25877-25821-NTN bearing: complete specifications & equivalents
The 25877-25821-NTN is a ANSI ABMA 19.2 radial bearing sized 34.925 x 73.025 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 | 34.925 mm |
| Outer diameter D | 73.025 mm |
| Width B | 23.812 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 78.5 kN |
| Basic static load rating C0 | 85 kN |
| Limiting speed (mechanical) | 5300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 473 g |
| Manufacturer designation | NTN 4T-25877/25821 |
| 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 | 1.375 in |
|---|---|
| Outer diameter D | 2.875 in |
| Width B | 0.937 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 19.1 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) | 34 of 148 |
| Bore above smallest 4t-inch-series size | 22.224999999999998 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 25877-25820 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN cone 4T-25877 paired with a different cup (25820): cone interchangeable, cup differs — OD, assembled width T and ratings follow the cup. Verify the full cone/cup reference before substituting. |
| 25877-25821 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 34.925×73.025×23.812 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 25877-25821-NTN model number is decoded
For an inch shaft of 34.925 mm carrying combined radial and thrust load, NTN lists 4T-25877/25821, a single-row 4T tapered roller set of 78.5 kN C and 85 kN C0 inside the 73.025 mm OD cup. 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 25877/25821 without it. Selection: C 78.5 kN against C0 85 kN gives a C0/C ratio of 1.08 for the 34.925 mm bore; the pair is counted as one adjusted unit when checking L10 at the equivalent combined load. Cup-side note for 25821: within the pure-numeric inch family tables the 25877 cone is listed against several cup options, and it is the cup that fixes the 73.025 mm OD and the 23.812 mm assembled width — quote the full 25877/25821 pair, never the cone alone. NTN grades inch 4T bearings as open bearings without integral seals; at 34.925 mm bore the application supplies sealing and the grease fill or oil feed.
Typical equipment & failure modes
Common applications
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
- truck and trailer axle hubs on inch-dimensioned axles
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- preload loss and noise after one bearing of the adjusted pair is replaced without resetting end play
- false brinelling on a stationary pair exposed to vibration during transport or standby
- 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 34.925 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-25877/25821.
- The pure-numeric inch family at 34.925 mm bore (73.025×23.812 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 25877/25821 reference at purchase.
- Fit selection follows the rotating ring: a rotating cone on a 34.925 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- Inch and metric bores collide on paper — 34.925 mm is 1.375 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- Do not confuse T (23.812 mm, the assembled cone-plus-cup width) with the cone width when drawing spacers; an abutment sized to T leaves the cup unseated.
- The 78.5/85 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-25877/25821; 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-25877/25821?
4T-25877/25821 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 34.925 mm bore (1.375 in), 73.025 mm outside diameter and 23.812 mm assembled width T (2.875 × 0.937 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 78.5 kN, C0 85 kN, grease limiting speed 5,300 r/min, oil speed 7,100 r/min, mass about 473 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-25877/25821 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 25877 cone or the 25821 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 78.5/85 kN ratings change with the cup.
What is the difference between 4T-25877/25821 and a metric ISO 355 tapered bearing?
4T-25877/25821 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 34.925×73.025×23.812 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-25877/25821 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 25877/25821 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-25877/25821 list two speeds, 5,300 and 7,100 r/min?
The lower figure, 5,300 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-25877/25821 at 7,100 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.