Passive magnetic bearings with permanent magnets

The various geometrical dispositions which allow to realize passive magnetic bearings with permanent magnets, have been Known for several decades. Devices running by attraction were the first to be built. When new magnets, which can be used in repulsion appeared on the market (SmCo5), new types of passive magnetic bearings, running by repulsion, started to be made. Up to now, to our knowledge, most of the devices realized have been made with radially magnetized rings. We proved that for identically shaped bearings, strengths and stiffnesses were exactly the same in both magnetic configurations : radial and axial magnetization. The proof is only based on the rigidity of the magnetization. These results are still true for axial or radial passive bearings, and can also be used for devices in attraction. Ring shaped magnets with radial magnetization are usually made of several sectors stuck together. Axial magnetization is much easier to manufacture because large sized rings are already industrially provided.