Surgical fastener applying apparatus

1. A surgical fastener applying apparatus, comprising:

a cartridge half-section and an anvil half-section, the cartridge half-section and anvil half-section being relatively movable from an unclamped position to a clamped position;

a loading unit receivable in the cartridge half-section and having a plurality of staples and a plurality of staple pusher members;

the cartridge half-section having:

a frame; and

a member being longitudinally movable through the loading unit to interact with the plurality of staple pusher members to fire the staples, wherein the member is a cam bar slidably coupled to said cartridge half-section, wherein said cam bar includes a pair of camming surface extensions for interacting with the staple pusher members to fire the staples; and

a lockout mechanism arranged to block advancement of the member in a locked-out position of the lockout mechanism, wherein the lockout mechanism includes a rocker pivotably mounted to said cartridge half-section, said rocker including a blocking surface and being biased toward a locked-out position, wherein said blocking surface engages said member to prevent a longitudinal movement of said cam bar arrangement and said camming surface extensions;

whereupon after loading of the loading unit in the surgical fastener applying apparatus and during subsequent clamping of the cartridge and anvil half sections, the lockout mechanism is moved from an initial position blocking advancement of the member to an unlocked position to allow an initial advancement of the member in order to fire the surgical fastener applying apparatus.

2. The surgical fastener applying apparatus of claim 1 , wherein said anvil half-section includes a downwardly extending portion configured and adapted to engage the loading unit, the loading unit urging said lockout mechanism to rotate to the unlocked position.

3. The surgical fastener applying apparatus of claim 1 , further comprising a lock-out, the lock-out being movable between an initial substantially horizontal position and a vertical blocking position extending between the cartridge and anvil half sections, wherein the lock-out prevents the cartridge half-section and anvil half section from returning to the clamped position after the plurality of staples have been at least partially fired, wherein the lock-out is pivotally attached to a tissue contacting side of the replaceable staple cartridge.

4. The surgical fastener applying apparatus of claim 1 , further comprising a lock-out, the lock-out being movable between an initial substantially horizontal position and a vertical blocking position extending between the cartridge and anvil half-sections, wherein the lock-out prevents the cartridge half-section and anvil half-section from returning to the clamped position after the plurality of staples have been at least partially fired, wherein the lock-out includes a transverse horizontal surface formed on an underside thereof, the transverse horizontal surface engaging a hook formed on an upper edge surface of a knife thereby retaining said lock-out in said blocking position.

5. The surgical fastener applying apparatus of claim 4 , wherein said lock out moves to said blocking position upon an unclamping of the cartridge and anvil half sections after the plurality of staples have been at least partially fired.

6. The surgical fastener applying apparatus of claim 4 , wherein the lock-out is confined between planes defined by opposed lateral side walls of said cartridge half-section when in the initial and blocking positions.

7. The surgical fastener applying apparatus of claim 1 , further comprising a lock-out movable between an initial position permitting a relative movement of the cartridge half-section and anvil half section to said clamped position and a blocking position preventing a relative movement of said cartridge half-section and anvil half section to said clamped position after said plurality of staples have been at least partially fired, wherein the lock-out is confined between planes defined by opposed lateral side walls of said cartridge half-section when in the initial and blocking positions, wherein the lock-out is maintained in the initial position by a knife supported in the cartridge half-section.

8. The surgical fastener applying apparatus of claim 7 , wherein the lock out includes a transverse horizontal surface formed on an underside thereof, the transverse horizontal surface engaging a hook formed on an upper edge surface of a knife thereby retaining said lock-out in the blocking position.

9. The surgical fastener applying apparatus of claim 7 , wherein the lock out moves to the blocking position upon an unclamping of the cartridge and anvil half-sections after the plurality of staples have been at least partially fired.