3875-3820 bearing: complete specifications & equivalents
The 3875-3820 is a ANSI ABMA 19.2 radial bearing sized 38.1 x 85.725 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 | 38.1 mm |
| Outer diameter D | 85.725 mm |
| Width B | 30.162 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 116 kN |
| Basic static load rating C0 | 132 kN |
| Limiting speed (mechanical) | 4500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 861 g |
| Manufacturer designation | NTN 4T-3875/3820 |
| 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 | 1.5 in |
|---|---|
| Outer diameter D | 3.375 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 23.8 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) | 42 of 148 |
| Bore above smallest 4t-inch-series size | 25.400000000000002 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3875 | 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 3875-3820 model number is decoded
The NTN 2203E inch table prints 4T-3875/3820 at 38.1 mm bore (1.5 in), 85.725 mm cup OD and 30.162 mm assembled T, with a grease limiting speed of 4,500 r/min and an oil ceiling of 6,000 r/min. Letter prefixes inherited from the inch convention mark the load family: LM reads as light-medium, HM as heavy-medium, LL as extra-light, J-prefixed codes as metric-envelope families — 3875 sits in the pure-numeric inch family. Contact-angle geometry of the pure-numeric inch family gives 4T-3875/3820 its radial/axial load split — at 116/132 kN the static rating is about 1.14× C, typical of inch tapered sets proportioned for combined duty. Housing fitment sequence for 4T-3875/3820: press the 3820 cup square into the 85.725 mm seat first, then bring the 3875 cone (on its 38.1 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. The rollers run with their large ends against the cone's guide rib; lubricant must reach that rib face of 4T-3875/3820, not only the raceway, or the pair smears on the first overloaded start.
Typical equipment & failure modes
Common applications
- industrial gearboxes built to inch shafting
- construction-equipment pivot and wheel positions
- mining and quarry conveyor drive pulleys
- machine-tool headstocks on inch spindles
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
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 38.1 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-3875/3820.
- The pure-numeric inch family at 38.1 mm bore (85.725×30.162 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3875/3820 reference at purchase.
- An unloaded 4T-3875/3820 near 4,500 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded high-speed pairs.
- ABMA makes the 38.1×85.725 mm envelope interchangeable, not the ratings: NTN prints 116/132 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 38.1 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- The 116/132 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3875/3820; 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-3875/3820?
4T-3875/3820 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 38.1 mm bore (1.5 in), 85.725 mm outside diameter and 30.162 mm assembled width T (3.375 × 1.187 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 116 kN, C0 132 kN, grease limiting speed 4,500 r/min, oil speed 6,000 r/min, mass about 861 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3875/3820 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3875 cone or the 3820 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 116/132 kN ratings change with the cup.
What is the difference between 4T-3875/3820 and a metric ISO 355 tapered bearing?
4T-3875/3820 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 38.1×85.725×30.162 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-3875/3820 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 3875/3820 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3875/3820 list two speeds, 4,500 and 6,000 r/min?
The lower figure, 4,500 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-3875/3820 at 6,000 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.