A screw press for extracting liquids from materials such as fruits, vegetables, or the like having a cylindrical barrel and a rotatable shaft and helical feed and compression screw concentric with the barrel and having the shaft extending through the barrel. A portion of the barrel rearward from the feed and compression screw forms a cylindrical pressing chamber having screen walls for passing extracted liquids therethrough. The outlet end of the cylindrical pressing chamber is closed by a circular door slidably mounted on the drive shaft. Hydraulic actuators apply adjustable pressure to the outside surface of the door closing the chamber when in a non-operating condition. When material is being pressed in the pressing chamber, the internal pressure will overcome the external pressure causing the door to open for ejection of the dried material. The inner surface of the door includes projecting cutter bars. A clutch coupled to the door and the rotating drive shaft automatically engages when the door opens to cause the door to rotate and the cutting bars to pare away a cake of dried material which forms in the pressing chamber. The hydraulic pressure is adjustable to control the door opening pressure and therefore the percentage of liquid extracted from the materials being pressed. The feed and compression screw is driven by an adjustable drive system to permit control for optimum throughput of the press.