Abstract: A recording disk is mounted on a hub in a recording disk drive. The hub is mounted on a rotation shaft. The lower end of the rotation shaft is received on a thrust bearing. The packing is interposed between the enclosure and the thrust bearing. The packing serves to protect the inner space of the enclosure from dust. When the rotation shaft, the hub, the thrust bearing, and the like are assembled into the enclosure, an urging force is applied on the upper end of the rotation shaft. The thrust bearing urges the packing against the enclosure. Since the top surface of the hub is set lower than the top end of the rotation shaft, the urging force is reliably received on the rotation shaft. The alignment cannot be deteriorated between the rotation shaft and the hub.

Abstract: A magnetic disk unit has two actuators each rotating on a common rotary shaft. The two actuators are driven by a voice coil motor. The voice coil motor comprises: a magnetic circuit comprising a magnet provided for the two actuators on a common basis and two yokes, which are associated with the two actuators, respectively, said two yokes being disposed at both sides between which the magnet intervenes; and two coils provided for the two actuators, respectively.

Abstract: A disk device has a housing structure capable of reducing unnecessary vibrations of the base of the disk device by improving the rigidity thereof. A bath-tub type base of the disk device includes a damping structure on the bottom or on the sides adjacent to the bottom for attenuating the vibrations of the base. Apparatus for writing a reference signal into the disk of the device using a reference head with a head insertion hole formed in the base is also provided.