The second and most commonly used mechanism for the production of elliptical oval vibration is called the "triple drive mechanism", in which three pair of exciters synchronized with gears are mounted at the approximate center of the screen body. One of the exciter pair rotates with a phase angle in the counter direction to the others.
· A belt conveyor uses a belt to transport material from one point to another. The belt is stretched across the conveyor length with pulleys at both ends to support the belt. A driving mechanism such as an electric motor rotates the pulleys, which moves the belt across the conveyor length. The belt's speed can be fixed or variable, depending upon the appliion .