Abstract: An apparatus is disclosed for mounting a magnetic disc on a rotatable spindle. The apparatus includes a molded plastic disc-carrying hub having a circumferential collar, a central housing supporting a centering element, and a diaphragm joining the collar and housing, stiff in the radial direction but allowing axial movement of the centering element with respect to the collar. The collar includes three bosses to which a magnetizable armature plate is attached, with sufficient clearance between the plate and each boss to permit armature plate movement radially on the hub. The armature is attracted to a rotatable spindle by an annular permanent magnet mounted on the spindle. A cup formed in the spindle at its center receives the centering element and guides it to the center of the spindle, thereby centering the hub on the spindle independently of the armature as the armature is attracted to the spindle.

Abstract: An apparatus is disclosed for centering one or more magnetic discs on a rotatable spindle. The apparatus includes a disc-carrying hub having a circumferential collar, a central housing supporting a centering ball, and a diaphragm joining the collar and housing, stiff in the radial direction but allowing axial movement of the centering element with respect to the collar. The hub is attracted to a rotatable spindle by an annular permanent magnet mounted on the spindle opposite a similarly sized armature mounted on the hub. A cup formed in the spindle at its center receives the centering ball and guides it to the center of the spindle as the hub is attracted to the spindle. After the centering ball is seated in the center of the cup, the diaphragm flexes to allow continued axial movement of the collar to full engagement with the spindle.