1218 bearing: complete specifications & equivalents
The 1218 is a ISO 15 radial bearing sized 90 x 160 x 30 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 90 mm |
| Outer diameter D | 160 mm |
| Width B | 30 mm |
| Seal / shield | open |
| Basic dynamic load rating C | 57.5 kN |
| Basic static load rating C0 | 23.5 kN |
| Fatigue load limit Pu | 0.94 kN |
| Limiting speed (mechanical) | 3600 rpm |
| Mass | 2560 g |
| Manufacturer designation | 1218S |
| 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 & 1200-series range
| Bore d | 3.543 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.181 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 35 mm |
| Smallest bore in 1200-series | 10 mm |
| Largest outer diameter in 1200-series | 200 mm |
| Width range across 1200-series | 9–38 mm |
| Bore position in 1200-series (smallest first) | 19 of 23 |
| Bore above smallest 1200-series size | 80 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the 1218 model number is decoded
In the 1200-series (ISO 15 dimension series) the leading digits 12 mark a double-row self-aligning ball bearing and the last two digits encode the bore: 1218 carries bore code 18 = 90 mm. Outside diameter 160 mm and width 30 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
- heavy industrial drive shafts
- large gearbox and reducer shafts
- industrial fan and blower rotors
- hoist, winch and crane drums
Known failure patterns
- contamination wear from dust and dirt ingress through the open arrangement
- lubricant starvation when no regreasing interval is maintained
- rolling-contact fatigue spalling after the rated L10 life is exceeded
- cage wear or fracture from sustained vibration or shock loading
Selection pitfalls — read before you substitute
- Mount this 90 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 12xx light section at 90 mm bore uses a smaller 160 mm OD than a 1318; load ratings are lower, so do not replace a failed 13-series bearing with a 12-series without re-rating the load.
- The open 1218 has no lubricant retention: grease escapes and contaminants migrate straight into the 90×160×30 mm raceway, so specify a sealed arrangement for dusty or washdown duty.
- Open bearings tolerate the highest speeds in the 1200-series but need a defined regreasing interval; run-to-failure lubrication is the dominant cause of early failure in open 1218 units.
- Shaft and housing fillets must clear the bearing chamfer so the 30 mm-wide ring seats square; provide an undercut or withdrawal groove instead of relying on an oversized radius.
Frequently asked questions
What are the dimensions of a 1218 self-aligning ball bearing?
A 1218 self-aligning ball bearing has a 90 mm bore, 160 mm outer diameter and 30 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 1218 bore code work?
The last two digits of 1218 are bore code 18, giving 18 × 5 = 90 mm bore. The 160 mm outside diameter and 30 mm width follow the ISO 15 diameter series, not the bore code alone.
What does the open suffix mean on 1218?
A bare 1218 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 1200 compare with other self-aligning series at the same 90 mm bore?
The 12xx is the light section: 160×30 mm with a 35.0 mm radial section at 90 mm bore — below 13/22/23 in load capacity, for light loads in compact spaces.
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.