Prevailing Torque vs. Breakaway Torque

In bolted joints that use lock nuts or other locking features, it helps to understand how prevailing torque vs breakaway torque relate to each other. Both describe resistance to rotation, but they are measured differently and tell you different things about how a fastener will perform in service.

What Is Prevailing Torque?

Prevailing torque is the torque required to turn a fastener with a built in locking feature before it is seated against the joint. It is usually measured while tightening or loosening a nut that has not yet clamped the joint. This torque comes from the locking element itself, such as a distorted thread or nylon insert, not from clamp load. For a concise definition, see our glossary entry on Prevailing Torque.

What Is Breakaway Torque?

Breakaway torque is the torque required to start a fastener moving from a fully seated or static condition. It is the peak torque needed to overcome static friction and any locking feature after the joint has been tightened. Learn more in our glossary entry on Breakaway Torque.

How Prevailing and Breakaway Torque Work Together

• Prevailing torque tells you how much resistance the locking feature itself provides as the nut turns on the threads.
• Breakaway torque reflects both the clamp load in the joint and any additional resistance from the locking feature once the fastener is fully tightened.
• Specifications for prevailing torque lock nuts often include both values so you can verify that the nut provides enough resistance to loosening without making installation or removal impractical.

When you select and install prevailing torque nuts and other locking hardware with Springs Fastener bolts, nuts, and washers, use the specified prevailing torque and breakaway torque values from your engineering or product data to ensure consistent joint performance.