3777-3720 bearing: complete specifications & equivalents
The 3777-3720 is a ANSI ABMA 19.2 radial bearing sized 46.038 x 93.264 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 | 46.038 mm |
| Outer diameter D | 93.264 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 | 934 g |
| Manufacturer designation | NTN 4T-3777/3720 |
| 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 | 1.813 in |
|---|---|
| Outer diameter D | 3.672 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 23.6 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) | 58 of 148 |
| Bore above smallest 4t-inch-series size | 33.337999999999994 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3777 | 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 3777-3720 model number is decoded
4T-3777/3720 is an NTN inch-series single-row tapered roller bearing: a separable cone-and-cup pair on the ABMA inch boundary plan, 46.038×93.264×30.162 mm (assembled width T), for a shaft of about 46.038 mm (1.813 in). Reading the designation: 4T-3777/3720 follows the ABMA inch convention — the number before the slash is the cone (inner ring with roller set and cage), the number after the slash is the cup (outer ring), and the pure-numeric inch family lettering ties the pair to its boundary plan. The 2.5 kN of dynamic capacity per millimetre of bore summarises the 113 kN rating over the 46.038 mm bore — sanity-check any interchange candidate against this ratio and the 30.162 mm T. The printed 113/134 kN ratings belong to the assembled 3777+3720 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-3777/3720 sets react differently to shaft bending; choose the orientation for the moment load before locking shoulder geometry.
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
- cup creep and housing fretting when the cup seat is cut too loose for the rotating load
- flaking on one cone only when a bent shaft loads the O/X pair unevenly
- cage damage from a mounting blow transmitted through the roller complement
- indentation of the raceways by hard particles in an open, unsealed arrangement
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 46.038 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-3777/3720.
- The pure-numeric inch family at 46.038 mm bore (93.264×30.162 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3777/3720 reference at purchase.
- Open 4T-3777/3720 sets have no seals: a hub or gearbox needs external sealing or the 4,000 r/min grease figure is meaningless once water reaches the cone rib.
- Never drive the 93.264 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.
- ABMA makes the 46.038×93.264 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.
- The 113/134 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3777/3720; 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-3777/3720?
4T-3777/3720 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 46.038 mm bore (1.813 in), 93.264 mm outside diameter and 30.162 mm assembled width T (3.672 × 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 934 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3777/3720 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3777 cone or the 3720 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-3777/3720 and a metric ISO 355 tapered bearing?
4T-3777/3720 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 46.038×93.264×30.162 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-3777/3720 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 3777/3720 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3777/3720 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-3777/3720 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.