Abstract: A steam turbine having a rotor and a stator, the rotor having rotor blade rings at the outer periphery thereof and the stator having a carrier for vanes interposed between the rotor blade rings respectively in axial direction of the rotor, the rotor blade rings having respective shroud bands at the radially outer periphery thereof, the shroud bands and the stator carrier defining gaps therebetween, a device for stabilizing the position of the rotor includes means for enlarging at least a part of the radial gaps, respectively, the means having channels of substantially circular cross section each extending in the form of a crescent in peripheral direction of the turbine over at least an upper half of the turbine.