NU2306 bearing: complete specifications & equivalents
The NU2306 is a ISO 15 radial bearing sized 30 x 72 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 | 30 mm |
| Outer diameter D | 72 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) | 464 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 NU2306 are being backfilled — use the inquiry form for certified values.
Dimensions in inches & NU2300-series range
| Bore d | 1.181 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 1.063 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 21 mm |
| Smallest bore in NU2300-series | 25 mm |
| Largest outer diameter in NU2300-series | 130 mm |
| Width range across NU2300-series | 24–46 mm |
| Bore position in NU2300-series (smallest first) | 2 of 8 |
| Bore above smallest NU2300-series size | 5 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NU2306 model number is decoded
In the NU2300-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 NU2306 are bore code 06 = 30 mm (code × 5 from 04 upward). The ISO 15 envelope is 72 mm outside diameter and 27 mm width — 1.181 × 2.835 × 1.063 in, with a 21.0 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
- small gearbox layshafts and pinion shafts
- fractional electric motor armatures
- two-wheeler and appliance transmissions
- small pump and fan rotor shafts
- textile and packaging machinery rolls
Known failure patterns
- 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
- roller-end and flange scoring when an NU bearing is forced to locate axially; only NJ/NUP designs carry thrust at the shoulders
- cage fatigue and fracture after sustained over-speed with marginal lubrication
Selection pitfalls — read before you substitute
- At 30 mm bore the small NU2306 commonly shares a gearbox bore with a 6-series deep-groove row; do not substitute by envelope alone — the cylindrical roller carries far more radial load but no thrust, so any helical-gear axial force needs a paired angular-contact or NJ locating row.
- The NU23 wide medium series (30×72×27 mm) packs the highest rating of the 30 mm-bore cylindrical rows into the NU3 housing bore; the 21.0 mm section and wide roller set tolerate no misalignment, so align the seats before selecting it over an NU306.
- The 27 mm-wide NU2306 seats against shaft and housing shoulders whose fillet must clear the ring chamfer: keep the corner radius inside the catalogue limit so the 30 mm bore and 72 mm OD faces abut square — an oversized radius lifts the ring and edge-loads the 21.0 mm section.
- For the interference inner ring of NU2306, heat to 80–100 °C with an induction heater (never a flame) and slide it dry to the 30 mm shaft shoulder; the roller assembly is fitted separately, and hammering cold through the 72 mm ring dents the raceways.
- Read the damage on a removed NU2306: uniform roller smearing points to minimum-load skidding, while spalling on one edge of the 72 mm raceway means misalignment or a tilted housing face — the two failures need opposite corrections, so inspect before ordering the replacement fit.
- Cylindrical rollers have no self-aligning capacity: line contact across the 27 mm-wide rollers means even a few tenths of a degree of misalignment edge-loads the 72 mm raceway; where shaft deflection is unavoidable, use a spherical roller or a self-aligning ball bearing instead.
- Keep the minimum load above the skid threshold (catalogue rule of thumb roughly 1–2% of the dynamic rating); an unloaded NU2306 on an idler or in a cold-start gearbox develops roller smearing, so add a spring preload or downsize the bearing if the duty is mostly empty.
Frequently asked questions
What are the dimensions of an NU2306 cylindrical roller bearing?
An NU2306 single-row cylindrical roller bearing per ISO 15 has a 30 mm bore, 72 mm outer diameter and 27 mm width (1.181 × 2.835 × 1.063 in), a 21.0 mm radial section and roughly 464 g geometry-based estimated mass; catalogue masses vary with cage and E design.
How does the NU2306 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 06: 06 × 5 = 30 mm. The 72 mm OD and 27 mm width come from the ISO 15 dimension series (NU2300), 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 NU2306) 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 NU2306 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 NU2306E) is the reinforced design: larger/optimised rollers raise the basic load rating over the basic designation in the same 30×72×27 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.