M12649-M12610 bearing: complete specifications & equivalents
The M12649-M12610 is a ANSI ABMA 19.2 radial bearing sized 21.43 x 50.005 x 17.526 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 21.43 mm |
| Outer diameter D | 50.005 mm |
| Width B | 17.526 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 42 kN |
| Basic static load rating C0 | 39 kN |
| Limiting speed (mechanical) | 8000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 169 g |
| Manufacturer designation | NTN 4T-M12649/M12610 |
| 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 | 0.844 in |
|---|---|
| Outer diameter D | 1.969 in |
| Width B | 0.69 in |
| ISO bore code | 49 |
| 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) | 11 of 148 |
| Bore above smallest 4t-inch-series size | 8.73 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| M12649-610 | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 M12649-M12610 model number is decoded
4T-M12649/M12610 belongs to the NTN inch 4T tapered roller range (medium M family); cone and cup are ordered by their own references and are individually interchangeable with like-numbered parts. Reading the designation: 4T-M12649/M12610 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 medium M family lettering ties the pair to its boundary plan. Contact-angle geometry of the medium M family gives 4T-M12649/M12610 its radial/axial load split — at 42/39 kN the static rating is about 0.93× C, typical of inch tapered sets proportioned for combined duty. The printed 42/39 kN ratings belong to the assembled M12649+M12610 pair; a sibling row using the same cone with a different cup carries its own rating row because the raceway track shifts with the cup. Mount the 21.43 mm cone with an induction heater (max 120 °C) and press the 50.005 mm cup with a sleeve; driving either ring through the rollers brinells the raceways.
Typical equipment & failure modes
Common applications
- small machine-tool feed and spindle counter-supports
- light trailer and boat-trailer wheel hubs
- small agricultural implement wheels and auger drives
- lawn, garden and powersport axle positions
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- 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
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- At 21.43 mm (0.844 in) bore the thin cone and cup distort under an over-tight shaft nut; set the 4T-M12649/M12610 pair with a dial indicator on end play rather than by locknut feel.
- The medium M family at 21.43 mm bore (50.005×17.526 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full M12649/M12610 reference at purchase.
- Replacing one half of an adjusted pair without resetting end play negates the 17.526 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- ABMA makes the 21.43×50.005 mm envelope interchangeable, not the ratings: NTN prints 42/39 kN for this execution and another make of the same number can differ in roller complement.
- Inch and metric bores collide on paper — 21.43 mm is 0.844 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- The 42/39 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-M12649/M12610; 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-M12649/M12610?
4T-M12649/M12610 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 21.43 mm bore (0.844 in), 50.005 mm outside diameter and 17.526 mm assembled width T (1.969 × 0.69 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 42 kN, C0 39 kN, grease limiting speed 8,000 r/min, oil speed 11,000 r/min, mass about 169 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-M12649/M12610 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the M12649 cone or the M12610 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 42/39 kN ratings change with the cup.
What is the difference between 4T-M12649/M12610 and a metric ISO 355 tapered bearing?
4T-M12649/M12610 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 21.43×50.005×17.526 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-M12649/M12610 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 M12649/M12610 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-M12649/M12610 list two speeds, 8,000 and 11,000 r/min?
The lower figure, 8,000 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-M12649/M12610 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.