Right Handed + Left and Right Handed Threading Bolt and Left Handed Threading Security Nut

Votes: 1
Views: 177

An improvement upon the established fastener technology of the threaded bolt and nut for increased resistance to accidental or undesired unthreading in high-vibration applications or applications where torque may be experienced by either the bolt or nut, imparted unto them by the components they are meant to keep fastened together or the medium or environment they are in contact with or exposed to, where regular bolts and nuts would run a non-negligible or unacceptable risk of accidentally loosening or coming apart altogether.

An otherwise regular bolt has the outer portion of its threading made ambidextrous, enabling both left handed and right handed threading nuts to be screwed on to the bolt for the length of the span of the outer section of bidirectional threading.

However, only the regular, right handed threading primary nut can also continue on to the inner portion of regular, right handed threading on the bolt and screw all the way up to the head of the bolt, in the absence of any components which the bolt and nut would need to fasten together when in actual use.

The primary nut is followed on to the bolt by a secondary, security nut, which has left-handed threading and screws on counter-clockwise, but only for the length of the outer span of ambidextrous threading on the bolt, being unable to likewise continue on to the section of right-handed threading the way the primary nut can.

Because the primary and secondary nut respectively tighten and loosen by spinning in opposite directions, the secondary nut works to prevent the primary from loosening or loosening any further once the two are in contact. Since, once the two nuts are in contact, for the primary nut to loosen would require that the security nut spin in the same direction of spin, which would actually work to tighten the security nut further.

Although not shown in all of the included images, the proposed solution can be improved upon further still, in two additional ways.

First, the primary and secondary nuts can have straight, transversal holes drilled through them, offset radially/laterally so as to avoid their threading, enabling wire to be passed through and tied in a loop keeping the two nuts together and preventing the security nut from accidentally unwinding and loosening away from the primary nut.

The second improvement which can be made is to make the security nut taller (larger along the length of the bolt) and bore out the top section of its left handed threading to where the now smooth cylindrical walls of the larger diameter smooth bore section in front of its remaining section of left handed threading can ride above the crests of the bolt's inner, right handed threading without interference. Which, in turn, enables the security nut to reach some distance above the end of the bolt's section of outer, ambidextrous threading and into the inner section of regular, right handed threading so as to make contact with the primary nut above where it normally could.


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  • Name:
    Laurentiu Victor Visan
  • Type of entry:
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  • Laurentiu Victor is inspired by:
    Wanting to do what is in my power to try and make the world a better place by contributing to technological development and improvement in whichever area and by whichever amount I am capable of.
  • Software used for this entry:
    Autodesk 123D Design, MOI 3D, Light Tracer for Desktop
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