NJ338 bearing: complete specifications & equivalents
The NJ338 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 NJ338 |
| 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 & NJ300-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 NJ300-series | 17 mm |
| Largest outer diameter in NJ300-series | 580 mm |
| Width range across NJ300-series | 14–108 mm |
| Bore position in NJ300-series (smallest first) | 28 of 33 |
| Bore above smallest NJ300-series size | 173 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ338 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the 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 NJ338 model number is decoded
NJ338 is an NTN NJ cylindrical roller bearing: two integral ribs on the inner ring and one rib on the outer ring — it locates the shaft in one axial direction, inside the 190×400×78 mm ISO 15 envelope. The leading NJ defines the rib arrangement (inner ring two ribs + one outer rib); the dimension-series digits and the two-digit bore code resolve to 190 mm, with 400 mm OD and 78 mm width from the ISO 15 general plan. 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. The 5.7 kN-per-mm-bore figure (1080 kN over 190 mm) lets a NJ338 interchange candidate be screened quickly against the same-envelope ball or roller alternatives. Housing and shaft fillets must clear the ring chamfers of NJ338; 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
- 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
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- brinelling from static overload or impact during handling
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 NJ338 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 NJ300 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 NJ338: 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 NJ338 alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The NJ rib arrangement is not interchangeable with another prefix on the same 190 mm seat: inner ring two ribs + one outer rib. 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 NJ338 (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 NJ338?
NJ338 is an NTN NJ 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. NJ338 is two integral ribs on the inner ring and one rib on the outer ring — it locates the shaft in one axial direction.
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. NJ338 is supplied in the standard open execution shown in the table.
Can NJ338 take axial load and locate a shaft?
the NJ design accepts axial load in one direction and provides one-way shaft location. For two-direction location use an NUP execution or an NJ pair with loose rib rings.
What do Fw and Ew mean for NJ338?
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.