The invention relates to a turbomachine having at least one first and one second impeller wheel (1, 2) whose back faces (3a, 3b) confront each other, a rotor shaft (4) carrying the radial impeller wheels (1, 2) and a bearing system, wherein adjacent each of the radial-blade impeller wheels (1, 2) is an axial bearing (5a, 5b) each with one respective rotor bearing half (6a, 6b) and one respective stator bearing half (7a, 7b), and wherein the rotor bearing halves (6a, 6b) are each formed on the back face (3a, 3b) of the respective radial impeller wheel (1, 2), wherein the first radial impeller wheel (1) is permanently mounted and the second radial impeller wheel (2) is detachably mounted on the rotor shaft (4) and the rotor shaft (4) is of increasingly smaller cross-sectional size from the first radial impeller wheel (1) toward the second radial impeller wheel (2), or has a constant diameter.
