32318U bearing: complete specifications & equivalents
The 32318U is a ISO 355 radial bearing sized 90 x 190 x 67.5 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 | 190 mm |
| Width B | 67.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 500 kN |
| Basic static load rating C0 | 595 kN |
| Fatigue load limit Pu | 65.5 kN |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 8660 g |
| Manufacturer designation | NTN 32318U |
| 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 & 32300-series range
| Bore d | 3.543 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 2.657 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 50 mm |
| Smallest bore in 32300-series | 20 mm |
| Largest outer diameter in 32300-series | 460 mm |
| Width range across 32300-series | 22.25–154 mm |
| Bore position in 32300-series (smallest first) | 16 of 30 |
| Bore above smallest 32300-series size | 70 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32318U | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the supplier. |
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 32318U model number is decoded
32318U 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 90×190 mm ISO 355 envelope, with 67.5 mm overall assembled width T. Digit by digit, the bare number identifies the extra-heavy 32300 family and a bore code resolving to 90 mm; 190 mm OD and 67.5 mm assembled T are the matching ISO 355 boundary dimensions shared with other makers of the same dimension series. NTN adjusts these bearings by cup or cone position rather than shipping a preloaded set; the mounting drawing must state end play or preload for 32318U, since running clearance is set during assembly. Catalogue mass of the 32318U set is 8660 g (0.341 lb cone + cup); abutment and shaft shoulder design must carry that mass square to the axis. Fillet radii must clear the ring chamfers of the 190 mm cup and 90 mm cone; use undercut shoulders so the rings seat fully rather than bridging on a shaft radius.
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
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- 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
- rolling-contact fatigue after the catalogue L10 life at the actual combined 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 8660 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The extra-heavy 32300 family at 90 mm bore (190×67.5 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.
- Minimum load matters at high speed: an unloaded 32318U at a large fraction of 2,000 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
- Open 32318U 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.
- On slash-size and T-code bearings confirm the full code on both cone and cup before fitting: the 90 mm bore alone does not identify the cup, and a mismatched cone/cup set has no catalogue rating.
- The 500/595 kN ratings and 65.5 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32318U (ISO 355 2GD); 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 32318U?
32318U is a metric 4T tapered roller bearing to ISO 355: 90 mm bore, 190 mm outside diameter and 67.5 mm assembled width T (3.543 × 7.48 × 2.657 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 500 kN, C0 595 kN, Pu 65.5 kN, grease limiting speed 2,000 r/min, oil speed 2,700 r/min, mass about 8660 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32318U?
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 (32318U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32318U designation encode the 90 mm bore and what is 2GD?
last two digits 18 are the ISO bore code, ×5 = 90 mm (codes 00–03 use the 10/12/15/17 exception table). The 190 mm OD and 67.5 mm assembled T follow the ISO 355 dimension-series plan. 2GD 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 32318U 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 32318U 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 32318U mean?
Suffix reading on 32318U: 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.