Wet solids are conveyed by a shaftless one-bearing spiral into the press zone, which is a barrel shaped basket made from wedge wire. Very strong and with a large perforated area, it is optimal for dewatering. 

Counter pressure is controlled by back pressure inducing tension outlet doors. These are controlled by gas springs optimized for maximum dewatering. As the solids are pushed into the press zone, they are held back by the outlet doors, causing a counter pressure. 

As pressure increases, a plug will form at the discharge and free liquids are squeezed through the basket to the drain. This continues until the plug is solid enough to bypass the outlet doors.