Abstract: A safety and centering device for rotors suspended in contactless magnetic bearings, which provides almost instantaneous centering support for the rotor if the bearing magnets loose power. In a preferred embodiment, the rotor shaft has a collar with a conical friction surface, and a sleeve controlled by an electro magnet with counter-acting springs and also having a conical friction surface. In case of power failure the springs force the two surfaces together and provide centering support for the rotor. In another embodiment having a vertical rotor, the bearing magnets lift the rotor with the friction collar out of engagement with the matching stationary friction surface when the rotor is operating; but if the rotor bearings become de-energized the rotor drops with the collar falling into engagement with the matching friction surface.