Timken385A-90313TDO Two-Row Tapered Roller Bearing Assembly – 2.0000 in Bore, 3.9375 in Cup Outer Diameter, Two Cones and One Double Cup, Case-Hardened Steel

Product Description

What this part is

A Timken 385A-90313 complete two-row tapered roller bearing assembly in the TDO configuration, meaning tapered double outer. It consists of three pieces: two 385-A cones and one 384-ED double cup that both cones run in. Bore 2.0000 in, cup outside diameter 3-15/16 in, case-hardened steel throughout with stamped steel cages.

Decoding the designation

In Timken’s numbering the 385A is the cone, the inner ring with its roller and cage assembly, and the 384ED is the cup, the outer race. The -90313 suffix is what identifies this as a factory assembly rather than a loose component: Timken’s -90xxx numbers denote a complete, matched, ready-to-fit bearing. The D in 384ED marks the cup as a double cup, a single outer ring with two raceways ground into it, which is why it takes two cones.

What these specs mean in practice

A TDO puts both rows inside one outer ring, so the whole bearing drops into a single straight-bored housing and carries thrust in both directions from that one seat. Because the two rows sit apart with their effective load centres outside the bearing, a TDO is stiff against overturning moments, which is the usual reason for choosing one over two separate single-row bearings. The K factor of 1.65 is the ratio Timken uses to convert radial load into the induced thrust component; a higher K means a shallower cup angle and a more radial bearing. Each cone weighs 5.95 lb.

Ratings basis

The load ratings in the specification table are Timken’s published per-row figures for the 385A cone. The two-row radial rating for the complete assembly is a separate published value and is not reproduced here.

Quantity and configuration

One complete assembly, supplied as three pieces: two 385-A cones and one 384-ED double cup.

Fitting notes

The cup seats in a straight housing bore and the cones press onto the shaft. Timken publishes a maximum shaft fillet radius of 0.09 in, a shaft backing shoulder diameter of 2.36 in against the cone frontface and 2.4 in against the backface. The effective centre of each row sits 0.12 in inside the cone backface. Internal setting is established at the factory for the assembly number.

Interchange guidance

The 385A cone also runs against the 382A and 382 single cups and against the 384DC double cup. A 385A-90313 built on a 384ED double cup and an assembly built on a 384DC are separate assembly numbers with their own internal settings, so each is a related configuration rather than a drop-in interchange.