- What exactly is a retaining ring?
Definition: A fastener that holds components/assemblies onto a shaft or in a
housing/bore when installed in a groove.
- Why should I use a retaining ring instead of a screw,
nut and threads, cotter pin and washer and other traditional fasteners?
Retaining rings can do the same job for a lot less. A simple groove is all that’s
needed to accommodate a retaining ring. Other fastener methods, like nuts, require
machining threads, which is a lot more costly. They also require at least two components
to function (Ex. Cotter pin and washer, nut and washer), which adds to the costs.
- I don’ think retaining rings are strong
enough for my application. Aren’t they for light loads only?
This is one of the most common myths about retaining rings. Retaining rings are used on
everything from ABS brakes to mechanisms to adjust the tank tread on an M1 tank.
You’d be amazed at the holding power some types of rings exhibit.
- How do you install retaining rings?
That depends on the application, but you can be sure there is a tool for every retaining
ring we sell. No need to use fingers, hammers, screwdrivers or other tools that may damage
the ring and cause it to fail. We support our retaining rings with a complete line of
manual and pneumatic tools. We’ll even help you design your own equipment for high
- Should I design my own custom retaining ring instead
of relying on a standard one?
Selecting a standard retaining ring will always be more cost effective than designing a
custom retaining ring. It will also save on engineering time, eliminate production
problems and ensure timely delivery of product. A Rotor Clip technical sales
engineer can help you find a suitable standard replacement for a custom retaining ring.
- When would you use an inverted retaining ring
(HOI or SHI)?
Let’s say you have another assembly that must pass through the housing of your
application. Check the Clearance Diameters "L1" and "L2" dimensions.
This will tell you if the lugs of the ring will interfere with this assembly. If this is
the case, you can switch the ring to an HOI (HOusing Inverted) (or SHI SHaft Inverted for
a shaft application). This ring features inverted lugs for better clearance.
- When do you use an axial (installed
horizontally) versus a radial (installed vertically along the radius of a circle)
If your application can accept either an axial or a radial retaining ring, shoulder size,
thrust load and RPM may determine which type you use. Be sure to check these
specifications carefully before making your selection. (Keep in mind that radial rings
offer enlarged shoulder for part retention and generally cost less than standard axial
- I am using an E ring, but it is not strong
enough for my application. Do I have to scrap the shafts I have and start over?
If you select an E ring and later discover that it can not withstand the RPM generated by
your application, you can change it to a standard, heavy duty RE ring. RE rings fit into
the same grooves as E rings and can be easily interchanged without re-designing the
application. They can accommodate higher thrust loads.
- Why are there so many different E ring
designations in your catalog?
The "E" ring specification pages in the Rotor Clip catalog list many variations.
For example, E-18, SE-18, YE-18 and ZE-18 are not "specials" but simply
different parts that can be used on the same shaft size. They will function in
applications having either different groove diameters/groove depths for the same size
shaft (3/16"). They also offer optional geometry for a specific shaft size. Often,
the O.D., ring thickness and groove dimensions vary for SE, YE and ZE part numbers.
- What is the difference between a PO and a POL ring?
This ring series offers a similar advantage as the E and RE. The PO is complemented by a
"light" series known as POL that is thinner than the standard PO rings.
- When would I use an SHR over an SH retaining
An SHR is a heavy-duty version of an SH ring with increased thickness and minimum/maximum
sections that will give you increased thrust load and RPM limits. Keep in mind that an SHR
requires a wider groove than an SH before you make the switch.
- Why are some of your ring designations repeated
in your catalog?
Some retaining rings are listed twice in the catalog (Ex. HO-156). This means that the
same ring will function in two separate applications that have different housing/shaft and
- What are some common measurements for retaining
rings that I should be aware of?
Free Diameter, Axial Rings—This dimension can only be measured accurately on rings
that have never been installed. Measuring free diameter on an HO ring where the lugs have
been compressed (or on an SH ring where they have been expanded) will yield a false
Free Diameter, E Rings---Do not take this measurement on an E ring using a caliper. The
correct way is to use a pin gauge that makes three-point contact with the ring’s
Free Diameter, Inverted Rings—The standard way of measuring free diameter for an
axial ring does not hold true for an HOI and SHI retaining ring. For the correct method,
see the HOI and SHI specification pages in the Rotor Clip catalog.
Hardness—To check hardness effectively, you must first remove any finishes from both
sides of the ring. Using a properly calibrated hardness tester, take a reading on the ring
with the burr side up. Compare results to those listed in the hardness tables of the
catalog specification page for that ring.
- What are typical installation
considerations for retaining rings?
An external axial ring (SH, SHI, etc.) can be over expanded during installation. To
prevent this, take a pin gauge 1% larger than the nominal shaft diameter of your
application. Using a Rotor Clip retaining ring plier and safety goggles, expand the ring
and release it on the gauge. With the tips still in the lugs, adjust the stop on the plier
to this opened condition.