FAGNN3040ASKMSPDouble Row Cylindrical Roller Bearing 200 mm Taper Bore x 310 x 82 mm, SP Super Precision, Brass Cage

Product Description

What this part is

A FAG NN3040-AS-K-M-SP double-row cylindrical roller bearing — 200 mm tapered bore, 310 mm outside diameter, 82 mm wide, machined brass cage, FAG SP super-precision class, with a lubrication groove and radial holes in the outer ring.

Decoding the designation

NN — double-row cylindrical roller, two rows of straight rollers
3040 — NN30 dimension series, 200 mm bore
AS — lubrication groove in the outer ring with radial holes
K — 1:12 tapered bore
M — machined brass cage
SP — FAG special precision, the super-precision spindle grade

What these specs mean in practice

Two rows of straight rollers give very high radial stiffness in a short axial length, which is what a machine-tool spindle front bearing needs. The 1:12 tapered bore on an NN type seats directly on a tapered spindle journal: driving the inner ring up the journal taper expands it and sets the radial preload, so preload is a setting made at assembly rather than a fixed property of the bearing. That is the opposite arrangement to a tapered-bore spherical roller, which uses an adapter sleeve. The SP class tightens bore, outside diameter and running accuracy to spindle tolerances. An NN carries radial load only, so shaft position is located by a separate thrust or angular contact bearing in the same spindle.

Published specifications

Bore: 200 mm, tapered 1:12
Outside diameter: 310 mm
Width: 82 mm
Rows: 2
Rolling element: cylindrical roller
Cage: machined brass
Precision class: FAG SP (super precision, ISO class 5 grade)
Relubrication: outer ring groove with radial holes
Axial location: non-locating — radial load only
Closure: open

Quantity and configuration

1 Pc. Bearing only, comprising the double outer ring, two roller rows with the brass cage, and the tapered-bore inner ring.

Fitting notes

The bore seats on a 1:12 taper machined into the spindle journal, with no sleeve between. Drive-up on the taper expands the inner ring and reduces radial internal clearance, so the preload is set by measured drive-up distance or by measured radial clearance across the mounting.

Interchange guidance

The ISO base number NN3040K identifies the same envelope and bore form across brands: SKF NN 3040 K/SPW33, NSK NN3040TBKRE44CC1P4 and NTN NN3040KC1NAP4 are the same size, taper and super-precision territory. An NN3040-AS-M-SP without the K is a straight bore and mounts differently. An NNU4940 is a different series with the roller rows guided on the outer ring, so it is a related size rather than an equivalent. A standard-precision NN3040 is a different tolerance grade.