3780-3726 bearing: complete specifications & equivalents
The 3780-3726 is a ANSI ABMA 19.2 radial bearing sized 50.8 x 95.25 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 | 50.8 mm |
| Outer diameter D | 95.25 mm |
| Width B | 30.162 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 | 134 kN |
| Limiting speed (mechanical) | 4000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 899 g |
| Manufacturer designation | NTN 4T-3780/3726 |
| 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 in |
|---|---|
| Outer diameter D | 3.75 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 22.2 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) | 64 of 148 |
| Bore above smallest 4t-inch-series size | 38.099999999999994 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3780-3720-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN cone 4T-3780 paired with a different cup (3720): cone interchangeable, cup differs — OD, assembled width T and ratings follow the cup. Verify the full cone/cup reference before substituting. |
| 3780-3732 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN cone 4T-3780 paired with a different cup (3732): cone interchangeable, cup differs — OD, assembled width T and ratings follow the cup. Verify the full cone/cup reference before substituting. |
| 3780-3720 | 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 3780-3726 model number is decoded
The NTN 2203E inch table prints 4T-3780/3726 at 50.8 mm bore (2 in), 95.25 mm cup OD and 30.162 mm assembled T, with a grease limiting speed of 4,000 r/min and an oil ceiling of 5,300 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 3780/3726 without it. Contact-angle geometry of the pure-numeric inch family gives 4T-3780/3726 its radial/axial load split — at 113/134 kN the static rating is about 1.19× C, typical of inch tapered sets proportioned for combined duty. The printed 113/134 kN ratings belong to the assembled 3780+3726 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. Back-to-back (O) and face-to-face (X) arrangements of two 4T-3780/3726 sets react differently to shaft bending; choose the orientation for the moment load before locking shoulder geometry.
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
- 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 fatigue when the pair runs continuously near the grease limiting speed without oil cooling
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 50.8 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-3780/3726.
- The pure-numeric inch family at 50.8 mm bore (95.25×30.162 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3780/3726 reference at purchase.
- ABMA makes the 50.8×95.25 mm envelope interchangeable, not the ratings: NTN prints 113/134 kN for this execution and another make of the same number can differ in roller complement.
- Fit selection follows the rotating ring: a rotating cone on a 50.8 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- An unloaded 4T-3780/3726 near 4,000 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded high-speed pairs.
- The 113/134 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3780/3726; 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-3780/3726?
4T-3780/3726 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 50.8 mm bore (2 in), 95.25 mm outside diameter and 30.162 mm assembled width T (3.75 × 1.187 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 113 kN, C0 134 kN, grease limiting speed 4,000 r/min, oil speed 5,300 r/min, mass about 899 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3780/3726 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3780 cone or the 3726 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 113/134 kN ratings change with the cup.
What is the difference between 4T-3780/3726 and a metric ISO 355 tapered bearing?
4T-3780/3726 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 50.8×95.25×30.162 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-3780/3726 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 3780/3726 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3780/3726 list two speeds, 4,000 and 5,300 r/min?
The lower figure, 4,000 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-3780/3726 at 5,300 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.