Timken25527Tapered Roller Bearing Cup 3.3465″ OD, 0.875″ Width, Cup Only, Mates Timken 25577 Cone, Set of 4

Product Description

What this part is

A Timken 25527 tapered roller bearing cup — the outer race only, 3.3465 inch outside diameter by 0.875 inch wide, in case-carburised bearing steel. The cup is the half that presses into the housing; it carries no rollers of its own.

What ships and what does not

Cups only, four of them. There is no cone, no rollers and no cage in this listing. The mating cone for a 25527 is a Timken 25577, which has a 1.688 inch bore — the pair is quoted as 25577/25527. If you are rebuilding, order the cones as well; complete sets can be supplied on request. Never press a 25527 cup against a cone outside its published pairing: the raceway angle is matched between the halves.

Decoding the designation

25527 is the Timken cup number and 25577 is its cone. The full assembly number for this combination reads 25527-20024 in Timken’s system. A 255xx-90xxx number, by contrast, would be a complete pre-set assembly rather than a component.

Published ratings and dimensions

Component: cup (outer race) onlyOutside diameter (D): 3.3465 in (85.001 mm)Cup width (C): 0.8750 in (22.225 mm)Material: case-carburised bearing steele factor: 0.33 · Y factor: 1.79Matching cone: Timken 25577 — bore (d) 1.6880 in (42.875 mm), cone width (B) 1.0000 in (25.400 mm)Assembly dynamic radial load rating, 1M revs (C1): 20,300 lbf (90,500 N)Assembly dynamic radial load rating, 90M revs (C90): 5,270 lbf (23,500 N)K factor: 1.74Assembly weight: 2.92 lb (1.323 kg)Effective centre location (a): −0.25 inDesign units: imperial

The ratings and cone data are the published figures for the complete 25577/25527 assembly, given so you can size the position; they are not a claim about a cup on its own.

Condition, read this before ordering

These are new old stock and carry some surface oxidation from storage, visible in the photos. Light surface staining on the outside diameter and faces is cosmetic and normal for stock of this age. Inspect the raceway itself before fitting — pitting or rust in the roller path is not usable, whereas dry surface bloom on the outer diameter is.

What these specs mean in practice

The cup is a press fit in the housing and it is the part that sets the roller path angle. That is why a worn or spalled cup must be replaced together with its cone: the two wear into each other, and a new cone on an old raceway concentrates load on a mismatched contact band.

The K factor of 1.74 is the ratio Timken uses to convert thrust into an equivalent radial load, and it tells you this is a reasonably thrust-capable size for its envelope — usual for the opposed pairs found in gearboxes, wheel hubs and pinion positions.

Quantity and configuration

Sold as a set of 4 pcs — four cups. A pair of cups covers one shaft in an opposed arrangement, so a set of four does two shafts.

Fitting notes

Press the cup into a clean, deburred housing bore square, driving on the cup backface only with a driver that does not touch the raceway. Make sure the housing shoulder supports the cup face and clears its backface radius. Fit the 25577 cone to the shaft, then set the opposed pair to the endplay or preload the equipment maker specifies, rotating the assembly as you adjust so the rollers seat against the large rib.

Interchange guidance

25527 is an industry-standard cup number supplied by Timken, NTN, SKF, Koyo and Bower / BCA to the same boundary dimensions, all pairing with a 25577 cone. Related, not interchangeable: a 25527D would be a double cup for a two-row arrangement, a -3, *3 or #3 suffix denotes a Class 3 precision cup, and a Y1S-25527 is a cup spacer rather than a cup.