6386-6320 bearing: complete specifications & equivalents
The 6386-6320 is a ANSI ABMA 19.2 radial bearing sized 66.675 x 135.755 x 53.975 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 66.675 mm |
| Outer diameter D | 135.755 mm |
| Width B | 53.975 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 310 kN |
| Basic static load rating C0 | 380 kN |
| Limiting speed (mechanical) | 2900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3640 g |
| Manufacturer designation | NTN 4T-6386/6320 |
| 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 | 2.625 in |
|---|---|
| Outer diameter D | 5.345 in |
| Width B | 2.125 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 34.5 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) | 84 of 148 |
| Bore above smallest 4t-inch-series size | 53.974999999999994 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 6386-K-6320 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Model-number interchange per ISO 15; confirm dimensions, sealing and ratings in the supplier catalogue. |
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 6386-6320 model number is decoded
The NTN 2203E inch table prints 4T-6386/6320 at 66.675 mm bore (2.625 in), 135.755 mm cup OD and 53.975 mm assembled T, with a grease limiting speed of 2,900 r/min and an oil ceiling of 3,800 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 6386/6320 without it. Contact-angle geometry of the pure-numeric inch family gives 4T-6386/6320 its radial/axial load split — at 310/380 kN the static rating is about 1.23× C, typical of inch tapered sets proportioned for combined duty. The printed 310/380 kN ratings belong to the assembled 6386+6320 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. Mount the 66.675 mm cone with an induction heater (max 120 °C) and press the 135.755 mm cup with a sleeve; driving either ring through the rollers brinells the raceways.
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
- 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
- cage damage from a mounting blow transmitted through the roller complement
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- Mount the 66.675 mm cone by induction heating (max 120 °C) and the 135.755 mm cup with a press sleeve; at 3640 g a cocked ring brinells the raceway directly.
- The pure-numeric inch family at 66.675 mm bore (135.755×53.975 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 6386/6320 reference at purchase.
- Shaft and housing fillets must clear the ring chamfers of 6386 and 6320; use undercut shoulders so the rings seat on the face, not on a radius.
- Never drive the 135.755 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.
- Open 4T-6386/6320 sets have no seals: a hub or gearbox needs external sealing or the 2,900 r/min grease figure is meaningless once water reaches the cone rib.
- The 310/380 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-6386/6320; 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-6386/6320?
4T-6386/6320 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 66.675 mm bore (2.625 in), 135.755 mm outside diameter and 53.975 mm assembled width T (5.345 × 2.125 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 310 kN, C0 380 kN, grease limiting speed 2,900 r/min, oil speed 3,800 r/min, mass about 3640 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-6386/6320 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 6386 cone or the 6320 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 310/380 kN ratings change with the cup.
What is the difference between 4T-6386/6320 and a metric ISO 355 tapered bearing?
4T-6386/6320 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 66.675×135.755×53.975 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-6386/6320 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 6386/6320 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-6386/6320 list two speeds, 2,900 and 3,800 r/min?
The lower figure, 2,900 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-6386/6320 at 3,800 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.