Timken74849DDouble Tapered Roller Bearing Cup — 8.5 in Outside Diameter, 3-3/16 in Width, Two Raceways, Case-Carburized Steel

Product Description

What this part is

A Timken 74849D double cup: the one-piece outer race of a two-row tapered roller bearing, machined with two tapered raceways on a single ring. Outside diameter is 8.5 in and overall width is 3-3/16 in. Material is case-carburized bearing steel.

Decoding the designation

In Timken’s imperial tapered roller scheme the cone and the cup carry separate part numbers. A D suffix on a cup number marks a double cup, so the 74849D is a single ring carrying two raceways and running against two separate cones. The mirror convention applies on the other half: a D suffix on a cone number marks a one-piece double cone running against two single cups. The 74000 block is an imperial series in the 8 in outside diameter range.

What these specs mean in practice

A double cup is the outer race used in a TDO arrangement, where two rows of tapered rollers face outward inside one common outer ring. Because both raceways are ground in the same ring, their relative axial position and included angle are fixed at manufacture, so row-to-row alignment is set by the ring rather than by the housing bore. That makes a TDO the usual choice where a single housing bore has to locate a shaft in both axial directions, and it removes one press fit from the assembly compared with two single cups.

Quantity and configuration

Double cup only, one ring with two raceways. It runs against two cones and, in most TDO arrangements, a cone spacer. Sold as 1 Pc.

Bore form

A cup has no bore and no seal. Its inner surfaces are the two ground tapered raceways; its outer cylindrical surface is the housing fit. The cup carries no rollers of its own, since the roller complement and cage are retained on each cone.

Fitting notes

The double cup presses into the housing bore as a single unit and is clamped or shouldered axially. The two cones then enter from opposite ends and are drawn up on the shaft to set bearing endplay or preload. Full support of the cup outer surface across its whole width keeps the two raceways round under load.

Interchange guidance

Any manufacturer’s 74849D double cup ground to the same imperial envelope is a direct interchange. Two single cups of the equivalent size are a related configuration rather than a substitution, because they set row spacing from the housing instead of from the ring. The 74851DC in the same series is a related size and not the same part.