32921XA bearing: complete specifications & equivalents
The 32921XA is a ISO 355 radial bearing sized 105 x 145 x 25 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 | 145 mm |
| Width B | 25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 139 kN |
| Basic static load rating C0 | 219 kN |
| Fatigue load limit Pu | 25 kN |
| Limiting speed (mechanical) | 2300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1200 g |
| Manufacturer designation | NTN 32921XA |
| 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 & 32900-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 5.709 in |
| Width B | 0.984 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 20 mm |
| Smallest bore in 32900-series | 35 mm |
| Largest outer diameter in 32900-series | 600 mm |
| Width range across 32900-series | 14–100 mm |
| Bore position in 32900-series (smallest first) | 15 of 37 |
| Bore above smallest 32900-series size | 70 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32921XA | 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 32921XA model number is decoded
NTN supplies this 105 mm bore tapered roller position as 32921XA: one cone assembly, one cup, line-contact rollers and a steel cage, rated 139 kN basic dynamic and 219 kN static on the extra-light thin-section 32900 family. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 32921XA by the metric ISO 355 number: 105 mm bore, 145 mm OD. At 139 kN C the bearing offers about 1.3 kN of dynamic capacity per millimetre of the 105 mm bore — compare any substitution on this ratio and the 25 mm assembled T, not on bore alone. Grease relubrication at 2,300 r/min limiting speed targets the rib contact; if the drive needs 3,000 r/min it must be arranged for oil lubrication with a defined flow to the large roller ends. After mounting check the contact pattern with marking blue: a pattern biased to the large or small roller end means the 105 mm pair is misadjusted and the 25 mm T set will edge-load in service.
Typical equipment & failure modes
Common applications
- rolling-mill auxiliary and pinion-stand shafts
- large conveyor and bucket-elevator pulleys
- mineral-processing feeder and crusher auxiliaries
- marine winch and deck-machinery 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
- cage damage from a mounting blow delivered through the roller complement instead of the ring face
- false brinelling on a stationary paired set exposed to external vibration
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 1200 g ring mass makes cocking during fitting a direct raceway-brinelling risk.
- The thin 25 mm section of 32921XA is built for low friction and tight envelopes, not the heavy preload of a 322/323 set; over-tightening adjustment on this 105 mm bore smears the roller ends against the rib.
- Do not confuse T (25 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.
- Grease packs must leave free volume in the 25 mm-wide set; over-greasing a paired bearing churning at the 3,000 r/min oil-band speed raises temperature and destroys the preload setting.
- Open 32921XA 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.
- The 139/219 kN ratings and 25 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32921XA; 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 32921XA?
32921XA is a metric 4T tapered roller bearing to ISO 355: 105 mm bore, 145 mm outside diameter and 25 mm assembled width T (4.134 × 5.709 × 0.984 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 139 kN, C0 219 kN, Pu 25 kN, grease limiting speed 2,300 r/min, oil speed 3,000 r/min, mass about 1200 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32921XA?
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 (32921XA); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32921XA designation encode the 105 mm bore?
last two digits 21 are the ISO bore code, ×5 = 105 mm (codes 00–03 use the 10/12/15/17 exception table). The 145 mm OD and 25 mm assembled T follow the ISO 355 dimension-series plan.
Why does 32921XA 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 32921XA 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 32921XA mean?
Suffix reading on 32921XA: X marks the execution built to the ISO boundary-dimension section (interchangeable envelope, NTN internal geometry); the trailing A/C/D (or E1) letter marks an NTN contact-angle or internal-design revision of the base number, not a seal or clearance code; 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.