21320-NTN bearing: complete specifications & equivalents
The 21320-NTN is a ISO 15 radial bearing sized 100 x 215 x 47 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 100 mm |
| Outer diameter D | 215 mm |
| Width B | 47 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 410 kN |
| Basic static load rating C0 | 465 kN |
| Fatigue load limit Pu | 42.5 kN |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 8890 g |
| Manufacturer designation | NTN 21320 |
| 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 | 3.937 in |
|---|---|
| Outer diameter D | 8.465 in |
| Width B | 1.85 in |
| ISO bore code | 20 |
| Radial section height (D−d)/2 | 57.5 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) | 13 of 14 |
| Bore above smallest 21300-series size | 60 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21320K | 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 21320K (K/K30 sleeve or tapered-seat mounting). Verify shaft arrangement. |
| 21320 | 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. |
| 21320-EK | 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 21320-NTN model number is decoded
21320 is the C design-code execution of NTN's spherical roller range for a 100 mm shaft — 410 kN basic dynamic capacity in a 8890 g, open ISO 15 envelope. The leading digits are the ISO 15 dimension series (21300 series); the bore code resolves to 100 mm (two-digit code ×5, with the 00–03 exception table), and 215 mm OD / 47 mm width follow the general plan. Suffix reading on 21320: C is the cage/design code for the NTN 213 series, CK adding the tapered bore; quote the full code because each suffix is a distinct article. Equivalent-load planning keeps a radial plus moderate axial combination on 21320; if the axial component dominates, pair with a thrust bearing rather than running one roller row unloaded. Never mount 21320 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 215 mm race.
Typical equipment & failure modes
Common applications
- large gearbox and marine gear shafts
- wind-turbine gearbox and rotor bearings
- large vibrating screens and mining feeders
- heavy conveyor and bucket-excavator pulleys
Known failure patterns
- raceway spalling at the roller ends when misalignment or deflection concentrates the line contact
- pressed EA cage fatigue under sustained vibration when minimum load is not maintained
- roller-end smearing during skidding starts under light load and high viscosity grease
- fretting corrosion between adapter sleeve and tapered bore when the drive-up is insufficient
- hard-particle indentation through the open arrangement in dusty mining duty
Selection pitfalls — read before you substitute
- Mount the 100 mm ring with induction heat or the sleeve drive-up procedure; at 8890 g cocking damages the spherical raceways, and repositioning after seating is impractical.
- Minimum load must be maintained even at rest under vibration: an unloaded 21320 on a stopped screen false-brinells; parking brakes and shaker isolation both matter.
- Never substitute 21320 by envelope alone: the 465 kN C0 and 42.5 kN Pu are specific to the NTN C design-code execution, and vibrating duty depends heavily on cage identity.
- 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 100 mm bearing, and drive-up procedures differ.
- The two roller rows must share load equally — a tilted spacer or unequal abutment on the 47 mm-wide ring loads one row only and shows as asymmetric race polish during inspection.
- The 410/465 kN ratings, 42.5 kN Pu and 8890 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 21320 (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 21320?
21320 is an NTN double-row spherical roller bearing to ISO 15: 100 mm bore, 215 mm OD and 47 mm width (3.937 × 8.465 × 1.85 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 410 kN, C0 465 kN, Pu 42.5 kN, grease limiting speed 2,000 r/min, oil 2,600 r/min, mass about 8890 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?
21320 has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 21320K (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. 21320 is the C design-code execution.
What do D1 and W33 mean on 21320?
21320 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 21320 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 — 410 kN C / 465 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.