SKF21309ADouble-Row Spherical Roller Bearing, 45 x 100 x 25 mm, Straight Bore, Normal Clearance

Product Description

What this part is

An SKF 21309 A double-row spherical roller bearing. Bore 45 mm, outside diameter 100 mm, width 25 mm, straight cylindrical bore, open on both faces. Two rows of barrel-shaped rollers run on a common spherical raceway in the outer ring, so the inner ring and roller set swivel bodily inside the outer ring and the bearing carries load through shaft deflection and housing misalignment.

Decoding the designation

The 213 dimension series is the narrower of the spherical roller series, sitting on a larger outside diameter than the 222 series for a given bore — here 100 mm on a 45 mm bore against the 85 mm of a 22209. The bore code 09 gives 45 mm. There is no K, so the bore is straight, and no clearance suffix, so radial internal clearance is normal, CN. The trailing A is an SKF internal design-variant letter that is not part of the current published suffix scheme, and it is carried here as a searchable reference rather than as a specification.

What these specs mean in practice

The 213 series buys a smaller axial envelope than a 222 of the same bore, at a lower radial load rating, which is the trade that suits a shaft where housing width is limited rather than where load is the constraint. Like all double-row spherical rollers it takes thrust in both directions and tolerates misalignment as a normal service condition. Normal CN clearance is the general-purpose setting, leaving enough running room for an interference fit on the shaft and a moderate temperature difference across the rings.

Quantity and configuration

1 Pc. Straight bore, mounting directly onto a cylindrical shaft seat. Open both faces, with sealing handled by the housing. No adapter sleeve, no locknut, no stabilising ring.

Fitting notes

The inner ring is an interference fit on the shaft and is mounted by even heating rather than by pressing across the rollers. Residual radial internal clearance is measured with a feeler at the unloaded roller row after mounting, since the interference fit consumes part of the original allowance.

Interchange guidance

The 21309 base number is common across the spherical roller programmes of FAG, NSK, NTN and Koyo at 45 x 100 x 25 mm, and a straight-bore CN example of any of those is a genuine substitution. The SKF 21309 AK and 21309 K are the 1:12 tapered-bore versions of this size and mount on an adapter sleeve rather than directly on the shaft, so they are related sizes; the 21309 CC and 21309 E are different cage and internal designs in the same envelope.