolation spring failures
• Improper screen stroke characteristics

To verify the screen operational speed, use a tachometer and measure the screen shaft rotational speed. Each machine will have a unique speed; check with our HelpDesk team to determine the required speed for your machine.

1. Access the screen shaft on the opposite side to the drive by removing the cover.
2. Start the screen box and measure the speed with the tachometer

If the screen box speed is found to be too low, adjust the flow control valve to the screen (if fitted). If no flow control valve is installed, the hydraulic supply pump needs replacement. The pump would need replacement as the internal gear set would have worn to such an extent that the designed oil flow cannot be reached.

For the newer machines, check the screen operational speed every six months. For older machines the speed should be checked more often to ensure an efficient screen.