Disk drive comprising a ratchet arm applied to a disk and disengaged through windage generated by the disk rotating

1. A disk drive comprising:

(a) an enclosure;

(b) a disk;

(c) a head actuated radially over the disk;

(d) a spindle motor for rotating the disk; and

(e) a ratchet arm for engaging a surface of the disk, the ratchet arm comprising:

a base end connected to the enclosure of the disk drive; and

a wind vane extending from the base end adjacent the disk;

wherein 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.

2. The disk drive as recited in claim 1 , wherein the wind vane extends over a top or bottom surface of the disk.

3. The disk drive as recited in claim 1 , wherein the ratchet arm further comprises a stopper for engaging a side surface of the disk when the disk is not rotating and disengages from the side surface of the disk by the wind vane when the disk is rotating at an angular velocity greater than the threshold.

4. The disk drive as recited in claim 3 , further comprising a spring for attaching the base end of the ratchet arm to the enclosure of the disk drive, the spring for biasing the stopper toward the side surface of the disk.

5. The disk drive as recited in claim 4 , wherein the windage rotates the ratchet arm about a pivot in a first direction, and the spring applies a biasing force to rotate the ratchet arm about the pivot in a second direction opposite the first direction.

6. The disk drive as recited in claim 1 , wherein when the ratchet arm engages the disk:

(a) the ratchet arm applies a first frictional force to the disk while the disk is rotating in a first direction; and

(b) the ratchet arm applies a second frictional force to the disk while the disk is attempting to rotate in a second direction opposite the first direction, wherein the second frictional force is greater than the first frictional force.

7. The disk drive as recited in claim 1 , wherein:

(a) the wind vane biases the ratchet arm toward a top or bottom surface of the disk; and

(b) the windage pushes the wind vane in an axial direction to disengage the ratchet arm from the top or bottom surface of the disk when the disk is rotating at an angular velocity greater than the threshold.

8. The disk drive as recited in claim 7 , wherein the ratchet arm is radially-fixed.

9. A method of ratcheting rotation of a disk in a disk drive to help prevent the disk from rotating in a predetermined direction during shipping of the disk drive, the method comprising:

(a) biasing a stopper against a surface of the disk when the disk is not rotating;

(b) rotating the disk to generate windage; and

(c) harnessing the windage to disengage the stopper from the surface of the disk.

10. The method as recited in claim 9 , wherein a wind vane extending over a top or bottom surface of the disk harnesses the windage.

11. The method as recited in claim 10 , wherein the stopper engages the surface of the disk when the disk is not rotating and disengages from the surface of the disk by the wind vane when the disk is rotating at an angular velocity greater than a threshold.

12. The method as recited in claim 11 , wherein a spring biases the stopper against the surface of the disk.

13. The method as recited in claim 12 , wherein the windage rotates the wind vane about a pivot in a first direction, and the spring applies a biasing force to rotate the wind vane about a pivot in a second direction opposite the first direction.

14. The method as recited in claim 11 , wherein:

(a) the stopper engages a top or bottom surface of the disk; and

(b) the wind vane pushes the stopper in an axial direction away from the top or bottom surface of the disk when the disk is rotating at an angular velocity greater than the threshold.

15. The method as recited in claim 14 , wherein the wind vane is radially-fixed.

16. The method as recited in claim 9 , wherein:

(a) the stopper applies a first frictional force to the surface of the disk while the disk is rotating in a first direction; and

(b) the stopper applies a second frictional force to the surface of the disk while the disk attempts to rotate in a second direction opposite the first direction, wherein the second frictional force is greater than the first frictional force.