Wrist mechanism for a robot arm
 An improved wrist mechanism for a robot arm is disclosed. A first drive mechanism is provided which includes a hollow upper knuckle portion adapted for rotation about a first axis. The upper knuckle portion terminates in an angled end. A second drive mechanism is provided which includes a first hollow torque tube journalled in the upper knuckle portion for rotation relative thereto and a lower knuckle portion having an angled end journalled to the upper knuckle portion curved end for rotation about a second axis. The first torque tube and the lower knuckle portion engage each other for rotation together, and the first and second axes of rotation intersect at a first point. A third drive mechanism includes a second hollow torque tube journalled in the first torque tube for rotation relative thereto, an intermediate drive member journalled in the lower knuckle portion curved end, and an output tube journalled in the lower knuckle portion for rotation about a third axis. The output tube carries a tool mounting surface for attaching a tool thereto. The second torque tube, the intermediate drive means, and the output tube engage one another for rotation together, and the second and third axes of rotation intersect each other at a second point. The first and second points of intersection are offset from one another by a predetermined distance to provide a large radius of curvature for actuating or supply lines carried in a hollow internal passageway of the wrist mechanism to the tool mounted thereon. 
Champion Spark Plug Company
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B25J Y10T Y10T B25J Y10T
inventional additional additional inventional additional
Dirk A.
Peter