NU310 bearing: complete specifications & equivalents
The NU310 is a ISO 15 radial bearing sized 50 x 110 x 27 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 50 mm |
| Outer diameter D | 110 mm |
| Width B | 27 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 127 kN |
| Basic static load rating C0 | 112 kN |
| Fatigue load limit Pu | 15 kN |
| Reference speed (thermal) | 6700 rpm |
| Limiting speed (mechanical) | 8000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1100 g |
| Manufacturer designation | NU 310 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 | 1.969 in |
|---|---|
| Outer diameter D | 4.331 in |
| Width B | 1.063 in |
| ISO bore code | 10 |
| Radial section height (D−d)/2 | 30 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) | 8 of 34 |
| Bore above smallest NU300-series size | 33 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU310-NTN | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 50×110×27 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 6310 | 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. |
| 6310-2RS | 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. |
| 6310-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. |
| N310-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 boundary envelope and equivalent catalogue ratings; SKF N 310 ECP is a different execution with its own cage/flange configuration. |
| NJ310-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 boundary envelope and equivalent catalogue ratings; SKF NJ 310 ECP is a different execution with its own cage/flange configuration. |
| NUP310-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 boundary envelope and equivalent catalogue ratings; SKF NUP 310 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 NU310 model number is decoded
Ordering number NU 310 ECP in SKF catalogue PUB BU/P1 17000 denotes a single-row cylindrical roller bearing for a 50 mm shaft, standard section, with an open polymer-cage execution and separable inner ring assembly. Digit by digit, NU310 reads as bearing type NU (single-row, inner ring separable), standard series 3, and bore reference 10 resolving to 50 mm; 110 mm OD and 27 mm width are the matching ISO 15 boundary values. 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. The 30.0 mm radial section height ((110−50)/2) and 1100 g catalogue mass frame a 50 mm bore bearing rated at 127 kN C — roughly 2.54 kN of dynamic capacity per millimetre of bore before application factors. Fit selection follows the rotating ring — interference on a rotating inner ring — and the outer ring is free to slide axially in the housing; a 50 mm shaft typically takes a k5 seat with an H7 housing bore.
Typical equipment & failure modes
Common applications
- electric-motor shafts in pumps and fans
- machine-tool main spindles (radial set)
- paper-machine wet-section rolls
- rolling-mill auxiliary gear trains
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
- edge loading from shaft deflection beyond the bearing alignment limit (≈ 3-4 minutes of arc for single-row CRB)
Selection pitfalls — read before you substitute
- On this 50 mm bore, thermal expansion of the shaft can preload the inner ring if the fit is too tight; calculate the residual interference at operating temperature and confirm the outer ring can still slide axially in the housing.
- The NU300 series at 50 mm bore (110×27 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.
- The 1100 g mass and 27 mm width mean abutment faces must be square to the axis within the bearing's own P0 tolerance; a tilted spacer tilts the outer ring and concentrates load on one roller row of NU310.
- Shaft and housing fillets must clear the bearing chamfer so the 27 mm-wide outer ring seats square; use an undercut or withdrawal groove rather than an oversized radius that locks on the ring face.
- The 127/112 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 NU310 (ECP polymer cage, ECJ pressed steel, ECM machined brass); they are not interchangeable order numbers — quote the full NU 310 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 NU310?
The NU 310 ECP is a single-row cylindrical roller bearing with 50 mm bore, 110 mm outer diameter and 27 mm width (1.969 × 4.331 × 1.063 in) per ISO 15. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 127 kN, C0 112 kN, fatigue load limit Pu 15 kN, reference speed 6,700 r/min, limiting speed 8,000 r/min, mass about 1100 g. It is an open, separable bearing with a glass-fibre reinforced polyamide cage.
How does the NU310 bore code work?
The last two digits of NU310 are bore code 10, so 10 × 5 = 50 mm bore. The 110 mm OD and 27 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 NU310?
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 NU310 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 NU310 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.