A self-aligning bolt has an eccentric pilot tip extending forwardly of the externally threaded shank thereof. A self-aligning nut has an eccentric counter-bore formed therein on the side of the seating face and offset from the axis of the internally threaded bore of the nut....http://www.google.com/patents/US5073073?utm_source=gb-gplus-sharePatent US5073073 - Self-aligning bolt and a self-aligning nut
