FAGNN3011ASM.SP-W33Double-Row Cylindrical Roller Bearing 55 x 90 x 26 mm, Straight Bore, Machined Brass Cage, Lube Groove and Three Holes, Super-Precision SP

Product Description

What this part is:

A FAG NN3011-AS-M-SP double-row cylindrical roller bearing, 55 mm bore x 90 mm outside diameter x 26 mm wide, with a straight cylindrical bore, a machined brass cage, super-precision tolerances and an annular lubrication groove with three radial feed holes in the outer ring. Two rows of rollers in a 17.5 mm cross-section carry 72 kN dynamic load at up to 9 000 rpm. This is a machine-tool spindle and precision gearbox bearing.

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.
• AS — FAG code for an annular lubrication groove and three radial holes in the outer ring, the feature other makers designate W33. Both codes appear in this listing’s part numbers and refer to the same feature.
• M — machined brass cage, roller-centred.
• SP — FAG super-precision: ISO tolerance class 5 dimensional accuracy with class 4 running accuracy.
• Bore form: cylindrical. The absence of a K in the designation is what identifies the straight bore.

Bore form and how clearance is set:

This is the straight-bore member of the NN3011 family, and the bore form is the single most important thing to match. A straight bore seats on a cylindrical journal with an interference fit, and radial internal clearance is fixed by the clearance class the bearing was built to. The tapered-bore version, NN3011-AS-K-M-SP, seats on a 1:12 tapered journal and has its clearance set by measured axial drive-up. The two require different spindle journals and are separate order codes.

What these specs mean in practice:

The AS lubrication feature feeds oil or grease into the bearing through the housing rather than past the ring faces, which is what allows the 9 000 rpm limiting speed alongside roller-bearing load capacity. 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 tolerates the temperature excursions and the oil-air lubrication typical 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 Cr: 72 kN
• Fatigue limit load Cu: 15.6 kN
• Limiting speed: 9 000 rpm
• Bore form: straight cylindrical
• Rows: 2 — rolling element: cylindrical roller — open, no seals or shields
• Cage: machined brass, roller-centred
• Outer ring: annular lubrication groove with three radial holes (FAG AS, the same feature as W33)
• Tolerance class: SP — ISO class 5 dimensional, class 4 running accuracy
• Operating temperature range: −30 °C to +150 °C
• Material: through-hardened bearing steel

Quantity and configuration:

Sold as 1 Pc — one complete bearing: the ribless outer ring with its lubrication groove, and the straight-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 onto a cylindrical journal ground to the interference fit the spindle drawing calls for, with the inner ring heated or pressed square to the shoulder. The three lubrication holes in the outer ring line up with the housing feed port, and the outer ring stays free to slide axially in its bore, which is what makes this the non-locating position. Radial internal clearance is a built-in property of this bearing rather than something set at assembly.

Interchange guidance:

Other-maker part numbers are not listed because none has been verified against this exact specification: 55 x 90 x 26 mm, straight bore, machined brass cage, lubrication groove and holes. Related sizes, not substitutes: NN3011-AS-K-M-SP has a 1:12 tapered bore and belongs on a tapered journal; 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 NN3011 holds a different accuracy class from an SP bearing.