What are Prevailing-Torque Locknuts and How are They Used?

Prevailing torque locknuts on metal work bench.

Locknuts can be broadly categorized into three types: prevailing-torque, free-spinning, and structural. While these three types of locknuts all provide a cost-effective and vibration-resistant solution to fasten joints, each has significant differences.

This blog specifically covers prevailing-torque locknuts, detailing how they differ from other kinds of locknuts, how they work, and the applications in which they are ideal.

How do Prevailing-Torque Locknuts Work?

Unlike free-spinning locknuts, which are designed for easy installation and reusability, prevailing-torque locknuts provide exceptional locking strength by creating constant frictional resistance between the threads and the bolt. This frictional resistance results from metal threads deforming into bolt threads. For nylon-insert locknuts, a polymer piece deforms into the bolt threads instead.

An important note on prevailing-torque locknuts is that, due to the deformation, they are not typically designed to be loosened or reused.

Different Types of Prevailing-Torque Locknuts

There are many types of prevailing-torque locknuts, each designed for specific application demands. At Lok-MorĀ®, we offer our customers 12 kinds of American-made prevailing-torque locknuts. Our most popular ones include:

The N-LOCā„¢
The N-LOCā„¢ is our nylon-insert prevailing-torque locknut. The nylon insertwithin this locknut grips the bolt threads when tightened, preventing loosening over time.
The TRI-LOCĀ®
This triple locknut features three locking elements that deflect the locknutā€™sown threads to create a reliable, vibration-resistant locking mechanism
The DURA-FLEXā„¢
This locknut features a slotted collar at the top, creating six flex-locking elements designed to elastically deform during installation.
The DOME-LOCĀ®
The DOME-LOCĀ® is our dome-style locknut, named for its oval locking feature. This oval shape makes it ideal for automated assembly processes.

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Applications for Prevailing-Torque Locknuts

The frictional resistance created when installing prevailing-torque locknuts makes them ideal for applications involving continuous vibration, shock, and extreme temperatures. Prevailing-torque locknuts are commonly used in manufacturing industries, including:

Automotive ā€“ Prevailing-torque locknuts can withstand the constant vibration experienced by vehiclesā€™ suspension systems, wheel assemblies, and exhaust joints without loosening.

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Machinery and Equipment ā€“ The locking strength of prevailing-torque locknuts makes them ideal for heavy machinery often subjected to extreme vibration.

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Construction ā€“ Structures exposed to the environment, such as bridges and utility towers, require locknuts that can withstand wind, rain, and other stressors indefinitely.

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A Brief Summary

While all locknuts offer vibration-resistance, prevailing-torque locknuts continue to be popular in manufacturing industries due to their exceptional locking strength, which stems from the locknut deforming around the bolt threads.

There are many types of prevailing-torque locknuts to better match application requirements. Interested in which prevailing-torque locknut is best for your application? Browse our complete line of prevailing-torque locknuts, contact a Lok-MorĀ® expert today, or email us at [email protected].

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