Unbalanced mass driven vibratory conveyors with a small damping (ζ ≤ 0.1) have the risk of "stalling" at resonance or crossing resonance with unduly large amplitude of vibration. To eliminate this risk, it is better to start the conveyor with "load" (i.e. the conveyor trough filled with material) rather than empty. This paper presents a study on such a "starting", taking into account the dynamics of material motion and its effect on the conveyor during the cross-over of resonance. The equations developed enable one to predict whether, or not a give vibratory conveyor (with load) would start and cross the resonance "safely". © 1987.