687-672-NTN bearing: complete specifications & equivalents
The 687-672-NTN is a ANSI ABMA 19.2 radial bearing sized 101.6 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 | 101.6 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 | 3400 g |
| Manufacturer designation | NTN 4T-687/672 |
| 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 | 4 in |
|---|---|
| Outer diameter D | 6.625 in |
| Width B | 1.625 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 33.3 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) | 119 of 148 |
| Bore above smallest 4t-inch-series size | 88.89999999999999 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 687-672 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 101.6×168.275×41.275 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application 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 687-672-NTN model number is decoded
NTN supplies this 4 in (101.6 mm) shaft position as 4T-687/672: cone 687, cup 672, profiled rollers and a pressed-steel cage, rated 247 kN basic dynamic and 340 kN static. Reading the designation: 4T-687/672 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. Grease relubrication at the 2,100 r/min limiting speed targets the cone-rib contact; sustaining 2,800 r/min needs an oil supply directed at the large roller ends. Housing fitment sequence for 4T-687/672: press the 672 cup square into the 168.275 mm seat first, then bring the 687 cone (on its 101.6 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. NTN grades inch 4T bearings as open bearings without integral seals; at 101.6 mm bore the application supplies sealing and the grease fill or oil feed.
Typical equipment & failure modes
Common applications
- paper-machine and calender roll supports
- off-highway and forestry machine axles
- marine winch and deck-machinery shafts
- crusher and screening-plant eccentric shafts
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
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- Mount the 101.6 mm cone by induction heating (max 120 °C) and the 168.275 mm cup with a press sleeve; at 3400 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 101.6 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 687/672 reference at purchase.
- Inch and metric bores collide on paper — 101.6 mm is 4 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- Fit selection follows the rotating ring: a rotating cone on a 101.6 mm shaft takes a m6/n6 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- Shaft and housing fillets must clear the ring chamfers of 687 and 672; use undercut shoulders so the rings seat on the face, not on a radius.
- The 247/340 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-687/672; 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-687/672?
4T-687/672 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 101.6 mm bore (4 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 3400 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-687/672 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 687 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-687/672 and a metric ISO 355 tapered bearing?
4T-687/672 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 101.6×168.275×41.275 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-687/672 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 687/672 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-687/672 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-687/672 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.