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 | Generic ISO interchange (unbranded) |
| Bore diameter d | 50 mm |
| Outer diameter D | 110 mm |
| Width B | 27 mm |
| Seal / shield | open |
| Internal clearance | CN / C3 / C4 available |
| Tolerance class | P0 |
| Cage | steel |
| Operating temperature | -30 to +120 °C |
| Mass (geometry estimate) | 1039 g |
| Standard | ISO 15 |
| Catalog version | iso15-crb-geometry |
| Last verified | 2026-09-24 |
Source: ISO 15 boundary-dimensions standard · extracted 2026-09-24
Standard-interchange bearing: dimensions per ISO 15; CN clearance, P0 tolerance and a stamped-steel cage are catalogue defaults unless the supplier states otherwise, and mass is a geometry-derived estimate. Brand catalogue load ratings and limiting speeds for NU310 are being backfilled — use the inquiry form for certified values.
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 | 20 mm |
| Largest outer diameter in NU300-series | 215 mm |
| Width range across NU300-series | 15–47 mm |
| Bore position in NU300-series (smallest first) | 7 of 17 |
| Bore above smallest NU300-series size | 30 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NU310 model number is decoded
In the NU300-series (ISO 15 dimension series) the leading NU marks a single-row cylindrical roller: the outer ring has two integral shoulders and the inner ring none, so the inner-ring/roller assembly floats axially both ways and the bearing locates radially only; the last two digits of NU310 are bore code 10 = 50 mm (code × 5 from 04 upward). The ISO 15 envelope is 110 mm outside diameter and 27 mm width — 1.969 × 4.331 × 1.063 in, with a 30.0 mm radial section height. Straight cylindrical rollers give line contact for high radial capacity at low friction, with no self-alignment; catalogue practice for a rotating inner ring is a k5 shaft seat, H7 housing and C3 clearance. NJ adds one inner shoulder (one-direction location), NUP two shoulders (full location); E denotes a reinforced roller complement — verify against the actual load direction.
Typical equipment & failure modes
Common applications
- industrial helical and planetary gearboxes
- medium electric motor drives
- centrifugal pump and compressor shafts
- machine tool gearboxes and feed drives
- conveyor and hoist gearcase shafts
Known failure patterns
- false brinelling indentations at the roller pitch when an idle bearing sits in machine vibration
- inner-ring shoulder damage from cold mounting force transmitted through the roller set
- thermal seizure when an interference fit plus hot running removes all residual C3 clearance
- roller and raceway smearing when a lightly loaded NU row skids at start-up or below the minimum load
- edge loading and rib spalling from shaft-to-housing misalignment — cylindrical rollers run on line contact and cannot self-align
Selection pitfalls — read before you substitute
- On this 50 mm-bore NU310, set C3 as the default for an interference inner-ring fit and recheck play after mounting; a row that turned freely on the bench can be fully clamped once the 50 mm shaft reaches operating temperature.
- The NU3 medium series at 50 mm bore uses the 110 mm OD and 27 mm width for heavy radial load; it needs stiffer shaft and housing shoulders and runs lower limiting speed than an NU210, so it is a poor choice in a high-rpm gearbox stage sized for the light row.
- Before fitting NU310, machine the 50 mm shaft seat and 110 mm housing bore with a relief or undercut so nothing bridges the chamfer; the separable rings only carry load when their full faces abut, and a large fillet pinches the 30.0 mm radial section.
- With a separable NU310, mount the inner-ring/roller assembly on the shaft and the plain outer ring in the housing independently; check that the outer ring is free to float the specified amount after closing the housing — a pinched outer ring turns the floating bearing into an accidental locating one.
- When reusing separable NU310 rings, keep the matched pair together and inspect both seats: a crept inner ring frets a polished groove into the 50 mm journal that a new bearing will repeat unless the shaft is repaired or reclaimed.
- The rings of an NU310 are separable and supplied as a matched unit: never mix the outer ring of one bearing with the inner-ring/roller assembly of another — the raceway and roller complement are graded together, and cross-matching shortens life even at identical 50×110 dimensions.
- Apply mounting force to the ring with the interference fit — inner ring for a shaft fit, outer ring for a housing fit; pushing the 50 mm inner ring home through the rollers brinells the 110 mm outer raceway.
Frequently asked questions
What are the dimensions of an NU310 cylindrical roller bearing?
An NU310 single-row cylindrical roller bearing per ISO 15 has a 50 mm bore, 110 mm outer diameter and 27 mm width (1.969 × 4.331 × 1.063 in), a 30.0 mm radial section and roughly 1039 g geometry-based estimated mass; catalogue masses vary with cage and E design.
How does the NU310 bore code work?
The letters give the ring/shoulder design (NU = axially free, NJ = one inner shoulder, NUP = two shoulders) and the last two digits are bore code 10: 10 × 5 = 50 mm. The 110 mm OD and 27 mm width come from the ISO 15 dimension series (NU300), which shares its boundary plan with the 6-series deep-groove envelopes.
What is the difference between NU, NJ, N and NUP designs?
NU (like the NU310) has a shoulderless inner ring and floats axially in both directions; NJ has one integral inner-ring shoulder and locates the shaft in one direction; N has two inner shoulders and a shoulderless outer ring (mirror of NU); NUP adds a second, loose shoulder so the inner ring locates in both directions. Select by the shaft locating scheme, not by load rating — the envelopes are identical.
Can an NU310 take axial load or misalignment?
No thrust in the NU design: any sustained axial force scores the roller ends and ring flanges, so locate the shaft with an NJ/NUP row, a paired angular-contact bearing or a deep-groove row elsewhere. Misalignment is likewise not tolerated — line contact between cylindrical rollers and raceways edges under even small angular errors; use a spherical roller bearing where shaft deflection or housing misalignment is expected.
What does the E suffix mean and which clearance should be ordered?
E (as in NU310E) is the reinforced design: larger/optimised rollers raise the basic load rating over the basic designation in the same 50×110×27 mm envelope. For clearance, C3 is the usual default with an interference fit on a rotating inner ring because fit and thermal growth reduce residual play; use CN mainly for loose floating outer-ring mounts and C4 for hot or vibratory duty.
Reviewed & verified by the MPN Base engineering desk against source catalog iso15-crb-geometry on 2026-09-24. Read our editorial & correction policy.