The invention relates to a rotor block (1) comprising a housing (2) with at least one connection surface (3A) that absorbs the load and pivot bearing seats (4) for plain and/or anti-friction bearings (5) that are designed to support a rotor (6). To dismount the rotor (6) from the housing (2), the plain and/or anti-friction bearings (5) can be dismantled from the exterior and the rotor (6) from a side (8) lying transversally to the bearings. The pivot bearing seats (4) take the form of recesses (9) that are directly configured in the housing wall, without the use of annular bodies. To facilitate the mounting and dismounting processes and to improve the precision of the rotor alignment, the pivot bearing seats (4) are configured in such a way that they form a segment greater than a semi-circle around the plain and/or anti-friction bearings (5), leaving a section open on one side (8) in relation to said bearings (5), thus forming a narrowing (13).