SKFSpherical Roller Bearing – Straight Bore, 45 mm ID, 100 mm OD, 25 mm Width, Open, Reinforced E Design, W33 Lubrication Groove, CN Clearance

Product Description

What this part is

A double-row spherical roller bearing in the SKF 213 series, 45 mm bore, 100 mm outside diameter, 25 mm width. Barrel-profile rollers in two rows run on a common spherical outer raceway, so the inner ring, roller and cage assembly swivels inside the outer ring and absorbs shaft-to-housing misalignment up to 2° while carrying heavy radial load.

Decoding the designation

21309 gives the ISO base: 213 dimension series, bore code 09 for 45 mm. The E suffix is the reinforced internal design — a fuller roller complement carried on a pressed steel cage, which is why the E ratings sit above the older base design. There is no K in the designation, so the bore is straight and cylindrical. W33 is the outer-ring lubrication feature: a circumferential groove in the outer ring with three radial holes into the rolling-element space. No clearance suffix follows the designation, so internal clearance is normal, CN.

What these specs mean in practice

A double-row spherical roller bearing carries thrust in both axial directions as well as radial load, and the self-aligning geometry keeps the load path central when the housing bore is misaligned or the shaft deflects. The pressed steel cage of the E design keeps rotating mass low, which supports a limiting speed of 8500 rpm. The 213 series is shallower in cross-section than the 223 series at the same bore, trading load rating for a tighter radial envelope.

Lubrication feature

The W33 groove and its three radial holes admit grease or oil directly into the rolling-element space through a ported housing, so relubrication happens without dismantling. In a housing with no lubrication port the groove is simply unused.

Quantity and configuration

1 Pc. Open bearing, no seals and no shields. Straight bore, seated directly on the shaft. No adapter sleeve, locknut or lockwasher.

Fitting notes

A straight-bore spherical roller bearing is pressed onto the shaft seat against the inner ring face, with mounting force applied to the inner ring only so the rollers do not transmit the press load. The outer ring is free to align itself once the housing is closed. Operating temperature range is −30 °C to 200 °C.

Interchange guidance

FAG 21309-E1 and NSK 21309E share the ISO envelope, the 213 dimension series and the reinforced design, and interchange directly. 21309 CC and 21309 CCK are related sizes rather than substitutes: the CC cage carries a different rating, and the K variant has a 1:12 tapered bore that mounts on an adapter sleeve instead of directly on the shaft.