6461A-6420 bearing: complete specifications & equivalents
The 6461A-6420 is a ANSI ABMA 19.2 radial bearing sized 76.2 x 149.225 x 53.975 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 76.2 mm |
| Outer diameter D | 149.225 mm |
| Width B | 53.975 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 320 kN |
| Basic static load rating C0 | 410 kN |
| Limiting speed (mechanical) | 2500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 4240 g |
| Manufacturer designation | NTN 4T-6461A/6420 |
| 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 | 3 in |
|---|---|
| Outer diameter D | 5.875 in |
| Width B | 2.125 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 36.5 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) | 94 of 148 |
| Bore above smallest 4t-inch-series size | 63.5 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6461A | 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 6461A-6420 model number is decoded
The NTN 2203E inch table prints 4T-6461A/6420 at 76.2 mm bore (3 in), 149.225 mm cup OD and 53.975 mm assembled T, with a grease limiting speed of 2,500 r/min and an oil ceiling of 3,400 r/min. Reading the designation: 4T-6461A/6420 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-6461A/6420 cone-plus-cup set is 4240 g; shaft and housing shoulders must carry that mass square to the axis during fitting. Housing fitment sequence for 4T-6461A/6420: press the 6420 cup square into the 149.225 mm seat first, then bring the 6461A cone (on its 76.2 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. A single-row tapered bearing reacts thrust in one direction only; 4T-6461A/6420 is adjusted against a second bearing so the shaft is located in both directions.
Typical equipment & failure modes
Common applications
- plant gearboxes on inch-dimensioned shaft lines
- large conveyor head pulleys in bulk-handling plant
- paper-machine and calender roll supports
- off-highway and forestry machine axles
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
- edge loading when shaft deflection exceeds the few arc-minutes an adjusted pair tolerates
Selection pitfalls — read before you substitute
- Mount the 76.2 mm cone by induction heating (max 120 °C) and the 149.225 mm cup with a press sleeve; at 4240 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 76.2 mm bore (149.225×53.975 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 6461A/6420 reference at purchase.
- Replacing one half of an adjusted pair without resetting end play negates the 53.975 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Quote the full 6461A/6420 pair at ordering: the 6461A cone also ships against sibling cups, and a cup from another reference changes the 53.975 mm assembled width and the rating.
- Quote the full 6461A/6420 pair at ordering: the 6461A cone also ships against sibling cups, and a cup from another reference changes the 53.975 mm assembled width and the rating.
- The 320/410 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-6461A/6420; 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-6461A/6420?
4T-6461A/6420 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 76.2 mm bore (3 in), 149.225 mm outside diameter and 53.975 mm assembled width T (5.875 × 2.125 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 320 kN, C0 410 kN, grease limiting speed 2,500 r/min, oil speed 3,400 r/min, mass about 4240 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-6461A/6420 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 6461A cone or the 6420 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 320/410 kN ratings change with the cup.
What is the difference between 4T-6461A/6420 and a metric ISO 355 tapered bearing?
4T-6461A/6420 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 76.2×149.225×53.975 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-6461A/6420 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 6461A/6420 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-6461A/6420 list two speeds, 2,500 and 3,400 r/min?
The lower figure, 2,500 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-6461A/6420 at 3,400 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.