33218U bearing: complete specifications & equivalents
The 33218U is a ISO 355 radial bearing sized 90 x 160 x 55 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 90 mm |
| Outer diameter D | 160 mm |
| Width B | 55 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 360 kN |
| Basic static load rating C0 | 490 kN |
| Fatigue load limit Pu | 56 kN |
| Limiting speed (mechanical) | 2300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 4620 g |
| Manufacturer designation | NTN 33218U |
| 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 | 3.543 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 2.165 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 35 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) | 16 of 18 |
| Bore above smallest 33200-series size | 65 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 33218U | 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 33218U model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, the NTN order number 33218U denotes the medium-wide 33200 family of metric tapered roller bearings, 90 mm bore, 160 mm outside diameter and 55 mm assembled width T (3.543 × 6.299 × 2.165 in) to the ISO 355 boundary plan. NTN also quotes this bearing with its ISO 355 dimension-series abbreviation, 3FE, which is the maker-neutral cross-reference for the 90×160 mm envelope; 4T is NTN's own tapered-roller brand mark on the parts. The rollers run with their large ends against the cone's integral guide rib; the rib/end-flange contact carries the thrust component and is the reason lubricant must reach the rib face of 33218U, not only the raceway. The two speed columns differ by a factor of .77 (grease/limiting 2,300 vs oil 3,000 r/min); heat generation at the cone rib decides which lubrication a real 33218U arrangement can sustain. Mount the 90 mm-bore cone on the shaft first (induction heat, max 120 °C), fit the cup square in its housing, then set preload or end play; never drive the cup home through the rollers of 33218U.
Typical equipment & failure modes
Common applications
- paper-machine press-section rolls
- large agricultural and forestry machine axles
- heavy industrial gearboxes and crane travel drives
- rolling-mill auxiliary and pinion-stand shafts
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- pressed-steel cage pocket wear from roller skid at light radial load and high speed
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- Mount the 90 mm cone by induction heating (max 120 °C) and the cup with a press sleeve; the 4620 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The medium-wide 33200 family at 90 mm bore (160×55 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 3,000 r/min oil ceiling.
- Never fit the 90 mm cone by hammering the 160 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 33218U units have no seals: a wheel-hub or gearbox application needs external sealing or the 2,300 r/min grease figure is meaningless once water reaches the cone rib.
- Back-to-back and face-to-face arrangements react differently to shaft bending: pick the pair orientation for the moment load before locking the 90 mm shoulder geometry, because retrofitting flips the cups.
- The 360/490 kN ratings and 56 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 33218U (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 33218U?
33218U is a metric 4T tapered roller bearing to ISO 355: 90 mm bore, 160 mm outside diameter and 55 mm assembled width T (3.543 × 6.299 × 2.165 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 360 kN, C0 490 kN, Pu 56 kN, grease limiting speed 2,300 r/min, oil speed 3,000 r/min, mass about 4620 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 33218U?
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 (33218U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 33218U designation encode the 90 mm bore and what is 3FE?
last two digits 18 are the ISO bore code, ×5 = 90 mm (codes 00–03 use the 10/12/15/17 exception table). The 160 mm OD and 55 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 33218U list two speeds, 2,300 and 3,000 r/min?
The lower figure, 2,300 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 33218U at 3,000 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 33218U mean?
Suffix reading on 33218U: 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.