NTN39580Tapered Roller Bearing Cone, 2-1/4 in. Bore, 1.1875 in. Inner Ring Width, Imperial Inch Series

Product Description

What this part is

A single-row imperial tapered roller bearing cone in the ISO/ANSI 39580 size — the inner ring with its full complement of tapered rollers and cage. It is the shaft-side half of a two-piece TS single-row tapered bearing. Cone only. The matching cup is the Timken 39520, with the 39521 as the second published pairing.

Decoding the designation

39580 is an inch-series number in the ANSI/ABMA interchange scheme, so the same digits describe the same cone geometry at NTN, Timken, Koyo and SKF. Cone numbers in this scheme end in a lower digit group than their cups, which is why a 39580 cone pairs with a 39520 cup. Tapered roller bearings carry no clearance suffix; the running clearance is set during mounting.

What these specs mean in practice

The K factor of 1.72 describes the split between radial and thrust capability for the matched pair. A lower K means a steeper cup angle and proportionally more thrust capacity for the same envelope, so the 39580/39520 handles a higher axial share than a 1.9-class bearing of similar size. The effective centre sits 0.26 in. inside the cone backface, which is the load-line position used when calculating the effective span between two opposed rows.

Published ratings and mounting data

Bore (d): 2-1/4 in. (57.150 mm)
Inner ring width (B): 1.1875 in. (30.163 mm)
Dynamic radial rating C1, matched 39580/39520 assembly: 37,500 lbf (167,000 N)
Dynamic radial rating C90, matched 39580/39520 assembly: 9,730 lbf (43,300 N)
Dynamic thrust rating Ca90, matched assembly: 5,650 lbf (25,100 N)
Static radial rating C0, matched assembly: 50,300 lbf (224,000 N)
K factor: 1.72
Maximum shaft fillet radius: 0.14 in. (3.600 mm)
Shaft backing shoulder diameter: 2.68 in. frontface, 2.91 in. backface
Cone weight: 6.45 lb (2.927 kg)

Quantity and configuration

One cone assembly, sold individually. Single row, tapered rollers, steel cage.

Fitting notes

The cone takes an interference fit on the shaft and is pressed from the backface against the shoulder, with the driving force carried by the inner ring rather than the cage. Endplay or preload is set once the cup is seated in its housing bore.

Interchange guidance

39580 interchanges directly across Timken, NTN, Koyo, SKF and FAG (as K-39580), since the inch-series number defines the geometry. The 39590 and 39585 are related sizes in the same family with different inner ring geometry and are separate parts.