32306-NTN bearing: complete specifications & equivalents
The 32306-NTN is a ISO 355 radial bearing sized 30 x 72 x 28.75 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 30 mm |
| Outer diameter D | 72 mm |
| Width B | 28.75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 89.5 kN |
| Basic static load rating C0 | 90 kN |
| Limiting speed (mechanical) | 5700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 577 g |
| Manufacturer designation | NTN 32306 |
| 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 | 1.181 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 1.132 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 21 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) | 3 of 30 |
| Bore above smallest 32300-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 32306 | 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 32306-NTN model number is decoded
NTN supplies this 30 mm bore tapered roller position as 32306: one cone assembly, one cup, line-contact rollers and a steel cage, rated 89.5 kN basic dynamic and 90 kN static on the extra-heavy 32300 family. The last two digits 06 are the ISO bore code, ×5 = 30 mm (codes 00–03 use the 10/12/15/17 exception table) under the ISO 355 numbering; the 28.75 mm value printed here is T, the width of the fully assembled cone-plus-cup set, not the inner-ring width alone. 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 32306, since running clearance is set during assembly. 2203E does not print a Pu fatigue load limit for 32306; life work for this size uses the 89.5/90 kN C/C0 pair directly. When pairing 32306 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
- pump and compressor drive shafts carrying combined load
- machine-tool gearbox and headstock shafts
- axle final-drive and differential positions
- construction-equipment wheel and pivot hubs
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
- brinell marks on cone and cup raceways from impact during handling or hammering during fitting
Selection pitfalls — read before you substitute
- Hub and pinion bearings of this 30 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 32306.
- The extra-heavy 32300 family at 30 mm bore (72×28.75 mm assembled) carries more capacity than the lighter 320/329 sections but generates more preload heat; confirm oil availability before running near the 7,600 r/min oil ceiling.
- Open 32306 units have no seals: a wheel-hub or gearbox application needs external sealing or the 5,700 r/min grease figure is meaningless once water reaches the cone rib.
- Minimum load matters at high speed: an unloaded 32306 at a large fraction of 5,700 r/min lets rollers skid and smear the cone rib; spring-preload lightly loaded pair arrangements.
- On slash-size and T-code bearings confirm the full code on both cone and cup before fitting: the 30 mm bore alone does not identify the cup, and a mismatched cone/cup set has no catalogue rating.
- The 89.5/90 kN ratings here are NTN Ball and Roller Bearings CAT.No.2203E figures for 32306 (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 32306?
32306 is a metric 4T tapered roller bearing to ISO 355: 30 mm bore, 72 mm outside diameter and 28.75 mm assembled width T (1.181 × 2.835 × 1.132 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 89.5 kN, C0 90 kN (2203E prints no Pu for this size), grease limiting speed 5,700 r/min, oil speed 7,600 r/min, mass about 577 g. It is an open, separable cone/cup bearing with a pressed-steel cage.
What does the 4T prefix mean on 32306?
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 (32306); the lower-case 4t- factory spelling of the code is retained among the search aliases.
How does the 32306 designation encode the 30 mm bore and what is 2FD?
last two digits 06 are the ISO bore code, ×5 = 30 mm (codes 00–03 use the 10/12/15/17 exception table). The 72 mm OD and 28.75 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 32306 list two speeds, 5,700 and 7,600 r/min?
The lower figure, 5,700 r/min, is the grease-lubricated limiting speed — the mechanical ceiling for the cage, rollers and cone-rib contact. With oil lubrication NTN rates 32306 at 7,600 r/min because oil removes rib-contact heat better. Real limits still depend on preload, oil flow and cooling.
What does the suffix on 32306 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.