NJ318 bearing: complete specifications & equivalents
The NJ318 is a ISO 15 radial bearing sized 90 x 190 x 43 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 90 mm |
| Outer diameter D | 190 mm |
| Width B | 43 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 266 kN |
| Basic static load rating C0 | 265 kN |
| Fatigue load limit Pu | 29.3 kN |
| Limiting speed (mechanical) | 3700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5180 g |
| Manufacturer designation | NTN NJ318 |
| 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 | 3.543 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.693 in |
| ISO bore code | 18 |
| Radial section height (D−d)/2 | 50 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) | 16 of 33 |
| Bore above smallest NJ300-series size | 73 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ318-ECP | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 90×190×43 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 NJ318 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, NJ318 appears as a 90 mm bore single-row cylindrical roller bearing (266 kN C / 265 kN C0) with a pressed sheet-steel cage, listed to the ISO 15 boundary plan. Digit by digit, NJ318 reads as NJ (inner ring two ribs + one outer rib), ISO 15 series, and bore 90 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. At 4,300 r/min with oil versus 3,700 r/min with grease (a 600 r/min band), lubrication choice for NJ318 is a thermal decision, not just a sealing one. Selection arithmetic: Pu 29.3 kN is the fatigue load limit feeding the adjusted-life equation, and the C0/C ratio of 1.00 (265/266 kN) shows the high-static-capacity proportioning of this 90 mm bore. Keep the open bearing wrapped until fitting: the line-contact raceways of the 90 mm bore indent under a single hard particle, and the steel cage provides no sealing of its own.
Typical equipment & failure modes
Common applications
- marine gearbox and deck-machinery shafts
- large electric-motor and generator rotors
- cement and mining conveyor drive pulleys
- heavy industrial gearbox and reducer shafts
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- cage distortion after a mounting blow carried through the roller set
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- rolling-contact fatigue after the catalogue L10 life is exceeded
- electrical pitting on VFD-driven motor shafts without grounding protection
Selection pitfalls — read before you substitute
- Induction-heat the 90 mm inner ring (max 120 °C) and mount it before fitting the outer ring; the ring mass makes square guidance essential — driving through the rollers brinells the 190 mm raceway.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 266/265 kN pair here belongs to NJ318 as printed, not to the bare size.
- If the shaft must be located both ways, do not use NJ318 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 90 mm seat: inner ring two ribs + one outer rib. Swapping NU for NJ changes axial location behaviour even though the 190×43 mm envelope matches.
- Grease limiting speed 3,700 r/min and oil 4,300 r/min are different limits for NJ318: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The 266/265 kN ratings, 29.3 kN Pu and 5180 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NJ318 (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 NJ318?
NJ318 is an NTN NJ single-row cylindrical roller bearing to ISO 15: 90 mm bore, 190 mm OD and 43 mm width (3.543 × 7.48 × 1.693 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 266 kN, C0 265 kN, Pu 29.3 kN, grease limiting speed 3,700 r/min, oil 4,300 r/min, mass about 5180 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. NJ318 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. NJ318 is supplied in the standard open execution shown in the table.
Can NJ318 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 NJ318?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 115 mm, Ew 165 mm. The nominal bore/OD remain 90/190 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 3,700 r/min grease / 4,300 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.