Patent ID: 7066042

Claim:
A advancing/retracting mechanism comprising: a first cam including an angled surface and one of a first shoe and a helical surface having an axis of rotation; a second cam including an angled surface and one of a second shoe and a surface perpendicular to the axis of rotation; and a barrel including the other of the first shoe and the helical surface and the other of the second shoe and the perpendicular surface, the first shoe abutting the helical surface and the second shoe abutting the perpendicular surface, at least a portion of one of the cams being disposed in the barrel, wherein the angled surfaces of the first and second cams substantially correspond in a first state, and are at least partially opposed in a second state, and the first cam travels a first distance along the longitudinal axis of the barrel from the first to the second state and the second cam travels a second distance that is greater then the first distance from the first to the second state.