21315 bearing: complete specifications & equivalents
The 21315 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 | SKF |
| 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 | 291 kN |
| Basic static load rating C0 | 325 kN |
| Fatigue load limit Pu | 34.5 kN |
| Reference speed (thermal) | 4000 rpm |
| Limiting speed (mechanical) | 5600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3750 g |
| Manufacturer designation | SKF 21315 E |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.1 spherical roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.1 spherical roller bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.1 spherical roller bearings); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.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 |
|---|---|---|---|
| 21315-NTN | NTN | 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. |
| 6315 | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Identical envelope but a different bearing type — confirm load and speed suitability before substitution. |
| 6315-2RS | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Identical envelope but a different bearing type — confirm load and speed suitability before substitution. |
| 6315-ZZ | SKF | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Identical envelope but a different bearing type — confirm load and speed suitability before substitution. |
| 21315-EK | SKF | full Dimensions and internal design equivalent — standard interchange. | Tapered-bore (1:12) execution on H315 adapter sleeve; same ISO 15 envelope, separate order number. |
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 model number is decoded
21315 is a double-row spherical roller bearing in the 21300-series family: two rows of barrel rollers on a common sphered outer raceway, self-aligning under shaft deflection, listed by SKF in SKF catalogue PUB BU/P1 17000. Digit by digit, 21315 reads as bearing type 2 (spherical roller, two barrel-roller rows), dimension series 13, and bore reference 15 resolving to 75 mm; 160 mm OD and 37 mm width are the matching ISO 15 boundary values. The trailing E is the SKF optimized internal design: larger rollers and a stamped window-type steel cage give higher load ratings than the older CC geometry; EK is the same bearing with a 1:12 tapered bore for adapter sleeves. The 34.5 kN Pu figure feeds the adjusted-life equation at contaminated or partial-film conditions, and the 1.12 C0/C balance shows this execution is tuned to heavy radial-plus-axial duty with misalignment tolerance. Spherical roller bearings are routinely specified with C3 clearance because the tight inner-ring fit and inner/outer temperature gradient eat into the CN running clearance — check the residual clearance after mounting with feeler gauges.
Typical equipment & failure modes
Common applications
- cement-mill trunnion and drive shafts
- heavy conveyor head shafts in mining
- jaw and cone crusher main shafts
- paper-machine press and dryer rolls
Known failure patterns
- raceway fatigue spalling of the sphered outer raceway after extended service above the catalogue L10 rating
- inner-ring raceway spalling from edge loading when misalignment exceeds the self-aligning recovery range
- cage pocket wear or fracture from roller skew at insufficient minimum load or rapid acceleration
- roller-end scoring from starved lubricant at start-up before the grease channel purges
- fretting corrosion on a loose rotating shaft seat or in vibratory stand-still
Selection pitfalls — read before you substitute
- Mount the 75 mm bore 21315 by induction heating (max 120 °C) or oil injection — driving a bearing of this section home through the rollers brinells both raceways, and the damage only speaks up as vibration hours later.
- The 21300-series series at 75 mm bore (160×37 mm) pairs a heavy OD with a narrow section — a compact way to add capacity, but the shoulder and abutment diameters differ from the 222 series; it is not a drop-in swap.
- Open spherical roller bearings rely on the housing seals; in screening or crusher duty a failed seal lets grit into the sphered raceway and the 21315 pits long before its L10 life.
- Shaft and housing fillets must clear the bearing chamfer so the 37 mm-wide rings seat square; use an undercut or withdrawal groove rather than an oversized radius that locks on the ring face.
- The 291/325 kN ratings are SKF catalogue values for this exact execution (21315 E); SKF can revise internal geometry without changing the order number, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the specification and re-verify for critical drives.
- SKF lists several executions of 21315 (cylindrical bore as listed, tapered-bore 21315 EK variant, plus sealed and vibrating-screen options in the same envelope); they are not interchangeable order numbers — quote the full 21315 E designation when purchasing.
Frequently asked questions
What are the dimensions and catalogue data of 21315?
The 21315 E is a double-row spherical roller bearing with 75 mm bore, 160 mm outer diameter and 37 mm width (2.953 × 6.299 × 1.457 in) per ISO 15. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 291 kN, C0 325 kN, fatigue load limit Pu 34.5 kN, reference speed 4,000 r/min, limiting speed 5,600 r/min, mass about 3750 g. It is an open, self-aligning bearing with a stamped window-type steel cage.
How does the 21315 bore code work?
The last two digits of 21315 are bore code 15, so 15 × 5 = 75 mm bore. The 160 mm OD and 37 mm width come from the ISO 15 dimension-series plan (dimension series 13 (heavy OD, normal width)), shared with other spherical roller bearings of the same code.
What does the E suffix mean on 21315?
E is the SKF optimized internal design with larger rollers and a stamped window-type steel cage for higher load ratings. The EK variant is the same bearing with a 1:12 tapered bore for adapter sleeves.
Can 21315 accommodate misalignment and axial load?
Yes on both counts. The sphered outer raceway lets the bearing self-align ≈ 0.5–2.5° depending on series, absorbing shaft deflection and housing-seat errors. The two barrel-roller rows also carry bidirectional axial load in addition to heavy radial load — this is the key difference from cylindrical roller bearings, which take no axial load.
When should the tapered-bore 21315K variant be used instead?
Choose the K (1:12 tapered bore) variant when the bearing must seat on an adapter or withdrawal sleeve — typical for long shafts, frequent dismounting, or stepped shafts where machining a precision journal is impractical. Sleeve mounting requires measuring clearance reduction or axial drive-up, not nut torque. The cylindrical-bore 21315 listed here seats directly on a machined journal.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 9.1 spherical roller bearings on 2026-09-26. Read our editorial & correction policy.