Drive units produce a vertical and horizontal component of vibration - this is the source of vibration to the feeder bowl. They are mechanically and electronically tuned to the weight and mass of the feeder bowl.They vary in size from 4" to a 36" diameter and are usually square in construction. Our feeder bowls are equipped with standard dual coil drive units and controller. In-line drive units are available in various sizes to meet track length requirements.