Timken387A-90315Double-Row Tapered Roller Bearing Assembly – 2.2500 in Bore, 3.9370 in Outside Diameter, 1.9370 in Width, TDO Double Cup, Case-Carburized Steel

Product Description

What this part is:

Timken 387A-90315 double-row tapered roller bearing assembly, TDO (tapered double outer) configuration, Series 385, inch design. Bore Diameter: 2.2500 in (57.150 mm). Outside Diameter: 3.9370 in (100.000 mm). Overall Width: 1.9370 in (49.197 mm). The assembly is built from two 387A cones and one 384ED double cup.

Decoding the designation:

387A — Timken inch tapered roller cone, 2.2500 in bore, inner ring width 0.8640 in (21.946 mm), K factor 1.65.

384ED — double cup: a single outer ring carrying two raceways, so both cone rows seat in one housing bore.

-90315 — Timken assembly number: the two cones and the double cup are supplied together as one matched, bench-set unit.

What these specs mean in practice:

Rolling Elements: Tapered Roller. Number Of Rows: 2. Bore Type: Straight. Closure Type: Open. Bearing Material: Case-carburized steel. Lubricant: grease or oil. Series: 385.

The two rows sit back to back inside the double cup, which gives a wide effective bearing spread. The assembly takes radial load, thrust in both directions and overturning moment from a single housing bore, and it arrives with the internal setting already established.

K Factor: 1.65. Geometry Factor (Cg): 0.0859. G1 Factor: 42. G2 Factor: 15.7. Per cone row, the dynamic radial rating at 90 million revolutions (C90) is 28,000 N and the dynamic axial rating (Ca90) is 16,900 N.

Mounting data:

Shaft backing shoulder diameter at the frontface (da): 2.48 in (63 mm). Shaft backing shoulder diameter at the backface (db): 2.76 in (70 mm). Maximum shaft fillet radius cleared by the cone corner: 0.140 in (3.600 mm). Cage location relative to the cone backface (Aa): 0.03 in (0.8 mm). Cage location relative to the cone frontface (Ab): 0.11 in (2.8 mm).

Quantity and configuration:

Unit Quantity: 3 Pcs — two 387A cones and one 384ED double cup, together forming the complete 387A-90315 assembly.

Interchange guidance:

387A and 384ED are industry-standard inch tapered roller designations and are carried under the same numbers by SKF, FAG, NSK, NTN, Koyo, Nachi, Bower/BCA, Fersa and PEER. The 387A cone also runs against the single cups 382A and 382. Base Number: 387A-90315. Searchable variants of the designation include 387A/384ED, 387A 384ED, 387-A and 384-ED.