495AS-493 bearing: complete specifications & equivalents
The 495AS-493 is a ANSI ABMA 19.2 radial bearing sized 77.788 x 136.525 x 30.162 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 77.788 mm |
| Outer diameter D | 136.525 mm |
| Width B | 30.162 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 143 kN |
| Basic static load rating C0 | 189 kN |
| Limiting speed (mechanical) | 2600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1780 g |
| Manufacturer designation | NTN 4T-495AS/493 |
| 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 | 3.063 in |
|---|---|
| Outer diameter D | 5.375 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 29.4 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) | 95 of 148 |
| Bore above smallest 4t-inch-series size | 65.088 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 495AS | 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 495AS-493 model number is decoded
4T-495AS/493 belongs to the NTN inch 4T tapered roller range (pure-numeric inch family); cone and cup are ordered by their own references and are individually interchangeable with like-numbered parts. 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 495AS/493 without it. Grease relubrication at the 2,600 r/min limiting speed targets the cone-rib contact; sustaining 3,500 r/min needs an oil supply directed at the large roller ends. Cup-side note for 493: within the pure-numeric inch family tables the 495AS cone is listed against several cup options, and it is the cup that fixes the 136.525 mm OD and the 30.162 mm assembled width — quote the full 495AS/493 pair, never the cone alone. Mount the 77.788 mm cone with an induction heater (max 120 °C) and press the 136.525 mm cup with a sleeve; driving either ring through the rollers brinells the raceways.
Typical equipment & failure modes
Common applications
- crusher and screening-plant eccentric shafts
- heavy truck and bus drive-axle differentials
- plant gearboxes on inch-dimensioned shaft lines
- large conveyor head pulleys in bulk-handling plant
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
- 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 77.788 mm cone by induction heating (max 120 °C) and the 136.525 mm cup with a press sleeve; at 1780 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 77.788 mm bore (136.525×30.162 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 495AS/493 reference at purchase.
- Open 4T-495AS/493 sets have no seals: a hub or gearbox needs external sealing or the 2,600 r/min grease figure is meaningless once water reaches the cone rib.
- ABMA makes the 77.788×136.525 mm envelope interchangeable, not the ratings: NTN prints 143/189 kN for this execution and another make of the same number can differ in roller complement.
- Inch and metric bores collide on paper — 77.788 mm is 3.063 in, not a round metric size; a metric bearing that seems 0.1 mm off will not seat on the inch shaft.
- The 143/189 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-495AS/493; 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-495AS/493?
4T-495AS/493 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 77.788 mm bore (3.063 in), 136.525 mm outside diameter and 30.162 mm assembled width T (5.375 × 1.187 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 143 kN, C0 189 kN, grease limiting speed 2,600 r/min, oil speed 3,500 r/min, mass about 1780 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-495AS/493 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 495AS cone or the 493 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 143/189 kN ratings change with the cup.
What is the difference between 4T-495AS/493 and a metric ISO 355 tapered bearing?
4T-495AS/493 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 77.788×136.525×30.162 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-495AS/493 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 495AS/493 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-495AS/493 list two speeds, 2,600 and 3,500 r/min?
The lower figure, 2,600 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-495AS/493 at 3,500 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.