3578-3525 bearing: complete specifications & equivalents
The 3578-3525 is a ANSI ABMA 19.2 radial bearing sized 44.45 x 87.312 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 | 44.45 mm |
| Outer diameter D | 87.312 mm |
| Width B | 30.162 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 104 kN |
| Basic static load rating C0 | 117 kN |
| Limiting speed (mechanical) | 4400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 780 g |
| Manufacturer designation | NTN 4T-3578/3525 |
| 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 | 1.75 in |
|---|---|
| Outer diameter D | 3.437 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 21.4 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) | 51 of 148 |
| Bore above smallest 4t-inch-series size | 31.750000000000004 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3578-3520 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN cone 4T-3578 paired with a different cup (3520): cone interchangeable, cup differs — OD, assembled width T and ratings follow the cup. Verify the full cone/cup reference before substituting. |
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 3578-3525 model number is decoded
NTN supplies this 1.75 in (44.45 mm) shaft position as 4T-3578/3525: cone 3578, cup 3525, profiled rollers and a pressed-steel cage, rated 104 kN basic dynamic and 117 kN static. Cone and cup of 4T-3578/3525 are separately stocked parts: a worn 3525 cup can be replaced against the existing 3578 cone, provided the new cup carries the identical reference — pairing across references changes the 30.162 mm assembled width and the rating. Selection: C 104 kN against C0 117 kN gives a C0/C ratio of 1.13 for the 44.45 mm bore; the pair is counted as one adjusted unit when checking L10 at the equivalent combined load. The printed 104/117 kN ratings belong to the assembled 3578+3525 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. After bedding-in, re-check the end play of the adjusted 4T-3578/3525 pair — initial seating of the ring faces relaxes the setting slightly.
Typical equipment & failure modes
Common applications
- machine-tool headstocks on inch spindles
- pump and blower drive shafts with combined load
- truck and trailer axle hubs on inch-dimensioned axles
- agricultural tractor transmission and PTO shafts
Known failure patterns
- cone-rib and roller large-end smearing when the adjusted pair runs with preload but starved lubricant film
- 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 damage from a mounting blow transmitted through the roller complement
- water-induced pitting when the open bearing sees washdown without external seals
Selection pitfalls — read before you substitute
- Hub and pinion positions of this 44.45 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-3578/3525.
- The pure-numeric inch family at 44.45 mm bore (87.312×30.162 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3578/3525 reference at purchase.
- Open 4T-3578/3525 sets have no seals: a hub or gearbox needs external sealing or the 4,400 r/min grease figure is meaningless once water reaches the cone rib.
- Fit selection follows the rotating ring: a rotating cone on a 44.45 mm shaft takes a k5/m5 seat, and a rotating cup reverses the logic — decide from the load diagram, not from habit.
- Quote the full 3578/3525 pair at ordering: the 3578 cone also ships against sibling cups, and a cup from another reference changes the 30.162 mm assembled width and the rating.
- The 104/117 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3578/3525; 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-3578/3525?
4T-3578/3525 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 44.45 mm bore (1.75 in), 87.312 mm outside diameter and 30.162 mm assembled width T (3.437 × 1.187 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 104 kN, C0 117 kN, grease limiting speed 4,400 r/min, oil speed 5,900 r/min, mass about 780 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3578/3525 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3578 cone or the 3525 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 104/117 kN ratings change with the cup.
What is the difference between 4T-3578/3525 and a metric ISO 355 tapered bearing?
4T-3578/3525 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 44.45×87.312×30.162 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-3578/3525 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 3578/3525 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3578/3525 list two speeds, 4,400 and 5,900 r/min?
The lower figure, 4,400 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-3578/3525 at 5,900 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.