A machine has an uncooled rotor body, which is mounted to rotate about a rotational axis, and has a superconducting rotor winding that is located in at least one cryostat and is cooled by a coolant. To facilitate the assembly of the winding and the cryostat, the exterior of the rotor body is provided with flattened sections, which accommodate at least one cryostat. At least one coil of the rotor winding is located in a retaining device that essentially only absorbs tensile stress. Said tensile stress absorption of the retaining device is thus carried out in the flattened sections of the rotor body. HTS material is preferably used for the rotor conductors.