323-32C bearing: complete specifications & equivalents
The 323-32C is a ISO 355 radial bearing sized 32 x 75 x 29.75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 32 mm |
| Outer diameter D | 75 mm |
| Width B | 29.75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 93.5 kN |
| Basic static load rating C0 | 102 kN |
| Limiting speed (mechanical) | 5200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 652 g |
| Manufacturer designation | NTN 323/32C |
| 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 | 1.26 in |
|---|---|
| Outer diameter D | 2.953 in |
| Width B | 1.171 in |
| ISO bore code | 23 |
| Radial section height (D−d)/2 | 21.5 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) | 4 of 30 |
| Bore above smallest 32300-series size | 12 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 323 | 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 323-32C model number is decoded
NTN supplies this 32 mm bore tapered roller position as 323/32C: one cone assembly, one cup, line-contact rollers and a steel cage, rated 93.5 kN basic dynamic and 102 kN static on the extra-heavy 32300 family. On the NTN nameplate the parts carry 4T plus the bare code, while 2203E orders 323/32C by the metric ISO 355 number (ISO series abbreviation 5FD): 32 mm bore, 75 mm OD. 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 323/32C, since running clearance is set during assembly. The two speed columns differ by a factor of .75 (grease/limiting 5,200 vs oil 6,900 r/min); heat generation at the cone rib decides which lubrication a real 323/32C arrangement can sustain. With a rotating shaft a k5/m5 shaft seat and a press-fit cup are typical catalogue practice for 323/32C; reverse the logic if the cup rotates, and re-verify against load direction and magnitude.
Typical equipment & failure modes
Common applications
- machine-tool gearbox and headstock shafts
- axle final-drive and differential positions
- construction-equipment wheel and pivot hubs
- truck and bus wheel hubs in paired arrangements
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 fatigue when the pair is run continuously near the grease limiting speed without oil cooling
- fretting corrosion on a loose cone seat that creeps under rotating load
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 32 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 323/32C.
- The extra-heavy 32300 family at 32 mm bore (75×29.75 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 6,900 r/min oil ceiling.
- ISO 355 makes the 32×75 mm envelope interchangeable but not the ratings: NTN prints 93.5/102 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- ISO 355 makes the 32×75 mm envelope interchangeable but not the ratings: NTN prints 93.5/102 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- On slash-size and T-code bearings confirm the full code on both cone and cup before fitting: the 32 mm bore alone does not identify the cup, and a mismatched cone/cup set has no catalogue rating.
- The 93.5/102 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 323/32C (ISO 355 5FD); 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 323/32C?
323/32C is a metric 4T tapered roller bearing to ISO 355: 32 mm bore, 75 mm outside diameter and 29.75 mm assembled width T (1.26 × 2.953 × 1.171 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 93.5 kN, C0 102 kN (2203E prints no Pu for this size), grease limiting speed 5,200 r/min, oil speed 6,900 r/min, mass about 652 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 323/32C?
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 (323/32C); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 323/32C designation encode the 32 mm bore and what is 5FD?
32 mm bore is printed directly after the slash in the slash-size convention. The 75 mm OD and 29.75 mm assembled T follow the ISO 355 dimension-series plan. 5FD 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 323/32C list two speeds, 5,200 and 6,900 r/min?
The lower figure, 5,200 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 323/32C at 6,900 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 323/32C mean?
Suffix reading on 323/32C: 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.