Universal-joint rotor-hub method and system

1 . A universal-joint cross assembly comprising:

a ring-shaped cross comprising a ring and four trunnions connected around a periphery of the ring;

four compression rings, each of the four compression rings mounted around a respective one of the four trunnions;

wherein each of the four trunnions is positioned at a 90° interval relative to adjacent ones of the four trunnions;

four inner balls positioned on the four trunnions entirely radially outboard of the four compression rings relative to the ring; and

wherein each of the four inner balls is fixed to one of the four compression rings and forms a portion of a spherical bearing.

2 . The universal-joint cross assembly of claim 1 , comprising:

four ball caps; and

wherein each of the four ball caps is fixed to an outboard end of one of the four inner balls.

3 . The universal-joint cross assembly of claim 2 , wherein each of the four ball caps:

comprises a face perpendicular to an axis of rotation of the universal-joint cross assembly formed between opposing pairs of the four compression rings; and

has formed therein a through hole to permit a removable fastener to be used to mount removably an inner ball of the four inner balls relative to a respective one of the four compression rings.

4 . The universal-joint cross assembly of claim 1 , wherein the four inner balls are formed of metal.

5 . The universal-joint cross assembly of claim 1 , wherein the four inner balls are formed of a ceramic.

6 . The universal-joint cross assembly of claim 1 , wherein the four inner balls are elastomeric.

7 . The universal-joint cross assembly of claim 1 , wherein terminal positions of the ring-shaped cross are on a circumference of the ring of the ring-shaped cross.