Bearing unit, carriage assembly with the bearing unit, and magnetic disk apparatus

摘要

A bearing unit of a carriage assembly includes a support shaft and a sleeve rotatably supported outside the support shaft through a lower bearing and an upper bearing. The sleeve has a flange on its upper end portion. A threaded portion with which a fixing nut is to be threadably engaged is formed on the outer circumference of the lower end portion of the sleeve. The threaded portion is aligned with the lower bearing in the radial direction of the sleeve. A groove is formed in the lower end of the sleeve at a position between the threaded portion and the lower bearing. This groove reduces a load acting on the lower bearing when the nut is threadably engaged with the threaded portion.