Patent ID: 8348122

Claim:
A surgical stapling device comprising: a handle portion; a body portion; a head portion including an anvil assembly and a shell assembly; an approximation mechanism including an approximation knob, a drive screw and an anvil retainer, the anvil retainer being operably connected to the drive screw, the drive screw including a helical channel having a first pitch, wherein the approximation knob is operably connected to a pin which is positioned within the helical channel such that rotation of the approximation knob effects linear movement of the anvil retainer between a first advanced position and a second retracted position; wherein the anvil assembly includes an anvil center rod configured to releasably engage the anvil retainer, the approximation mechanism being operable to retract engaged portions of the anvil center rod and the anvil retainer within the shell assembly to lock the anvil center rod to the anvil retainer; and wherein the helical channel of the screw includes a dwell portion, the dwell portion of the helical channel having a second pitch which is smaller than the first pitch, the dwell portion being positioned along the helical channel to provide a tactile indication to a surgeon that the anvil retainer has been advanced to a third position between the first advanced position and the second retracted position, wherein in the third position, the engaged portions of the anvil center rod and anvil retainer have been advanced from the shell assembly to a position to unlock the anvil center rod and the anvil retainer.