Timken15580B/15520Tapered Roller Bearing Cone and Cup Assembly, 1-1/16 in ID x 2-1/4 in OD x 0.6875 in Wide, Single-Row Imperial TS

Product Description

What this part is

This is a complete single-row imperial tapered roller bearing in the Timken TS (Tapered Single) style. It is the most common tapered roller configuration in industry: a cone (the inner ring with its roller and cage assembly) that runs inside a separate cup (the outer ring). Cone and cup are separable parts, and the two are sold and stocked independently, which is exactly why the “is the mating race included?” question matters so much on this type.

Both cone and cup are included — verified from the photographs:
We checked the product photographs specifically to answer this. The bearing pictured is assembled: the cone with its rollers is seated inside its outer cup, in its original poly bag, alongside the Timken carton marked 15580B / 15520. So this listing is a complete bearing assembly — one cone (15580B) plus one cup (15520). You do not need to buy an outer race separately. A cone supplied on its own with no cup is the classic trap on tapered roller listings; that is not the case here.

Decoding the designation

15580 — the Timken cone (inner ring plus tapered rollers and cage), 1.0625 in bore.
15520 — the matching Timken cup (outer ring), 2.25 in O.D.
15580B — the carton on this item reads 15580B rather than plain 15580. The trailing B is a Timken cone-specific marking; Timken publishes the dimensional and rating data for this envelope under the 15580 / 15520 assembly number, and we have not found a published Timken decode for the B character, so we are not guessing at one. It is recorded here and in the cross-references exactly as printed on the box. Treat it as the 15580 cone envelope.
Written as a pair, 15580/15520 is the assembly number. Cone-and-cup pairs in the 155xx family share the 15520 cup, so 15578/15520, 15580/15520 and 15590/15520 differ only in bore — a useful check if you are working from a housing bore rather than a shaft size.

What these specs mean in practice

A tapered roller bearing carries heavy radial load and thrust in one direction only, because the rollers and races are set on a cone angle that pushes the cone out of the cup under reverse thrust. That is why tapered rollers are almost always mounted in opposing pairs — two bearings back-to-back or face-to-face on the same shaft — so that each one takes thrust one way and the pair is stable. If you are replacing one end of such a pair, plan on replacing both: a new bearing running against a worn mate will not hold the setting you dial in.

The K factor of 1.69 is the ratio of radial to thrust rating for this geometry, and the Y factor of 1.73 and e factor of 0.35 are what you feed into the equivalent-load calculation when the load is combined rather than purely radial. Because cone and cup are separable, mounting is straightforward: press the cone onto the shaft and the cup into the housing independently, then set endplay or preload by adjusting the two against each other.

Published ratings and mounting data

All figures below are from The Timken Company’s own catalogue entry for 15580 / 15520.

Bore (d): 1.0625 in / 26.988 mm
Outside diameter (D): 2.25 in / 57.150 mm
Assembled width (T): 0.6875 in / 17.463 mm
Cone (inner ring) width B: 0.6875 in / 17.463 mm
Cup (outer ring) width C: 0.5313 in / 13.495 mm
Dynamic radial load rating C1 (ISO, 1 million revs): 10,300 lbf / 46,000 N
Dynamic radial load rating C90 (Timken method, 90 million revs): 2,680 lbf / 11,900 N
Dynamic axial rating Ca90: 1,590 lbf / 7,070 N
Static radial load rating C0: 11,300 lbf / 50,100 N
K factor 1.69 · e factor 0.35 · Y factor 1.73
G1 factor 12.7 · G2 factor 10.3 · geometry factor Cg 0.0577
Effective centre location: −0.2 in / −5.1 mm (inside the cone backface)
Shaft backing shoulder diameter: 1.26 in / 32 mm frontface (da), 1.52 in / 38.5 mm backface (db)
Housing backing shoulder diameter: 2.11 in / 53.10 mm frontface (Da), 2.01 in / 51.05 mm backface (Db)
Maximum shaft fillet radius: 0.14 in / 3.600 mm · maximum housing fillet radius: 0.06 in / 1.52 mm
Cage location relative to backface (Aa): 0 in · relative to frontface (Ab): 0.1 in / 2.5 mm
Catalogue weight: 0.4 lb / 0.20 kg

Quantity and configuration

One bearing assembly — one 15580B cone plus one 15520 cup. If your application uses an opposed pair, you need two of these, and only one is in stock, so check availability before you plan a two-bearing rebuild around it.

Fitting notes

Respect the backing shoulder diameters listed above: a shoulder that is too small lets the cone backface deflect, one that is too large fouls the cage. Keep shaft and housing fillet radii inside the published maxima so the bearing corners clear. Cone and cup should be seated square and driven only on the ring being fitted — never through the rollers. This item is new old stock in the original Timken carton; the bearing is still in its factory wrapping. Verify the preservative coating and re-lubricate with the grease or oil your application specifies before commissioning.

Interchange guidance

15580 and 15520 are industry-standard ANSI/ABMA imperial tapered roller part numbers, so the same numbers are used by SKF, NTN, Koyo, NSK, Fersa, Nachi and others for the same boundary dimensions. Load ratings and internal geometry differ between makers even when the number matches, so if your application is rating-critical, compare the maker’s own C90 rather than assuming parity. Timken is also the successor brand to Fafnir and to Torrington bearing lines, so Fafnir-era references may point here.