A disk drive is disclosed comprising an enclosure, a disk, a head actuated
radially over the disk, a spindle motor for rotating the disk, and a
ratchet arm having a base end connected to the enclosure of the disk drive
and a wind vane extending from the base end adjacent the disk. The ratchet
arm engages the disk when the disk is not rotating, and the ratchet arm
disengages from the disk due to windage pushing on the wind vane, the
windage generated by the disk rotating at an angular velocity greater than
a threshold.
