GD wobbler feeder consists of a frame, onto which some roller-holder shafts are fixed with grease lubricated bearings; Grooved rollers are mounted opposite one another to create openings forming a kind of grid for the passage of waste material. The special shape of the rollers on the surface of the machine causes a wave motion allowing the material to clean the rollers. Thanks to the wave motion, the material is submitted to a pre-screening.