Seat assembly having an adjustable head restraint assembly

1. A seat assembly comprising:

a seat back;

a support post disposed on the seat back; and

a headrest moveably disposed on the support post, the headrest including:

first and second transverse members disposed on the support post;

a spindle assembly rotatably associated with the first and second transverse members; and

a locking mechanism disposed on the first transverse member;

wherein the locking mechanism engages the spindle assembly to inhibit movement of the headrest and disengages the spindle assembly to permit movement of the headrest.

2. The seat assembly of claim 1 wherein the second transverse member further comprises a bushing that is fixedly disposed on the second transverse member and includes a threaded through hole that engages a threaded portion of the spindle assembly.

3. The seat assembly of claim 1 wherein the headrest moves from a first position toward a second position when the locking mechanism is disengaged from the spindle assembly and an actuation force is applied to an exterior surface of the headrest.

4. The seat assembly of claim 1 wherein the spindle assembly rotates in response to a sufficient actuation force applied to an external surface of the headrest when the locking mechanism is disengaged from the spindle assembly and the spindle assembly does not rotate in response to the actuation force when the locking mechanism is engaged with the spindle assembly.

5. The seat assembly of claim 1 wherein the first transverse member is moveably disposed on the support post and the second transverse member is fixedly disposed on the support post.

6. The seat assembly of claim 1 wherein the spindle assembly includes a gear received by the first transverse member.

7. The seat assembly of claim 6 wherein the locking mechanism includes a locking pin that engages the gear to inhibit movement of the headrest and disengages the gear to permit movement of the headrest.

8. The seat assembly of claim 7 wherein the first transverse member further comprises a slot that receives the locking pin.

9. The seat assembly of claim 7 wherein the locking mechanism further comprises a button and a linkage that extends from the button to the locking pin.

10. A seat assembly comprising:

a seat back;

a first support post fixedly disposed on the seat back; and

a headrest moveably disposed on the first support post, the headrest including:

a first transverse member moveably disposed on the first support post;

a second transverse member fixedly disposed on the first support post, the second transverse member having a threaded bushing;

a spindle assembly rotatably received by the first and second transverse members, the spindle assembly including a threaded portion that engages the threaded bushing; and

a locking mechanism disposed on the first transverse member;

wherein the locking mechanism disengages the spindle assembly to permit the spindle assembly to rotate about an axis of rotation to move the headrest along the first support post.

11. The seat assembly of claim 10 wherein the threaded portion moves through the threaded bushing as the second transverse member moves toward the first transverse member.

12. The seat assembly of claim 10 further comprising a second support post, wherein the spindle assembly is disposed between the first and second support posts.

13. The seat assembly of claim 10 wherein the first and second transverse members are spaced apart when disposed in a first position and are not spaced apart when disposed in a second position.

14. The seat assembly of claim 10 wherein the spindle assembly continuously rotates about the axis of rotation when the headrest is actuated.

15. The seat assembly of claim 10 wherein the second transverse member is disposed at an end of the support post and the first transverse member is disposed between the second transverse member and the seat back.

16. The seat assembly of claim 10 wherein the locking mechanism further comprises a pin disposed in a slot in the first transverse member, a button disposed proximate the first transverse member, a linkage extending between the button and the pin, and a spring that exerts a biasing force on the button to bias the pin toward the spindle assembly.