An end effector comprises a base portion defining a linear elongated slot extending along a longitudinal axis. A distal end of the base portion is adapted to be operatively mounted to an articulation mechanism. Each link of a first pair of links is pivotally connected to the base portion at a fixed pivot point. Each link of a second pair of links is pivotally connected at a fixed pivot point to one or the other of the first pair of links. The second pair of links is pivotally connected together through the slot of the base portion for linear movement along the slot relative to the base portion constraining movement of the first pair of links to relative rotation only in opposite directions.
