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Machine Design

Reusable locknut

A novel locknut design lets a nutand-bolt assembly exert maximum holding power,

yet the assembly is infinitely adjustable without any loss of holding power and can be taken apart and put back together at least 50 times. In essence, an insert locks the bolt, while the nut secures the joint. The complete assembly is vibration and shakeproof, according to its maker, Security Locknut Inc., Chicago ( The locknut is comprised of an elliptical steel-spring insert permanently joined to the nut body. Installation requires no special tools, just a standard torque wrench or ratchet, and once installed, never need retightening. They are heat resistant to 750°F (395°C), available in sizes 0.375 to 4 in. in full and jam-nut styles with fine or coarse threads, and are compatible with Grade 5 and 8 bolts.

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