32221U bearing: complete specifications & equivalents
The 32221U is a ISO 355 radial bearing sized 105 x 190 x 53 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 105 mm |
| Outer diameter D | 190 mm |
| Width B | 53 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 420 kN |
| Basic static load rating C0 | 540 kN |
| Fatigue load limit Pu | 59 kN |
| Limiting speed (mechanical) | 1900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 6230 g |
| Manufacturer designation | NTN 32221U |
| Standard | ISO 355 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); 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 & 32200-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 2.087 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 42.5 mm |
| Smallest bore in 32200-series | 17 mm |
| Largest outer diameter in 32200-series | 580 mm |
| Width range across 32200-series | 17.25–159 mm |
| Bore position in 32200-series (smallest first) | 20 of 36 |
| Bore above smallest 32200-series size | 88 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32221U | 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 32221U model number is decoded
The NTN 2203E table prints 32221U in the heavy-section 32200 family: 105 mm bore, 190 mm cup OD, 53 mm T, with a grease limiting speed of 1,900 r/min and an oil-lubricated ceiling of 2,500 r/min. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 32221U by the metric ISO 355 number (ISO series abbreviation 3FC): 105 mm bore, 190 mm OD. At 420 kN C the bearing offers about 4.0 kN of dynamic capacity per millimetre of the 105 mm bore — compare any substitution on this ratio and the 53 mm assembled T, not on bore alone. The 4.0 kN-per-mm-bore capacity figure for 32221U summarises the 420 kN rating over 105 mm bore; use it to sanity-check an interchange candidate before swapping brands. Fillet radii must clear the ring chamfers of the 190 mm cup and 105 mm cone; use undercut shoulders so the rings seat fully rather than bridging on a shaft radius.
Typical equipment & failure modes
Common applications
- large conveyor and bucket-elevator pulleys
- mineral-processing feeder and crusher auxiliaries
- marine winch and deck-machinery shafts
- paper-machine press-section rolls
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- brinell marks on cone and cup raceways from impact during handling or hammering during fitting
Selection pitfalls — read before you substitute
- Mount the 105 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 6230 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The heavy-section 32200 family at 105 mm bore (190×53 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 2,500 r/min oil ceiling.
- Do not confuse T (53 mm assembled width of cone + cup) with the cone width when drawing spacers; an abutment sized to T instead of the ring width leaves the cup unseated.
- Open 32221U units have no seals: a wheel-hub or gearbox application needs external sealing or the 1,900 r/min grease figure is meaningless once water reaches the cone rib.
- Open 32221U units have no seals: a wheel-hub or gearbox application needs external sealing or the 1,900 r/min grease figure is meaningless once water reaches the cone rib.
- The 420/540 kN ratings and 59 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32221U (ISO 355 3FC); internal geometry legitimately differs between manufacturers, so re-verify ratings, adjustment and suffix before substituting another make on a rated drive.
Frequently asked questions
What are the dimensions and catalogue ratings of NTN 32221U?
32221U is a metric 4T tapered roller bearing to ISO 355: 105 mm bore, 190 mm outside diameter and 53 mm assembled width T (4.134 × 7.48 × 2.087 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 420 kN, C0 540 kN, Pu 59 kN, grease limiting speed 1,900 r/min, oil speed 2,500 r/min, mass about 6230 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32221U?
4T is NTN's tapered roller bearing brand mark, stamped on the cone and cup in the factory. It identifies the NTN 4T programme and is not a dimension, so the catalogue and this page list the bare ISO 355 number (32221U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32221U designation encode the 105 mm bore and what is 3FC?
last two digits 21 are the ISO bore code, ×5 = 105 mm (codes 00–03 use the 10/12/15/17 exception table). The 190 mm OD and 53 mm assembled T follow the ISO 355 dimension-series plan. 3FC is the maker-neutral ISO 355 abbreviation for this dimension series (the same code other manufacturers print); 4T is NTN's own brand mark.
Why does 32221U list two speeds, 1,900 and 2,500 r/min?
The lower figure, 1,900 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32221U at 2,500 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32221U mean?
Suffix reading on 32221U: U marks the reinforced/uprated internal design of the bare number, a separate order number with higher load capacity than the basic execution; the suffix is part of the order number and the variants are not interchangeable articles.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.