Patent ID: 8342063

Claim:
An open-ended wrench comprising: a handle; and a wrench head attached to the handle, the wrench head defining an opening to receive a work piece, the wrench head comprising: a first jaw comprising at least a first surface to engage with a surface of the work piece; a second jaw comprising a first curved surface facing the opening; a plate mounted on the second jaw and movable relative the second jaw, the plate comprising at least a second surface to engage with another surface of the work piece, and the plate also comprising a second curved surface engaging the first curved surface and being slidable against the first curved surface, and a pin in a slot and movable within the slot to enable the second curved surface to slide against the first curved surface, the pin being restrained from contacting edges of the slot; wherein the pin is fastened to the plate and the slot is in the second jaw, or the pin is fastened to the second jaw and the slot is in the plate; wherein the plate has a center of rotation and the work piece has a center of rotation; and wherein the wrench head is configured so that, throughout motion of the wrench head, the center of rotation of the plate is between the center of rotation of the work piece and the handle, and the second jaw extends beyond both the center of rotation of the work piece and the center of rotation of the plate.