Cylindrical Bearing Nomenclature: As Easy as A-B-C and 1-2-3

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cylindrical, roller, bearing, nomenclature

Customers often ask about our product nomenclature for cylindrical roller bearings: the numbers and letters that determine a product description. Here’s the “inside story.” For your specific application questions, schedule time with an application specialist.

Cylindrical Roller Bearing Nomenclature Example

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Let’s use the following product number as an example: M-A-5-2-06-E-X. In this case, “M” is the series designation, for cylindrical roller bearings, it’s always an M, which stands for “metric.”

Inner Ring Style

The second field is the inner ring style, and it has three variations:
A = plain (no ribs, separable in two directions)
R = single ring (one rib, separable in one direction)
U = double ring (two ribs, non-separable)

cylindrical, roller, bearing, nomenclature, inner ring style

Our example indicates a plain inner ring style.

Width Series

Now let’s look at the third field, which is the width series. Again, there are three variations:
1 = narrow
5 = wide
7 = Intermediate

 cylindrical, roller, bearing, nomenclature, width series

Our example reflects a wide width series bearing.
The fourth field is the diameter series. In our example, it’s “2,” which means light series. Other designations include:
0 = extra light
2 = light (as in our example)
3 = medium
9 = extra, extra light

Shaft Size

Next, we’ll determine shaft size, indicated as 1/5 of the bore size in millimeters. In our example, “06” represents a bore size of 30mm (6 x 5 = 30mm).

Now, let’s determine the outer ring, which we classify as follows:
C = plain cylindrical, no ribs, separable in two directions
D = one rib, separable in one direction
E = two ribs, non-separable
T= no ribs, 2 snap ring grooves, non-separable
U = one rib, 1 snap ring groove, non-separable

cylindrical, roller, bearing, nomenclature, shaft size

Retainer Style

The final specification is retainer style. Here are the variations:
X = segmented steel, high-speed, high-load, best lubrication
M = full complement, highest load, lower speed
B = polymeric, quiet
V= formed steel, good value (works for 90% of applications)
cylindrical, roller, bearing, nomenclature, retainer style

To recap, our example bearing is metric, with a plain cylindrical-no-ribs-separable in two directions inner ring, wide width series, light diameter series, 30mm bore, a double-ribbed non-separable outer ring and a segmented steel retainer.

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Mark Czubak

Mark Czubak is a Principal Engineer with the Rexnord Bearing business. He has spent nearly 40 years with Rexnord where he has managed all facets of engineering, including application, design and manufacturing, giving him a cradle to grave knowledge of mounted roller bearings. With this experience, Mark shares his passion and knowledge through bearing training, application assistance and installation. “Bearings are overlooked for the more expensive components of the system, but a bearing failure can cause just as much downtime as any other component so choose your bearings wisely, and save time and money.”