Patent ID: 7607523

Claim:
A lock mechanism for selectively coupling two concentric shafts rotatable about a common axis of rotation comprising: a locking ring assembly movable along said axis of rotation of the two concentric shafts between a locked position and an unlocked position; a first locking portion extending radially from said locking ring assembly circumferentially about said axis of rotation for engaging a first of the two shafts; a second locking portion extending radially from said locking ring assembly opposite said first locking portion circumferentially about said axis of rotation for engaging a second of the two shafts; and a third locking portion spaced from said second locking portion along said axis of rotation and extending radially from said locking ring assembly opposite said first locking portion circumferentially about said axis of rotation for engaging the second of the two shafts, wherein all of said first, second and third locking portions are operable to move along said rotation axis, and wherein said locking ring assembly further comprises: a first locking member extending about said axis of rotation wherein said first locking portion extends from said first locking member; a second locking member extending about said axis of rotation wherein said second locking portion and said third locking portion extend from said second locking member; and a fourth locking portion extending radially from said first locking member opposite said first locking portion circumferentially about said axis of rotation; and a fifth locking portion extending radially from said second locking member opposite said second and third locking portions circumferentially about said axis of rotation wherein said fourth locking portion and said fifth locking portion engage one another and guide relative movement between said first locking member and said second locking member along said axis of rotation.