is mounted in place regarding a second variation shown in fig8 through 10 of the first embodiment of the invention differing solely from the first variation by the geometry of the ring 20 the four shoes 25 coming to rest against the turbine shaft 39 s inside wall 21 consist of thin cylindrical walls exhibiting in their rest mode an outside radius r 2 less than the turbine shaft 39 s inside radius e 2 the radially inner part of the ring 20 comprises several cylindrical circumferentially spaced cylindrical segments 27 alternating with the shoes 25 the ends 25 a and 25 b of each foot 25 are respectively imbedded in two adjacent segments 27 a slit 22 is subtended in one of the segments 27 expansion of this ring 20 on the sheath 9 by the cone system and by tightening the nut 14 entails an increase of the radius of the circle touching the four shoes 25 at rest this second embodiment variation of the centering device is mounted in the same manner as the above described first variation the foot center zones 28 will bend as a tightening torque is applied by the nut 14 to increase the radius r 2 until the shoes 39 s outside radius is the same as the radius e 2 of the turbine shaft next the tube 3 is installed the areas of the shoes 25 resting against the turbine shaft 39 s inside wall 21 are substantially larger than those of the state of the art discussed in the above introduction where the shoes are undeforming rigid blocks alternating with cross sectionally smaller connecting segments in a second illustrative embodiment of the present invention shown in fig1.