3975-3920 bearing: complete specifications & equivalents
The 3975-3920 is a ANSI ABMA 19.2 radial bearing sized 50.8 x 112.712 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 | 112.712 mm |
| Width B | 30.162 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 132 kN |
| Basic static load rating C0 | 174 kN |
| Limiting speed (mechanical) | 3200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1530 g |
| Manufacturer designation | NTN 4T-3975/3920 |
| 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 | 4.437 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 31 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 |
|---|---|---|---|
| 3975 | 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 3975-3920 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the order number 4T-3975/3920 denotes the pure-numeric inch family of NTN inch tapered roller bearings — cone 3975 and cup 3920 delivered as a matched, separable pair of 50.8 mm bore and 112.712 mm outside diameter. Cone and cup of 4T-3975/3920 are separately stocked parts: a worn 3920 cup can be replaced against the existing 3975 cone, provided the new cup carries the identical reference — pairing across references changes the 30.162 mm assembled width and the rating. Two single-row inch sets are normally mounted as an adjusted O or X pair; the 30.162 mm T of each 4T-3975/3920 enters the spacer calculation, so the tolerance on assembled width matters as much as the bore fit. Housing fitment sequence for 4T-3975/3920: press the 3920 cup square into the 112.712 mm seat first, then bring the 3975 cone (on its 50.8 mm shaft) into adjustment — the two references are separate engineering parts that happen to ship as one set. Fillet radii must clear the chamfers of the 3975 cone and 3920 cup; undercut shoulders seat the rings fully instead of bridging on a radius.
Typical equipment & failure modes
Common applications
- truck and trailer axle hubs on inch-dimensioned axles
- agricultural tractor transmission and PTO shafts
- industrial gearboxes built to inch shafting
- construction-equipment pivot and wheel positions
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- 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
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- edge loading when shaft deflection exceeds the few arc-minutes an adjusted pair tolerates
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-3975/3920.
- The pure-numeric inch family at 50.8 mm bore (112.712×30.162 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3975/3920 reference at purchase.
- An unloaded 4T-3975/3920 near 3,200 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded high-speed pairs.
- Replacing one half of an adjusted pair without resetting end play negates the 30.162 mm T logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- ABMA makes the 50.8×112.712 mm envelope interchangeable, not the ratings: NTN prints 132/174 kN for this execution and another make of the same number can differ in roller complement.
- The 132/174 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3975/3920; 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-3975/3920?
4T-3975/3920 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 50.8 mm bore (2 in), 112.712 mm outside diameter and 30.162 mm assembled width T (4.437 × 1.187 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 132 kN, C0 174 kN, grease limiting speed 3,200 r/min, oil speed 4,300 r/min, mass about 1530 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3975/3920 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3975 cone or the 3920 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 132/174 kN ratings change with the cup.
What is the difference between 4T-3975/3920 and a metric ISO 355 tapered bearing?
4T-3975/3920 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 50.8×112.712×30.162 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-3975/3920 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 3975/3920 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3975/3920 list two speeds, 3,200 and 4,300 r/min?
The lower figure, 3,200 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-3975/3920 at 4,300 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.