US Patent 7258013 Device and method to measure a bearing system

A device to measure a fluid dynamic bearing system, particularly the inside diameter of the bearing bore of a bearing sleeve or the outside diameter of a shaft using a sensor element. A capacity acting sensor element is used to determine, for example, the inside diameter of the bearing bore, the sensor element being designed as part of the surface of a shaft prepared for measurement purposes. To determine the outside diameter of the shaft, the sensor element is correspondingly designed as part of the surface of the bearing bore of a bearing sleeve prepared for measurement purposes. Means of introducing a measuring fluid, preferably compressed air, into the bearing gap remaining between the bearing sleeve and the shaft are provided so that during the measurement process the shaft is automatically aligned and centered within the bearing bore.