NSK21318CDE4Double Row Spherical Roller Bearing 90x190x43 mm, Straight Bore, Lubrication Groove and Three Holes, 200 °C Stabilised

Product Description

What this part is

A double-row spherical roller bearing in the 90 mm bore × 190 mm outside diameter × 43 mm width envelope, the ISO 21318 size. Straight cylindrical bore, pressed steel cage, with a lubrication groove and three radial holes in the outer ring.

Decoding the designation

The 213 prefix marks a double-row spherical roller bearing in the narrower dimension series, and the bore code 18 gives a 90 mm bore, since ISO bore codes above 04 are multiplied by five. CD is the NSK pressed steel cage with a floating guide ring. E4 is NSK’s own code for the feature other makers call W33: a lubrication groove machined around the outer ring with three radial holes through it. The alternate designation on this carton reads 21318-CD-E4/W33, carrying both codes at once. S11 marks the rings and rollers as dimensionally stabilised for service to 200 °C. There is no K suffix, so the bore is straight.

Bore form and mounting

Straight bore. This bearing mounts directly on a cylindrical shaft seat. A tapered-bore version, designated 21318K, mounts on a 1:12 taper by way of an H2318 adapter sleeve, which is a separate part. No adapter sleeve, locknut or lockwasher applies to this straight-bore version.

What these specs mean in practice

The two rows of barrel-shaped rollers run in a common spherical outer raceway, so the inner ring and roller set swivel bodily within the outer ring. That is what allows the bearing to absorb static and dynamic angular misalignment between shaft and housing without losing capacity, and it is why the type is standard for long shafts and for housings that cannot be held perfectly in line. Both rows are loaded, so the bearing carries very heavy radial load and takes thrust in both directions.

The 213 series is the narrower and lower-section of the two common spherical roller series. It trades some capacity for a shorter axial length and a smaller cross-section at the same bore, which is what suits it where housing width is constrained. The lubrication groove and three holes let grease or oil enter at the centre of the outer ring and feed both roller rows directly, making relubrication through the housing effective. The 200 °C stabilisation means the rings hold their dimensions at temperatures where untreated bearing steel would grow and lose clearance.

Quantity and configuration

1 Pc. One complete bearing, inner ring, outer ring, both roller rows and cage. Supplied without a housing, adapter sleeve, locknut or seals.

Fitting notes

The bearing goes onto a clean cylindrical seat against a square shoulder, mounted by even pressure or by controlled heating rather than by blows on the rings. Where the housing is drilled for relubrication, the outer ring is oriented so the groove and holes align with the housing feed. The self-aligning action accommodates misalignment between seatings, so the outer ring is not required to be perfectly square to the shaft.

Interchange guidance

The same-spec equivalents are SKF 21318EK-less straight-bore form 21318E, FAG 21318E1-K-less 21318E1 and Timken 21318EJW33, all straight bore with the outer ring groove and holes. The tapered-bore 21318K is a related size rather than a substitution. A 22318 shares the 90 mm bore and 190 mm outside diameter but is a wider, heavier-section bearing from the 223 series and is a different part.