Unbalanced motors are usually only available with a range of comparably lower dynamic moments, whereas exciters are built to cover the higher range. (Dynamic moment is the vibrating mass x vibrating stroke).

It follows therefore that unbalanced motors are used on the smaller lighter screens and feeders, and exciters on the larger heavier models.

There is of course an area of overlap, and there the choice us usually based on economics - which would normally favour the unbalanced motor. ■

Unbalanced motors are getting more expensive with sizes and to change the runnning speed you a frequency controller. For smaler size screen you'd use unbalanced motor.

Unbalanced motors will be used in pairs for linear motion screen but you can always use a single unbalanced mechanism for the same purpose.

If you want to built vibrating screens it is a good idea to design a range of vibrating mechanisms to cover your requirements. ■