M86643-M86610 bearing: complete specifications & equivalents
The M86643-M86610 is a ANSI ABMA 19.2 radial bearing sized 25.4 x 64.292 x 21.433 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 25.4 mm |
| Outer diameter D | 64.292 mm |
| Width B | 21.433 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 57.5 kN |
| Basic static load rating C0 | 64.5 kN |
| Limiting speed (mechanical) | 6100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 372 g |
| Manufacturer designation | NTN 4T-M86643/M86610 |
| 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 in |
|---|---|
| Outer diameter D | 2.531 in |
| Width B | 0.844 in |
| ISO bore code | 43 |
| Radial section height (D−d)/2 | 19.4 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) | 19 of 148 |
| Bore above smallest 4t-inch-series size | 12.7 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| M86643 | 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 M86643-M86610 model number is decoded
For an inch shaft of 25.4 mm carrying combined radial and thrust load, NTN lists 4T-M86643/M86610, a single-row 4T tapered roller set of 57.5 kN C and 64.5 kN C0 inside the 64.292 mm OD cup. Cone and cup of 4T-M86643/M86610 are separately stocked parts: a worn M86610 cup can be replaced against the existing M86643 cone, provided the new cup carries the identical reference — pairing across references changes the 21.433 mm assembled width and the rating. Selection: C 57.5 kN against C0 64.5 kN gives a C0/C ratio of 1.12 for the 25.4 mm bore; the pair is counted as one adjusted unit when checking L10 at the equivalent combined load. The printed 57.5/64.5 kN ratings belong to the assembled M86643+M86610 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. Running clearance of 4T-M86643/M86610 is set at mounting by axial displacement of cone or cup — the catalogue does not ship a preloaded set, so the drawing must state end play or preload.
Typical equipment & failure modes
Common applications
- construction-equipment pivot and wheel positions
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- false brinelling on a stationary pair exposed to vibration during transport or standby
- preload loss and noise after one bearing of the adjusted pair is replaced without resetting end play
- cage fatigue when the pair runs continuously near the grease limiting speed without oil cooling
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 25.4 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-M86643/M86610.
- The medium M family at 25.4 mm bore (64.292×21.433 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full M86643/M86610 reference at purchase.
- Grease packs must leave free volume inside the 21.433 mm-wide set; over-greasing a pair churning near the oil-band speed of 8,100 r/min raises temperature and destroys the setting.
- Shaft and housing fillets must clear the ring chamfers of M86643 and M86610; use undercut shoulders so the rings seat on the face, not on a radius.
- Inch and metric bores collide on paper — 25.4 mm is 1 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- The 57.5/64.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-M86643/M86610; 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-M86643/M86610?
4T-M86643/M86610 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 25.4 mm bore (1 in), 64.292 mm outside diameter and 21.433 mm assembled width T (2.531 × 0.844 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 57.5 kN, C0 64.5 kN, grease limiting speed 6,100 r/min, oil speed 8,100 r/min, mass about 372 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-M86643/M86610 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the M86643 cone or the M86610 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 57.5/64.5 kN ratings change with the cup.
What is the difference between 4T-M86643/M86610 and a metric ISO 355 tapered bearing?
4T-M86643/M86610 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 25.4×64.292×21.433 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-M86643/M86610 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 M86643/M86610 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-M86643/M86610 list two speeds, 6,100 and 8,100 r/min?
The lower figure, 6,100 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-M86643/M86610 at 8,100 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.