Surgical stapling instrument with mechanical mechanism for limiting maximum tissue compression

A circular stapling device, comprising:

• a staple drive member configured to operably support a circular staple cartridge therein;
• a closure shaft assembly supported for axial travel relative to said staple drive member in a proximal direction and a distal direction;
• an anvil attachable to said closure shaft assembly for proximal and distal travel therewith relative to the circular staple cartridge supported within said staple drive member, such that upon application of an opening motion to said closure shaft assembly, said closure shaft assembly moves said anvil in said distal direction away from the circular staple cartridge and upon application of closing motion to said closure shaft assembly, said closure shaft assembly draws said anvil in said proximal direction towards the circular staple cartridge to enable tissue to be clamped between said anvil and the circular staple cartridge under a predetermined amount of compression;
• and
• a closure assembly operably communicating with said closure shaft assembly and configured to apply said opening motion to said closure shaft assembly upon activation of said closure assembly in a first direction and to apply said closing motion to said closure shaft assembly upon activation of said closure assembly in a second direction, said closure assembly being further configured to prevent any further application of said closing motion to said closure shaft assembly when said predetermined amount of compression has been attained in the tissue clamped between said anvil and the cartridge as said closure assembly continues to be activated in said second direction;
• a handle assembly operably supporting said closure assembly;
• a firing assembly operably supported by said handle assembly and configured to selectively generate a staple drive firing motion and a staple drive retraction motion;
• an elongate shaft assembly coupled to said handle assembly and said staple drive member and configured to transmit said staple drive firing motions and said staple drive retraction motions to said staple drive member, said elongate shaft assembly axially supporting said closure shaft assembly therein;
• a knife operably mounted within said staple drive member;
• wherein said closure assembly comprises:
• a closure knob operably supported by said handle assembly for rotation in said first direction and said second direction;
• a closure nut assembly rotatably supported within said handle assembly and in driving engagement with said closure shaft assembly;
• and
• a slip clutch assembly cooperating with said closure knob and said closure nut assembly such that upon rotatable activation of said closure knob in said first direction, said closure nut assembly axially moves said closure shaft assembly in said distal direction and upon rotatable activation of said closure knob in said second direction, said slip clutch assembly transmits rotatable motion in said second direction to said closure nut assembly to cause said closure nut assembly to move said adjustment shaft in said proximal direction until said predetermined amount of compression has been attained;
• and
• wherein said slip clutch assembly comprises:
• a first friction pad supported by said closure knob;
• a clutch hub rotatably supported by said closure knob and coupled to said closure nut assembly for transmitting the rotational motion in the first and second directions thereto;
• and
• a second friction pad supported by said clutch hub in frictional engagement with said first friction pad such that rotation of said closure knob in said second rotational direction causes said clutch hub and said closure nut assembly to rotate in said second rotational direction to draw said closure shaft assembly and said anvil in said proximal direction until said predetermined amount of compression is achieved whereby further rotation of said closure knob causes said first friction pad to slip relative to said second friction pad.