A storage box for storing power tool bits comprises a container, a bit holder and a control device. A stationary shaft has a middle section which is fitted into a cylindrical portion of the rotary structure, and a dynamic pressure type radial bearing is arranged between the cylindrical portion and the middle section. The system further includes one or more maintenance systems that schedule routine andor special maintenance based on analysis of the diagnostic information. A lighting arrangement of such lighting systems is also disclosed. The computer determines if the first duration of the identified first episode is greater than the associated duration of each of the two or more free time slots.