32320U bearing: complete specifications & equivalents
The 32320U is a ISO 355 radial bearing sized 100 x 215 x 77.5 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 | 215 mm |
| Width B | 77.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 635 kN |
| Basic static load rating C0 | 770 kN |
| Fatigue load limit Pu | 82 kN |
| Limiting speed (mechanical) | 1800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 12800 g |
| Manufacturer designation | NTN 32320U |
| 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 | 3.937 in |
|---|---|
| Outer diameter D | 8.465 in |
| Width B | 3.051 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 57.5 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) | 18 of 30 |
| Bore above smallest 32300-series size | 80 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32320U | 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 32320U model number is decoded
32320U belongs to the NTN metric 4T tapered roller range (extra-heavy 32300 family); the open bearing leaves sealing to the application and is normally ordered and mounted as an adjustable matched pair. The last two digits 20 are the ISO bore code, ×5 = 100 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 77.5 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. At 635 kN C the bearing offers about 6.3 kN of dynamic capacity per millimetre of the 100 mm bore — compare any substitution on this ratio and the 77.5 mm assembled T, not on bore alone. Imperial cross-check for the drawing: 100×215×77.5 mm is 3.937 × 8.465 × 3.051 in; ISO 355 makes the envelope interchangeable but C/C0, 635/770 kN, is NTN-specific. With a rotating shaft a k5/m5 shaft seat and a press-fit cup are typical catalogue practice for 32320U; reverse the logic if the cup rotates, and re-verify against load direction and magnitude.
Typical equipment & failure modes
Common applications
- heavy industrial gearboxes and crane travel drives
- rolling-mill auxiliary and pinion-stand shafts
- large conveyor and bucket-elevator pulleys
- mineral-processing feeder and crusher auxiliaries
Known failure patterns
- cone-raceway spalling at the large rib when preload is set too high for the lubricant film
- 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
- indentation of the raceways by hard particles in unsealed open arrangements
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 12800 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The extra-heavy 32300 family at 100 mm bore (215×77.5 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 2,400 r/min oil ceiling.
- Grease packs must leave free volume in the 77.5 mm-wide set; over-greasing a paired bearing churning at the 2,400 r/min oil-band speed raises temperature and destroys the preload setting.
- Replacing one half of an adjusted pair without resetting end play negates the 77.5 mm T dimension logic: re-adjust the set and re-verify the contact pattern rather than reusing the old spacer stack.
- Open 32320U units have no seals: a wheel-hub or gearbox application needs external sealing or the 1,800 r/min grease figure is meaningless once water reaches the cone rib.
- The 635/770 kN ratings and 82 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32320U (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 32320U?
32320U is a metric 4T tapered roller bearing to ISO 355: 100 mm bore, 215 mm outside diameter and 77.5 mm assembled width T (3.937 × 8.465 × 3.051 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 635 kN, C0 770 kN, Pu 82 kN, grease limiting speed 1,800 r/min, oil speed 2,400 r/min, mass about 12800 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32320U?
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 (32320U); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32320U designation encode the 100 mm bore and what is 2GD?
last two digits 20 are the ISO bore code, ×5 = 100 mm (codes 00–03 use the 10/12/15/17 exception table). The 215 mm OD and 77.5 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 32320U list two speeds, 1,800 and 2,400 r/min?
The lower figure, 1,800 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32320U at 2,400 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32320U mean?
Suffix reading on 32320U: 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.