Patent Publication Number: US-2023137555-A1

Title: Bolts and bolt and nut fasteners

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Pat. Application No. 63/205,671, filed 04 Jan. 2021, incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to bolts, bolt and nut fasteners, and bolted joints. 
     BACKGROUND OF THE INVENTION 
     In many manufactured products, it is essential to join two or more elements or surfaces together. Bolted joints are useful for this when the elements require periodic disassembly and assembly without destroying the joint. 
     Bolted joints include fasteners that capture and join other parts, and are secured by mating screw threads. A bolted joint is either a soft joint or a hard joint. A soft-bolted joint is when the hardness of at least one of the elements is below 30 RC. A hard-bolted joint is when the hardness of all the elements is greater than 30 RC. A bolted joint may use a through-hole or a tapped hole. A through-hole or stud joint relies on parts joined together using a stud. A tapped hole or screw joint relies on parts joined together using a threaded hole and a threaded fastener. 
     The objective of a bolted joint is to maintain joint cohesiveness, whether a tension joint or a shear joint. The axial forces exerted by the parts of a tension joint try to separate the joint. Accordingly, the bolt of a tension joint must serve as a clamp to hold the parts together. The shear forces exerted by the elements of a shear joint try to separate the joint. Accordingly, the bolt of a shear joint must serve as a pin to keep the parts stationary. 
     A standard bolt is a longitudinally straight shank including a first end, a second end, a head proximate to the first end, and an external thread. The external thread between the first and second ends is configured to thread on an internal thread of a tapped nut, through-hole, or blind hole. A standard bolted joint includes the internal thread exerting an axial clamping force and the bolt’s shank acting as a dowel, pinning the joint against lateral shear forces. The locking method of the bolted joint includes the internal thread of the nut, opening, or blind bore on the external thread of the bolt. Rotational engagement of the internal thread over and on the external thread creates axial clamping. 
     Vibration and prevailing torque capable of inducing relative movement between bolted structures can loosen bolted joints by unwinding the bolt’s external thread from the applied internal thread. While skilled artisans have developed locknuts, jam nuts, lock washers, and thread-locking fluid to resist loosening, existing methods are not entirely satisfactory, unreliable, and, in many implementations, impracticable, necessitating continued improvement in the art. 
     SUMMARY OF THE INVENTION 
     According to the invention, a bolt includes a shank including a first end, a second end configured with an enlarged head for bolt-turn purposes, a first external thread proximate to the first end, and a second external thread proximate to the second end. The first external thread twists in a first direction, and the second external thread twists in a second direction different from the first direction. The first external thread includes a first pitch, the second external thread includes a second pitch, and the first pitch is different from the second pitch. A body of the shank separates the first external thread from the second external thread. The body of the shank is unthreaded. The first external thread includes a minor diameter, the second external thread includes a major diameter, and the minor diameter of the first external thread is greater than the major diameter of the second external thread. A nut includes a threaded hole including an internal thread having a minor diameter and a pitch. The pitch of the nut is equal to the first pitch, the minor diameter of the internal thread is greater than the major diameter of the second external thread, and the internal thread corresponds to and is configured to thread on the first external thread. 
     According to the invention, a bolt includes a shank including a first end, a second end, an enlarged head proximate to the first end, the enlarged head configured with a first external thread and a radial bearing surface between the shank and the first external thread and facing the second end, and a second external thread proximate to the second end. The first external thread twists in a first direction and includes a minor diameter, and the second external thread twists in a second direction different from the first direction and includes a major diameter less than the minor diameter. The first external thread includes a first pitch, the second external thread includes a second pitch, and the first pitch is equal to the second pitch. The enlarged head is configured with one of a socket and a key for bolt-turn purposes. A body of the shank separates the first external thread from the second external thread. The body of the shank is unthreaded. A nut includes a threaded hole including an internal thread having a minor diameter and a pitch. The pitch of the nut is equal to both the first pitch and the second pitch. The minor diameter of the internal thread greater than the major diameter of the second external thread, and the internal thread corresponds to and is configured to thread on the first external thread. 
     According to the invention, a bolt includes a shank including a first end, a second end, a first external thread proximate to the first end, and a second external thread proximate to the second end. The first external thread twists in a first direction and includes a first pitch and a minor diameter. The second external thread twists in a second direction different from the first direction and includes a second pitch equal to the first pitch and a major diameter less than the minor diameter. A nut includes a threaded hole including an internal thread having a minor diameter and a pitch. The pitch of the nut is equal to both the first pitch and the second pitch, the minor diameter of the internal thread is greater than the major diameter of the second external thread, and the internal thread corresponds to and is configured to thread on the first external thread. A body of the shank separates the first external thread from the second external thread. The body of the shank is unthreaded. 
     According to the invention, a fastener includes a bolt, an anchor nut, and a locknut. The bolt includes a shank having a first end, a second end, and a first external thread proximate to the first end and including a major diameter. The anchor nut includes a head, a second external thread including a minor diameter greater than the major diameter, and a first hole including a first internal thread configured to thread on the first external thread. The locknut includes a second hole including a second internal thread configured to thread on the second external thread. The first external thread and the first internal thread twist in a first direction, and the second external thread and the second internal thread twist in a second direction different from the first direction. The first external thread, the second external thread, the first internal thread, and the second internal thread including identical pitches. An enlarged head is adjacent to the second end. The anchor nut additionally includes a first open end, a second open end, the first hole extends through the anchor nut from the first open end to the second open end, the head is proximate to the first open end, and the second external thread is proximate to the second open end. The anchor nut has a radial bearing surface between the head and the second external thread. The locknut includes a first side, a second side, a first dimension from the first side to the second side, the second hole extends through the locknut from the first side to the second side, and the anchor nut includes a second dimension from the radial bearing surface to the second open end. In one embodiment, the second dimension is less than the first dimension, the first internal thread extends from the first open end to a runout between the first open and the second open end, and the first hole is unthreaded from the runout to the second open end. In another embodiment, the second dimension is greater than the first dimension, and the first internal thread extends from the first open end to the second open end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Specific objects and advantages of the invention will be readily apparent to those skilled in the art from the following detailed description of illustrative embodiments thereof, taken in conjunction with the drawings in which: 
         FIGS.  1  and  2    are perspective views of a fastener constructed and arranged according to the invention, the fastener including a bolt and a nut shown disassembled; 
         FIG.  3    is a central longitudinal section view along line 3-3 of  FIG.  2   ; 
         FIGS.  4  and  5    are perspective views of the fastener of  FIGS.  1  and  2    showing the bolt and the nut assembled; 
         FIG.  6    is a central longitudinal section view along line 6-6 of  FIG.  5   ; 
         FIG.  7    is a view corresponding to  FIG.  6    illustrating the fastener in use; 
         FIG.  8    is a perspective view of another embodiment of a fastener constructed and arranged according to the invention; 
         FIG.  9    is a central longitudinal section view along line 9-9 of  FIG.  8   ; 
         FIG.  10    is a view corresponding to  FIG.  9    illustrating the fastener in use; 
         FIGS.  11  and  12    are perspective views of a yet another embodiment of a fastener constructed and arranged according to the invention, the fastener including a bolt and a nut shown disassembled; 
         FIG.  13    is a side elevation view of the fastener of  FIGS.  11  and  12    showing the bolt and the nut assembled; 
         FIGS.  14  and  15    are perspective views of the fastener of  FIGS.  11  and  12    shown assembled; 
         FIG.  16    is a central longitudinal section view along line 16-16 of  FIG.  15   ; 
         FIG.  17    is a view corresponding to  FIG.  16    illustrating the fastener in use; 
         FIG.  18    is perspective view of still another embodiment of a fastener constructed and arranged according to the invention; 
         FIG.  19    is a perspective view of yet still another embodiment of a fastener constructed and arranged according to the invention, the fastener including a bolt, an anchor nut, and a locknut shown disassembled; 
         FIG.  20    is a central longitudinal section view of the bolt along line 20-20 of  FIG.  19   ; 
         FIG.  21    is a central longitudinal section of the anchor nut and the locknut along line 20-20 of  FIG.  19     
         FIG.  22    is a side elevation view of the anchor nut and the locknut of  FIG.  19    shown assembled to form an anchor nut assembly; 
         FIG.  23    is a central longitudinal section view along line 23-23 of  FIG.  22   ; 
         FIGS.  24  and  25    are perspective views of the fastener of  FIG.  19    showing the bolt, the anchor nut, and the locknut assembled; 
         FIG.  26    is a side elevation view of the embodiment of  FIGS.  24  and  25   ; 
         FIG.  27    is a section view along line 27-27 of  FIG.  26   ; 
         FIG.  28    is a view corresponding to  FIG.  27    illustrating the fastener in use; 
         FIG.  29    is a perspective view of still another embodiment of a fastener constructed and arranged according to the invention and shown disassembled, the fastener including a bolt, an anchor nut, and a locknut; 
         FIG.  30    is a central longitudinal section view of the anchor nut and the locknut of  FIG.  29    shown assembled to form an anchor nut assembly; and 
         FIG.  31    is a central longitudinal section view of fastener of  FIG.  29    showing the bolt, the anchor nut, and the locknut assembled and in use. 
     
    
    
     DETAILED DESCRIPTION 
     Improved bolts, bolt and nut fasteners, and bolted joints are disclosed. 
     I. 
     Turning now to the drawings, like reference characters indicating corresponding elements throughout the several views,  FIGS.  1  and  2    illustrate fastener  50  constructed and arranged according to the invention. Fastener  50  is useful in forming bolted joints and includes bolt  52  and nut  54  configured to be repeatedly and quickly assembled and disassembled. All diameters referenced throughout this specification related to fastener  50  are constant. 
     In  FIGS.  1 ,  2 , and  3   , bolt  52  includes longitudinally straight cylindrical shank  60  extending from proximal end  62  configured with enlarged head  100  to distal end  64 , and external threads  70  and  80  on either side of unthreaded body  90 , including a diameter  92  in  FIG.  3   . Head  100  has wrench flats  102 , six in this example, for bolt-turn purposes, and underside  104 . Shank  60  extends outwardly to distal end  64  from proximal end  62  affixed centrally to underside  104  of head  100 . Radial bearing surface or radius  104 A of underside  232  radiates outwardly from body  90 . 
     In  FIGS.  1 - 3   , external thread  70  near head  100  twists in a left-hand direction and is exemplary of a standard left-handed external thread. In  FIG.  3   , external thread  70  includes thread length  71  extending from closely adjacent to proximal end  62  and radial bearing surface  104  to runout  72  on a proximal side of body  70 , minor diameter  73 , major diameter  74 , and pitch  75 , the distance between adjacent peaks or crests of the thread. Minor diameter  73  occurs at the roots of external thread  70 , and major diameter  74  occurs at the crests of external thread  70 . 
     In  FIGS.  1 - 3   , external thread  80  near distal end  64  twists in a right-hand direction opposite to the left-hand direction of external thread  70  and is exemplary of a standard right-handed external thread. In  FIG.  3   , external thread  80  includes thread length  81  extending from distal end  64  to runout  82  on a distal side of body  70 , minor diameter  83 , major diameter  84 , and pitch  85 , the distance between adjacent peaks or crests of the thread. Minor diameter  83  occurs at the roots of external thread  80 . Major diameter  84  occurs at the crests of external thread  80 . 
     External threads  70  and  80  twist in opposite directions, as described. Accordingly, external threads  70  and  80  are counter-threads configured to threadedly receive counter-rotating internally-threaded elements. External thread  70  is the proximal left-handed external thread of bolt  52  near or otherwise proximate to radial bearing surface  104  of head  100 . External thread  80  opposite to external thread  70  is the distal right-handed external thread proximate to distal end  64 . Thread length  81  of external thread  80  is greater than thread length  71  of external thread  70  and less than grip length  94  of body  90  extending from runout  72  to runout  82 . Grip length  94  is the length of the unthreaded portion of shank  60 , namely, body  90 . Grip length  94  is the free length of bolt  52  that is stretched under tension. Pitch  75  is slightly larger than pitch  85 , and this can be reversed in an alternate embodiment. Pitches  75  and  85  can be the same in a specific embodiment. Minor diameter  73  of external thread  70  is larger than diameter  92  of body  90  and major diameter  84  of external thread  80 . Accordingly, external thread  70  is the major external thread of bolt  52 , and external thread  80  is the minor external thread of bolt  52 . 
     In  FIGS.  1  and  2   , nut  54  and is an annular block configured with a threaded hole  111 , including internal thread  112 . Threaded hole  111  extends through nut  54  from an inner side  54 A of nut  54  to an outer side  54 B of nut  54 . Inner and outer sides  54 A and  54 B of nut  54  are radial bearing surfaces. Nut  54  has a thickness from inner side  54 A to outer side  54 B. Internal thread  112  runs along the inside of nut  54  between the opposed inner and outer sides  54 A and  54 B and twists in the same left-hand direction as external thread  70 . In  FIG.  6   , internal thread  112  includes minor diameter  113 , major diameter  114 , and pitch  115 , the distance between adjacent peaks or crests of the thread. Minor diameter  113  occurs at the crests of internal thread  112 , and major diameter  114  occurs at the roots of internal thread  112 . Pitches  75  and  115  are identical. Minor diameter  113  of internal thread  112  is greater than diameter  92  of body  90  and major diameter  84  of external thread  80 . Minor and major diameters  113  and  114  of internal thread  112  correspond to the respective minor and major diameters  73  and  74  of external thread  70 . External thread  70  and internal thread  112  correspond by being the same size and having identical pitches. 
     Since minor diameter  113  of internal thread  112  is greater than major diameter  84  of external thread  80  and diameter  92  of body  90 , threaded hole  111  is configured to receive therethrough in a direction from outer side  54 B of body  54  to inner side  54 A of body  54  distal end  64  shank  60  and sequentially pass over external thread  80  and body  90  to runout  72  of external thread  70  without interference from external thread  80 . Since pitch  115  of internal thread  112  and pitch  75  of external thread  70  are the same, minor and major diameters  113  and  114  of internal thread  112  correspond to the respective minor and major diameters  73  and  74  of external thread  70 , internal thread  112  twists in the same left-hand direction as external thread  70 , and internal and external threads  112  and  70  are correspondingly sized, internal thread  112  corresponds to and is configured to thread rotationally over and on external thread  70  from runout  72  in the direction of arrow B in  FIGS.  4 - 6    when rotated in the direction of arrow A and off external thread  70  from runout  72  in the direction of arrow D when rotated in the direction of arrow C. Accordingly, internal thread  112  corresponds to and is configured to thread over and on external thread  70  but not on external thread  80 . 
     Nut  54  advances toward underside  104  of head  100  and away from distal end  64  in the direction of arrow B in  FIGS.  4 - 6   , when nut is  54  is rotated over and on external thread  70  in a counterclockwise direction of arrow A in  FIGS.  4  and  5    when seen from the point of view facing distal end  64  on the central longitudinal axis of shank  60 . Nut  54  is suitably sized to extend entirely over external thread  70  from outer side  54 B of nut  54  tightened directly against underside  104  of head  100  to inner side  54 A of nut  54  proximate to body  90  outboard of external thread  70  in the assembled fastener  50 , when nut  54  is tightened directly against underside  104  of head  100  by rotating it in the direction of arrow A tightly against underside  104  of head  100 . Nut  54  withdraws from underside  104  of head  100  and away from distal end  64  in the direction of arrow D in  FIGS.  4 - 6    when nut  54  is rotated on external thread  70  in a clockwise direction of arrow C in  FIGS.  4  and  5    when seen from the point of view facing distal end  64  on the central longitudinal axis of shank  60 . Once nut  54  is free from external thread  70 , the user may withdraw nut  54  from bolt  52   in the direction of arrow D to separate nut  54  from bolt  52 . The described process for assembling and disassembling fastener  50  is repeatable is needed. In  FIGS.  1 ,  2 ,  4 , and  5   , nut  54  has parallel and circumferentially spaced-apart wrench grooves  118  for nut-turn purposes. Repeated reference to the described directions of arrows A, B, C, and D is made throughout this specification with the various embodiments disclosed herein and used in the various figures for reference purposes. 
     The assembled fastener  50  in  FIGS.  4 - 6    is useful in forming bolted joints, such as bolted joint  120  in  FIG.  7   .  FIG.  7    illustrates two members  122  and  124  secured together by assembled fastener  50 . Members  122  and  124 , metal plates in this example, have registered through bores  126  and  128 , respectively. Bore  128  is tapped with internal thread  130 , and is exemplary of a tapped or internally threaded bore  128 . Thread  130  is a right-hand thread and corresponds to external thread  80 , enabling it to thread conventionally on external thread  80  when bolt  52  is turned in the direction of arrow A. 
     A user forms bolted joint  120  with fastener  50  to secure members  122  and  124  together by inserting bolt  60  distal end  64  first into and through bore  126  to bore  128 . He threads internal thread  130  over and on external thread  80  and advances bolt  52  in the direction of arrow D by rotating bolt  52  in the direction of arrow A until inner side  54 A of nut  54  tightens against member  122 . Bolt length  94 , the free length of bolt  52  that is stretched under tension, extends through bore  126  of member  122  to external thread  80  threaded to internally threaded bore  128 . He alternately rotates nut  54  and bolt  52  in the direction of arrow A while holding the other one stationary. This alternately tightens outer side  54 B of nut  54  against underside  104  of head  100  and inner side  54 A of nut  54  against member  122  until the desired tension is achieved, tightly clamping member  122  between member  124  and inner side  54 A of nut  54  and tightly clamping nut  54  between underside  104  of head  100  and member  122 . Since rotation of bolt  52  in the direction of arrow A urges bolt  52  in the direction of arrow D and rotation of nut  54  relative to bolt  52  in the same direction of arrow A urges nut  54  in the opposite direction of arrow B, nut  54  with its outer side  54 B tightened directly against underside  104  of head  100  and its inner side  54 A tightened directly against member  122  disables bolt  52  from loosening by rotating in the direction of arrow C. Accordingly, nut  54  serves as a locknut counter-rotated relative to bolt  52  aggressively disabling bolt  52  from loosening by rotating in the direction of arrow C. Fastener  50  securing bolted joint  120  is surprisingly strong and aggressive and resistant to axial failure, shear failure, and loosening in response to vibrational and prevailing torsional forces. Nut  54  additionally serves to distribute the load of fastener  50 . The user need only reverse this operation to release bolted joint  120   and withdraw fastener  50 . The skilled artisan will readily appreciate that handedness of the threads described in conjunction with fastener  50  can be reversed in alternate embodiments. 
     The assembled fastener  50  in  FIGS.  4 - 6    is also useful with a nut  140  and washer  148  in  FIG.  8    to form an alternate embodiment of a fastener  50 ′ useful in forming bolted joint  160  in  FIG.  10   , including members  162  and  164  secured together by fastener  50 ′. Fastener  50 ′ is the assembly of bolt  52 , nut  54 , nut  140 , and washer  148 . Members  162  and  164  in  FIG.  10   , metal plates in this example, have registered through bores  166  and  168 , respectively.  FIG.  9    is a section view along 9-9 of fastener  50 ′ of  FIG.  8    illustrating the assembly of bolt  52 , nut  54 , nut  140 , and washer  148 . The assembly of bolt  52  and nut  54  in  FIGS.  9  and  10    incorporate the reference characters as fastener  50  in  FIGS.  6  and  7   . 
     Nut  140  is an annular block configured with a threaded hole  141 , including internal thread  142 . Threaded hole  141  extends through nut  140  from an inner side  140 A of nut  140  to an outer side  140 B of nut  140 . Inner and outer sides  140 A and  140 B of nut  140  are radial bearing surfaces. Internal thread  142  runs along the inside of nut  140  between the opposed inner and outer sides  140 A and  140 B and twists in the same right-hand direction as external thread  80 . Internal thread  142  includes minor diameter  143 , major diameter  144 , and pitch  145 , the distance between adjacent peaks or crests of the thread. Minor diameter  143  occurs at the crests of internal thread  142 , and major diameter  144  occurs at the roots of internal thread  142 . Pitch  145  is identical to pitch  85 . Minor and major diameters  143  and  144  of internal thread  142  correspond to the respective minor and major diameters  83  and  84  of external thread  80 . Since pitch  145  of internal thread  142  and pitch  85  of external thread  80  are the same, minor and major diameters  143  and  114  of internal thread  142  correspond to the respective minor and major diameters  83  and  84  of external thread  80 , internal thread  142  twists in the same right-hand direction as external thread  80 , and internal and external threads  142  and  80  are correspondingly sized, internal thread  142  corresponds to and is configured to thread rotationally over and on external thread  80  from distal end  64  and off external thread  80  from distal end  64 . External thread  80  and internal thread  142  correspond by being the same size and having identical pitches. 
     In  FIG.  10   , a user forms bolted joint  160  with fastener  50 ′ to secure members  162  and  164  together by inserting bolt  60  distal end  64  first into and through bore  166  to bore  168  to bring inner side  54 A of nut  54  against member  162  on one side of the bolted joint  160  and extend external thread  80  outwardly from bore  168  to distal end  64  on the opposite side of the bolted joint  160 . The user locates washer  148  over external thread  80 . He threads internal thread  142  on external thread  80  by inserting distal end  64  into threaded hole  141  and rotating nut  140  in the direction of arrow C. This advances nut  140  in the direction of arrow B until nut  140  is tightened directly against washer  148  initially clamped between outer side  140 B of nut  54  and member  164 . Bolt length  94  extends through bores  166  and  168  to external thread  80 , extending outwardly from bore  166  to distal end  64 . He either holds nut  140  from rotating or urges rotation of nut  140  in the direction of arrow C and at the same time alternately rotates nut  54  and bolt  52  in the direction of arrow A while holding the other one stationary as in joint  120 . As described above, this alternately tightens outer side  54 B of nut  54  against underside  104  of head  100  and inner side  54 A of nut  54  against member  122  until the desired tension is achieved, tightly clamping members  162  and  164  between washer  148  and inner side  54 A of nut  54  and tightly clamping nut  54  between underside  104  of head  100  and member  162 . Nut  54  serves as a locknut counter-rotated relative to bolt  52  aggressively disabling bolt  52  from loosening by rotating in the direction of arrow C in bolted joint  160  as in bolted joint  120 . Fastener  50 ′ securing bolted joint  160  is surprisingly strong and aggressive and resistant to axial failure, shear failure, and loosening in response to vibrational and prevailing torsional forces. Nut  54  serves to distribute the load of fastener  50 ′ as described above in bolted joint  120 . The user need only reverse this operation to release bolted joint  160  and withdraw fastener  50 ′. The skilled artisan will readily appreciate that handedness of the threads described in conjunction with fastener  50 ′ can be reversed in alternate embodiments. 
     II. 
       FIGS.  11 - 13    illustrate another embodiment of a fastener  180  constructed and arranged according to the invention. Fastener  180  is useful in forming bolted joints and includes bolt  182  and nut  184  is configured to be repeatedly and quickly assembled and disassembled. All diameters referenced throughout this specification related to fastener  180  are constant. 
     Bolt  182  includes longitudinally straight cylindrical shank  190  extending from proximal end  192  configured with enlarged head  230  to distal end  194 . External threads  200  and  210  are on either side of unthreaded body  220 , including a diameter  222  in  FIG.  13   . Head  230 , an enlarged cylindrical body, includes underside  232  and opposed outer side  234 . Head  230  is circumferentially enlarged relative to shank  190  and is externally threaded with thread  200  extending between underside  232  and outer side  234 . Shank  190  extends outwardly to distal end  194  from proximal end  192  affixed centrally to underside  232  of head  230 . Radial bearing surface or radius  232 A of underside  232  radiates outwardly from body  220  to external thread  200 . In  FIG.  12   , blind keyway  236  for bolt-turn purposes extends into head  230  centrally from outer side  234 . All diameters referenced related to fastener  180  are constant. 
     In  FIGS.  11 - 13   , external thread  200  near proximal extremity  192  twists in a left-hand direction and is exemplary of a standard left-handed external thread. In  FIG.  13   , external thread  200  includes thread length  201  extending between underside  232  adjacent to proximal end  192  and outer side  234 , minor diameter  203 , major diameter  204 , and pitch  205 , the distance between adjacent peaks or crests of the thread. Minor diameter  203  occurs at the roots of external thread  200 , and major diameter  204  occurs at the crests of external thread  200 . 
     External thread  210  near distal end  194  twists in a right-hand direction opposite to the left-hand direction of external thread  200  and is exemplary of a standard right-handed external thread. In  FIG.  13   , external thread  200  includes thread length  211  extending from distal end  194  to runout  212 , minor diameter  213 , major diameter  214 , and pitch  215 , the distance between adjacent peaks or crests of the thread. Minor diameter  213  occurs at the roots of external thread  210 . Major diameter  214  occurs at the crests of external thread  200 . 
     External threads  200  and  210  twist in opposite directions, as described. Accordingly, external threads  200  and  210  are counter-threads configured to threadedly receive counter-rotating internally-threaded elements. External thread  200  is the proximal left-handed external thread of bolt  182  proximate to proximal end  192 . External thread  210  opposite to external thread  200  is the distal right-handed external thread of bolt  182  proximate to distal end  194 . Thread length  211  of external thread  210  is greater than thread length  201  of external thread  200  and less than grip length  224  of body  220  extending from underside  232  of externally-threaded head  230  to runout  212 . Grip length  224 , the length of the unthreaded portion of shank  190 , namely, body  220 , is the free length of bolt  182  that is stretched under tension. Pitches  205  and  215  are identical. Minor diameter  203  of external thread  200  is larger than diameter  222  of body  190  and major diameter  214  of external thread  210 . Accordingly, external thread  200  is the major external thread of bolt  182 , and external thread  210  is the minor external thread of bolt  182 . External threads  200  and  210  are the same size and have identical pitches. 
     In  FIGS.  11  and  12   , nut  184  is an annular block configured with a threaded hole  240 , including internal thread  242 . Threaded hole  240  extends through nut  184  from an inner side  184 A of nut  184  to an outer side  184 B of nut  184 . Inner and outer sides  184 A and  184 B of nut  184  are radial bearing surfaces. Nut  184  has a thickness from inner side  184 A to outer side  184 B. Internal thread  142  runs along the inside of nut  184  between the opposed inner and outer sides  184 A and  184 B and twists in the same left-hand direction as external thread  200 . In  FIG.  16   , internal thread  242  includes minor diameter  243 , major diameter  244 , and pitch  245 , the distance between adjacent peaks or crests of the thread. Minor diameter  243  occurs at the crests of internal thread  242 , and major diameter  244  occurs at the roots of internal thread  242 . Pitches  205 ,  215 , and  245  are identical. Minor diameter  243  of internal thread  242  is greater than diameter  222  of body  220  and major diameter  214  of external thread  210 . Minor and major diameters  243  and  244  of internal thread  242  correspond to the respective minor and major diameters  203  and  204  of external thread  200 . External thread  200  and internal thread  242  correspond by being the same size and having identical pitches. Further, external threads  200  and  210  and internal thread  242  are the same size and have identical pitches. 
     Since pitch  245  of internal thread  242  and pitch  205  of external thread  200  are the same, minor and major diameters  243  and  244  of internal thread  242  correspond to the respective minor and major diameters  203  and  204  of external thread  200 , internal thread  242  twists in the same left-hand direction as external thread  200 , and internal and external threads  242  and  200  are correspondingly sized, internal thread  242  corresponds to and is configured to thread rotationally over and on external thread  200  and off external thread  200  from outer side  234  of head  230 . Accordingly, internal thread  242  corresponds to and is configured to thread over and on external thread  200  but not on external thread  210 . 
     A user assembles fastener  180  in  FIGS.  14 ,  15 , and  16    by inserting bolt  182  outer side  234  of head  230  first into threaded hole  241  from inner outer side  184 A. He advances nut  184  in the direction of arrow D toward underside  232  of head  230  by rotating nut  184  in the direction of arrow A over external thread  200 . Nut  184  is suitably sized to extend entirely over external thread  200  from inner side  184 A of nut  184  proximate to underside  232  of head  230  to outer side  184 B of nut  184  proximate to outer side  234  of head  230 , when internal thread  242  is completely threaded over external thread  200  in the assembled fastener  180  in  FIGS.  14 - 16   . A user withdraws nut  184  from head  230  to disassemble fastener  180  by reversing this operation. The described process for assembling and disassembling fastener  180  is repeatable as needed. In  FIGS.  11 - 15   , nut  184  has parallel and circumferentially spaced-apart wrench grooves  248  for nut-turn purposes. 
     The assembled fastener  180  in  FIGS.  14 - 16    is useful in forming bolted joint  250  in  FIG.  17   .  FIG.  17    illustrates two members  252  and  254  secured together by assembled fastener  180 . Members  252  and  254 , metal plates in this example, have registered through bores  256  and  258 , respectively. Bore  258  of member  254  is tapped with internal thread  260  and is exemplary of a tapped or internally threaded bore  258 . Thread  130  corresponds to external thread  80 , enabling it to thread conventionally on external thread  80 . 
     A user forms bolted joint  250  with fastener  180  in  FIG.  17    to secure members  252  and  254  together by inserting bolt  190  distal end  194  first into and through bore  256  to bore  258 . He threads internal thread  260  on external thread  210  to advance bolt  182  in the direction of arrow D by rotating bolt  182  in the direction of arrow A until radial bearing surface  232 A of underside  232  of head  230  and inner side  184 A of nut  184  initially tighten against member  252 . Bolt length  224  extends through bore  256  of member  252  to external thread  210  threaded to internally threaded bore  258 . He alternately rotates nut  184  and bolt  182  in the direction of arrow A while holding the other one stationary. This alternately tightens outer side  184 B of nut  54  and radial bearing surface  232 A of underside  232  of head  230  against member  252  until the desired tension is achieved, clamping member  252  between member  254  and both inner side  184 A of nut  54  and radial bearing surface  232 A of head  232 . Since rotation of bolt  182  in the direction of arrow A urges bolt  52  in the direction of arrow D and rotation of nut  184  relative to bolt  182  in the same direction of arrow A urges nut  184  in the opposite direction of arrow B, nut  184  serves as a locknut counter-rotated relative to head  230  of bolt  184  aggressively disabling bolt  182  from loosening by rotating in the direction of arrow C. Radial bearing surface  232 A of head  230  additionally serves to distribute the load of fastener  180  without the need for a washer, although one can use a separate washer between radial bearing surface  232 A and member  252  if desired. Since external threads  200  and  210  and internal thread  242  are identically sized and have the same pitches, the threaded attachments are strong and resistant to stripping. Fastener  180  securing bolted joint  250  is surprisingly strong and aggressive and resistant to axial failure, shear failure, and loosening in response to vibrational and prevailing torsional forces. The user need only reverse this operation to release bolted joint  250  and withdraw fastener  180 . Like fastener  50 ′, the assembled fastener  180  in  FIGS.  14 - 16    is also useful with a nut and washer to form an alternate embodiment of a fastener useful in forming a bolted joint. The skilled artisan will readily appreciate that handedness of the threads described in conjunction with fastener  180  can be reversed in alternate embodiments. 
     Keyway  236  in  FIGS.  12  and  15 - 17    is multifaced and exemplary of an Allen keyway configured to accept an Allen key of a tool used to drive bolt  182  rotationally. In an alternate embodiment of a fastener  180 ′ in  FIG.  18    that, in common with fastener  180 , shares bolt  182  and nut  184 , bolt  182  is configured with a key  265  for bolt-turn purposes. Key  265  is multifaced and exemplary of a standard Allen key configured to accept a standard Allen keyway of a tool used to drive bolt  182  rotationally. In  FIG.  18   , key  265  for bolt-turn purposes extends outwardly from head  230  centrally from outer side  234 . 
     III. 
       FIG.  19    illustrates yet another embodiment of a fastener  300  constructed and arranged according to the invention. Fastener  300  is useful in forming bolted joints and includes bolt  302 , anchor nut  304 , and locknut  306  configured to be repeatedly and quickly assembled and disassembled. Anchor nut  304  and locknut  306  are configured to be repeatedly assembled in  FIGS.  22  and  23    to form an anchor nut assembly  345  and disassembled in  FIGS.  19  and  21    independently from bolt  302 . All diameters referenced throughout this specification related to fastener  300  are constant. 
     In  FIGS.  19  and  20   , bolt  302  includes longitudinally straight cylindrical shank  310  extending from proximal end  312  configured with enlarged lug or head  340  to distal end  314 , external thread  320  and unthreaded body  330 , including a diameter  332  in  FIG.  20   . Shank  60  extends outwardly to distal end  314  from proximal end  312  affixed centrally to head  240  configured to be anchored in a counterbore. External thread  320  twists in a right-hand direction and is exemplary of a standard right-handed external thread. In  FIG.  20   , external thread  320  includes thread length  321  extending from distal end  314  to runout  322  on a distal side of body  330 , minor diameter  323 , major diameter  324 , and pitch  325 , the distance between adjacent peaks or crests of the thread. Minor diameter  323  occurs at the roots of external thread  320 . Major diameter  324  occurs at the crests of external thread  320 . Thread length  321  of external thread  320  is less than grip length  334  of body  330  extending from head  340  to runout  322 . Grip length  334 , the length of the unthreaded portion of shank  310 , namely, body  330 , is the free length of bolt  302  that is stretched under tension. 
     In  FIGS.  19  and  21   , anchor nut  304  is an annular block or body including open inner end  350 , open outer end  352 , flange  354 , head  356 , external thread  360 , and hole  370  configured with internal thread  372 . Hole  370  extends through anchor nut  304  from open inner end  350  to open outer end  352 . Head  356  has wrench flats  358 , six in this example, for nut-turn purposes, and extends from open inner end  350  to the inner or proximal side of flange  354 . Flange  354  extends from its inner side at head  356  to its outer or distal side, including radial bearing surface  304 A. Radial bearing surface  304 A faces external thread  360 . External thread  360  extends between radial bearing surface  304 A and outer end  352 , twists in a left-hand direction opposite to external thread  320  of bolt  302 , and is exemplary of a standard left-handed external thread. Head  356  and flange  354  together form an integrated flanged head of anchor nut  304 . 
     In  FIG.  21   , left-handed external thread  360  includes thread length  361  extending along the length of anchor nut  304  between radial bearing surface  304 A and outer end  352 , minor diameter  363 , major diameter  364 , and pitch  365 , the distance between adjacent peaks or crests of the thread. Minor diameter  363  occurs at the roots of external thread  360 , and major diameter  364  occurs at the crests of external thread  360 . External threads  320  and  360  twist in opposite directions, as described. Accordingly, external threads  320  and  360  are counter-threads configured to threadedly receive counter-rotating internally-threaded elements. 
     Hole  370  extending through anchor nut  304  from open inner end  350  to open outer end  352  in  FIG.  21    has an internally threaded part  370 A and coaxial unthreaded part  370 B. Internally threaded part  370 A includes internal thread  372  extending from open inner end  50  to runout  374  at an intermediate location of hole  370  between open inner end  350  and open outer end  352 . Unthreaded part extends from runout  374  to open outer end  352 . Unthreaded part  370 B has internal diameter  376  greater than major diameter  324  of external thread  320  and diameter  332  of body  330  in  FIG.  20   . 
     In  FIG.  21   , internal thread  372  runs along the inside of anchor nut  304  between open inner end  350  and runout  374  and twists in the same right-hand direction as external thread  320  of bolt  302  opposite to the left-hand direction of external thread  360 . Internal thread  372  includes minor diameter  383 , major diameter  384 , and pitch  385 , the distance between adjacent peaks or crests of the thread. Minor diameter  383  occurs at the crests of internal thread  372 , and major diameter  384  occurs at the roots of internal thread  372 . Pitches  325 ,  365 , and  385  are identical. Minor and major diameters  383  and  384  of internal thread  372  correspond to the respective minor and major diameters  323  and  324  of external thread  320 . External thread  320  and  360  and internal thread  372  are the same size and have identical pitches. 
     Since diameter  376  of unthreaded part  370 B of hole  370  of anchor nut  304  is greater than major diameter  324  of external thread  320 , unthreaded part  370 B of hole  370  is configured to receive therethrough in a direction from open outer end  352  distal end  324  of shank  310  and pass over external thread  320  until external thread  320  at proximal end  314  encounters runout  374 . Since pitch  385  of internal thread  372  and pitch  325  of external thread  320  are the same, minor and major diameters  383  and  384  of internal thread  372  correspond to the respective minor and major diameters  323  and  324  of external thread  320 , internal thread  372  twists in the same right-hand direction as external thread  320 , and internal and external threads  372  and  320  are correspondingly sized, internal thread  372  corresponds to and is configured to thread rotationally over and on external thread  320  from runout  374  in  FIG.  27    and off external thread  320  from runout  374 . Accordingly, internal thread  372  corresponds to and is configured to thread over and on external thread  320 . 
     In  FIGS.  19  and  21   , locknut  306  and is an annular block configured with a threaded hole  401 , including internal thread  402 . Threaded hole  401  extends through locknut  306  from an inner side  306 A of locknut  306  to an outer side  306 B of locknut  306 . Inner and outer sides  306 A and  306 B of locknut  306  are radial bearing surfaces. Nut locknut  306  has a thickness  406  from inner side  306 A to outer side  306 B. In  FIG.  21   , internal thread  402  runs along the inside of locknut  306  between the opposed inner and outer sides  306 A and  306 B and twists in the same left-hand direction as external thread  360  opposite to the right-hand hand direction of external thread  320  of bolt  302  and internal thread  372  of anchor nut  304 . Internal thread  402  includes minor diameter  403 , major diameter  404 , and pitch  405 , the distance between adjacent peaks or crests of the thread. Minor diameter  403  occurs at the crests of internal thread  402 , and major diameter  404  occurs at the roots of internal thread  402 . Pitches  325 ,  365 ,  385 , and  405  are identical. Minor and major diameters  403  and  404  of internal thread  402  correspond to the respective minor and major diameters  363  and  364  of external thread  360 . External threads  320  and  360  and internal threads  372  and  402  are the same size and have identical pitches. In  FIGS.  19 ,  22 , and  24 - 26   , locknut  306  has parallel and circumferentially spaced-apart wrench grooves  408  for nut-turn purposes. 
     Since pitch  405  of internal thread  402  and pitch  365  of external thread  360  are the same, minor and major diameters  403  and  404  of internal thread  402  correspond to the respective minor and major diameters  363  and  364  of external thread  360 , internal thread  402  twists in the same left-hand direction as external thread  360 , and internal and external threads  402  and  360  are correspondingly sized, internal thread  402  corresponds to and is configured to thread rotationally over and on external thread  360  from open outer end  352  of anchor nut  304  in  FIG.  23    and off external thread  360  from open outer end  352 . Accordingly, internal thread  402  corresponds to and is configured to thread over and on external thread  360  for assembling anchor nut  304  and locknut  306  to form anchor nut assembly  345  in  FIGS.  22  and  23   . Internal threads  372  and  402  twist in opposite directions, as described, internal thread  372  in the same direction as external thread  320  and internal thread  402  in the same direction as external thread  360 . Accordingly, internal threads  372  and  402  are counter-threads configured to threadedly receive counter-rotating externally-threaded elements. 
     In  FIG.  23   , a user assembles anchor nut assembly  345  by threading internal thread  402  over and on external thread  360 . The user threads internal thread  402  over and on external thread  360  by inserting open outer end  352  of anchor nut  304  into threaded hole  401  from inner side  306 A and rotating locknut  306  in the direction of arrow C. This advances locknut  306  in the direction of arrow D until inner side  306 A of locknut  306  is tightened directly against radial bearing surface  304 A of flange  354 . Locknut  306  is suitably sized to extend entirely over external thread  360  from inner side  306 A of locknut  306  tightened directly against radial bearing surface  304 A, shown also in  FIG.  22   , to outer side  306 B of locknut  306  outboard of open outer end  352  in the assembly of anchor nut  304  and locknut  306  in  FIG.  23   , when locknut  306  is tightened directly against radial bearing surface  304 A of flange  304  by rotating it in the direction of arrow C tightly against radial bearing surface  304 A of flange  304 . Accordingly, the dimension of locknut  306  from inner side  306 A to outer side  306 B, the thickness  406  of locknut  306  from inner side  306 A to outer side  306 B in  FIG.  21   , is greater than the dimension of anchor nut  304  from radial bearing surface  304 A to open outer end  352 , the thickness  366  of anchor nut  304  from radial bearing surface  304 A to open outer end  352  in  FIG.  21   . Rotating locknut  306  in the direction of arrow A opposite to the direction of arrow C withdraws locknut  306  from radial bearing surface  304 A in the direction of arrow B. Accordingly, a user need only reverse the operation threading locknut  306  on anchor nut  304  to separate locknut  306  from anchor nut  304 . Anchor nut  304  and locknut  306  may be repeatedly assembled and disassembled as needed. 
     The assembly of bolt  302  and anchor nut assembly  345  forms fastener  300  in  FIGS.  24 - 27   . Referring to  FIGS.  24 - 27    in relevant part, a user assembles anchor nut assembly  345  and bolt  302  by inserting bolt  302  distal end  314  first into and through unthreaded part  370 A of bore  370  through open outer end  352  until external thread  320  at distal end  314  encounters runout  374 . He threads internal thread  372  on external thread  320  and advances anchor nut assembly  345  in the direction of arrow D by rotating bolt  302  in the direction of arrow A until internal thread  372  is threaded completely on external thread  320  in  FIG.  27   . In  FIG.  27   , locknut  306  is between radial bearing surface  304 A and head  340 , inner side  306 A is tightened directly against radial bearing surface  304 A, and external thread  320  extends through unthreaded part  370 B of hole  370  from open outer end  352  to runout  374  and through threaded part  370 A of hole  370  from runout  374  to open inner end  350  and beyond open inner end  350  to distal end  314  without interference from locknut  306  threaded on external thread  360  of anchor nut  304 . External threads  320  and  360  twist in opposite right and left directions, as described. Accordingly, anchor nut  304  threaded on bolt  302  and locknut  306  threaded on anchor nut  306  are counter-rotated. Rotating anchor nut  304  equipped with its attached locknut  306  in the direction of arrow A opposite to the direction of arrow C withdraws anchor nut assembly  345  from external thread  320  of bolt  302  in the direction of arrow D. Accordingly, a user need only reverse the operation threading anchor nut  304  on bolt  302  to separate anchor nut assembly  345  from bolt  302 . Bolt  302  and anchor nut assembly  345  may be repeatedly assembled and disassembled as needed. 
     Fastener  300  is useful in forming bolted joint  410  in  FIG.  28   , including members  412  and  414  secured together by fastener  300 , the assembly of bolt  302 , anchor nut  304 , and locknut  306 . Members  412  and  414 , metal plates in this example, have registered through bores  416  and  418 , respectively. A user forms bolted joint  410  to secure members  412  and  414  together by inserting bolt  302  free of anchor nut assembly  345  distal end  314  first into and through bore  416  to bore  418  to seat head  340  in bore’s  416  counterbore  416 A on one side of the bolted joint  410  and extend external thread  320  outwardly from bore  418  to distal end  314  on the opposite side of bolted joint  410 . Head  340  and counterbore  416 A are correspondingly shaped. The user installs anchor nut assembly  345  on bolt  302  to assemble fastener  300  by inserting bolt  310  distal end  314  first into and through unthreaded part  370 A of bore  370  through open outer end  352  until external thread  320  at distal end  314  encounters runout  374 . He threads internal thread  372  on external thread  320  by rotating anchor nut  304  equipped with its installed locknut  306  in the direction of arrow C. This advances anchor nut assembly  345  in the direction of arrow B until internal thread  372  is threaded completely on external thread  320  between distal end  324  and member  414  and outer side  306 B of locknut  306  is tightened directly against member  414  initially clamping locknut  306  between radial bearing surface  304 A of anchor nut  304  and member  414 . Since the dimension of locknut  306  from inner side  306 A to outer side  306 B is greater than the dimension of anchor nut  304  from radial bearing surface  304 A to open outer end  352 , open outer end  352  is disabled from coming into direct contact against member  414 . Bolt length  334  extends through bores  416  and  418  from head  340  in counterbore  416 A to external thread  320 , extending outwardly from bore  418  to anchor nut assembly  345  and distal end  314  outboard of open inner end  350 . He alternately rotates anchor nut  304  and locknut  306  in the direction of arrow C. This alternately tightens inner side  306 A of locknut  306  against radial bearing surface  304 A and outer side  306 B of locknut  306  against member  414  until the desired tension is achieved, tightly clamping members  412  and  414  between head  340  anchored in counterbore  416 A on one side of bolted joint  410  and outer side  306 B of locknut  306  on the opposite side of bolted joint  410  and tightly clamping locknut  306  between radial bearing surface  304 A tightened directly against inner side  306 A of locknut  306  and member  414  tightened directly against outer side  306 B of locknut  306 . Locknut  306  tightened directly against radial bearing surface  304 A and member  414  serves its function as a locknut counter-rotated relative to external thread  320  of bolt  302  and internal thread  372  of anchor nut  304  aggressively disabling bolt  302  from loosening by rotating in the direction of arrow C. Since external threads  320  and  360  and internal threads  372  and  402  are identically sized and have the same pitches, the threaded attachments are strong and resistant to stripping. Fastener  300  securing bolted joint  410  is surprisingly strong and aggressive and resistant to axial failure, shear failure, and loosening in response to vibrational and prevailing torsional forces. The user need only reverse this operation to release bolted joint  410  and withdraw fastener  300 . The skilled artisan will readily appreciate that handedness of the threads described in conjunction with fastener  300  can be reversed in alternate embodiments. 
     The thickness  406  of locknut  306  from inner side  306 A to outer side  306 B in  FIG.  21    is greater than the thickness  366  of anchor nut  304  from radial bearing surface  304 A to open outer end  352  in  FIG.  21   . This disables open outer end  352  from coming into direct contact against member  414 . In an alternate embodiment, the thickness  406  of locknut  306  from inner side  306 A to outer side  306 B in  FIG.  21    can be the same or slightly less than the thickness  366  of anchor nut  304  from radial bearing surface  304 A to open outer end  352  in  FIG.  21    to enable open outer end  352  to come into direct contact against member  414 . In yet another embodiment, anchor nut  304  can be internally threaded by thread  372  from open inner end  350  to open outer end  352 . 
     IV. 
       FIG.  29    illustrates still another embodiment of a fastener  450  constructed and arranged according to the invention. Fastener  450  is useful in forming bolted joints and includes the previously-described bolt  302  appropriately marked as needed with its corresponding reference numerals for reference purposes, anchor nut  454 , and locknut  456  configured to be repeatedly and quickly assembled and disassembled. Anchor nut  454  and locknut  456  are configured to be repeatedly assembled in  FIG.  30    to form an anchor nut assembly  458  and disassembled in  FIG.  29    independently from bolt  452 . All diameters referenced throughout this specification related to fastener  450  are constant. 
     In  FIGS.  29  and  30   , anchor nut  454  is an annular block or body including open inner end  460 , open outer end  462 , head  464 , external thread  470 , and hole  480  configured with internal thread  482 . Hole  480  extends through anchor nut  454  from open inner end  460  to open outer end  462 . Head  464  has wrench flats  466 , six in this example, for nut-turn purposes, and extends from open inner end  460  to radial bearing surface  458  of head  464 . Radial bearing surface  458  faces external thread  470 . External thread  470  extends between radial bearing surface  458  and outer end  462 , twists in a left-hand direction opposite to external thread  320  of bolt  302 , and is exemplary of a standard left-handed external thread. 
     In  FIG.  30   , left-handed external thread  470  extends between radial bearing surface  458  and outer end  462  and includes minor diameter  473 , major diameter  474 , and pitch  475 , the distance between adjacent peaks or crests of the thread. Minor diameter  473  occurs at the roots of external thread  470 , and major diameter  474   occurs at the crests of external thread  470 . External threads  320  and  470  twist in opposite directions, as described. Accordingly, external threads  320  and  470  are counter-threads configured to threadedly receive counter-rotating internally-threaded elements. 
     Hole  480  extending through anchor nut  454  from open inner end  460  to open outer end  462  in  FIG.  21    is internally threaded by internal thread  482  from open inner end  460  to open outer end  462 . Internal thread  482  runs along the inside of anchor nut  454  from open inner end  460  to open outer end  462  and twists in the same right-hand direction as external thread  320  of bolt  302  opposite to the left-hand direction of external thread  470 . Internal thread  482  includes minor diameter  483 , major diameter  484 , and pitch  485 , the distance between adjacent peaks or crests of the thread. Minor diameter  483  occurs at the crests of internal thread  482 , and major diameter  484  occurs at the roots of internal thread  482 . Pitch  485  of internal thread  482  and pitch  325  of external thread  320  of bolt  302  in  FIG.  31    are identical. Minor and major diameters  483  and  484  of internal thread  482  correspond to the respective minor and major diameters  323  and  324  of external thread  320  in  FIG.  31   . Internal thread  482  and external thread  320  correspond and are the same size and have identical pitches. 
     Since pitch  485  of internal thread  482  and pitch  325  of external thread  320  are the same, minor and major diameters  483  and  484  of internal thread  482  correspond to the respective minor and major diameters  323  and  324  of external thread  320 , internal thread  482  twists in the same right-hand direction as external thread  320 , and internal and external threads  482  and  320  are correspondingly sized, internal thread  482  corresponds to and is configured to thread rotationally over and on external thread  320  from open outer end  462  in  FIGS.  30  and  31    and off external thread  320  from open outer end  462 . Accordingly, internal thread  482  corresponds to and is configured to thread over and on external thread  320 . 
     In  FIGS.  29  and  30   , locknut  456  and is an annular block configured with a threaded hole  491 , including internal thread  492 . Threaded hole  491  extends through locknut  456  from an inner side  456 A of locknut  306  to an outer side  456 B of locknut  306  in  FIG.  30   . Inner and outer sides  456 A and  456 B of locknut  456  are radial bearing surfaces. Locknut  456  has a thickness  486  from inner side  456 A to outer side  456 B. In  FIG.  30   , internal thread  492  runs along the inside of locknut  456  between the opposed inner and outer sides  456 A and  456 B and twists in the same left-hand direction as external thread  470  opposite to the right-hand hand direction of external thread  320  of bolt  302  and internal thread  482  of anchor nut  454 . Internal thread  492  includes minor diameter  493 , major diameter  494 , and pitch  495 , the distance between adjacent peaks or crests of the thread. Minor diameter  493  occurs at the crests of internal thread  492 , and major diameter  494  occurs at the roots of internal thread  492 . Pitches  475  and  495  are identical and somewhat smaller than pitches  485  and  325 . Minor and major diameters  493  and  494  of internal thread  492  correspond to the respective minor and major diameters  473  and  474  of external thread  470 . External thread  470  and internal thread  492  are the same size and have identical pitches. In  FIG.  29   , locknut  456  has parallel and circumferentially spaced-apart wrench grooves  498  for nut-turn purposes. 
     Since pitch  495  of internal thread  492  and pitch  475  of external thread  470  are the same, minor and major diameters  493  and  494  of internal thread  492  correspond to the respective minor and major diameters  473  and  474  of external thread  470 , internal thread  492  twists in the same left-hand direction as external thread  470 , and internal and external threads  492  and  470  are correspondingly sized, internal thread  492  corresponds to and is configured to thread rotationally over and on external thread  470  from open outer end  462  of anchor nut  454  in  FIGS.  30  and  31    and off external thread  470  from open outer end  462 . Accordingly, internal thread  492  corresponds to and is configured to thread over and on external thread  470  for assembling anchor nut  454  and locknut  456  to form anchor nut assembly  458  in  FIGS.  30  and  31   . Internal threads  482  and  492  twist in opposite directions, as described, internal thread  482  in the same direction as external thread  320  of bolt  302  and internal thread  492  in the same direction as external thread  470 . Accordingly, internal threads  482  and  492  are counter-threads configured to threadedly receive counter-rotating externally-threaded elements. 
     In  FIG.  30   , a user assembles anchor nut assembly  458  by threading internal thread  492  over and on external thread  470 . The user threads internal thread  492  over and on external thread  470  by applying open outer end  462  of anchor nut  454  into threaded hole  491  from inner side  456 A and rotating locknut  456  in the direction of arrow C. This advances locknut  456  in the direction of arrow D until inner side  456 A of locknut  456  and radial bearing surface  468  of head  466  are juxtaposed. Locknut  456  is suitably sized to extend entirely over external thread  470  from inner side  456 A of locknut  456  juxtaposed with radial bearing surface  468  to outer side  456 B of locknut  456  at open outer end  462  in the assembly of anchor nut  454  and locknut  456  in  FIG.  30   , when locknut  456  is threaded on anchor nut  454 . The dimension of locknut  456  from inner side  456 A to outer side  456 B, the thickness  486  of locknut  456  from inner side  456 A to outer side  456 B, is less than the dimension of anchor nut  454  from radial bearing surface  468  to open outer end  462 , the thickness  476  of anchor nut  454  from radial bearing surface  468  to open outer end  462 . Rotating locknut  456  in the direction of arrow A opposite to the direction of arrow C withdraws locknut  456  from radial bearing surface  468  and off anchor nut  454  in the direction of arrow B. Accordingly, a user need only reverse the operation threading locknut  456  on anchor nut  454  to separate locknut  456  from anchor nut  454 . Anchor nut  454  and locknut  456  may be repeatedly assembled and disassembled as needed. 
     The assembly of bolt  302  and anchor nut assembly  458  forms fastener  450  in  FIG.  31   . A user assembles anchor nut assembly  458  and bolt  302  by inserting bolt  302  distal end  314  first into open outer end  462  until external thread  320  at distal end  314  encounters internal thread  482  at open outer end  462 . He threads internal thread  482  on external thread  320  and advances anchor nut assembly  458  in the direction of arrow D by rotating bolt  302  in the direction of arrow A until internal thread  482  is threaded completely on external thread  320 . Locknut  456  is between radial bearing surface  468  and head  340 , inner side  456 A and radial bearing surface  468  are juxtaposed, outer side  456 B and open outer end  462  are juxtaposed, and external thread  320  extends through internally threaded hole  480  from open outer end  462  to open inner end  460  and beyond open inner end  460  to distal end  314  without interference from locknut  456  threaded on external thread  470  of anchor nut  454 . External threads  320  and  470  twist in opposite right and left directions, as described. Accordingly, anchor nut  454  threaded on bolt  302  and locknut  456  threaded on anchor nut  454  are counter-rotated. Rotating anchor nut  454  equipped with its attached locknut  456  in the direction of arrow A opposite to the direction of arrow C withdraws anchor nut assembly  458  from external thread  320  of bolt  302  in the direction of arrow D. Accordingly, a user need only reverse the operation threading anchor nut  454  on bolt  302  to separate anchor nut assembly  458  from bolt  302 . Bolt  302  and anchor nut assembly  458  may be repeatedly assembled and disassembled as needed. 
     Fastener  450  is useful in forming bolted joint  500  in  FIG.  31   , including members  502  and  504  secured together by fastener  450 , the assembly of bolt  302 , anchor nut  454 , and locknut  456 . Members  502  and  504 , metal plates in this example, have registered through bores  506  and  508 , respectively. A user forms bolted joint  500  to secure members  502  and  504  together by inserting bolt  310  distal end  314  first into and through bore  506  to bore  508  to seat head  340  in bore’s  506  counterbore  506 A on one side of the bolted joint  500  and extend external thread  320  outwardly from bore  508  to distal end  314  on the opposite side of bolted joint  500 . Head  340  and counterbore  506 A are correspondingly shaped. The user installs anchor nut assembly  458  on bolt  302  to assemble fastener  450  by inserting bolt  310  distal end  314  first into open outer end  462  so external thread  320  at distal end  314  encounters internal thread  482 . He threads internal thread  482  on external thread  320  by rotating anchor nut  454  equipped with its installed locknut  456  in the direction of arrow C. This advances anchor nut assembly  458  in the direction of arrow B until internal thread  482  is threaded completely on external thread  320  and outer side  456 B of locknut  456  and open outer end  456  are is concurrently tightened directly against member  504 . Since the dimension of locknut  456  from inner side  456 A to outer side  456 B is less than the dimension of anchor nut  454  from radial bearing surface  468  to open outer end  462 , open outer end  462  is enabled to come into direct contact against member  414 . Bolt length  334  extends through bores  506  and  508  from head  340  in counterbore  506 A to external thread  320 , extending outwardly from bore  508  to anchor nut assembly  458  and distal end  314 . He alternately rotates anchor nut  454  and locknut  456  in the direction of arrow C. This alternately tightens outer side  456 B of locknut  456  and open outer end  462  of anchor nut  454  against member  504  until the desired tension is achieved, clamping members  502  and  504  between head  340  anchored in counterbore  506 A on one side of bolted joint  500  and outer side  456 B of locknut  456  and open outer end  462  of anchor nut  454  concurrently tightened directly against member  504  on the opposite side of bolted joint  500 . With both outer side  456 B of locknut  456  and open outer end  462  of anchor nut  454  concurrently tightened directly against member  504 , locknut  456  serves its function as a locknut counter-rotated relative to external thread  320  of bolt  302  and internal thread  372  of anchor nut  454  aggressively disabling bolt  302  from loosening by rotating in the direction of arrow C. Fastener  450  securing bolted joint  500  is surprisingly strong and aggressive and resistant to axial failure, shear failure, and loosening in response to vibrational and prevailing torsional forces. The user need only reverse this operation to release bolted joint  500  and withdraw fastener  450 . The skilled artisan will readily appreciate that handedness of the threads described in conjunction with fastener  450  can be reversed in alternate embodiments. 
     The thickness  486  of locknut  456  from inner side  456 A to outer side  456 B is less than the thickness  476  of anchor nut  454  from radial bearing surface  468  to open outer end  462 . In an alternate embodiment, the thickness  486  of locknut  456  from inner side  456 A to outer side  456 B can be the same as the thickness  476  of anchor nut  454  from radial bearing surface  468  to open outer end  462 . 
     V. 
     The person having ordinary skill in the art will readily appreciate that disclosed are exemplary bolts, bolt and nut fasteners, and bolted joints formed therewith. The various embodiments are configured to be readily and quickly assembled and disassembled, efficient, and are structured and arranged as disclosed to be suitably resistant to loosening in response to vibrational, shear and prevailing torque forces, even when exposed to or submerged in oil or other lubricant. The various embodiments disclosed herein are manufactured of standard materials routinely used in the manufacture of bolts and nuts and may be appropriately sized to relate to specific applications. 
     The present invention is described above with reference to illustrative embodiments. Those skilled in the art will recognize that changes and modifications may be made in the described embodiments without departing from the nature and scope of the present invention. Various changes and modifications to the embodiments herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof.