27691-27620 bearing: complete specifications & equivalents
The 27691-27620 is a ANSI ABMA 19.2 radial bearing sized 83.345 x 125.412 x 25.4 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 83.345 mm |
| Outer diameter D | 125.412 mm |
| Width B | 25.4 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 113 kN |
| Basic static load rating C0 | 163 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1040 g |
| Manufacturer designation | NTN 4T-27691/27620 |
| 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 | 3.281 in |
|---|---|
| Outer diameter D | 4.937 in |
| Width B | 1 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 21 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) | 100 of 148 |
| Bore above smallest 4t-inch-series size | 70.645 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 27691 | 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 27691-27620 model number is decoded
The NTN 2203E inch table prints 4T-27691/27620 at 83.345 mm bore (3.281 in), 125.412 mm cup OD and 25.4 mm assembled T, with a grease limiting speed of 2,700 r/min and an oil ceiling of 3,600 r/min. Cone and cup of 4T-27691/27620 are separately stocked parts: a worn 27620 cup can be replaced against the existing 27691 cone, provided the new cup carries the identical reference — pairing across references changes the 25.4 mm assembled width and the rating. The 1.4 kN of dynamic capacity per millimetre of bore summarises the 113 kN rating over the 83.345 mm bore — sanity-check any interchange candidate against this ratio and the 25.4 mm T. The printed 113/163 kN ratings belong to the assembled 27691+27620 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. With a rotating shaft a k5/m5 cone seat and an easy-push cup seat are typical practice for 4T-27691/27620; reverse the fit logic when the cup rotates.
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
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- cage damage from a mounting blow transmitted through the roller complement
- indentation of the raceways by hard particles in an open, unsealed arrangement
Selection pitfalls — read before you substitute
- Mount the 83.345 mm cone by induction heating (max 120 °C) and the 125.412 mm cup with a press sleeve; at 1040 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 83.345 mm bore (125.412×25.4 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 27691/27620 reference at purchase.
- ABMA makes the 83.345×125.412 mm envelope interchangeable, not the ratings: NTN prints 113/163 kN for this execution and another make of the same number can differ in roller complement.
- Quote the full 27691/27620 pair at ordering: the 27691 cone also ships against sibling cups, and a cup from another reference changes the 25.4 mm assembled width and the rating.
- Never drive the 125.412 mm cup home through the rollers: fitting force goes through the ring faces only, or brinell marks release as noise within the first running hours.
- The 113/163 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-27691/27620; 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-27691/27620?
4T-27691/27620 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 83.345 mm bore (3.281 in), 125.412 mm outside diameter and 25.4 mm assembled width T (4.937 × 1 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 113 kN, C0 163 kN, grease limiting speed 2,700 r/min, oil speed 3,600 r/min, mass about 1040 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-27691/27620 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 27691 cone or the 27620 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 113/163 kN ratings change with the cup.
What is the difference between 4T-27691/27620 and a metric ISO 355 tapered bearing?
4T-27691/27620 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 83.345×125.412×25.4 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-27691/27620 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 27691/27620 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-27691/27620 list two speeds, 2,700 and 3,600 r/min?
The lower figure, 2,700 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-27691/27620 at 3,600 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.