685-672 bearing: complete specifications & equivalents
The 685-672 is a ANSI ABMA 19.2 radial bearing sized 98.425 x 168.275 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 | 98.425 mm |
| Outer diameter D | 168.275 mm |
| Width B | 41.275 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 247 kN |
| Basic static load rating C0 | 340 kN |
| Limiting speed (mechanical) | 2100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3570 g |
| Manufacturer designation | NTN 4T-685/672 |
| 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 | 3.875 in |
|---|---|
| Outer diameter D | 6.625 in |
| Width B | 1.625 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 34.9 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) | 115 of 148 |
| Bore above smallest 4t-inch-series size | 85.725 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 685 | 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 685-672 model number is decoded
4T-685/672 is the NTN 4T catalogue entry for a 98.425×168.275×41.275 mm inch tapered roller bearing — an ABMA-dimensioned cone/cup set, not an ISO 355 metric bearing, even though the table quotes metric equivalents. Cone and cup of 4T-685/672 are separately stocked parts: a worn 672 cup can be replaced against the existing 685 cone, provided the new cup carries the identical reference — pairing across references changes the 41.275 mm assembled width and the rating. Catalogue mass of the 4T-685/672 cone-plus-cup set is 3570 g; shaft and housing shoulders must carry that mass square to the axis during fitting. The printed 247/340 kN ratings belong to the assembled 685+672 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. NTN grades inch 4T bearings as open bearings without integral seals; at 98.425 mm bore the application supplies sealing and the grease fill or oil feed.
Typical equipment & failure modes
Common applications
- marine winch and deck-machinery shafts
- crusher and screening-plant eccentric shafts
- heavy truck and bus drive-axle differentials
- plant gearboxes on inch-dimensioned shaft lines
Known failure patterns
- rib-face scoring when the thrust share of the combined load exceeds what the cone rib of this size carries
- 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
- indentation of the raceways by hard particles in an open, unsealed arrangement
Selection pitfalls — read before you substitute
- Mount the 98.425 mm cone by induction heating (max 120 °C) and the 168.275 mm cup with a press sleeve; at 3570 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 98.425 mm bore (168.275×41.275 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 685/672 reference at purchase.
- Quote the full 685/672 pair at ordering: the 685 cone also ships against sibling cups, and a cup from another reference changes the 41.275 mm assembled width and the rating.
- Quote the full 685/672 pair at ordering: the 685 cone also ships against sibling cups, and a cup from another reference changes the 41.275 mm assembled width and the rating.
- Inch and metric bores collide on paper — 98.425 mm is 3.875 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- The 247/340 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-685/672; 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-685/672?
4T-685/672 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 98.425 mm bore (3.875 in), 168.275 mm outside diameter and 41.275 mm assembled width T (6.625 × 1.625 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 247 kN, C0 340 kN, grease limiting speed 2,100 r/min, oil speed 2,800 r/min, mass about 3570 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-685/672 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 685 cone or the 672 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 247/340 kN ratings change with the cup.
What is the difference between 4T-685/672 and a metric ISO 355 tapered bearing?
4T-685/672 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 98.425×168.275×41.275 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-685/672 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 685/672 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-685/672 list two speeds, 2,100 and 2,800 r/min?
The lower figure, 2,100 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-685/672 at 2,800 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.