ConsolidatedNN3018KMDouble Row Cylindrical Roller Bearing 90x140x37 mm, 1:12 Tapered Bore, Machined Brass Cage, Non-Locating

Product Description

What this part is

A Consolidated NN3018KM double-row cylindrical roller bearing, 90 mm bore x 140 mm outside diameter x 37 mm wide, with a 1:12 tapered bore and a machined brass cage. Two rows of rollers in a 25 mm cross-section give it the radial capacity and radial stiffness that make the NN30 series the default choice for machine-tool spindles, gearbox shafts and rolling-mill roll necks.

Decoding the designation

NN — double row, ribs on the inner ring, no ribs on the outer ring. The bearing accommodates axial displacement in both directions.
30 — ISO dimension series 30 (medium section).
18 — 90 mm bore.
K — tapered bore, taper 1:12.
M — machined brass cage, roller-guided.

What these specs mean in practice

The K taper is a working feature, not a detail. Pressing the inner ring up a tapered seat or an adapter sleeve expands it by a controlled amount, so you set radial clearance — or a deliberate light preload — by measured drive-up rather than by hoping the shaft tolerance was right. That is why machine-tool builders specify tapered-bore cylindrical rollers.

With no ribs on the outer ring this bearing is non-locating: radial load only, and the shaft is free to grow and shrink axially. It needs a locating bearing elsewhere on the shaft. It will not hold a shaft in position and should never be asked to.

The machined brass cage handles higher speed, higher temperature and shock loading than a polyamide cage, which is what you want in an oil-lubricated gearbox or a spindle running warm.

Published ratings and mounting data

Consolidated does not publish its own rating tables. The figures below are the published catalogue values for the NN3018 / NN3018K envelope and are given as envelope reference data:

Basic dynamic load rating Cr: 158 kN (straight bore) — 143 kN quoted for the tapered variant in some catalogues
Basic static load rating C0r: 228 kN
Limiting speed, straight bore: 6 000 rpm grease / 7 300 rpm oil — tapered bore runs lower, around 4 500 / 5 200 rpm
Bore d 90 mm — OD D 140 mm — Width B 37 mm
Outer-ring raceway diameter E: 127 mm — inner-ring raceway diameter Fw: 98 mm
Chamfer r min: 1.5 mm
Shaft abutment da: 98 mm — housing abutment Da: approx. 132 mm
Rows 2 — cage machined brass — open, no seals
Approximate mass: 2.07 kg

Quantity and configuration

Sold as 1 Pc — one complete bearing: the ribless outer ring plus the tapered-bore inner ring carrying both roller rows and cages. Separable design, so it comes apart into those two assemblies; they are matched and belong together.

Fitting notes

Because both rings can be fitted independently, this type is the standard answer where both the shaft and the housing want an interference fit. Drive the inner ring up the taper in measured steps and check radial clearance as you go. Leave the outer ring free to slide in its housing bore — that is what makes it the floating bearing. Watch the 1.5 mm chamfer at the abutments so a shaft shoulder does not foul the ring face.

Interchange guidance

Dimensionally interchangeable with 90x140x37 mm tapered-bore double-row cylindrical roller bearings: SKF NN 3018 KTN9/SP, FAG NN3018-AS-K-M-SP, NSK NN3018K, NTN NN3018K, Nachi NN3018K, Koyo NN3018K, RKW NN3018K. Match the tolerance class and clearance to the application — a commercial-class bearing is not a substitute for a super-precision spindle bearing. Related sizes are not substitutes: the straight-bore NN3018 cannot set clearance on a tapered seat; NNU4918 puts its ribs on the outer ring; and single-row NU1018 or NU218 bearings in a similar envelope have far lower capacity and stiffness. Cage type matters too — a TN9 polyamide cage version is a different thermal and speed proposition from this brass-caged unit.