Abstract: A surgical stapler includes a moving driver and an anvil moving in the same direction as the driver to pick off a staple from a supply, and to transport it to a forming station. The anvil is there stopped, but the driver continues to move forwardly forming the staple about the anvil. The anvil is locked against retraction until the driver is partially retracted in order to facilitate staple ejection. A drive linkage includes a four-bar linkage and a trigger mounted cam drive for dispersing required input forces over the trigger movement and minimizing force variations and maximum input. Modular features and construction provide use and manufacturing advantages. Methods are included.

Abstract: In a surgical stapler having a driver and an anvil for forming a staple in tissue, a four-bar linkage is driven by a drive cam which is at least partially curved. The curved cam provides, with the linkage, an increasing mechanical advantage for reducing forces required to operate the stapler and to form a staple. The drive minimizes the range of forces required to operate the stapler throughout an operating cycle. Cam and linkage relationships are disclosed.