'Tab and Slot' Self-Locking Ring: What is it, How Does it Work, and When Should You Use One?

What is a ‘Tab and Slot’ Self-Locking Ring?

Spirolox®, a division of Smalley, invented the ‘Tab and Slot’ Self-Locking Ring back in 1958. The innovative design has been proven in thousands of high-speed applications.

So, what is it?

Let’s first define what a self-locking ring is. A self-locking ring is a custom retaining ring feature that increases a ring’s rotational capacity. They are typically specified for high RPM applications such as electric motors.

A ‘Tab and Slot’ Self-Locking Ring is one type of self-locking ring. The self-locking tabs can be designed on the outside edge diameter (for external retaining rings) or on the centerline of the ring. The placement of the self-locking feature depends on the application.

Fig 1. ‘Tab and Slot’ Self-Locking Ring in the outer and centerline diameter ‘tab and slot’ configurations.

How Does the Self-Locking Feature On a ‘Tab and Slot’ Self-Locking Ring Work?

The self-locking feature consists of a ‘tab and slot’ design that interlocks to prevent the ring from expanding due to centrifugal forces. The tab lines up with a slot on the mating turn such that when the ring is installed into the groove, the tab locates inside the slot securing the ring from expansion.

What Are the Advantages of Using a ‘Tab and Slot’ Self-Locking Ring for High Rotational Capacity Applications?

The unique ‘tab and slot’ design allows the ring to function properly at speeds far exceeding the rotational capacity of a standard retaining ring.

Advantages of a ‘Tab and Slot’ Self-Locking Ring:

• Can withstand vibration, function under rapid acceleration, and absorb a degree of impact loading
• Secure retention
• Highest RPM capabilities of self-locking ring options

You may want to consider other options if:

• High volume automated installation capabilities are important to you

No semi or fully-automated installation is currently available for ‘Tab and Slot’ Self-Locking Rings.

A different self-locking ring called the Revolox^® Self-Locking Ring is designed with automated installation capabilities.

• Ease of installation is important to you

Improper installation may cause result in tab misalignment and damage. This may result in premature ring failure.

Additionally, rings with heavier cross-sections are generally more difficult to install. Heavier cross-sections require more material and are therefore more costly. ‘Dome and Slot’ Self-Locking Rings may have a thinner cross-section.

Read more about Revolox^® ‘Dome and Slot’ Self-Locking Rings. Always consult with a Smalley Engineer to determine the right Self-Locking Ring style for your unique application.

Key Points

• A Self-Locking Retaining Ring is a custom retaining ring feature that increases a ring’s rotational capacity
• The ‘Tab and Slot’ Self-Locking Ring consists of a ‘tab and slot’ design that interlocks to prevent ring expansion
• ‘Tab and Slot’ Self-Locking Rings have the highest RPM capabilities but do not offer high volume automated installation capabilities.
• Consulting with a Smalley Engineer will help you determine if a self-locking ring is appropriate for your unique application.

Download the High RPM Retaining Ring Solutions Technical Guide

Download the E-Book today.

Next Steps?

Here are some additional resources beyond our E-Book that you might find helpful:

• Get started on high RPM design! Submit your Application Requirements. 
• Try out a sample – get free prototypes.
• Looking for more than just a high RPM ring? Explore our 2021 Ring and Spring Catalog and Design Guide. We have over 10,000 rings and springs in stock!
• Have a question? Contact a Smalley Engineer.