Sandeep,

The purpose of screen support springs is to isolate the vibratory forces from the support structure, and their selection is only indirectly related to the screen amplitude (and even more indirectly to the size of exciter).

Explained in simple terms – the greater the spring compression under load (in other words the softer the spring) the more efficient will be the springs isolation efficiency, and the lower the operating frequency of the screen – the greater will be the compression required to achieve the same isolation result.

As an example:

To achieve say a 95% isolation of vibratory forces, a screen operating at 1500 rpm would require each spring to have a minimum loaded compression of 8.5mm. However the same screen operating at 750 rpm would require a minimum spring compression of 34 mm to achieve the 95% isolation figure.

Therefore because the operating frequency is a consideration in support spring selection, and because the screen frequency is selected to work in sympathy with the screen amplitude - we therefore have our indirect relationship.

I practical terms cannot understand any requirement to increase the exciter size due high spring stiffness. The only logic that I can figure would be the reverse. i.e.: if the exciter size is increased, then the increased mass (of the exciter and drive beam etc.) may require a stiffer spring. ■

John (or anyone else that knows),

How did you arrive at those isolation efficiencies?

Thanks, ■

Rob,

A little lengthy to explain on a post, but if you care to provide an email address I can send you explanatory notes. ■

John,

I'm also very keen to know the explanatory on how to arrive at those isolation efficiencies.

Please kindly send me a note: lijian@mindac.com.

Thanks a lot.

-----------------

Li Jian ■

Li Jian,

I will shortly email you my explanatory notes. ■

ok they are on their way shortly ■