21320K bearing: complete specifications & equivalents
The 21320K 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 | 8780 g |
| Manufacturer designation | NTN 21320K |
| 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 | — |
| 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 |
|---|---|---|---|
| 21320-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same NTN 21300-series envelope, cage and ratings; this is the tapered-bore execution (K, 1:12) of the cylindrical-bore 21320-NTN — mounting (adapter/withdrawal sleeve or tapered seat, drive-up) differs. Verify shaft arrangement. |
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 21320K model number is decoded
For heavy radial load with misalignment on a 100 mm shaft, NTN supplies 21320K: sphered outer raceway, two roller rows, pressed-steel cage of the 213-series C design, oil speed 2,600 r/min. Reading the full code: the number gives the 100×215 mm envelope, C/CK names the cage/capacity execution, K marks the 1:12 tapered bore for adapter/withdrawal-sleeve mounting, and plain outer ring (no D1/W33 groove) completes the order number. The 1:12 tapered bore mounts on an adapter/withdrawal sleeve (or tapered seat); drive-up sets the residual radial clearance and fixes the axial position of the 100 mm bore assembly. Speed planning: 2,000 r/min grease limiting speed is the cage/kinematic ceiling and 2,600 r/min is the oil-lubricated value for the 100 mm bore; vibrating screens rarely approach either and are load/cage limited instead. Never mount 21320K 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
- paper-machine dryer and press rolls
- cement-mill and kiln auxiliary drives
- large gearbox and marine gear shafts
- wind-turbine gearbox and rotor bearings
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
- rolling-contact fatigue after the catalogue L10 life at the actual load
- false brinelling on stopped machines exposed to screen or crusher vibration
Selection pitfalls — read before you substitute
- Mount the 100 mm ring with induction heat or the sleeve drive-up procedure; at 8780 g cocking damages the spherical raceways, and repositioning after seating is impractical.
- 213-series C/CK executions use the C cage/design code — CK adds the 1:12 tapered bore; quote 21320K in full because a C cannot be mounted on an adapter-sleeve tapered seat.
- Never substitute 21320K 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.
- Do not confuse EA and EM at the same number: 21320K carries C design-code; swapping to the other cage execution changes mass, speed behaviour and sometimes suitability for vibration, even though the 100×215 mm envelope is identical.
- Do not confuse EA and EM at the same number: 21320K carries C design-code; swapping to the other cage execution changes mass, speed behaviour and sometimes suitability for vibration, even though the 100×215 mm envelope is identical.
- The 410/465 kN ratings, 42.5 kN Pu and 8780 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 21320K (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 21320K?
21320K 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 8780 g. It is open, with pressed-steel cage of the 213-series C design and a 1:12 tapered bore.
What is the difference between the K/K30 tapered bore and the cylindrical bore versions?
K denotes a 1:12 tapered bore. 21320K mounts on an adapter sleeve (or tapered shaft seat) and is driven up to the specified residual clearance; its cylindrical-bore counterpart in the same envelope and ratings is 21320.
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. 21320K is the C design-code execution.
What do D1 and W33 mean on 21320K?
21320K 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 21320K 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.