641-633 bearing: complete specifications & equivalents
The 641-633 is a ANSI ABMA 19.2 radial bearing sized 66.675 x 130.175 x 41.275 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 66.675 mm |
| Outer diameter D | 130.175 mm |
| Width B | 41.275 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 215 kN |
| Basic static load rating C0 | 262 kN |
| Limiting speed (mechanical) | 2800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2410 g |
| Manufacturer designation | NTN 4T-641/633 |
| 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 | 2.625 in |
|---|---|
| Outer diameter D | 5.125 in |
| Width B | 1.625 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 31.8 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) | 84 of 148 |
| Bore above smallest 4t-inch-series size | 53.974999999999994 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 641-632 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN cone 4T-641 paired with a different cup (632): cone interchangeable, cup differs — OD, assembled width T and ratings follow the cup. Verify the full cone/cup reference before substituting. |
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 641-633 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the order number 4T-641/633 denotes the pure-numeric inch family of NTN inch tapered roller bearings — cone 641 and cup 633 delivered as a matched, separable pair of 66.675 mm bore and 130.175 mm outside diameter. Reading the designation: 4T-641/633 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. The 31.8 mm radial section over the 66.675 mm bore positions the contact line of the pair; abutment shoulders and spacers are dimensioned from that geometry, not from the bore alone. Cup-side note for 633: within the pure-numeric inch family tables the 641 cone is listed against several cup options, and it is the cup that fixes the 130.175 mm OD and the 41.275 mm assembled width — quote the full 641/633 pair, never the cone alone. A single-row tapered bearing reacts thrust in one direction only; 4T-641/633 is adjusted against a second bearing so the shaft is located in both directions.
Typical equipment & failure modes
Common applications
- off-highway and forestry machine axles
- marine winch and deck-machinery shafts
- crusher and screening-plant eccentric shafts
- heavy truck and bus drive-axle differentials
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- preload loss and noise after one bearing of the adjusted pair is replaced without resetting end play
- false brinelling on a stationary pair exposed to vibration during transport or standby
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- rolling-contact fatigue spalling after the catalogue L10 life at the actual combined load
Selection pitfalls — read before you substitute
- Mount the 66.675 mm cone by induction heating (max 120 °C) and the 130.175 mm cup with a press sleeve; at 2410 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 66.675 mm bore (130.175×41.275 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 641/633 reference at purchase.
- Grease packs must leave free volume inside the 41.275 mm-wide set; over-greasing a pair churning near the oil-band speed of 3,800 r/min raises temperature and destroys the setting.
- Shaft and housing fillets must clear the ring chamfers of 641 and 633; use undercut shoulders so the rings seat on the face, not on a radius.
- ABMA makes the 66.675×130.175 mm envelope interchangeable, not the ratings: NTN prints 215/262 kN for this execution and another make of the same number can differ in roller complement.
- The 215/262 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-641/633; 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-641/633?
4T-641/633 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 66.675 mm bore (2.625 in), 130.175 mm outside diameter and 41.275 mm assembled width T (5.125 × 1.625 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 215 kN, C0 262 kN, grease limiting speed 2,800 r/min, oil speed 3,800 r/min, mass about 2410 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-641/633 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 641 cone or the 633 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 215/262 kN ratings change with the cup.
What is the difference between 4T-641/633 and a metric ISO 355 tapered bearing?
4T-641/633 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 66.675×130.175×41.275 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-641/633 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 641/633 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-641/633 list two speeds, 2,800 and 3,800 r/min?
The lower figure, 2,800 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-641/633 at 3,800 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.