3578-3520 bearing: complete specifications & equivalents
The 3578-3520 is a ANSI ABMA 19.2 radial bearing sized 44.45 x 84.138 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 | 84.138 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 | 701 g |
| Manufacturer designation | NTN 4T-3578/3520 |
| 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 | 3.313 in |
| Width B | 1.187 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 19.8 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) | 51 of 148 |
| Bore above smallest 4t-inch-series size | 31.750000000000004 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3578-3525 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN cone 4T-3578 paired with a different cup (3525): 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 3578-3520 model number is decoded
The NTN 2203E inch table prints 4T-3578/3520 at 44.45 mm bore (1.75 in), 84.138 mm cup OD and 30.162 mm assembled T, with a grease limiting speed of 4,400 r/min and an oil ceiling of 5,900 r/min. Cone and cup of 4T-3578/3520 are separately stocked parts: a worn 3520 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. Speed planning uses both catalogue columns: grease 4,400 r/min is the mechanical ceiling for 4T-3578/3520, oil 5,900 r/min with circulating oil — a 1,500 r/min margin at this size. The printed 104/117 kN ratings belong to the assembled 3578+3520 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. Minimum load matters at speed: an unloaded 4T-3578/3520 run near 4,400 r/min lets the rollers skid; lightly spring-preload high-speed pair arrangements.
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
- preload loss and noise after one bearing of the adjusted pair is replaced without resetting end play
- false brinelling on a stationary pair exposed to vibration during transport or standby
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- 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-3578/3520.
- The pure-numeric inch family at 44.45 mm bore (84.138×30.162 mm assembled) is one of several inch families sharing similar bores; cross-series swaps change OD, T and contact angle, so match the full 3578/3520 reference at purchase.
- Do not confuse T (30.162 mm, the assembled cone-plus-cup width) with the cone width when drawing spacers; an abutment sized to T leaves the cup unseated.
- ABMA makes the 44.45×84.138 mm envelope interchangeable, not the ratings: NTN prints 104/117 kN for this execution and another make of the same number can differ in roller complement.
- Shaft and housing fillets must clear the ring chamfers of 3578 and 3520; use undercut shoulders so the rings seat on the face, not on a radius.
- The 104/117 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 4T-3578/3520; 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-3578/3520?
4T-3578/3520 is an inch-series single-row tapered roller bearing to the ABMA boundary plan: 44.45 mm bore (1.75 in), 84.138 mm outside diameter and 30.162 mm assembled width T (3.313 × 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 701 g. It is an open, separable cone/cup set with a pressed-steel cage.
Are the cone and cup of 4T-3578/3520 interchangeable separately?
Yes — ABMA inch parts are individually interchangeable: the 3578 cone or the 3520 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-3578/3520 and a metric ISO 355 tapered bearing?
4T-3578/3520 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 44.45×84.138×30.162 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-3578/3520 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 3578/3520 references; the 4T spelling is retained among this page's search aliases.
Why does 4T-3578/3520 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-3578/3520 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.