31597-31520 bearing: complete specifications & equivalents
The 31597-31520 is a ANSI ABMA 19.2 radial bearing sized 36.512 x 76.2 x 29.37 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 36.512 mm |
| Outer diameter D | 76.2 mm |
| Width B | 29.37 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 89.5 kN |
| Basic static load rating C0 | 97 kN |
| Limiting speed (mechanical) | 5100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 606 g |
| Manufacturer designation | NTN 4T-31597/31520 |
| 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 | 1.437 in |
|---|---|
| Outer diameter D | 3 in |
| Width B | 1.156 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 19.8 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) | 40 of 148 |
| Bore above smallest 4t-inch-series size | 23.812 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31597 | 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 31597-31520 model number is decoded
The NTN 2203E inch table prints 4T-31597/31520 at 36.512 mm bore (1.437 in), 76.2 mm cup OD and 29.37 mm assembled T, with a grease limiting speed of 5,100 r/min and an oil ceiling of 6,800 r/min. The 4T prefix is NTN's tapered roller quality mark stamped on both parts; it is a brand mark, not a size code, so cross-references quote 31597/31520 without it. Selection: C 89.5 kN against C0 97 kN gives a C0/C ratio of 1.08 for the 36.512 mm bore; the pair is counted as one adjusted unit when checking L10 at the equivalent combined load. The printed 89.5/97 kN ratings belong to the assembled 31597+31520 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 36.512 mm bore the application supplies sealing and the grease fill or oil feed.
Typical equipment & failure modes
Common applications
- construction-equipment pivot and wheel positions
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
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
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 36.512 mm class are adjusted in pairs; verify end play against the axle or gearbox drawing and re-torque after bedding-in instead of trusting the first setting on 4T-31597/31520.
- The pure-numeric inch family at 36.512 mm bore (76.2×29.37 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 31597/31520 reference at purchase.
- An unloaded 4T-31597/31520 near 5,100 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded high-speed pairs.
- Quote the full 31597/31520 pair at ordering: the 31597 cone also ships against sibling cups, and a cup from another reference changes the 29.37 mm assembled width and the rating.
- Inch and metric bores collide on paper — 36.512 mm is 1.437 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- The 89.5/97 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-31597/31520; 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-31597/31520?
4T-31597/31520 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 36.512 mm bore (1.437 in), 76.2 mm outside diameter and 29.37 mm assembled width T (3 × 1.156 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 89.5 kN, C0 97 kN, grease limiting speed 5,100 r/min, oil speed 6,800 r/min, mass about 606 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-31597/31520 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 31597 cone or the 31520 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 89.5/97 kN ratings change with the cup.
What is the difference between 4T-31597/31520 and a metric ISO 355 tapered bearing?
4T-31597/31520 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 36.512×76.2×29.37 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-31597/31520 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 31597/31520 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-31597/31520 list two speeds, 5,100 and 6,800 r/min?
The lower figure, 5,100 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-31597/31520 at 6,800 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.