NU348 bearing: complete specifications & equivalents
The NU348 is a ISO 15 radial bearing sized 240 x 500 x 95 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 240 mm |
| Outer diameter D | 500 mm |
| Width B | 95 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1590 kN |
| Basic static load rating C0 | 1950 kN |
| Fatigue load limit Pu | 160 kN |
| Limiting speed (mechanical) | 1300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 91300 g |
| Manufacturer designation | NTN NU348 |
| 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 & NU300-series range
| Bore d | 9.449 in |
|---|---|
| Outer diameter D | 19.685 in |
| Width B | 3.74 in |
| ISO bore code | 48 |
| Radial section height (D−d)/2 | 130 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) | 31 of 34 |
| Bore above smallest NU300-series size | 223 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU348-MA | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 NU348 model number is decoded
NTN lists NU348 on the 240×500 mm envelope, 95 mm wide: a line-contact radial bearing with a pressed sheet-steel cage and a grease limiting speed of 1,300 r/min. The leading NU defines the rib arrangement (outer ring ribbed, inner ring ribless); the dimension-series digits and the two-digit bore code resolve to 240 mm, with 500 mm OD and 95 mm width from the ISO 15 general plan. Minimum radial load matters: an unloaded NU348 at high speed skids its rollers and smears the raceway; spring preload or the rotor weight typically covers the requirement in motors and pumps. The 6.6 kN-per-mm-bore figure (1590 kN over 240 mm) lets a NU348 interchange candidate be screened quickly against the same-envelope ball or roller alternatives. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a NU348 non-locating position preloads the bearing when the shaft grows.
Typical equipment & failure modes
Common applications
- rolling-mill work-roll and backup-roll positions
- large turbine and generator rotor bearings
- wind-turbine gearbox planet and rotor shafts
- ship propulsion line shafts and reduction gears
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- 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
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- At 240 mm bore, oil-lubricated arrangements toward 1,500 r/min need positive flow and drain design; the 91300 g NU348 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Open NU348 units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 240 mm contact.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 500 mm race brinells and releases as vibration within hours.
- Open NU348 units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 240 mm contact.
- Do not replace NU348 with a deep-groove ball bearing on rating alone: line contact gives 1590 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- The 1590/1950 kN ratings, 160 kN Pu and 91300 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU348 (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 NU348?
NU348 is an NTN NU single-row cylindrical roller bearing to ISO 15: 240 mm bore, 500 mm OD and 95 mm width (9.449 × 19.685 × 3.74 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1590 kN, C0 1950 kN, Pu 160 kN, grease limiting speed 1,300 r/min, oil 1,500 r/min, mass about 91300 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. NU348 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. NU348 is supplied in the standard open execution shown in the table.
Can NU348 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 NU348?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 310 mm, Ew 430 mm. The nominal bore/OD remain 240/500 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,300 r/min grease / 1,500 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.