Industrial MRO Reference Library · Technical Reference

Cylindrical & Spherical Roller Bearings

Cylindrical roller bearings carry heavy radial loads with low friction, and spherical roller bearings carry heavy loads while tolerating shaft misalignment. This sheet explains the common cylindrical rib styles, spherical series and suffixes, and how to tell them apart.

Ref MRO-0006ISO 15

Draft, open for review. Check every value against the governing standard and the manufacturer’s data before use.

What it is

A cylindrical roller bearing uses straight rollers in line contact with the rings. It carries high radial load and allows high speed, but most styles take little or no axial load. The style letters show which rings have ribs (flanges) that guide the rollers. A spherical roller bearing has two rows of barrel-shaped rollers running in a spherical outer ring raceway. The inner ring and rollers can tilt relative to the outer ring, so the bearing tolerates misalignment and shaft deflection. Spherical roller bearings are used on conveyors, fans, crushers, vibrating screens and paper machines.

How to identify

Read the number on the ring face. Cylindrical bearings start with N-type letters, such as NU 210 or NJ 2310. Spherical roller bearings carry a five-digit number beginning with 2, such as 22216 or 23120, followed by suffixes. Physically, a spherical bearing has two rows of rollers and its inner ring swivels inside the outer ring. A cylindrical bearing has one or more rows of straight rollers. See the bearing numbers decoded sheet and the bore code chart for the basic number.

Cylindrical roller rib styles

Style	Outer ring ribs	Inner ring ribs	Axial location
NU	Two	None	None; floats both ways
N	None	Two	None; floats both ways
NJ	Two	One	One direction
NF	One	Two	One direction
NUP	Two	One plus loose rib	Both directions

Common spherical roller suffixes

Suffix	Meaning
K	Tapered bore, 1:12 taper
K30	Tapered bore, 1:30 taper (wide series)
W33	Lubrication groove and holes in the outer ring
C3, C4	Internal clearance greater than normal

Key points

NU and N styles are the usual choice for the floating bearing on a shaft, because they allow thermal growth.
Separable designs let the rings be mounted separately. Confirm both parts are present on a return.
Tapered bore spherical bearings mount on adapter or withdrawal sleeves. The sleeve has its own part number.
Cage and internal design suffixes differ by maker. Cross-reference them in the maker's interchange, not by guess.
Allowable misalignment and load ratings come from the maker's catalog.

Common mistakes

Replacing an NJ with an NU and losing axial location.
Ordering a spherical bearing without the K suffix for a tapered sleeve mount.
Ignoring the clearance suffix, especially C3 on motors and fans.
Dropping the W33 suffix on a bearing that is greased through the housing.

Governing standards: ISO 15 (radial bearing boundary dimensions); manufacturer catalogs for designs, suffixes and ratings.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.

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