3490-3420-NTN bearing: complete specifications & equivalents
The 3490-3420-NTN is a ANSI ABMA 19.2 radial bearing sized 38.1 x 79.375 x 29.37 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 38.1 mm |
| Outer diameter D | 79.375 mm |
| Width B | 29.37 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 103 kN |
| Basic static load rating C0 | 114 kN |
| Limiting speed (mechanical) | 4900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 688 g |
| Manufacturer designation | NTN 4T-3490/3420 |
| 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 | 1.5 in |
|---|---|
| Outer diameter D | 3.125 in |
| Width B | 1.156 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 20.6 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) | 42 of 148 |
| Bore above smallest 4t-inch-series size | 25.400000000000002 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3490-3420 | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 3490-3420-NTN model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the order number 4T-3490/3420 denotes the pure-numeric inch family of NTN inch tapered roller bearings — cone 3490 and cup 3420 delivered as a matched, separable pair of 38.1 mm bore and 79.375 mm outside diameter. Letter prefixes inherited from the inch convention mark the load family: LM reads as light-medium, HM as heavy-medium, LL as extra-light, J-prefixed codes as metric-envelope families — 3490 sits in the pure-numeric inch family. Two single-row inch sets are normally mounted as an adjusted O or X pair; the 29.37 mm T of each 4T-3490/3420 enters the spacer calculation, so the tolerance on assembled width matters as much as the bore fit. Cup-side note for 3420: within the pure-numeric inch family tables the 3490 cone is listed against several cup options, and it is the cup that fixes the 79.375 mm OD and the 29.37 mm assembled width — quote the full 3490/3420 pair, never the cone alone. Back-to-back (O) and face-to-face (X) arrangements of two 4T-3490/3420 sets react differently to shaft bending; choose the orientation for the moment load before locking shoulder geometry.
Typical equipment & failure modes
Common applications
- industrial gearboxes built to inch shafting
- construction-equipment pivot and wheel positions
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- cage fatigue when the pair runs continuously near the grease limiting speed without oil cooling
- brinell marks on cone and cup raceways from impact during handling or hammer fitting
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 38.1 mm class are adjusted in pairs; verify end play against the axle or gearbox drawing and re-torque after bedding-in instead of trusting the first setting on 4T-3490/3420.
- The pure-numeric inch family at 38.1 mm bore (79.375×29.37 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3490/3420 reference at purchase.
- Quote the full 3490/3420 pair at ordering: the 3490 cone also ships against sibling cups, and a cup from another reference changes the 29.37 mm assembled width and the rating.
- Grease packs must leave free volume inside the 29.37 mm-wide set; over-greasing a pair churning near the oil-band speed of 6,600 r/min raises temperature and destroys the setting.
- Inch and metric bores collide on paper — 38.1 mm is 1.5 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- The 103/114 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3490/3420; 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-3490/3420?
4T-3490/3420 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 38.1 mm bore (1.5 in), 79.375 mm outside diameter and 29.37 mm assembled width T (3.125 × 1.156 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 103 kN, C0 114 kN, grease limiting speed 4,900 r/min, oil speed 6,600 r/min, mass about 688 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3490/3420 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3490 cone or the 3420 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 103/114 kN ratings change with the cup.
What is the difference between 4T-3490/3420 and a metric ISO 355 tapered bearing?
4T-3490/3420 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 38.1×79.375×29.37 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-3490/3420 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 3490/3420 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3490/3420 list two speeds, 4,900 and 6,600 r/min?
The lower figure, 4,900 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-3490/3420 at 6,600 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.