There are two modes of vibration that can move
materials ranging in form from bulky, somewhat amorphous
or plastic wet pulps (water-quenched ash), dry
granular materials, or solid objects (unit loads). One
utilizes a simple harmonic vibration, pitched at an
upward angle to the plane of the conveying surface,
and the other, a complex, differential velocity straightline
oscillation in the plane of the conveying surface.