SKFNJ2218Single Row Cylindrical Roller Bearing, 90 x 160 x 40 mm, NJ Design — One Flanged Inner Ring, One-Direction Axial Location

Product Description

What this part is

An SKF single row cylindrical roller bearing, 90 mm bore, 160 mm outside diameter, 40 mm wide. Cylindrical rollers contact the raceway along a line rather than at a point, which is why this bearing type carries far more radial load than a ball bearing of the same envelope. It is the workhorse of gearboxes, electric motors, rolling mills and any shaft where radial load is the dominant problem.

Decoding the designation — NJ is not NU

The two letters in front of the number describe the flange arrangement, and that determines what the bearing does axially. It is the most important thing on this page.

NJ — two flanges on the outer ring and one integral flange on the inner ring. The rollers are trapped against that single inner flange, so the bearing can take a modest thrust load in one direction and locate the shaft that way.NU — two flanges on the outer ring, no flange on the inner ring. The inner ring and shaft can float axially through the bearing. This is the free-end bearing.NUP — an NJ plus a loose retaining ring on the other side of the inner ring, giving two-direction axial location.
A typical shaft uses one located bearing and one free bearing, so that thermal growth has somewhere to go. Fit an NJ where the drawing calls for an NU and you have created a second located position — the shaft can no longer expand, and the axial load it generates as it heats has nowhere to go but into the roller ends and the flanges. That failure looks like heavy wear on the roller ends and the inner flange face, and it is entirely a design-substitution error, not a bearing defect.

NJ2218 or NJ218 — check the width before you order:
These two designations are one character apart and they are not the same bearing. Both are 90 mm bore and 160 mm outside diameter. NJ2218 is 40 mm wide. NJ218 is 30 mm wide. The 22-series prefix denotes the wider dimension series with a correspondingly higher load rating. Ordering by number alone, without checking width, is a genuinely common mistake here, and the published load ratings for the two differ substantially — so a specification worked out for one will be wrong for the other. This listing is the 40 mm wide NJ2218.

Published ratings for this envelope

On provenance: SKF’s own product page for the NJ 2218 variants was not directly retrievable, and several distributor mirrors conflate NJ2218 with the narrower NJ218. The figures below are trade-published values for the 90 × 160 × 40 mm NJ2218 envelope and are given as an envelope-level guide rather than as SKF’s certified data for a specific cage suffix.

Bore (d): 90 mmOutside diameter (D): 160 mmWidth (B): 40 mmDynamic radial load rating C: approx. 280 kNStatic radial load rating C0: approx. 314 kNLimiting speed, grease: approx. 4,400 rpmLimiting speed, oil: approx. 7,500 rpmNumber of rows: 1Rolling elements: cylindrical rollersAxial location: one direction (NJ design)

Cage suffixes and what they buy you

The NJ 2218 is catalogued by SKF in several cage variants and the suffix matters if you are running near the speed limit or in a high-temperature installation:

ECP — glass-fibre reinforced polyamide 6,6 cage. Light, quiet, low friction, but polyamide has a service-temperature ceiling and is degraded by some synthetic oils and by oil oxidation products.ECM / ECML — machined brass cage. Heavier and dearer, but tolerant of high temperature, oil-mist and jet lubrication, shock load and aggressive lubricants. ML denotes the brass cage centred on the inner ring.EC — SKF’s optimised internal design, giving a higher load rating and better roller-end/flange lubrication than the older non-EC build.
The plain NJ2218 designation on this record does not carry a cage suffix. If your application is hot, oil-jet lubricated, or shock-loaded, a brass cage is what you want and it is worth confirming which cage this unit has before ordering — ask and we will look.

Quantity, configuration and fitting notes

One bearing in stock. This is a complete, one-piece bearing — both rings, rollers and cage. Cylindrical roller bearings are separable in the sense that the inner ring can usually be drawn out of the outer ring and roller set, which is a mounting convenience on a blind installation: press the inner ring onto the shaft and the outer ring into the housing separately, then bring them together. Do that carefully — a roller set forced onto an inner ring at an angle will scuff the raceway before the machine ever turns. Heat mounting the inner ring is the preferred method at this size. Press only on ring faces, never through the rollers.

Interchange guidance

Search forms include NJ2218, NJ-2218, NJ 2218, NJ2218E, NJ 2218 ECP, NJ 2218 ECM, NJ 2218 ECML, NJ2218ECJ. Same-envelope alternatives at 90 × 160 × 40 mm: FAG NJ2218-E-XL-TVP2 and NJ2218-E-M1; NSK, NTN and Koyo NJ2218; and NU2218 or NUP2218 if a different axial arrangement is what your shaft actually needs — NU2218 E and its variants share the same boundary dimensions. Do not substitute the 30 mm wide NJ218 family.