21315-NTN bearing: complete specifications & equivalents
The 21315-NTN is a ISO 15 radial bearing sized 75 x 160 x 37 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 75 mm |
| Outer diameter D | 160 mm |
| Width B | 37 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 266 kN |
| Basic static load rating C0 | 287 kN |
| Fatigue load limit Pu | 27.5 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3810 g |
| Manufacturer designation | NTN 21315 |
| 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 | 2.953 in |
|---|---|
| Outer diameter D | 6.299 in |
| Width B | 1.457 in |
| ISO bore code | 15 |
| Radial section height (D−d)/2 | 42.5 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) | 8 of 14 |
| Bore above smallest 21300-series size | 35 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 21315K | 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 21315K (K/K30 sleeve or tapered-seat mounting). Verify shaft arrangement. |
| 21315 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 75×160×37 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 21315-EK | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 75×160×37 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 21315-NTN model number is decoded
For heavy radial load with misalignment on a 75 mm shaft, NTN supplies 21315: sphered outer raceway, two roller rows, pressed-steel cage of the 213-series C design, oil speed 3,500 r/min. On the NTN nameplate the suffix cluster after the size reads in order: cage design (C/CK), bore (cylindrical), lubrication feature (none); 21315 is assembled exactly in that order. Pu 27.5 kN is the catalogue fatigue load limit for 21315, used in the adjusted-life equation at contaminated or partial-film conditions typical of mining and vibrating duty. With about 3.5 kN of C per millimetre of the 75 mm bore, 21315 screens interchange candidates quickly — then verify cage (EA/EM), bore (K/K30) and lubrication feature (D1/W33) suffixes. Fillet radii on shaft and housing must clear the ring chamfers of the 37 mm-wide set; use the NTN shoulder/withdrawal-groove table rather than copying a ball-bearing layout.
Typical equipment & failure modes
Common applications
- wind-turbine gearbox and rotor bearings
- large vibrating screens and mining feeders
- heavy conveyor and bucket-excavator pulleys
- jaw/cone crusher eccentric and shaft positions
Known failure patterns
- lubricant starvation at the centre rib area when the D1/W33 groove is not connected to a relubrication supply
- pressed EA cage fatigue under sustained vibration when minimum load is not maintained
- micro-pitting when the EHL film is thinner than the raceway composite roughness
- asymmetric wear on the two roller rows from sustained angular misalignment beyond the self-aligning range
- rolling-contact fatigue after the catalogue L10 life at the actual load
Selection pitfalls — read before you substitute
- Mount the 75 mm ring with induction heat or the sleeve drive-up procedure; at 3810 g cocking damages the spherical raceways, and repositioning after seating is impractical.
- Oil relubrication toward 3,500 r/min needs drain and level design; flooding the 37 mm cavity churns heat through the heavy roller set and cage despite the higher oil speed figure.
- 213-series C/CK executions use the C cage/design code — CK adds the 1:12 tapered bore; quote 21315 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 266 kN rating no longer applies.
- The D1/W33 groove only helps if the housing has a matching grease passage; mounting a grooved 21315 in a solid block with no port wastes the feature and leaves the centre rows under-lubricated.
- The 266/287 kN ratings, 27.5 kN Pu and 3810 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for 21315 (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 21315?
21315 is an NTN double-row spherical roller bearing to ISO 15: 75 mm bore, 160 mm OD and 37 mm width (2.953 × 6.299 × 1.457 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 266 kN, C0 287 kN, Pu 27.5 kN, grease limiting speed 2,700 r/min, oil 3,500 r/min, mass about 3810 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?
21315 has a cylindrical bore and mounts directly on a machined shaft seat. Its tapered-bore counterpart is 21315K (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. 21315 is the C design-code execution.
What do D1 and W33 mean on 21315?
21315 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 21315 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 — 266 kN C / 287 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.