What this part is:

SKF NN 3028 KC/C481 double row cylindrical roller bearing. Bore: 140 mm, tapered 1:12. Outside diameter: 210 mm. Width: 53 mm. Series: NN 30. Two rows of cylindrical rollers, machined brass cage, open.

Decoding the designation:

NN: double row cylindrical roller design. 3028: NN 30 series, 140 mm bore. K: tapered bore, 1:12 taper. C in the KC group: a cage execution variant. C481: a special internal specification held to a customer drawing.

What these specs mean in practice:

Basic dynamic load rating: 297 kN (66,770 lbf). Basic static load rating: 480 kN (107,910 lbf). On cylindrical rollers the static rating sits well above the dynamic rating, and that is the normal relationship for the type. Two rows of rollers in line contact give this bearing very high radial capacity and very high radial stiffness for its section. Limiting speed: 4,500 r/min. Precision class P5, with running accuracy held to match.

Bore form and mounting:

The bore is tapered at 1:12 and seats directly on a matching tapered spindle journal. Radial clearance is set by the axial drive-up distance on the taper, which is what allows a very fine clearance setting on a machine tool spindle. Internal clearance class C4.

Load direction:

Cylindrical rollers carry radial load. The ribs on the inner ring locate the roller sets, and axial location for the shaft comes from a separate bearing in the arrangement.

Quantity and configuration:

One bearing. Mass: 6.52 kg (14.37 lbs).

Interchange guidance:

Same-envelope equivalents at 140 x 210 x 53 mm with a 1:12 tapered bore and machined brass cage: FAG NN3028-AS-K-M-SP, NSK NN3028MBKRE44. The straight-bore NN 3028 is a related size at the same section. Searchable forms: NN3028KC481, NN-3028-KC/C481, NN 3028 K C481, NN-3028-K-C481, NN3028K, NN3028.