2690-2631 bearing: complete specifications & equivalents
The 2690-2631 is a ANSI ABMA 19.2 radial bearing sized 29.367 x 66.421 x 23.812 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 29.367 mm |
| Outer diameter D | 66.421 mm |
| Width B | 23.812 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 71.5 kN |
| Basic static load rating C0 | 72.5 kN |
| Limiting speed (mechanical) | 6200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 407 g |
| Manufacturer designation | NTN 4T-2690/2631 |
| 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 | 1.156 in |
|---|---|
| Outer diameter D | 2.615 in |
| Width B | 0.937 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 18.5 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) | 25 of 148 |
| Bore above smallest 4t-inch-series size | 16.667 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 2690 | 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 2690-2631 model number is decoded
The NTN 2203E inch table prints 4T-2690/2631 at 29.367 mm bore (1.156 in), 66.421 mm cup OD and 23.812 mm assembled T, with a grease limiting speed of 6,200 r/min and an oil ceiling of 8,200 r/min. Reading the designation: 4T-2690/2631 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. Contact-angle geometry of the pure-numeric inch family gives 4T-2690/2631 its radial/axial load split — at 71.5/72.5 kN the static rating is about 1.01× C, typical of inch tapered sets proportioned for combined duty. Cup-side note for 2631: within the pure-numeric inch family tables the 2690 cone is listed against several cup options, and it is the cup that fixes the 66.421 mm OD and the 23.812 mm assembled width — quote the full 2690/2631 pair, never the cone alone. Running clearance of 4T-2690/2631 is set at mounting by axial displacement of cone or cup — the catalogue does not ship a preloaded set, so the drawing must state end play or preload.
Typical equipment & failure modes
Common applications
- construction-equipment pivot and wheel positions
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- 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
- rolling-contact fatigue spalling after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 29.367 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-2690/2631.
- The pure-numeric inch family at 29.367 mm bore (66.421×23.812 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 2690/2631 reference at purchase.
- Shaft and housing fillets must clear the ring chamfers of 2690 and 2631; use undercut shoulders so the rings seat on the face, not on a radius.
- Replacing one half of an adjusted pair without resetting end play negates the 23.812 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Open 4T-2690/2631 sets have no seals: a hub or gearbox needs external sealing or the 6,200 r/min grease figure is meaningless once water reaches the cone rib.
- The 71.5/72.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-2690/2631; 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-2690/2631?
4T-2690/2631 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 29.367 mm bore (1.156 in), 66.421 mm outside diameter and 23.812 mm assembled width T (2.615 × 0.937 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 71.5 kN, C0 72.5 kN, grease limiting speed 6,200 r/min, oil speed 8,200 r/min, mass about 407 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-2690/2631 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 2690 cone or the 2631 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 71.5/72.5 kN ratings change with the cup.
What is the difference between 4T-2690/2631 and a metric ISO 355 tapered bearing?
4T-2690/2631 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 29.367×66.421×23.812 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-2690/2631 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 2690/2631 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-2690/2631 list two speeds, 6,200 and 8,200 r/min?
The lower figure, 6,200 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-2690/2631 at 8,200 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.