28990-28920 bearing: complete specifications & equivalents
The 28990-28920 is a ANSI ABMA 19.2 radial bearing sized 61.976 x 101.6 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 | 61.976 mm |
| Outer diameter D | 101.6 mm |
| Width B | 24.608 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 100 kN |
| Basic static load rating C0 | 134 kN |
| Limiting speed (mechanical) | 3500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 766 g |
| Manufacturer designation | NTN 4T-28990/28920 |
| 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 | 2.44 in |
|---|---|
| Outer diameter D | 4 in |
| Width B | 0.969 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 19.8 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) | 79 of 148 |
| Bore above smallest 4t-inch-series size | 49.275999999999996 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 28990 | 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 28990-28920 model number is decoded
For an inch shaft of 61.976 mm carrying combined radial and thrust load, NTN lists 4T-28990/28920, a single-row 4T tapered roller set of 100 kN C and 134 kN C0 inside the 101.6 mm OD cup. Unlike ISO 355 metric numbers, this ABMA code does not encode the bore arithmetically: 28990 identifies the cone of 61.976 mm (2.44 in) bore by catalogue lookup, and 28920 fixes the 101.6 mm OD. The 19.8 mm radial section over the 61.976 mm bore positions the contact line of the pair; abutment shoulders and spacers are dimensioned from that geometry, not from the bore alone. Cup-side note for 28920: within the pure-numeric inch family tables the 28990 cone is listed against several cup options, and it is the cup that fixes the 101.6 mm OD and the 24.608 mm assembled width — quote the full 28990/28920 pair, never the cone alone. Minimum load matters at speed: an unloaded 4T-28990/28920 run near 3,500 r/min lets the rollers skid; lightly spring-preload high-speed pair arrangements.
Typical equipment & failure modes
Common applications
- marine winch and deck-machinery shafts
- crusher and screening-plant eccentric shafts
- heavy truck and bus drive-axle differentials
- plant gearboxes on inch-dimensioned shaft lines
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- 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
- brinell marks on cone and cup raceways from impact during handling or hammer fitting
Selection pitfalls — read before you substitute
- Mount the 61.976 mm cone by induction heating (max 120 °C) and the 101.6 mm cup with a press sleeve; at 766 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 61.976 mm bore (101.6×24.608 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 28990/28920 reference at purchase.
- Inch and metric bores collide on paper — 61.976 mm is 2.44 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- Never drive the 101.6 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.
- Quote the full 28990/28920 pair at ordering: the 28990 cone also ships against sibling cups, and a cup from another reference changes the 24.608 mm assembled width and the rating.
- The 100/134 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-28990/28920; 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-28990/28920?
4T-28990/28920 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 61.976 mm bore (2.44 in), 101.6 mm outside diameter and 24.608 mm assembled width T (4 × 0.969 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 100 kN, C0 134 kN, grease limiting speed 3,500 r/min, oil speed 4,700 r/min, mass about 766 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-28990/28920 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 28990 cone or the 28920 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 100/134 kN ratings change with the cup.
What is the difference between 4T-28990/28920 and a metric ISO 355 tapered bearing?
4T-28990/28920 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 61.976×101.6×24.608 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-28990/28920 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 28990/28920 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-28990/28920 list two speeds, 3,500 and 4,700 r/min?
The lower figure, 3,500 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-28990/28920 at 4,700 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.