2306 bearing: complete specifications & equivalents
The 2306 is a ISO 15 radial bearing sized 30 x 72 x 27 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 | 27 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 32 kN |
| Basic static load rating C0 | 8.75 kN |
| Fatigue load limit Pu | 0.38 kN |
| Limiting speed (mechanical) | 8000 rpm |
| Mass | 500 g |
| Manufacturer designation | 2306S |
| Standard | ISO 15 |
| Catalog version | CAT. No. 2203-3/E 2024 |
| Last verified | 2026-09-25 |
Source: catalog reference (CAT. No. 2203-3/E 2024) · extracted 2026-09-25
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (CAT. No. 2203-3/E 2024); 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 & 2300-series range
| Bore d | 1.181 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 1.063 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 21 mm |
| Smallest bore in 2300-series | 10 mm |
| Largest outer diameter in 2300-series | 215 mm |
| Width range across 2300-series | 17–73 mm |
| Bore position in 2300-series (smallest first) | 7 of 21 |
| Bore above smallest 2300-series size | 20 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 2306 model number is decoded
In the 2300-series (ISO 15 dimension series) the leading digits 23 mark a double-row self-aligning ball bearing and the last two digits encode the bore: 2306 carries bore code 06 = 30 mm. Outside diameter 72 mm and width 27 mm follow the ISO 15 general plan. The cylindrical bore fits directly on a machined shaft seat; a tapered-bore K variant is available for adapter-sleeve mounting. Two rows of balls run on a common sphered outer raceway, allowing the inner ring to pivot and compensate for shaft deflection or housing misalignment.
Typical equipment & failure modes
Common applications
- electric motors and generators
- centrifugal pump shafts
- small gearbox input/output shafts
- conveyor roller and pulley shafts
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- edge loading and stress concentration from excessive misalignment beyond the allowable angle
- raceway smearing under marginal lubrication at start-up
Selection pitfalls — read before you substitute
- At a 30 mm bore, a shaft-seat burr or an overtight setscrew can score the thin inner ring of 2306; check shaft finish and runout (target Ra ≤ 1.6 µm) before pressing it home.
- The 23xx heavy wide-section at 30 mm bore is built for high-load, lower-speed duty; specifying it in a high-rpm application gives excess heat and short grease life — use 12/13 there.
- The open 2306 has no lubricant retention: grease escapes and contaminants migrate straight into the 30×72×27 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- Open bearings tolerate the highest speeds in the 2300-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 2306 units.
- Do not use a self-aligning ball bearing where high radial rigidity is required — the sphered outer raceway allows more radial movement than a deep-groove or cylindrical roller bearing.
Frequently asked questions
What are the dimensions of a 2306 self-aligning ball bearing?
A 2306 self-aligning ball bearing has a 30 mm bore, 72 mm outer diameter and 27 mm width, per ISO 15 boundary dimensions. This is the cylindrical-bore version; a tapered-bore K variant is available for adapter-sleeve mounting.
How does the 2306 bore code work?
The last two digits of 2306 are bore code 06, giving 06 × 5 = 30 mm bore. The 72 mm outside diameter and 27 mm width follow the ISO 15 diameter series, not the bore code alone.
What does the open suffix mean on 2306?
A bare 2306 designation means open: no shields or seals, normal CN radial clearance and P0 normal tolerance unless further suffixes are ordered. The application must supply and retain the lubrication.
How does the 2300 compare with other self-aligning series at the same 30 mm bore?
The 23xx is the wide heavy section: 72×27 mm, 21.0 mm radial section at 30 mm bore — the highest-capacity double-row self-aligning option here, aimed at lower-speed, high-load shafts.
Reviewed & verified by the MPN Base engineering desk against source catalog CAT. No. 2203-3/E 2024 on 2026-09-25. Read our editorial & correction policy.