Rotary coupling with magnetic preload

A rotary coupling comprising:

• a first coupling body having a first rotation axis;
• a second coupling body disposed adjacent to the first coupling body and having a second rotation axis that is parallel to the first rotation axis, wherein the first coupling body and the second coupling body are separated from each other;
• a first cylindrical element disposed on the first coupling body and having a first cylinder axis;
• a second cylindrical element disposed on the second coupling body and adjacent to the first cylindrical element, the second cylindrical element having a second cylinder axis that is perpendicular to the first cylinder axis;
• a first magnet disposed on the first coupling body and having a pole disposed at the separation;
• and
• a second magnet disposed on the second coupling body and having a pole disposed across the separation from the pole of the first magnet, wherein the poles of the first and second magnets disposed at the separation have a same magnetic polarity such that a repulsive magnetic force is imparted on each of the first and second coupling bodies to thereby preload the first and second cylindrical elements against each other at a point of contact.