A surgical stapling device including a self-righting anvil assembly is disclosed. The anvil assembly includes an anvil center rod and a pivotable anvil head. The surgical stapling device includes an anvil retainer assembly having a locking member in the form of a trocar for moving the anvil head from its tilted position to its operative position upon attachment of the anvil assembly to the stapling device. A cam member is provided to retain the locking member in a first or locked position and, thus, the anvil head in the operative position until after the stapling device has been fired. In another embodiment, a tiltable anvil assembly for use with a surgical stapling device is disclosed. The anvil assembly includes a center rod and a head assembly which is pivotally secured to the center rod. The head assembly includes a housing, a post, an anvil plate and a backup member. The backup member is movably positioned about the post from a first position preventing pivotal movement of the head assembly to a second position permitting pivotal movement of the head assembly. A retainer member is positioned between the backup member and the housing to prevent movement of the backup member from its first position to its second position until a predetermined force has been applied to the backup member. In another embodiment, a passive lockout mechanism is disclosed which is operably associated with a trigger lock on the handle assembly of the surgical stapling device. The passive lockout mechanism is positioned to prevent movement of the anvil assembly in relation to the shell assembly of the device from an approximated position to an unapproximated position when the trigger lock is in an unlocked position.
