33220U bearing: complete specifications & equivalents
The 33220U is a ISO 355 radial bearing sized 100 x 180 x 63 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 100 mm |
| Outer diameter D | 180 mm |
| Width B | 63 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 465 kN |
| Basic static load rating C0 | 650 kN |
| Fatigue load limit Pu | 71.5 kN |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 6760 g |
| Manufacturer designation | NTN 33220U |
| 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 & 33200-series range
| Bore d | 3.937 in |
|---|---|
| Outer diameter D | 7.087 in |
| Width B | 2.48 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 40 mm |
| Smallest bore in 33200-series | 25 mm |
| Largest outer diameter in 33200-series | 180 mm |
| Width range across 33200-series | 22–63 mm |
| Bore position in 33200-series (smallest first) | 18 of 18 |
| Bore above smallest 33200-series size | 75 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 33220U | 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 33220U model number is decoded
33220U is a metric single-row tapered roller bearing in the NTN 4T programme: a pressed-steel cage guides profiled rollers between a separable cone and cup on the 100×180 mm ISO 355 envelope, with 63 mm overall assembled width T. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 33220U by the metric ISO 355 number (ISO series abbreviation 3FE): 100 mm bore, 180 mm OD. At 465 kN C the bearing offers about 4.7 kN of dynamic capacity per millimetre of the 100 mm bore — compare any substitution on this ratio and the 63 mm assembled T, not on bore alone. The 40.0 mm section height over the 100 mm bore positions the load centre; axial location of the pair depends on that contact line, so spacer faces must be square within the P0 tolerance of the bearing. Open 4T bearings need application seals; without them the grease at the cone rib of 33220U washes out and the rib/roller-end contact smears on the first wet or dusty shift.
Typical equipment & failure modes
Common applications
- mineral-processing feeder and crusher auxiliaries
- marine winch and deck-machinery shafts
- paper-machine press-section rolls
- large agricultural and forestry machine axles
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- preload loss from racewear when one bearing of the paired set is replaced without re-adjusting end play
- rib scoring when axial load is carried beyond the cone rib capacity of the adjusted pair
- cage damage from a mounting blow delivered through the roller complement instead of the ring face
- water-induced pitting when the open bearing is exposed to washdown without external seals
Selection pitfalls — read before you substitute
- Mount the 100 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 6760 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The medium-wide 33200 family at 100 mm bore (180×63 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 2,700 r/min oil ceiling.
- Replacing one half of an adjusted pair without resetting end play negates the 63 mm T dimension logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Never fit the 100 mm cone by hammering the 180 mm cup: force for both press fits goes through the ring faces only, or brinell marks release as noise within the first running hours.
- Open 33220U units have no seals: a wheel-hub or gearbox application needs external sealing or the 2,000 r/min grease figure is meaningless once water reaches the cone rib.
- The 465/650 kN ratings and 71.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 33220U (ISO 355 3FE); 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 33220U?
33220U is a metric 4T tapered roller bearing to ISO 355: 100 mm bore, 180 mm outside diameter and 63 mm assembled width T (3.937 × 7.087 × 2.48 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 465 kN, C0 650 kN, Pu 71.5 kN, grease limiting speed 2,000 r/min, oil speed 2,700 r/min, mass about 6760 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 33220U?
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 (33220U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 33220U designation encode the 100 mm bore and what is 3FE?
last two digits 20 are the ISO bore code, ×5 = 100 mm (codes 00–03 use the 10/12/15/17 exception table). The 180 mm OD and 63 mm assembled T follow the ISO 355 dimension-series plan. 3FE 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 33220U list two speeds, 2,000 and 2,700 r/min?
The lower figure, 2,000 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 33220U at 2,700 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 33220U mean?
Suffix reading on 33220U: 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.