32909XU bearing: complete specifications & equivalents
The 32909XU is a ISO 355 radial bearing sized 45 x 68 x 15 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 45 mm |
| Outer diameter D | 68 mm |
| Width B | 15 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 37.5 kN |
| Basic static load rating C0 | 51.5 kN |
| Fatigue load limit Pu | 6.3 kN |
| Limiting speed (mechanical) | 5300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 187 g |
| Manufacturer designation | NTN 32909XU |
| 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 | 1.772 in |
|---|---|
| Outer diameter D | 2.677 in |
| Width B | 0.591 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 11.5 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) | 3 of 37 |
| Bore above smallest 32900-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32909XU | 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 32909XU model number is decoded
NTN supplies this 45 mm bore tapered roller position as 32909XU: one cone assembly, one cup, line-contact rollers and a steel cage, rated 37.5 kN basic dynamic and 51.5 kN static on the extra-light thin-section 32900 family. NTN also quotes this bearing with its ISO 355 dimension-series abbreviation, 2BC, which is the maker-neutral cross-reference for the 45×68 mm envelope; 4T is NTN's own tapered-roller brand mark on the parts. At 37.5 kN C the bearing offers about 0.8 kN of dynamic capacity per millimetre of the 45 mm bore — compare any substitution on this ratio and the 15 mm assembled T, not on bore alone. Catalogue mass of the 32909XU set is 187 g (0.007 lb cone + cup); abutment and shaft shoulder design must carry that mass square to the axis. Mount the 45 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 32909XU.
Typical equipment & failure modes
Common applications
- industrial gearbox and speed-reducer shafts
- bevel and helical pinion drives with high thrust component
- pump and compressor drive shafts carrying combined load
- machine-tool gearbox and headstock shafts
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
- 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
- Hub and pinion bearings of this 45 mm bore class are commonly adjusted in pairs; verify end play against the axle drawing and re-torque after bedding-in rather than trusting the initial preload on 32909XU.
- The thin 15 mm section of 32909XU is built for low friction and tight envelopes, not the heavy preload of a 322/323 set; over-tightening adjustment on this 45 mm bore smears the roller ends against the rib.
- Open 32909XU units have no seals: a wheel-hub or gearbox application needs external sealing or the 5,300 r/min grease figure is meaningless once water reaches the cone rib.
- Never fit the 45 mm cone by hammering the 68 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 32909XU units have no seals: a wheel-hub or gearbox application needs external sealing or the 5,300 r/min grease figure is meaningless once water reaches the cone rib.
- The 37.5/51.5 kN ratings and 6.3 kN Pu here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32909XU (ISO 355 2BC); 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 32909XU?
32909XU is a metric 4T tapered roller bearing to ISO 355: 45 mm bore, 68 mm outside diameter and 15 mm assembled width T (1.772 × 2.677 × 0.591 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 37.5 kN, C0 51.5 kN, Pu 6.3 kN, grease limiting speed 5,300 r/min, oil speed 7,000 r/min, mass about 187 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32909XU?
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 (32909XU); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32909XU designation encode the 45 mm bore and what is 2BC?
last two digits 09 are the ISO bore code, ×5 = 45 mm (codes 00–03 use the 10/12/15/17 exception table). The 68 mm OD and 15 mm assembled T follow the ISO 355 dimension-series plan. 2BC 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 32909XU list two speeds, 5,300 and 7,000 r/min?
The lower figure, 5,300 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32909XU at 7,000 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32909XU mean?
Suffix reading on 32909XU: XU combines the X ISO boundary section with the U uprated internal design; 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.