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Security Locknut – Product Vibration Performance Evaluation

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article image The fixture used in the vibration test

Security Locknut recently commissioned an independent test lab to perform a test comparing the vibration resistance of security locknut to several other locknut products.

The tests were performed in accordance with MIL-STD-1312-A. The bolt/nut combination is installed in the fixture, the fixture subjected to a controlled vibration and times/cycles recorded when the assembly fails.

The test procedure was done with a 3/4-10 Grade 5 bolt and nut assembly installed to the maximum recommended torque of 280 ft-lbs. After running the vibration test for 90,000 cycles the Security Locknut assembly did not loosen. The test was run several more times with reduced installation torque on each subsequent test. When the torque was reduced to 50% of the maximum value (140 ft-lbs) the assemblies began to fail within the test time frame.


  • To ensure a bolted joint stays tight under vibration conditions it is important that the assembly (mating parts, bolt, and nut) is optimally designed and the proper torque is achieved during installation.
  • In real world applications these optimal conditions are difficult to achieve during initial installation and often impossible to maintain as the assembly is stressed. This conclusion is based on numerous field observations.
  • A prevailing torque locknut helps prevent an assembly from loosening.
  • The Security Locknut performs as well as the best prevailing torque locknuts at preventing joint loosening.
  • The Security Locknut outperforms all other locknuts by staying securely connected to the bolt after the initial tension is lost. This has proved to be a significant benefit on installations where complete separation of the nut and bolt would cause machinery downtime or a potential safety issue.
Security Locknut is distributed in Australia by Vibration Solutions .

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