Interchangeable surgical tool assemblies are disclosed. The interchangeable surgical tool assemblies can include an end effector including a first jaw, a second jaw, and a sled configured to translate relative to the first jaw and the second jaw. The interchangeable surgical tool assemblies can also include a firing member comprising a first flange configured to engage the first jaw and a second flange configured to engage the second jaw. The interchangeable surgical tool assemblies can further include a pusher plate and a firing bar selectively coupled to the pusher plate, wherein the firing bar is configured to move through a plurality of successive firing strokes including a first distal firing stroke, a first proximal firing stroke, a second distal firing stroke, a second proximal firing stroke. Additionally or alternatively, the interchangeable surgical tool assemblies can include a rotatable end effector and a flexible spine.
