Lock Nuts

Castle Nuts

Castle nuts, or castellated nuts, are positive-locking fasteners featuring a cylindrical crown with radial slots designed to align with a pre-drilled transverse hole in the mating bolt or shaft. Once torqued, a cotter pin or safety wire is inserted through the slots and the bolt hole, creating an absolute mechanical lock that cannot loosen under extreme vibration. Because they prioritize rotational security over precise preload tension, castle nuts are critical for safety-dependent applications including automotive steering linkages, aerospace assemblies, and heavy agricultural machinery axles.