Damper system and bearing centering device for magnetic bearing vacuum pump

A vacuum pump having a rotor adapted to rotate inside a stator, having at least one radial magnetic bearing which, in normal operation, holds said rotor in a centered radial position inside said stator to within a centered normal holding accuracy, and having at least one landing mechanical bearing which, if said radial magnetic bearings are not operating normally, limits radial movements of said rotor inside said stator by approximately centering said rotor, said landing mechanical bearing having a rotor rolling bearing race and a stator rolling bearing race with rolling members between them, a first radial clearance being provided between a first of said rotor or stator rolling bearing races and a corresponding first rotor or stator bearing surface, a second radial clearance being provided between the second of said rotor or stator rolling bearing races and a corresponding second rotor or stator bearing surface, elastic means and damping means with mechanical abutment means being provided between said second of said rotor or stator rolling bearing races and said corresponding second rotor or stator bearing surface to limit said second radial clearance, which elastic means and damper means include at least one coaxial ring of elastic and damping material in radial bearing engagement between said second of said rotor or stator rolling bearing races and said corresponding second rotor or stator bearing surface.