ConsolidatedNN3011KMDouble Row Cylindrical Roller Bearing 55x90x26 mm 1:12 Tapered Bore Machined Brass Cage

Product Description

What this part is

A double-row cylindrical roller bearing in the NN3011 envelope, 55 mm bore × 90 mm outside diameter × 26 mm width, with a 1:12 tapered bore and a machined brass cage.

Decoding the designation

NN — double-row cylindrical roller bearing, integral flanges on the inner ring, separable outer ring
30 — dimension series 30
11 — bore code, 55 mm bore
K — 1:12 tapered bore
M — machined brass cage
No clearance suffix — CN, normal radial internal clearance

What these specs mean in practice

Two rows of cylindrical rollers in a narrow section give very high radial capacity and high radial stiffness in a short axial space, with no axial load capacity, so the axial position is taken by a separate thrust or angular contact bearing. On an NN cylindrical the K tapered bore seats directly on a 1:12 tapered spindle journal, and axial position on that taper sets the radial internal clearance and preload — the adjustment mechanism that makes this family the standard front bearing in machine tool spindles. The machined brass cage tolerates higher temperatures and shock than a polyamide cage and accepts oil-jet and oil-mist lubrication.

Quantity and configuration

Unit quantity: 1 Pc
Bore: 1:12 taper, mounted directly on a tapered journal
Rows: 2, cylindrical rollers

Fitting notes

Clearance is set by the axial draw-up of the inner ring on the tapered journal, measured with a bore gauge or feeler before and after seating. No adapter sleeve is involved. The outer ring is separable from the roller-and-inner assembly, so the two halves are kept together as a matched unit.

Interchange guidance

Written also as NN 3011 K M, NN3011-K-M and NN3011KM. Same-envelope NN3011 bearings supplied with a cylindrical bore, a pressed-steel or polyamide cage, or a tightened precision class are related sizes rather than interchanges.