1280-1220 bearing: complete specifications & equivalents
The 1280-1220 is a ANSI ABMA 19.2 radial bearing sized 22.225 x 57.15 x 22.225 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 22.225 mm |
| Outer diameter D | 57.15 mm |
| Width B | 22.225 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 52.5 kN |
| Basic static load rating C0 | 49.5 kN |
| Limiting speed (mechanical) | 7100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 287 g |
| Manufacturer designation | NTN 4T-1280/1220 |
| 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 | 0.875 in |
|---|---|
| Outer diameter D | 2.25 in |
| Width B | 0.875 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 17.5 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) | 13 of 148 |
| Bore above smallest 4t-inch-series size | 9.525000000000002 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 1280 | 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 1280-1220 model number is decoded
4T-1280/1220 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. Unlike ISO 355 metric numbers, this ABMA code does not encode the bore arithmetically: 1280 identifies the cone of 22.225 mm (0.875 in) bore by catalogue lookup, and 1220 fixes the 57.15 mm OD. Contact-angle geometry of the pure-numeric inch family gives 4T-1280/1220 its radial/axial load split — at 52.5/49.5 kN the static rating is about 0.94× C, typical of inch tapered sets proportioned for combined duty. Housing fitment sequence for 4T-1280/1220: press the 1220 cup square into the 57.15 mm seat first, then bring the 1280 cone (on its 22.225 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. Minimum load matters at speed: an unloaded 4T-1280/1220 run near 7,100 r/min lets the rollers skid; lightly spring-preload high-speed pair arrangements.
Typical equipment & failure modes
Common applications
- small inch-shaft gearbox and reducer shafts
- conveyor roller and pulley shafts in inch-frame machinery
- utility-vehicle differential and pinion supports
- small machine-tool feed and spindle counter-supports
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- 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
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- edge loading when shaft deflection exceeds the few arc-minutes an adjusted pair tolerates
Selection pitfalls — read before you substitute
- At 22.225 mm (0.875 in) bore the thin cone and cup distort under an over-tight shaft nut; set the 4T-1280/1220 pair with a dial indicator on end play rather than by locknut feel.
- The pure-numeric inch family at 22.225 mm bore (57.15×22.225 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 1280/1220 reference at purchase.
- Fit selection follows the rotating ring: a rotating cone on a 22.225 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- Never drive the 57.15 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 1280/1220 pair at ordering: the 1280 cone also ships against sibling cups, and a cup from another reference changes the 22.225 mm assembled width and the rating.
- The 52.5/49.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-1280/1220; 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-1280/1220?
4T-1280/1220 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 22.225 mm bore (0.875 in), 57.15 mm outside diameter and 22.225 mm assembled width T (2.25 × 0.875 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 52.5 kN, C0 49.5 kN, grease limiting speed 7,100 r/min, oil speed 9,500 r/min, mass about 287 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-1280/1220 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 1280 cone or the 1220 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 52.5/49.5 kN ratings change with the cup.
What is the difference between 4T-1280/1220 and a metric ISO 355 tapered bearing?
4T-1280/1220 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 22.225×57.15×22.225 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-1280/1220 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 1280/1220 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-1280/1220 list two speeds, 7,100 and 9,500 r/min?
The lower figure, 7,100 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-1280/1220 at 9,500 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.