2789-2720 bearing: complete specifications & equivalents
The 2789-2720 is a ANSI ABMA 19.2 radial bearing sized 39.688 x 76.2 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 | 39.688 mm |
| Outer diameter D | 76.2 mm |
| Width B | 23.812 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 81 kN |
| Basic static load rating C0 | 90.5 kN |
| Limiting speed (mechanical) | 5100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 475 g |
| Manufacturer designation | NTN 4T-2789/2720 |
| 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 | 1.563 in |
|---|---|
| Outer diameter D | 3 in |
| Width B | 0.937 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 18.3 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) | 43 of 148 |
| Bore above smallest 4t-inch-series size | 26.988000000000003 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 2789-2729 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 39.688×76.2×23.812 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 2789-2720 model number is decoded
4T-2789/2720 belongs to the NTN inch 4T tapered roller range (pure-numeric inch family); cone and cup are ordered by their own references and are individually interchangeable with like-numbered parts. Reading the designation: 4T-2789/2720 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. Catalogue mass of the 4T-2789/2720 cone-plus-cup set is 475 g; shaft and housing shoulders must carry that mass square to the axis during fitting. Housing fitment sequence for 4T-2789/2720: press the 2720 cup square into the 76.2 mm seat first, then bring the 2789 cone (on its 39.688 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. Fillet radii must clear the chamfers of the 2789 cone and 2720 cup; undercut shoulders seat the rings fully instead of bridging on a radius.
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
- 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
- cage damage from a mounting blow transmitted through the roller complement
- edge loading when shaft deflection exceeds the few arc-minutes an adjusted pair tolerates
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 39.688 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-2789/2720.
- The pure-numeric inch family at 39.688 mm bore (76.2×23.812 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 2789/2720 reference at purchase.
- ABMA makes the 39.688×76.2 mm envelope interchangeable, not the ratings: NTN prints 81/90.5 kN for this execution and another make of the same number can differ in roller complement.
- Open 4T-2789/2720 sets have no seals: a hub or gearbox needs external sealing or the 5,100 r/min grease figure is meaningless once water reaches the cone rib.
- An unloaded 4T-2789/2720 near 5,100 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded high-speed pairs.
- The 81/90.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-2789/2720; 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-2789/2720?
4T-2789/2720 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 39.688 mm bore (1.563 in), 76.2 mm outside diameter and 23.812 mm assembled width T (3 × 0.937 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 81 kN, C0 90.5 kN, grease limiting speed 5,100 r/min, oil speed 6,800 r/min, mass about 475 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-2789/2720 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 2789 cone or the 2720 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 81/90.5 kN ratings change with the cup.
What is the difference between 4T-2789/2720 and a metric ISO 355 tapered bearing?
4T-2789/2720 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 39.688×76.2×23.812 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-2789/2720 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 2789/2720 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-2789/2720 list two speeds, 5,100 and 6,800 r/min?
The lower figure, 5,100 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-2789/2720 at 6,800 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.