3379-3320 bearing: complete specifications & equivalents
The 3379-3320 is a ANSI ABMA 19.2 radial bearing sized 34.925 x 80.167 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 | 34.925 mm |
| Outer diameter D | 80.167 mm |
| Width B | 29.37 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 105 kN |
| Basic static load rating C0 | 112 kN |
| Limiting speed (mechanical) | 4800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 736 g |
| Manufacturer designation | NTN 4T-3379/3320 |
| 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 | 1.375 in |
|---|---|
| Outer diameter D | 3.156 in |
| Width B | 1.156 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 22.6 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) | 34 of 148 |
| Bore above smallest 4t-inch-series size | 22.224999999999998 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3379 | 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 3379-3320 model number is decoded
4T-3379/3320 is the NTN 4T catalogue entry for a 34.925×80.167×29.37 mm inch tapered roller bearing — an ABMA-dimensioned cone/cup set, not an ISO 355 metric bearing, even though the table quotes metric equivalents. 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 3379/3320 without it. Imperial cross-check for the drawing: 34.925×80.167×29.37 mm converts to 1.375 × 3.156 × 1.156 in; the ABMA envelope swaps with like-numbered inch parts but the 105/112 kN ratings are NTN-specific. Cup-side note for 3320: within the pure-numeric inch family tables the 3379 cone is listed against several cup options, and it is the cup that fixes the 80.167 mm OD and the 29.37 mm assembled width — quote the full 3379/3320 pair, never the cone alone. Contact-pattern check with marking blue: a pattern biased to one roller end means the 34.925 mm pair is misadjusted and the set will edge-load in service.
Typical equipment & failure modes
Common applications
- agricultural tractor transmission and PTO shafts
- industrial gearboxes built to inch shafting
- construction-equipment pivot and wheel positions
- mining and quarry conveyor drive pulleys
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
- cage fatigue when the pair runs continuously near the grease limiting speed without oil cooling
- brinell marks on cone and cup raceways from impact during handling or hammer fitting
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 34.925 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-3379/3320.
- The pure-numeric inch family at 34.925 mm bore (80.167×29.37 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3379/3320 reference at purchase.
- ABMA makes the 34.925×80.167 mm envelope interchangeable, not the ratings: NTN prints 105/112 kN for this execution and another make of the same number can differ in roller complement.
- Grease packs must leave free volume inside the 29.37 mm-wide set; over-greasing a pair churning near the oil-band speed of 6,400 r/min raises temperature and destroys the setting.
- Replacing one half of an adjusted pair without resetting end play negates the 29.37 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- The 105/112 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3379/3320; 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-3379/3320?
4T-3379/3320 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 34.925 mm bore (1.375 in), 80.167 mm outside diameter and 29.37 mm assembled width T (3.156 × 1.156 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 105 kN, C0 112 kN, grease limiting speed 4,800 r/min, oil speed 6,400 r/min, mass about 736 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3379/3320 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3379 cone or the 3320 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 105/112 kN ratings change with the cup.
What is the difference between 4T-3379/3320 and a metric ISO 355 tapered bearing?
4T-3379/3320 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 34.925×80.167×29.37 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-3379/3320 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 3379/3320 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3379/3320 list two speeds, 4,800 and 6,400 r/min?
The lower figure, 4,800 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-3379/3320 at 6,400 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.