Error in Cardano hinge documentation
In the documentation of the Cardano hinge, the figure presents an incorrect definition of the reference system of the part on the left, the one whose axes are labeled 1', 2', and 3'. In fact, as correctly indicated in the text, the axis along which torque is transmitted should be 1', and the remaining axes should be labeled in analogy with those on the right, i.e. axis 2' on the left (and in the center hinge) should be loosely parallel to axis 2 on the right, and axis 3' on the left should be loosely parallel to axis 3 on the right (and in the center hinge).
I cannot fix this in the source, right now, because I don't have the source of the drawing handy. Perhaps Louis can help us?