Abstract: In order to prevent the material (52) from being pressed through the press plate seal between press plate (2) and surrounding barrel (50) by means of a press plate (2) when emptying a barrel (50) in which viscous material (52) is supplied, a two-stage construction is used in accordance with the invention: A press cylinder (22) is connected to the rear side of the press plate (2), in which in turn a conveying piston (24) is guided in a sealing manner, which in turn has a smaller end face than the press plate (2). In addition, non-return valves (19) are arranged in the press plate (2) in the region radially inside the press cylinder (22), which allow the material (52) to flow only in the direction of the conveying piston (24), but not vice versa, when the press plate (2) is pressed in the direction to the bottom (50a) of the barrel (50). After the press plate (2) has come to a standstill, the conveying piston (24) can thus be guided in the direction of the bottom of the press cylinder (22), i.e.