ConsolidatedNN3011KMSPDouble-Row Cylindrical Roller Bearing 55 x 90 x 26 mm, 1:12 Tapered Bore, Machined Brass Cage, Super-Precision SP

Product Description

What this part is

A Consolidated NN3011 K M SP double-row cylindrical roller bearing, 55 mm bore x 90 mm outside diameter x 26 mm wide, with a 1:12 tapered bore, a machined brass cage and super-precision tolerances. Consolidated Bearings is a US brand that sources European-built product; this one carries RKW manufacture. Two rows of cylindrical rollers in a 17.5 mm cross-section give around 85 kN dynamic capacity and high radial stiffness — roughly three times the radial rating of a 6011 ball bearing in the same envelope.

Decoding the designation

NN — double row, three ribs on the inner ring, ribless outer ring. Radial load, with axial displacement accommodated in both directions.
30 — ISO dimension series 30.
11 — 55 mm bore.
K — tapered bore, taper 1:12.
M — machined brass cage, roller-centred.
SP — super-precision: ISO tolerance class 5 dimensional accuracy with class 4 running accuracy.
RKW — Rheinische Kugellagerwerke, the German manufacturer marking on the bearing.

What these specs mean in practice

The 1:12 tapered bore is the working feature. On a cylindrical NN bearing the tapered inner ring seats directly on a tapered spindle journal, with no adapter sleeve in the assembly. Drawing the ring up the taper expands it a measured amount, so radial clearance — or a light preload — is set by axial travel rather than by ordering a clearance class, which is how a spindle builder reaches a repeatable running clearance.

The ribless outer ring makes this the floating position in a two-bearing arrangement: it slides in the housing bore as the shaft grows with temperature, and axial location comes from a thrust or angular-contact bearing elsewhere in the shaft. The machined brass cage suits oil, oil-air and grease lubrication and tolerates the temperature excursions of a hard-worked spindle.

Published ratings and mounting data

Bore d: 55 mm — Outside diameter D: 90 mm — Width B: 26 mm
Basic dynamic load rating C: 85.5 kN (ISO NN3011 envelope, machined brass cage)
Basic static load rating C0: 96.5 kN
Limiting speed, grease: 6 700 rpm — oil bath: 8 000 rpm
Outer-ring raceway diameter EW: 81 mm
Chamfer r min: 1.1 mm — ra max: 1 mm
Shaft abutment da min: 61.5 mm — housing abutment Da: 83–83.5 mm
Rows: 2 — rolling element: cylindrical roller — open, no seals or shields
Bore taper 1:12 — cage: machined brass — tolerance class: SP
Mass: approx. 0.65 kg

Quantity and configuration

Sold as 1 Pc — one complete bearing: the ribless outer ring, and the tapered-bore inner ring carrying both roller rows and both brass cages. The bearing separates into those two assemblies, which are a matched pair.

Fitting notes

Mounting is cold and clean, onto a tapered journal ground to the matching 1:12 taper. Bore expansion is measured at each increment of drive-up and radial clearance checked between increments until the target figure is reached. The outer ring stays free to slide axially in the housing bore, which is what makes this the non-locating position. The taper surface is a precision reference face and stays free of nicks, since a high spot there reads as spindle runout for the life of the machine.

Interchange guidance

Same-specification equivalents at 55 x 90 x 26 mm with a 1:12 tapered bore and machined brass cage: SKF NN 3011 KM/SP, FAG NN3011-AS-K-M-SP, NSK NN3011KM, NTN NN3011K, Koyo NN3011K, Nachi NN3011K, Rollway NN3011KM. Related sizes, not substitutes: the straight-bore NN3011 M seats on a cylindrical journal and sets clearance by class rather than by drive-up; NNU4911 in a comparable envelope carries its ribs on the outer ring and mounts the opposite way round; single-row NU1011 and N1011 have a fraction of the radial stiffness. A commercial-tolerance NN3011K holds a different accuracy class from an SP bearing.