Pre-load indicating washer

Claim 1

TENSION INDICATING MEANS FOR THREADED FASTENERS OF THE TYPE WHICH INCLUDES AN ELONGATE SHANK CONNECTIVELY PASSING THROUGH MEMBERS TO BE UNITED AND BEING TERMINATED ON AT LEAST ONE END THEREOF BY A MEMBER HAVING A SURFACE EXTENDING RADIALLY OF THE SHANK TRANSFORMING A TENSION LOAD IN THE FASTENER TO A COMPRESSION LOAD AGAINST THE ADJACENT ONE OF THE MEMBERS TO BE UNITED, COMPRISING: A HOLLOW RIGHT-CYLINDER WASHER MEANS SURROUNDING SAID SHANK AND DISPOSED BETWEEN SAID RADIALLY EXTENDING SURFACE AND SAID ADJACENT ONE OF THE MEMBERS, THE WASHER MEANS BEING OF A HARD DUCTILE METAL DEFORMABLE, IN COMPRESSION, AT ONE RATE PER INCREMENT OF LOADING WITHIN ITS ELASTIC RANGE AND AT A SUBSTANTIALLY GREATER RATE THAN SAID ONE RATE PER INCREMENT OF LOADING BEYOND ITS ELASTIC RANGE IN ITS PLASTIC RANGE; SAID WASHER MEANS HAVING AN INITIAL RELAXED HEIGHT AND BEING COMPRESSED UNDER AND BY SAID RADIALLY EXTENDING SURFACE TO A SECOND LESSER HEIGHT UNDER A LOAD WHICH IS EQUAL TO THE TENSION LOAD TO BE ESTABLISHED AND MAINTAINED IN THE FASTENER, THE CROSS-SECTIONAL THICKNESS OF THE WASHER MEANS AND THE INITIAL HEIGHT THEREOF BEING OF SUCH RATIO THAT A COMPRESSION LOAD APPLIED THERETO IN REDUCING THE WASHER MEANS TO ITS LESSER HEIGHT EFFECTS A BULGING OF ITS CROSS SECTION WHEREBY IT THICKENS ON ONE SIDE RADIALLY INWARDLY TOWARD THE SHANK AND RADIALLY OUTWARDLY ON ITS OTHER SIDE; SAID WASHER MEANS IN BEING REDUCED TO ITS LESSER HEIGHT UNDERGOING DEFORMATION IN ITS PLASTIC RANGE; SAID WASHER MEANS BEING SPACED AWAY FROM THE SHANK SUFFICIENTLY TO ACCOMMODATE THE RADIAL INWARD BULGING OF THE WASHER MEANS; AND A GUAGE MEMBER OUTWARDLY ADJACENT THE WASHER MEANS, SAID GAUGE MEMBER BEING AN ANNULUS SURROUNDING SAID WASHER MEANS AND ALSO DISPOSED BETWEEN THE RADIALLY EXTENDING SURFACE AND THE ADJACENT ONE OF THE MEMBERS, THE HEIGHT OF SAID GAUGE MEMBER, MEASURED AXIALLY OF THE SHANK, BEING EQUAL TO SAID SECOND LESSER HEIGHT OF THE WASHER MEANS WHEREBY THE REDUCTION OF THE HEIGHT OF THE WASHER MEANS TO ITS SECOND LESSER HEIGHT UPON ATTAINMENT OF THE TENSION LOAD TO BE ESTABLISHED IN THE FASTENER IS INDICATED BY THE GAUGE MEMBER BEING GRIPPED BETWEEN THE RADIALLY EXTENDING SURFACE AND SAID ONE OF THE MEMBERS TO BE UNITED; THE INNER SURFACE OF THE GAUGE MEMBER BEING SPACED FROM THE OUTER SURFACE OF SAID WASHER MEANS TO ACCOMMODATE, UNRESTRAINED, THE OUTWARD BULGING OF THE WASHER MEANS OCCURRING DURING ITS COMPRESSION.