Wrench head

A wrench head, comprising:

• a working axis;
• a first jaw, comprising a first-jaw arcuate convex contact surface, a second first-jaw arcuate convex contact surface, a third first-jaw arcuate convex contact surface, and a first-jaw planar contact surface, located between the second first-jaw arcuate convex contact surface and the third first-jaw arcuate convex contact surface;
• a second jaw, coupled with the first jaw, pivotable relative to the first jaw, and comprising a second-jaw arcuate convex contact surface and a second-jaw planar contact surface;
• a third jaw, coupled with the second jaw, pivotable relative to the second jaw, and comprising a-third-jaw arcuate convex contact surfaces;
• and
• wherein:
• a first-jaw virtual circle is perpendicular to the first-jaw arcuate convex contact surface, to the second first-jaw arcuate convex contact surface, and to the third first-jaw arcuate convex contact surface, has a single point contact with each one of the first-jaw arcuate convex contact surface, the second first-jaw arcuate convex contact surface, and the third first-jaw arcuate convex contact surface, is centered about the working axis, and is perpendicular to the working axis;
• when the second jaw is in a closed second-jaw orientation relative to the first jaw, the first-jaw virtual circle is perpendicular to the second-jaw arcuate convex contact surface and to the second-jaw planar contact surface, has a single point contact with the second-jaw arcuate convex contact surface and intersects the second-jaw planar contact surface at only two points;
• and
• when the second jaw is in the closed second-jaw orientation relative to the first jaw, and the third jaw is in a closed third-jaw orientation relative to the second jaw, the first-jaw virtual circle is perpendicular to the third-jaw arcuate convex contact surfaces and has a single point contact with each of the third-jaw arcuate convex contact surfaces.