12580-12520 bearing: complete specifications & equivalents
The 12580-12520 is a ANSI ABMA 19.2 radial bearing sized 20.638 x 49.225 x 19.845 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 20.638 mm |
| Outer diameter D | 49.225 mm |
| Width B | 19.845 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 41.5 kN |
| Basic static load rating C0 | 39 kN |
| Limiting speed (mechanical) | 8200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 183 g |
| Manufacturer designation | NTN 4T-12580/12520 |
| 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 | 0.813 in |
|---|---|
| Outer diameter D | 1.938 in |
| Width B | 0.781 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 14.3 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) | 10 of 148 |
| Bore above smallest 4t-inch-series size | 7.938000000000002 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 12580 | 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 12580-12520 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the order number 4T-12580/12520 denotes the pure-numeric inch family of NTN inch tapered roller bearings — cone 12580 and cup 12520 delivered as a matched, separable pair of 20.638 mm bore and 49.225 mm outside diameter. Unlike ISO 355 metric numbers, this ABMA code does not encode the bore arithmetically: 12580 identifies the cone of 20.638 mm (0.813 in) bore by catalogue lookup, and 12520 fixes the 49.225 mm OD. The 2.0 kN of dynamic capacity per millimetre of bore summarises the 41.5 kN rating over the 20.638 mm bore — sanity-check any interchange candidate against this ratio and the 19.845 mm T. Housing fitment sequence for 4T-12580/12520: press the 12520 cup square into the 49.225 mm seat first, then bring the 12580 cone (on its 20.638 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. With a rotating shaft a k5/m5 cone seat and an easy-push cup seat are typical practice for 4T-12580/12520; reverse the fit logic when the cup rotates.
Typical equipment & failure modes
Common applications
- small agricultural implement wheels and auger drives
- lawn, garden and powersport axle positions
- small inch-shaft gearbox and reducer shafts
- conveyor roller and pulley shafts in inch-frame machinery
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
- cage fatigue when the pair runs continuously near the grease limiting speed without oil cooling
- edge loading when shaft deflection exceeds the few arc-minutes an adjusted pair tolerates
Selection pitfalls — read before you substitute
- At 20.638 mm (0.813 in) bore the thin cone and cup distort under an over-tight shaft nut; set the 4T-12580/12520 pair with a dial indicator on end play rather than by locknut feel.
- The pure-numeric inch family at 20.638 mm bore (49.225×19.845 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 12580/12520 reference at purchase.
- Grease packs must leave free volume inside the 19.845 mm-wide set; over-greasing a pair churning near the oil-band speed of 11,000 r/min raises temperature and destroys the setting.
- Replacing one half of an adjusted pair without resetting end play negates the 19.845 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Shaft and housing fillets must clear the ring chamfers of 12580 and 12520; use undercut shoulders so the rings seat on the face, not on a radius.
- The 41.5/39 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-12580/12520; 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-12580/12520?
4T-12580/12520 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 20.638 mm bore (0.813 in), 49.225 mm outside diameter and 19.845 mm assembled width T (1.938 × 0.781 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 41.5 kN, C0 39 kN, grease limiting speed 8,200 r/min, oil speed 11,000 r/min, mass about 183 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-12580/12520 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 12580 cone or the 12520 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 41.5/39 kN ratings change with the cup.
What is the difference between 4T-12580/12520 and a metric ISO 355 tapered bearing?
4T-12580/12520 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 20.638×49.225×19.845 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-12580/12520 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 12580/12520 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-12580/12520 list two speeds, 8,200 and 11,000 r/min?
The lower figure, 8,200 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-12580/12520 at 11,000 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.