Timken8522Tapered Roller Bearing Cup – 12.9380 in Cup Outer Diameter, 1.4375 in Cup Width, e 0.41, Y 1.48, Case-Hardened Steel

Product Description

What this part is

A Timken 8522 single cup — the outer race of a TS single-row tapered roller bearing, one ring carrying one tapered raceway. Cup only. It seats in a housing bore and runs against a separate cone assembly; the cones Timken pairs with it are the 8573 and the 8575X. Outside diameter is 12.9380 in (328.625 mm) and outer ring width C is 1.4375 in (36.513 mm). The ring is case-hardened steel and weighs 25.40 lb (11.5 kg).

Decoding the designation

8522 is the cup number in Timken’s imperial 8500 series; the cone numbers that mate with it sit in the 8500s as well, at 8573 and 8575X. The number carries no precision suffix, so no tolerance class is published for this part — Timken writes Class 2 as an explicit -2 and Class 3 as a -3, *3 or #3. The order code also appears as 8522-20024, where the -20024 marks the cup supplied on its own rather than as part of an assembly.

Mounting and fitting data

The maximum housing fillet radius cleared by the cup corners is 0.130 in (3.30 mm). Housing backing shoulder diameter is 12.40 in (314.96 mm) at the frontface (Da) and 12.05 in (306.07 mm) at the backface (Db). The e factor is 0.41, the Y factor is 1.48 and the geometry factor Cg is 0.14.

What these specs mean in practice

The e and Y factors set how the bearing’s thrust load is treated in a life calculation: e is the thrust-to-radial ratio above which the thrust component begins to govern, and Y converts the thrust load into an equivalent radial load once that threshold is passed. An e of 0.41 with a Y of 1.48 describes a moderately steep raceway angle, so the 8522 carries meaningful thrust alongside its radial load rather than being a purely radial cup. At nearly 13 in outside diameter and 25 lb this is a large-envelope cup, the size used in heavy gearboxes, mill stands, crane and off-highway wheel positions where the housing fit and the backing shoulder do real work.

Housing fit

The 0.130 in maximum housing fillet radius is generous for a cup this size, which allows a substantial corner radius in the housing bore. The 0.35 in difference between the frontface and backface backing shoulder diameters reflects the cup’s taper, so the shoulder that supports the ring differs at each face.

Quantity and configuration

One piece, one single cup. One raceway, open with no seal or shield, and no bore — the shaft fit is taken by the cone, which is a separate part ordered by its own number. Single-row tapered roller bearings of this type are usually mounted in opposing pairs so the pair locates axially in both directions.

Interchange guidance

The cup number 8522 is used across the tapered roller trade for this envelope. The 8573 and 8575X cones are the mating inner assemblies for it and are separate parts. A cup number is not interchangeable with its cone number, and a cup from a different series will not share this raceway angle even where the outside diameter matches.