NJ344 bearing: complete specifications & equivalents
The NJ344 is a ISO 15 radial bearing sized 220 x 460 x 88 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 220 mm |
| Outer diameter D | 460 mm |
| Width B | 88 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1320 kN |
| Basic static load rating C0 | 1570 kN |
| Fatigue load limit Pu | 133 kN |
| Limiting speed (mechanical) | 1400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 71700 g |
| Manufacturer designation | NTN NJ344 |
| 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 | 8.661 in |
|---|---|
| Outer diameter D | 18.11 in |
| Width B | 3.465 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 120 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) | 30 of 33 |
| Bore above smallest NJ300-series size | 203 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ344-M | 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 NJ344 model number is decoded
NJ344 belongs to the NTN cylindrical roller range in NTN Ball and Roller Bearings CAT.No.2203E: line-contact rollers between ground raceways for a 1320 kN dynamic rating in the 220 mm bore. Numbering ties NJ344 to its envelope: type code NJ, series NJ300, 220 mm bore; the 460×88 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. With C 1320 kN and C0 1570 kN (C0/C ≈ 1.19) the bearing is proportioned for heavy radial load; the NJ design accepts axial load in one direction and provides one-way shaft location. The 6.0 kN-per-mm-bore figure (1320 kN over 220 mm) lets a NJ344 interchange candidate be screened quickly against the same-envelope ball or roller alternatives. Keep the open bearing wrapped until fitting: the line-contact raceways of the 220 mm bore indent under a single hard particle, and the steel cage provides no sealing of its own.
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
- 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
- false brinelling on standby machines exposed to external vibration
- electrical pitting on VFD-driven motor shafts without grounding protection
Selection pitfalls — read before you substitute
- At 220 mm bore, oil-lubricated arrangements toward 1,600 r/min need positive flow and drain design; the 71700 g NJ344 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Wide (22/23) and light (10/49) executions at 220 mm bore share bore but not OD/width; check the full NJ300 series code before substituting, because housing and shoulder geometry will not interchange.
- The 120.0 mm section at 220 mm bore leaves a narrow oil path; with the standard cage the relubrication groove and oil-level design must keep grease from churning in the 88 mm-wide cavity.
- Open NJ344 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 220 mm contact.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NJ344 skids at 1,400 r/min and fails by smearing long before L10 fatigue.
- The 1320/1570 kN ratings, 133 kN Pu and 71700 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NJ344 (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 NJ344?
NJ344 is an NTN NJ single-row cylindrical roller bearing to ISO 15: 220 mm bore, 460 mm OD and 88 mm width (8.661 × 18.11 × 3.465 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1320 kN, C0 1570 kN, Pu 133 kN, grease limiting speed 1,400 r/min, oil 1,600 r/min, mass about 71700 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. NJ344 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. NJ344 is supplied in the standard open execution shown in the table.
Can NJ344 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 NJ344?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 284 mm, Ew 396 mm. The nominal bore/OD remain 220/460 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,400 r/min grease / 1,600 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.