390A-394A bearing: complete specifications & equivalents
The 390A-394A is a ANSI ABMA 19.2 radial bearing sized 63.5 x 110 x 22 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 63.5 mm |
| Outer diameter D | 110 mm |
| Width B | 22 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 99.5 kN |
| Basic static load rating C0 | 120 kN |
| Limiting speed (mechanical) | 3200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 858 g |
| Manufacturer designation | NTN 4T-390A/394A |
| 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 | 2.5 in |
|---|---|
| Outer diameter D | 4.331 in |
| Width B | 0.866 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 23.3 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) | 81 of 148 |
| Bore above smallest 4t-inch-series size | 50.8 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 390A | 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 390A-394A model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the order number 4T-390A/394A denotes the pure-numeric inch family of NTN inch tapered roller bearings — cone 390A and cup 394A delivered as a matched, separable pair of 63.5 mm bore and 110 mm outside diameter. Reading the designation: 4T-390A/394A follows the ABMA inch convention — the number before the slash is the cone (inner ring with roller set and cage), the number after the slash is the cup (outer ring), and the pure-numeric inch family lettering ties the pair to its boundary plan. Speed planning uses both catalogue columns: grease 3,200 r/min is the mechanical ceiling for 4T-390A/394A, oil 4,300 r/min with circulating oil — a 1,100 r/min margin at this size. Housing fitment sequence for 4T-390A/394A: press the 394A cup square into the 110 mm seat first, then bring the 390A cone (on its 63.5 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. Contact-pattern check with marking blue: a pattern biased to one roller end means the 63.5 mm pair is misadjusted and the set will edge-load in service.
Typical equipment & failure modes
Common applications
- large conveyor head pulleys in bulk-handling plant
- paper-machine and calender roll supports
- off-highway and forestry machine axles
- marine winch and deck-machinery shafts
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- 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
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- Mount the 63.5 mm cone by induction heating (max 120 °C) and the 110 mm cup with a press sleeve; at 858 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 63.5 mm bore (110×22 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 390A/394A reference at purchase.
- Never drive the 110 mm cup home through the rollers: fitting force goes through the ring faces only, or brinell marks release as noise within the first running hours.
- Never drive the 110 mm cup home through the rollers: fitting force goes through the ring faces only, or brinell marks release as noise within the first running hours.
- Fit selection follows the rotating ring: a rotating cone on a 63.5 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- The 99.5/120 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-390A/394A; 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-390A/394A?
4T-390A/394A is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 63.5 mm bore (2.5 in), 110 mm outside diameter and 22 mm assembled width T (4.331 × 0.866 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 99.5 kN, C0 120 kN, grease limiting speed 3,200 r/min, oil speed 4,300 r/min, mass about 858 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-390A/394A interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 390A cone or the 394A 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 99.5/120 kN ratings change with the cup.
What is the difference between 4T-390A/394A and a metric ISO 355 tapered bearing?
4T-390A/394A 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 63.5×110×22 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-390A/394A 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 390A/394A references; the 4T spelling is retained among this page's search aliases.
Why does 4T-390A/394A list two speeds, 3,200 and 4,300 r/min?
The lower figure, 3,200 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-390A/394A at 4,300 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.