Preloaded nut

Claim 1

IN A PREVAILING TORQUE TYPE LOCK NUT ASSEMBLY INCLUDING A DRIVING SECTION HAVING TOOL ENGAGING SURFACES THEREON, AN INTERNALLY THREADED BODY SECTION AND A BREAKNECK IN THE FORM OF AN EXTERNAL ANNULAR GROOVE POSITIONED BETWEEN THE DRIVING AND BODY SECTIONS WHEREIN THE DRIVING SECTION IS ADAPTED TO BE SHEARED OFF AT THE BREAKNECK AND SEPARATED FROM THE BODY SECTION UNDER PREDETERMINED TORQUE CONDITIONS, SAID NUT BODY SECTION HAVING A CYLINDRICAL LOCK LOCATING SECTION OF UNIFORM WALL THICKNESS AND OF CIRCULAR CROSS SECTION ALIGNED CO-AXIALLY WITH THE NUT AXIS AND EXTENDING TOWARD THE BEARING FACE FROM THE INNERMOST EDGE OF THE BREAKNECK GROOVE, THE WALL THICKNESS IN SAID LOCK LOCATING SECTION BEING SUBSTANTIALLY GREATER THAN THE MINIMUM WALL THICKNESS OF THE BREAKNECK AND SUBSTANTIALLY LESS THAN THE WALL SECTION PORTIONS SURROUNDING THE THREADS IN THE REMAINING PORTIONS OF THE BODY SECTION, SAID ASSEMBLY HAVING A COUNTERBORE IN THE DRIVING SECTION THAT IS GENERALLY COAXIAL WITH THE AXIS OF THE NUT THREADS AND SLIGHTLY GREATER IN DIAMETER THAN THE MAJOR DIAMETER OF THE NUT THREADS, SAID COUNTERBORE EXTENDING FROM THE OUTERMOST END OF THE DRIVING SECTION TO A POINT WITHIN THE NUT BODY SECTION INWARDLY OF THE BREAKNECK AND GENERALLY ALIGNED WITH THE END PORTION OF THE LOCK LOCATING SECTION IMMEDIATELY ADJACENT THE BREAKNECK, SAID LOCK LOCATING SECTION HAVING A PREVAILING TORQUE THREAD LOCK APPLIED THERETO, SAID LOCK BEING CHARACTERIZED IN THAT THE THREAD IS RADIALLY INWARDLY DISTORTED AND THE DISTORTION IS LOCALIZED IN SMALL AREAS DISPOSED SYMMETRICALLY ABOUT THE NUT CIRCUMFERENCE AND THE PRIMARY DISTORTION IS LOCALIZED AND LIMITED TO THE THREADED PORTIONS THAT ARE AT LEAST 1.5 THREAD PITCHES INWARDLY OF THE FIRST FULL THREAD TURN ADJACENT THE BREAKNECK.