21312-NTN bearing: complete specifications & equivalents
The 21312-NTN is a ISO 15 radial bearing sized 60 x 130 x 31 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 60 mm |
| Outer diameter D | 130 mm |
| Width B | 31 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 186 kN |
| Basic static load rating C0 | 191 kN |
| Fatigue load limit Pu | 28.2 kN |
| Limiting speed (mechanical) | 3400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2100 g |
| Manufacturer designation | NTN 21312 |
| Standard | ISO 15 |
| 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 & 21300-series range
| Bore d | 2.362 in |
|---|---|
| Outer diameter D | 5.118 in |
| Width B | 1.22 in |
| ISO bore code | 12 |
| Radial section height (D−d)/2 | 35 mm |
| Smallest bore in 21300-series | 40 mm |
| Largest outer diameter in 21300-series | 240 mm |
| Width range across 21300-series | 23–50 mm |
| Bore position in 21300-series (smallest first) | 5 of 14 |
| Bore above smallest 21300-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21312K | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 21300-series envelope, cage and ratings; this is the cylindrical-bore execution of the tapered-bore 21312K (K/K30 sleeve or tapered-seat mounting). Verify shaft arrangement. |
| 21312 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 60×130×31 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 21312-EK | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 60×130×31 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 21312-NTN model number is decoded
21312 is the C design-code execution of NTN's spherical roller range for a 60 mm shaft — 186 kN basic dynamic capacity in a 2100 g, open ISO 15 envelope. The leading digits are the ISO 15 dimension series (21300 series); the bore code resolves to 60 mm (two-digit code ×5, with the 00–03 exception table), and 130 mm OD / 31 mm width follow the general plan. The sphered outer raceway lets the inner-ring assembly pivot, accommodating shaft deflection and housing misalignment (around 1–2° for this class; use the 2203E value for the exact series) without edge loading the rollers. Equivalent-load planning keeps a radial plus moderate axial combination on 21312; if the axial component dominates, pair with a thrust bearing rather than running one roller row unloaded. Never mount 21312 by striking the outer ring through the roller set; drive through ring faces (or the adapter sleeve nut) and support the ring square to avoid brinelling the 130 mm race.
Typical equipment & failure modes
Common applications
- large vibrating screens and mining feeders
- heavy conveyor and bucket-excavator pulleys
- jaw/cone crusher eccentric and shaft positions
- paper-machine dryer and press rolls
Known failure patterns
- raceway spalling at the roller ends when misalignment or deflection concentrates the line contact
- cage damage when a mounting force is applied through the roller set instead of the ring face
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- fretting corrosion between adapter sleeve and tapered bore when the drive-up is insufficient
- asymmetric wear on the two roller rows from sustained angular misalignment beyond the self-aligning range
Selection pitfalls — read before you substitute
- Mount the 60 mm ring with induction heat or the sleeve drive-up procedure; at 2100 g cocking damages the spherical raceways, and repositioning after seating is impractical.
- Open spherical rollers swallow dust in mining duty; specify labyrinth or taconite seals externally, or the 3,400 r/min grease rating is lost to abrasive wear long before fatigue.
- Open spherical rollers swallow dust in mining duty; specify labyrinth or taconite seals externally, or the 3,400 r/min grease rating is lost to abrasive wear long before fatigue.
- K and K30 are different tapers — K is 1:12 and K30 is 1:30 on the wide series; an adapter sleeve for one will not mount the other 60 mm bearing, and drive-up procedures differ.
- Minimum load must be maintained even at rest under vibration: an unloaded 21312 on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- The 186/191 kN ratings, 28.2 kN Pu and 2100 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 21312 (C design-code); another maker's same-envelope part revises internal geometry, so re-verify ratings and cage before substitution on vibrating or rated drives.
Frequently asked questions
What are the dimensions and catalogue data of 21312?
21312 is an NTN double-row spherical roller bearing to ISO 15: 60 mm bore, 130 mm OD and 31 mm width (2.362 × 5.118 × 1.22 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 186 kN, C0 191 kN, Pu 28.2 kN, grease limiting speed 3,400 r/min, oil 4,400 r/min, mass about 2100 g. It is open, with pressed-steel cage of the 213-series C design.
What is the difference between the K/K30 tapered bore and the cylindrical bore versions?
21312 has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 21312K (K = 1:12, or K30 = 1:30 on the wide series), intended for adapter/withdrawal-sleeve mounting.
What do EA and EM mean on NTN spherical roller bearings?
EA is the NTN standard-capacity/high-capacity execution with a pressed sheet-steel window cage; EM is the high-capacity execution with a one-piece machined brass cage. Both use the optimised symmetric-roller design, but cage identity changes mass, speed behaviour and suitability for duties like vibrating screens, so they are separate order numbers. 21312 is the C design-code execution.
What do D1 and W33 mean on 21312?
21312 is listed without a D1/W33 outer-ring groove in 2203E; lubrication is supplied from the ring sides. D1 (NTN spelling) and W33 add the annular groove plus holes and are ordered as distinct suffixed executions of the same envelope.
How much misalignment and axial load can 21312 take?
The sphered outer raceway compensates static and dynamic misalignment in the order of 1–2° (verify the exact 2203E figure for the 21300 series); beyond that, load concentrates on one roller row. Load is predominantly radial with a moderate axial share in either direction — 186 kN C / 191 kN C0 — but sustained pure axial load is not recommended because it unloads one row.
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.