A thin component such as the actuator arm (10) of a hard disk drive, is mounted on a pivot or pin (31), such as the pivot assembly of the hard disk drive, using a ring (32), e.g. a tolerance ring, having one or more projections (35), wherein the engagement of the component (30) and the ring (32) is such as to apply a force to the component (30) in a direction which is inclined to both the radial and axial directions of the pivot or pin (31). The pivot or pin (31) has a flange onto which the component (30) is pressed by the axial component of the force generated by the ring on the component. The edge of the ring (32) remote from the component (30) is engaged with a stop element, e.g. another flange (34) of the pivot or pin (31).