28678-28622 bearing: complete specifications & equivalents
The 28678-28622 is a ANSI ABMA 19.2 radial bearing sized 50.8 x 97.63 x 24.608 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 50.8 mm |
| Outer diameter D | 97.63 mm |
| Width B | 24.608 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 98 kN |
| Basic static load rating C0 | 128 kN |
| Limiting speed (mechanical) | 3700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 854 g |
| Manufacturer designation | NTN 4T-28678/28622 |
| 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 in |
|---|---|
| Outer diameter D | 3.844 in |
| Width B | 0.969 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 23.4 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) | 64 of 148 |
| Bore above smallest 4t-inch-series size | 38.099999999999994 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 28678 | 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 28678-28622 model number is decoded
4T-28678/28622 is an NTN inch-series single-row tapered roller bearing: a separable cone-and-cup pair on the ABMA inch boundary plan, 50.8×97.63×24.608 mm (assembled width T), for a shaft of about 50.8 mm (2 in). Unlike ISO 355 metric numbers, this ABMA code does not encode the bore arithmetically: 28678 identifies the cone of 50.8 mm (2 in) bore by catalogue lookup, and 28622 fixes the 97.63 mm OD. Imperial cross-check for the drawing: 50.8×97.63×24.608 mm converts to 2 × 3.844 × 0.969 in; the ABMA envelope swaps with like-numbered inch parts but the 98/128 kN ratings are NTN-specific. Cup-side note for 28622: within the pure-numeric inch family tables the 28678 cone is listed against several cup options, and it is the cup that fixes the 97.63 mm OD and the 24.608 mm assembled width — quote the full 28678/28622 pair, never the cone alone. After bedding-in, re-check the end play of the adjusted 4T-28678/28622 pair — initial seating of the ring faces relaxes the setting slightly.
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
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- false brinelling on a stationary pair exposed to vibration during transport or standby
- preload loss and noise after one bearing of the adjusted pair is replaced without resetting end play
- 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 50.8 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-28678/28622.
- The pure-numeric inch family at 50.8 mm bore (97.63×24.608 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 28678/28622 reference at purchase.
- Never drive the 97.63 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.
- Grease packs must leave free volume inside the 24.608 mm-wide set; over-greasing a pair churning near the oil-band speed of 4,900 r/min raises temperature and destroys the setting.
- ABMA makes the 50.8×97.63 mm envelope interchangeable, not the ratings: NTN prints 98/128 kN for this execution and another make of the same number can differ in roller complement.
- The 98/128 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-28678/28622; 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-28678/28622?
4T-28678/28622 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 50.8 mm bore (2 in), 97.63 mm outside diameter and 24.608 mm assembled width T (3.844 × 0.969 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 98 kN, C0 128 kN, grease limiting speed 3,700 r/min, oil speed 4,900 r/min, mass about 854 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-28678/28622 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 28678 cone or the 28622 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 98/128 kN ratings change with the cup.
What is the difference between 4T-28678/28622 and a metric ISO 355 tapered bearing?
4T-28678/28622 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 50.8×97.63×24.608 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-28678/28622 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 28678/28622 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-28678/28622 list two speeds, 3,700 and 4,900 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-28678/28622 at 4,900 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.