A surgical end effector includes a clevis and two jaws rotatably coupled to the clevis. Each jaw includes a face that is perpendicular to the axis of rotation of the jaw. A rocking pin is pivotally supported by the clevis. The opposite ends of the rocking pin engage the faces of the jaws to constrain the jaws to have opposite motions around the axes of rotation of the jaws. The clevis may be coupled to an elongate shaft with wires extending through the shaft to provide an endoscopic instrument. The jaws may be opened and closed by pushing and pulling on the wires. A wire guide may support the wires in the shaft such that they are able to transmit a compressive force without buckling. The wires may carry electricity to the jaws for electrocautery.
