NU338 bearing: complete specifications & equivalents
The NU338 is a ISO 15 radial bearing sized 190 x 400 x 78 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 190 mm |
| Outer diameter D | 400 mm |
| Width B | 78 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1080 kN |
| Basic static load rating C0 | 1260 kN |
| Fatigue load limit Pu | 111 kN |
| Limiting speed (mechanical) | 1600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 48300 g |
| Manufacturer designation | NTN NU338 |
| 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 | 7.48 in |
|---|---|
| Outer diameter D | 15.748 in |
| Width B | 3.071 in |
| ISO bore code | 38 |
| Radial section height (D−d)/2 | 105 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) | 28 of 34 |
| Bore above smallest NU300-series size | 173 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU338-ECM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 190×400×78 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 NU338 model number is decoded
NU338 belongs to the NTN cylindrical roller range in NTN Ball and Roller Bearings CAT.No.2203E: line-contact rollers between ground raceways for a 1080 kN dynamic rating in the 190 mm bore. Numbering ties NU338 to its envelope: type code NU, series NU300, 190 mm bore; the 400×78 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. NTN prints two speed ceilings: 1,600 r/min grease and 1,900 r/min oil — the pressed-steel cage and lubricant film set the real limit at the 190 mm bore. Mass 48300 g for the 190×400×78 mm NU338 execution covers the pressed-steel cage and full roller complement; substitute on mass plus rating, not envelope alone. Housing and shaft fillets must clear the ring chamfers of NU338; an oversized radius locks the ring on its face and tilts the 78 mm-wide seat.
Typical equipment & failure modes
Common applications
- heavy press and large gearbox main shafts
- rolling-mill work-roll and backup-roll positions
- large turbine and generator rotor bearings
- wind-turbine gearbox planet and rotor shafts
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- cage wear accelerated when the EA high-capacity roller complement runs continuously above its thermal balance
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- brinelling from static overload or impact during handling
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- At 190 mm bore, oil-lubricated arrangements toward 1,900 r/min need positive flow and drain design; the 48300 g NU338 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Wide (22/23) and light (10/49) executions at 190 mm bore share bore but not OD/width; check the full NU300 series code before substituting, because housing and shoulder geometry will not interchange.
- Grease limiting speed 1,600 r/min and oil 1,900 r/min are different limits for NU338: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Grease limiting speed 1,600 r/min and oil 1,900 r/min are different limits for NU338: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- If the shaft must be located both ways, do not use NU338 alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The 1080/1260 kN ratings, 111 kN Pu and 48300 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU338 (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 NU338?
NU338 is an NTN NU single-row cylindrical roller bearing to ISO 15: 190 mm bore, 400 mm OD and 78 mm width (7.48 × 15.748 × 3.071 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1080 kN, C0 1260 kN, Pu 111 kN, grease limiting speed 1,600 r/min, oil 1,900 r/min, mass about 48300 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. NU338 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. NU338 is supplied in the standard open execution shown in the table.
Can NU338 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 NU338?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 245 mm, Ew 345 mm. The nominal bore/OD remain 190/400 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,600 r/min grease / 1,900 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.