Abstract: An elongated tub-like container is supported for vibration by a set of springs mounted on a frame, and a plurality of sets of opposing electromagnets are positioned on opposite sides of corresponding armatures connected to the container for vibrating the container. A regulator is connected to vary the electric power supplied to only one set or a portion of the electromagnets while the remaining electromagnets are either energized or not energized depending on the level of power required for vibrating the container. In the embodiment illustrated with three sets of opposing electromagnets, the center set of electromagnets is controlled by a voltage regulator, and the outer sets of electromagnets are selectively energized to provide for obtaining any desired power between zero and the maximum in three stages with a voltage regulator of minimum size.

Abstract: A plurality of generally cylindrical parallel tubs are arranged in horizontally adjacent relation and define corresponding chambers for receiving loads of parts and treating media. The tubs are rigidly connected and are supported by a set of springs to provide a neutrally statically stable tub system which oscillates at a predetermined resonant frequency on an axis extending substantially through the center of gravity of the tub system. Preferably, the oscillatory tub system is excited at substantially the resonate frequency by a set of electro-magnets which are arranged in opposng relation on opposite sides of an armature positioned below the tubs and within a vertical plane extending through the pivot axis.