NU2308-NTN bearing: complete specifications & equivalents
The NU2308-NTN is a ISO 15 radial bearing sized 40 x 90 x 33 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 40 mm |
| Outer diameter D | 90 mm |
| Width B | 33 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 91.5 kN |
| Basic static load rating C0 | 88 kN |
| Fatigue load limit Pu | 10.7 kN |
| Limiting speed (mechanical) | 7000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 932 g |
| Manufacturer designation | NTN NU2308 |
| Standard | ISO 15 |
| Catalog version | NTN Ball and Roller Bearings CAT.No.2203E |
| Last verified | 2026-10-01 |
Source: catalog reference (NTN Ball and Roller Bearings CAT.No.2203E) · extracted 2026-10-01
Parameters extracted from the official NTN Ball and Roller Bearings catalogue (NTN Ball and Roller Bearings CAT.No.2203E); NTN® is a trademark of NTN Corporation, used here for identification only — mpnbase is not an authorized NTN distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at ntnglobal.com.
Dimensions in inches & NU2300-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 1.299 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in NU2300-series | 20 mm |
| Largest outer diameter in NU2300-series | 750 mm |
| Width range across NU2300-series | 21–224 mm |
| Bore position in NU2300-series (smallest first) | 5 of 35 |
| Bore above smallest NU2300-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU2308 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×33 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
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 NU2308-NTN model number is decoded
NU2308 is an NTN NU cylindrical roller bearing: two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially, inside the 40×90×33 mm ISO 15 envelope. Digit by digit, NU2308 reads as NU (outer ring ribbed, inner ring ribless), ISO 15 series, and bore 40 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. With C 91.5 kN and C0 88 kN (C0/C ≈ 0.96) the bearing is proportioned for heavy radial load; the NU design carries no axial load and floats axially on both sides. Thermal planning around the 7,000 r/min grease ceiling should include the cage type (a pressed sheet-steel cage) and oil-flow option to 8,200 r/min for continuously high-duty 40 mm positions. Housing and shaft fillets must clear the ring chamfers of NU2308; an oversized radius locks the ring on its face and tilts the 33 mm-wide seat.
Typical equipment & failure modes
Common applications
- papermaking and printing auxiliary drives
- fan and blower rotor positions
- industrial gearbox input and output shafts
- medium electric-motor and generator shafts
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- cage wear accelerated when the EA high-capacity roller complement runs continuously above its thermal balance
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- On this 40 mm bore, shaft thermal growth can preload the inner ring if the fit is too tight; verify residual interference at temperature and confirm the float ring still slides after mounting NU2308.
- Wide (22/23) and light (10/49) executions at 40 mm bore share bore but not OD/width; check the full NU2300 series code before substituting, because housing and shoulder geometry will not interchange.
- The 33 mm width and abutment faces must be square to the axis; a tilted spacer concentrates load across the roller set and shows as uneven raceway polish on the 40 mm inner ring.
- Do not replace NU2308 with a deep-groove ball bearing on rating alone: line contact gives 91.5 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NU2308 skids at 7,000 r/min and fails by smearing long before L10 fatigue.
- The 91.5/88 kN ratings, 10.7 kN Pu and 932 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU2308 (standard execution); other makes sharing the ISO 15 envelope revise internal geometry without changing the order number, so keep the 2203E reference with the specification for critical drives.
Frequently asked questions
What are the dimensions and catalogue data of NU2308?
NU2308 is an NTN NU single-row cylindrical roller bearing to ISO 15: 40 mm bore, 90 mm OD and 33 mm width (1.575 × 3.543 × 1.299 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 91.5 kN, C0 88 kN, Pu 10.7 kN, grease limiting speed 7,000 r/min, oil 8,200 r/min, mass about 932 g. It is open, with a pressed sheet-steel cage.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
The prefix states the rib arrangement: NU has two outer-ring ribs and a ribless inner ring (float, no axial load); NJ adds ribs for one-direction location; NUP adds a loose L-ring to locate both directions; N has two inner-ring ribs and a separable outer ring; NF has one rib per ring for one-direction guidance. NU2308 is two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially.
What do the EA, E and ＊ suffixes mean on NTN cylindrical roller bearings?
EA is NTN's high-capacity design with a pressed sheet-steel cage and optimised roller complement in the same ISO 15 envelope; E marks the high-capacity design at the larger bores; the ＊ symbol printed before the code in the NTN catalogue marks the ULTAGE new-generation specification and is not typed as part of the order number. NU2308 is listed among the ＊ ULTAGE-marked executions in 2203E.
Can NU2308 take axial load and locate a shaft?
the NU design carries no axial load and floats axially on both sides. Provide axial location with an adjacent locating bearing (angular-contact, deep-groove or a paired NJ/NUP set).
What do Fw and Ew mean for NU2308?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 53.5 mm, Ew 77.5 mm. The nominal bore/OD remain 40/90 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 7,000 r/min grease / 8,200 r/min oil.
Reviewed & verified by the MPN Base engineering desk against source catalog NTN Ball and Roller Bearings CAT.No.2203E on 2026-10-01. Read our editorial & correction policy.