387AS-382A bearing: complete specifications & equivalents
The 387AS-382A is a ANSI ABMA 19.2 radial bearing sized 57.15 x 96.838 x 21 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 57.15 mm |
| Outer diameter D | 96.838 mm |
| Width B | 21 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 86.5 kN |
| Basic static load rating C0 | 96.5 kN |
| Limiting speed (mechanical) | 3700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 575 g |
| Manufacturer designation | NTN 4T-387AS/382A |
| Standard | ANSI ABMA 19.2 |
| Catalog version | NTN 2203E 2026-09-25 |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN 2203E 2026-09-25) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN 2203E 2026-09-25); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & 4t-inch-series range
| Bore d | 2.25 in |
|---|---|
| Outer diameter D | 3.813 in |
| Width B | 0.827 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 19.8 mm |
| Smallest bore in 4t-inch-series | 12.7 mm |
| Largest outer diameter in 4t-inch-series | 260 mm |
| Width range across 4t-inch-series | 10.998–77.788 mm |
| Bore position in 4t-inch-series (smallest first) | 72 of 148 |
| Bore above smallest 4t-inch-series size | 44.45 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 387AS | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the 387AS-382A model number is decoded
4T-387AS/382A is an NTN inch-series single-row tapered roller bearing: a separable cone-and-cup pair on the ABMA inch boundary plan, 57.15×96.838×21 mm (assembled width T), for a shaft of about 57.15 mm (2.25 in). The 4T prefix is NTN's tapered roller quality mark stamped on both parts; it is a brand mark, not a size code, so cross-references quote 387AS/382A without it. Speed planning uses both catalogue columns: grease 3,700 r/min is the mechanical ceiling for 4T-387AS/382A, oil 5,000 r/min with circulating oil — a 1,300 r/min margin at this size. The printed 86.5/96.5 kN ratings belong to the assembled 387AS+382A pair; a sibling row using the same cone with a different cup carries its own rating row because the raceway track shifts with the cup. Mount the 57.15 mm cone with an induction heater (max 120 °C) and press the 96.838 mm cup with a sleeve; driving either ring through the rollers brinells the raceways.
Typical equipment & failure modes
Common applications
- heavy truck and bus drive-axle differentials
- plant gearboxes on inch-dimensioned shaft lines
- large conveyor head pulleys in bulk-handling plant
- paper-machine and calender roll supports
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- cage fatigue when the pair runs continuously near the grease limiting speed without oil cooling
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- Mount the 57.15 mm cone by induction heating (max 120 °C) and the 96.838 mm cup with a press sleeve; at 575 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 57.15 mm bore (96.838×21 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 387AS/382A reference at purchase.
- Do not confuse T (21 mm, the assembled cone-plus-cup width) with the cone width when drawing spacers; an abutment sized to T leaves the cup unseated.
- Quote the full 387AS/382A pair at ordering: the 387AS cone also ships against sibling cups, and a cup from another reference changes the 21 mm assembled width and the rating.
- Grease packs must leave free volume inside the 21 mm-wide set; over-greasing a pair churning near the oil-band speed of 5,000 r/min raises temperature and destroys the setting.
- The 86.5/96.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-387AS/382A; internal geometry legitimately differs between inch-series makers, so re-verify ratings, adjustment and the exact cone/cup references before substituting another brand on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 4T-387AS/382A?
4T-387AS/382A is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 57.15 mm bore (2.25 in), 96.838 mm outside diameter and 21 mm assembled width T (3.813 × 0.827 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 86.5 kN, C0 96.5 kN, grease limiting speed 3,700 r/min, oil speed 5,000 r/min, mass about 575 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-387AS/382A interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 387AS cone or the 382A cup can be replaced by an identical reference from NTN or another ABMA-dimensioned maker. Pairing the cone with a different cup reference is a different catalogue row: OD, assembled T and the 86.5/96.5 kN ratings change with the cup.
What is the difference between 4T-387AS/382A and a metric ISO 355 tapered bearing?
4T-387AS/382A follows the ABMA inch boundary plan with cone/cup references; ISO 355 bearings use metric dimension-series numbers (302, 322, …). Even where a metric size looks close to 57.15×96.838×21 mm, the envelopes and contact angles differ — the two systems are not drop-in interchangeable; check every boundary value before substituting.
What does the 4T prefix on 4T-387AS/382A mean?
4T is NTN's tapered roller bearing quality mark, stamped on cone and cup in the factory. It identifies NTN's 4T programme and is not a dimension or variant code, so interchange lists quote the bare 387AS/382A references; the 4T spelling is retained among this page's search aliases.
Why does 4T-387AS/382A list two speeds, 3,700 and 5,000 r/min?
The lower figure, 3,700 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 4T-387AS/382A at 5,000 r/min because oil removes rib-contact heat better. Real limits still depend on pair adjustment, oil flow and cooling.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN 2203E 2026-09-25 on 2026-10-01. Read our editorial & correction policy.