21312K bearing: complete specifications & equivalents
The 21312K 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 | 2070 g |
| Manufacturer designation | NTN 21312K |
| 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 | — |
| 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 |
|---|---|---|---|
| 21312-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 21312-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 21312K model number is decoded
21312K belongs to the 21300 series of NTN spherical rollers: self-aligning, high radial capacity, moderate axial load in either direction. On the NTN nameplate the suffix cluster after the size reads in order: cage design (C/CK), bore (K), lubrication feature (none); 21312K is assembled exactly in that order. Open by design, 21312K requires application seals and a grease or oil system; NTN vibrating-duty executions of this envelope are selected with cage and clearance choices that are separate order codes. Speed planning: 3,400 r/min grease limiting speed is the cage/kinematic ceiling and 4,400 r/min is the oil-lubricated value for the 60 mm bore; vibrating screens rarely approach either and are load/cage limited instead. Never mount 21312K 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
- machined EM cage wear from inadequate oil film at the cage-guiding surfaces
- sliding wear and heat when relubrication intervals ignore the groove (D1/W33) supply path
- brinelling from static overload or a hammer blow during sleeve mounting
- water-induced pitting in washdown or outdoor duty without effective external seals
Selection pitfalls — read before you substitute
- Mount the 60 mm ring with induction heat or the sleeve drive-up procedure; at 2070 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 21312K in full because a C cannot be mounted on an adapter-sleeve tapered seat.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 186 kN rating no longer applies.
- Adapter-sleeve mounting requires the correct sleeve series and locknut for the 60 mm shaft; a sleeve sized to bore alone ignores thread, width and the oil-injection option on large K seats.
- Self-aligning does not mean unlimited misalignment: beyond the catalogue angle the outer ring's spherical travel is exhausted and the 186 kN rating no longer applies.
- The 186/191 kN ratings, 28.2 kN Pu and 2070 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 21312K (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 21312K?
21312K 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 2070 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. 21312K 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 21312.
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. 21312K is the C design-code execution.
What do D1 and W33 mean on 21312K?
21312K 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 21312K 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.