1321 bearing: complete specifications & equivalents
The 1321 is a ISO 15 radial bearing sized 105 x 225 x 49 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 105 mm |
| Outer diameter D | 225 mm |
| Width B | 49 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 154 kN |
| Basic static load rating C0 | 64.5 kN |
| Fatigue load limit Pu | 1.8 kN |
| Limiting speed (mechanical) | 2600 rpm |
| Mass | 9580 g |
| Manufacturer designation | 1321S |
| 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 & 1300-series range
| Bore d | 4.134 in |
|---|---|
| Outer diameter D | 8.858 in |
| Width B | 1.929 in |
| ISO bore code | 21 |
| Radial section height (D−d)/2 | 60 mm |
| Smallest bore in 1300-series | 10 mm |
| Largest outer diameter in 1300-series | 240 mm |
| Width range across 1300-series | 11–50 mm |
| Bore position in 1300-series (smallest first) | 22 of 23 |
| Bore above smallest 1300-series size | 95 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 1321 model number is decoded
In the 1300-series (ISO 15 dimension series) the leading digits 13 mark a double-row self-aligning ball bearing and the last two digits encode the bore: 1321 carries bore code 21 = 105 mm. Outside diameter 225 mm and width 49 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
- pulp, paper and steel mill machinery
- heavy industrial drive shafts
- large gearbox and reducer shafts
- industrial fan and blower rotors
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- raceway smearing under marginal lubrication at start-up
- fretting corrosion on a loose shaft seat
Selection pitfalls — read before you substitute
- Mount this 105 mm bore bearing by heating the inner ring (induction heater, max 120 °C) — never drive it home through the outer ring or balls, that brinells the raceways.
- The 13xx medium section at 105 mm bore gains rating through a larger 225 mm OD and 49 mm width; verify the housing accepts the larger envelope before substituting for a 1221.
- The open 1321 has no lubricant retention: grease escapes and contaminants migrate straight into the 105×225×49 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- Open bearings tolerate the highest speeds in the 1300-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 1321 units.
- Suffixes stack in a defined order — clearance follows the bore code, e.g. 1321-C3. No clearance suffix means normal CN clearance.
Frequently asked questions
What are the dimensions of a 1321 self-aligning ball bearing?
A 1321 self-aligning ball bearing has a 105 mm bore, 225 mm outer diameter and 49 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 1321 bore code work?
The last two digits of 1321 are bore code 21, giving 21 × 5 = 105 mm bore. The 225 mm outside diameter and 49 mm width follow the ISO 15 diameter series, not the bore code alone.
What does the open suffix mean on 1321?
A bare 1321 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 1300 compare with other self-aligning series at the same 105 mm bore?
The 13xx is the medium section: 225×49 mm, 60.0 mm radial section at 105 mm bore, carrying more load than a 1221 but needing a larger housing bore.
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.