The invention relates to a separator drum (10) with a hydraulically actuated, axially movable piston slide valve (20) which can seal off a solids space (14) from at least one solids outlet (18), wherein the piston slide valve (20) can be held in its closed position via a closing chamber (30) that can be filled with closing liquid, in particular closing water, wherein the closing chamber (30) is formed between an underside (21) of the piston slide valve (20) and a top side (35) of a drum lower part (15). According to the invention, the closing chamber (30) has a first closing chamber portion (31) near the rotation axis (R) and a second closing chamber portion (32) remote from the rotation axis (R), wherein the first closing chamber portion (31) is formed by two mutually parallel portions (22, 36) of the underside (21) of the piston slide valve (20) and of the top side (35) of the drum lower part (15), and the second closing chamber portion (32) has at least in part a conical cross section.