32304-NTN bearing: complete specifications & equivalents
The 32304-NTN is a ISO 355 radial bearing sized 20 x 52 x 22.25 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 20 mm |
| Outer diameter D | 52 mm |
| Width B | 22.25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 51.5 kN |
| Basic static load rating C0 | 48.5 kN |
| Limiting speed (mechanical) | 8000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 242 g |
| Manufacturer designation | NTN 32304 |
| 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 | 0.787 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.876 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 16 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) | 1 of 30 |
| Bore above smallest 32300-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32304 | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per 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 32304-NTN model number is decoded
32304 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 20×52 mm ISO 355 envelope, with 22.25 mm overall assembled width T. NTN also quotes this bearing with its ISO 355 dimension-series abbreviation, 2FD, which is the maker-neutral cross-reference for the 20×52 mm envelope; 4T is NTN's own tapered-roller brand mark on the parts. The printed contact-angle geometry gives the extra-heavy 32300 family its characteristic load split — at 51.5/48.5 kN (C/C0) the static rating is about 0.94× C, typical of tapered bearings proportioned for heavy combined duty. The 16.0 mm section height over the 20 mm bore positions the load centre; axial location of the pair depends on that contact line, so spacer faces must be square within the P0 tolerance of the bearing. When pairing 32304 with a second tapered bearing, keep the matched arrangement clean: a single stray grit particle between cup and housing changes preload faster than the adjustment range can correct.
Typical equipment & failure modes
Common applications
- steering-knuckle and kingpin positions
- small automotive wheel hubs and trailer axles
- light-vehicle differential and pinion shafts
- agricultural implement hubs and ground-tool drives
Known failure patterns
- cup creep and housing fretting when the specified outer-ring press fit is not achieved
- flaking on one cone only when a back-to-back / face-to-face pair is loaded unevenly by a bent shaft
- smearing on the roller large ends and cone rib after a dry start with preload but no oil film
- 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
- At 20 mm bore the thin section and small rollers are adjustment-sensitive: a quarter-turn of the locknut moves end play by more than on large bearings, so set the 32304 pair with a dial indicator rather than by feel.
- The extra-heavy 32300 family at 20 mm bore (52×22.25 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 11,000 r/min oil ceiling.
- ISO 355 makes the 20×52 mm envelope interchangeable but not the ratings: NTN prints 51.5/48.5 kN for this execution, and a cheaper same-number part can differ in roller complement and steel.
- Open 32304 units have no seals: a wheel-hub or gearbox application needs external sealing or the 8,000 r/min grease figure is meaningless once water reaches the cone rib.
- Minimum load matters at high speed: an unloaded 32304 at a large fraction of 8,000 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
- The 51.5/48.5 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32304 (ISO 355 2FD); 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 32304?
32304 is a metric 4T tapered roller bearing to ISO 355: 20 mm bore, 52 mm outside diameter and 22.25 mm assembled width T (0.787 × 2.047 × 0.876 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 51.5 kN, C0 48.5 kN (2203E prints no Pu for this size), grease limiting speed 8,000 r/min, oil speed 11,000 r/min, mass about 242 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32304?
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 (32304); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32304 designation encode the 20 mm bore and what is 2FD?
last two digits 04 are the ISO bore code, ×5 = 20 mm (codes 00–03 use the 10/12/15/17 exception table). The 52 mm OD and 22.25 mm assembled T follow the ISO 355 dimension-series plan. 2FD 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 32304 list two speeds, 8,000 and 11,000 r/min?
The lower figure, 8,000 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32304 at 11,000 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32304 mean?
It is the basic open 4T execution — steel cage, adjusted mounting, no seal or feature suffix. NTN uses U for the uprated design, UTG for ULTAGE large-bearing specs, X for the ISO boundary section, and C/CA/D/A for contact-angle or internal-design variants; all are separate order numbers.
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.