NF338 bearing: complete specifications & equivalents
The NF338 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 NF338 |
| 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 & NF300-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 NF300-series | 20 mm |
| Largest outer diameter in NF300-series | 580 mm |
| Width range across NF300-series | 15–108 mm |
| Bore position in NF300-series (smallest first) | 27 of 32 |
| Bore above smallest NF300-series size | 170 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NF338 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 NF338 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, NF338 appears as a 190 mm bore single-row cylindrical roller bearing (1080 kN C / 1260 kN C0) with a pressed sheet-steel cage, listed to the ISO 15 boundary plan. Numbering ties NF338 to its envelope: type code NF, series NF300, 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 the raceway diameters for this size — Fw 245 mm and Ew 345 mm — the envelope inside the 190/400 mm bore/OD where the rollers actually run. Mass 48300 g for the 190×400×78 mm NF338 execution covers the pressed-steel cage and full roller complement; substitute on mass plus rating, not envelope alone. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a NF338 non-locating position preloads the bearing when the shaft grows.
Typical equipment & failure modes
Common applications
- large turbine and generator rotor bearings
- wind-turbine gearbox planet and rotor shafts
- ship propulsion line shafts and reduction gears
- mining SAG/ball-mill drive 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
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- brinelling from static overload or impact during handling
- hard-particle indentation of raceways in unfiltered oil or open arrangements
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 NF338 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 400 mm race brinells and releases as vibration within hours.
- The NF rib arrangement is not interchangeable with another prefix on the same 190 mm seat: one rib on each ring. Swapping NU for NJ changes axial location behaviour even though the 400×78 mm envelope matches.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NF338 skids at 1,600 r/min and fails by smearing long before L10 fatigue.
- The NF rib arrangement is not interchangeable with another prefix on the same 190 mm seat: one rib on each ring. Swapping NU for NJ changes axial location behaviour even though the 400×78 mm envelope matches.
- The 1080/1260 kN ratings, 111 kN Pu and 48300 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NF338 (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 NF338?
NF338 is an NTN NF 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. NF338 is one integral rib on each ring — separable inner ring with single-direction axial guidance and a defined shaft position.
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. NF338 is supplied in the standard open execution shown in the table.
Can NF338 take axial load and locate a shaft?
the NF design gives one-direction axial guidance via its single outer-ring rib. The loose rib ring still only suits light/short-duration axial guidance; heavy thrust belongs to a dedicated thrust bearing.
What do Fw and Ew mean for NF338?
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.