Herein a centrifugal separator structure (4) configured for cleaning of crankcase gases from an internal combustion engine is disclosed. The centrifugal separator structure (4) comprises a separator rotor (10) configured for rotation about a centre axis (22) arranged inside a stationary housing (8). The separator rotor (10) comprises an axle member (9) configured for connection to a shaft of a driving device. A stack (18) of separation discs (20) is supported on the axle member (9). Further an assembly comprising a centrifugal separator structure (4) and a driving device is disclosed herein.