• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • Advertise
  • Subscribe

Linear Motion Tips

Covering Linear Motion Systems, Components and Linear Motion Resources

  • News
    • Editor’s blog
    • Industry news
    • Motion Casebook
  • Applications
  • Slides + guides
    • Ball + roller guides
    • Track roller (cam + wheel) guides
    • Crossed-roller slides
    • Linear bearings
    • Plastic + composite guides
  • Drives
    • Ball + lead + roller screws
    • Belt + chain drives for linear
    • Rack + pinion sets
  • Actuators
    • Ball + leadscrew driven
    • Belt + chain driven
    • Linear motors
    • Mini + piezo + voice coil
    • Rack + pinion driven
    • Rigid-chain actuators
  • Encoders + sensors (linear) + I/O
  • Stages + gantries
  • Resources
    • Suppliers
    • Video

What is a follower nut, and what role does it play in lead screw operation?

★ By Danielle Collins Leave a Comment

Although the idea of a “follower nut” may seem to indicate that the nut serves a passive role in lead screw operation, it actually plays an important part in monitoring the condition and life of the screw assembly.


The wear characteristics of a lead screw nut make the expected service life of the assembly difficult – if not impossible – to predict. Because lead screws rely on sliding motion between the screw and the nut, there is no standard way to calculate (even theoretically) the life of a lead screw.

The L10 bearing life equation doesn’t work, because there are no balls or rollers carrying the load. And while the PV equation helps determine the maximum load-speed combination a lead screw nut can withstand, it is only valid for plastic nuts, and it still doesn’t provide an estimate of the life (number of revolutions, strokes, or time) the screw assembly will provide.

But there is a way to monitor the condition of a lead screw nut to determine when significant wear has occurred — enabling operators to perform proactive maintenance and avoid lead screw failure. This method involves using a follower nut.


Follower nuts (also referred to as “wear indicator nuts”) are also common in screw jack assemblies — especially in lift platform applications, where failure could be catastrophic to the product, equipment, or personnel.


As a lead screw nut wears, its threads degrade and become thinner. Manufacturers consider the life of the nut to be the point when the threads have lost ½ of the tooth thickness (¼ of the screw pitch). At this point, the nut will no longer have the material strength to support is full load rating.

follower nut
As a lead screw nut wears, backlash between the screw and nut increases.
Image credit: Nook Industries

Another consequence of decreasing tooth thickness is that the displacement, or backlash, between the screw and nut increases. A follower nut, or wear indicator nut, makes it easy to monitor this increase in backlash and determine the level of wear on the nut.

follower nut
As the main (primary) nut wears, the distance between it and the follower nut decreases. It’s important to note that the wear indicator nut is only reliable in vertical applications. 
Image credit: Nook Industries

The follower nut and main nut are typically both made of bronze, although the follower nut can be made of steel. The follower nut is pinned to the main nut, so it “follows along,” but it does not support the load.

As the main nut wears and its thread becomes thinner, it begins to “close the gap” between it and the follower nut. By measuring this gap — either with feeler gauges or with a proximity sensor — an operator can determine how much wear has occurred. When the gap indicates that ½ (or more) of the tooth thickness is gone, the main nut can be replaced to avoid failure.

Alternatively, if the follower nut is made of steel, when the main nut begins to fail, the follower nut takes up some of the load, resulting in steel-to-steel sliding between it and the screw, which causes noise that serves as an audible indicator of wear.

You Might Also Like

Filed Under: Ball + lead + roller screws, Ball + leadscrew driven, FAQs + basics, Featured

Reader Interactions

Leave a Reply

You must be logged in to post a comment.

Primary Sidebar

LEARNING CENTER

Design World Learning Center
“lmt
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for Design Engineering Professionals.
“linear

RSS Motion Control Tips

  • PI unveils motion solutions at LASER World of PHOTONICS
  • Rollon marks 50 years with new facility opening in Michigan
  • Controller/drive features FOC and sensorless control
  • Allient expands its Allied Motion SA Axial Flux Motor series
  • PICMA Plus piezo actuators offer extended displacement range

RSS Featured White Papers

  • Robotic Automation is Indispensable for the Logistics Industry’s Continued Growth and Success
  • Reliable Linear Motion For Packaging Machines
  • Technical Brief – “Understanding the Extensive Benefits of Total Linear Positioning Systems.”

Footer

Linear Motion Tips

Design World Network

Design World Online
The Robot Report
Coupling Tips
Motion Control Tips
Bearing Tips
Fastener Engineering
Wire and Cable Tips

Linear Motion Tips

Subscribe to our newsletter
Advertise with us
Contact us
About us

Copyright © 2025 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy