NU312 bearing: complete specifications & equivalents
The NU312 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 | SKF |
| 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 | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 173 kN |
| Basic static load rating C0 | 160 kN |
| Fatigue load limit Pu | 21.2 kN |
| Reference speed (thermal) | 5600 rpm |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1750 g |
| Manufacturer designation | NU 312 ECP |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical 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. 6.1 single-row cylindrical 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 & NU300-series range
| Bore d | 2.362 in |
|---|---|
| Outer diameter D | 5.118 in |
| Width B | 1.22 in |
| ISO bore code | 12 |
| Radial section height (D−d)/2 | 35 mm |
| Smallest bore in NU300-series | 17 mm |
| Largest outer diameter in NU300-series | 620 mm |
| Width range across NU300-series | 14–109 mm |
| Bore position in NU300-series (smallest first) | 10 of 34 |
| Bore above smallest NU300-series size | 43 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU312-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 60×130×31 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 6312 | 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. |
| 6312-2RS | 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. |
| 6312-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. |
| N312-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 boundary envelope and equivalent catalogue ratings; SKF N 312 ECP is a different execution with its own cage/flange configuration. |
| NJ312-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 boundary envelope and equivalent catalogue ratings; SKF NJ 312 ECP is a different execution with its own cage/flange configuration. |
| NUP312-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 boundary envelope and equivalent catalogue ratings; SKF NUP 312 ECP is a different execution with its own cage/flange configuration. |
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 NU312 model number is decoded
The NU 312 ECP is a 60×130×31 mm single-row cylindrical roller bearing — the standard entry in the NU300 series, with separable inner ring and roller assembly for easy mounting. On the SKF nameplate, NU312 follows the ISO 15 convention: NU for the separable-inner-ring type, 3 for the standard, final digits 12 for the 60 mm bore. The SKF catalogue adds the ECP suffix for the standard glass-fibre reinforced polyamide cage; ECJ (pressed steel) and ECM (machined brass) are alternative executions with different speed and temperature ratings. At 5,600 r/min reference speed the 35.0 mm-section NU312 is governed thermally by cage material and lubricant flow; oil or grease selection should be made against that value, with 6,700 r/min as the mechanical ceiling. Check raceway alignment after mounting: single-row cylindrical roller bearings tolerate only ≈ 3–4 minutes of arc misalignment; beyond that edge loading accelerates fatigue.
Typical equipment & failure modes
Common applications
- marine propulsion gearbox shafts
- heavy industrial gearbox shafts
- large pump and turbine shafts
- rolling-mill work-roll backup bearings
Known failure patterns
- inner-ring raceway spalling from overload or contamination in the line-contact hertz zone
- outer-ring raceway fatigue after extended service at loads above the catalogue L10 rating
- polymer cage cracking or softening after sustained running above 120 °C or with incompatible lubricant
- surface distress (micro-pitting) when the EHL film falls below the composite roughness at high specific load
- false brinelling on standby machines exposed to external vibration
Selection pitfalls — read before you substitute
- Mount the 60 mm bore NU312 by induction heating of the inner ring (max 120 °C — the polymer cage sets the ceiling, not the steel); driving it home through the rollers brinells the raceway.
- The NU300 series at 60 mm bore (130×31 mm) is the standard-section cylindrical roller envelope; stepping to a wide-section 22/23 variant changes OD, width and heat generation — it is not a drop-in swap when the housing and speed are fixed.
- Catalogue reference speed and limiting speed are different limits: the 5,600 r/min reference is a thermal criterion under load, while the 6,700 r/min limiting value is the mechanical ceiling — observe both.
- Never press the outer ring through the roller complement during fitting: force for a press fit goes through the ring faces only, or brinell marks on the 130 mm race release as noise within the first running hours.
- The 173/160 kN ratings are SKF catalogue 17000 values for the ECP polymer-cage execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
- SKF lists several executions of NU312 (ECP polymer cage, ECJ pressed steel, ECM machined brass); they are not interchangeable order numbers — quote the full NU 312 ECP designation when purchasing and match the execution to the speed and temperature requirements.
Frequently asked questions
What are the dimensions and catalogue data of NU312?
The NU 312 ECP is a single-row cylindrical roller bearing with 60 mm bore, 130 mm outer diameter and 31 mm width (2.362 × 5.118 × 1.22 in) per ISO 15. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 173 kN, C0 160 kN, fatigue load limit Pu 21.2 kN, reference speed 5,600 r/min, limiting speed 6,700 r/min, mass about 1750 g. It is an open, separable bearing with a glass-fibre reinforced polyamide cage.
How does the NU312 bore code work?
The last two digits of NU312 are bore code 12, so 12 × 5 = 60 mm bore. The 130 mm OD and 31 mm width come from the ISO 15 dimension-series plan, shared with other cylindrical bearings of the same code.
What does the ECP suffix mean on NU312?
ECP stands for a glass-fibre reinforced polyamide cage (PA66), the SKF standard for this size. Alternative executions include ECJ (pressed steel cage) and ECM (machined brass cage), which have different speed and temperature ratings and are separate order numbers.
Can NU312 take axial load?
No — the NU design has no ribs on the outer ring and cannot support axial load in either direction. It is intended for pure radial load with axial location provided by adjacent components. If axial location is required, consider NJ (one-direction) or NUP (two-direction) variants, or pair the NU bearing with a thrust or angular-contact bearing.
How does NU312 compare with a ball bearing of the same bore?
A cylindrical roller bearing has line contact and much higher radial capacity than a ball bearing of the same bore, but it cannot take axial load in the NU design and is sensitive to misalignment (≈ 3–4 minutes of arc). Speed limits are generally lower than deep-groove ball bearings. A ball bearing cannot be dropped into a pure radial cylindrical-roller position without re-checking life and deflection, and vice versa.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings on 2026-09-26. Read our editorial & correction policy.