What is the primary function of a locknut in fastening applications?

The primary function of a locknut in fastening applications is to prevent loosening. Locknuts are designed to maintain a secure connection by resisting vibration and movement, which can cause standard nuts to loosen over time. This inherent resistance to loosening is typically achieved through various design features, such as a nylon insert in a nylon locknut or specific geometries that create friction between the nut and the bolt. By serving this crucial role, locknuts enhance the reliability and safety of mechanical assemblies, helping to ensure that components remain securely fastened in place during operation.

In comparison, other options do not serve the primary purpose of a locknut. While enhancing decorative appearance might be relevant for some fasteners, it is not a function of locknuts. Increasing weight does not contribute to the effectiveness of a fastening system. Lastly, acting as a primary fastener suggests a role that locknuts do not serve, as they are not typically the main load-bearing fastener; instead, they complement another fastener by providing additional security against loosening.