NJ324 bearing: complete specifications & equivalents
The NJ324 is a ISO 15 radial bearing sized 120 x 260 x 55 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 120 mm |
| Outer diameter D | 260 mm |
| Width B | 55 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 500 kN |
| Basic static load rating C0 | 510 kN |
| Fatigue load limit Pu | 51 kN |
| Limiting speed (mechanical) | 2700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 12500 g |
| Manufacturer designation | NTN NJ324 |
| 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 | 4.724 in |
|---|---|
| Outer diameter D | 10.236 in |
| Width B | 2.165 in |
| ISO bore code | 24 |
| Radial section height (D−d)/2 | 70 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) | 21 of 33 |
| Bore above smallest NJ300-series size | 103 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ324-ECJ | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 120×260×55 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 NJ324 model number is decoded
NJ324 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 120×260×55 mm ISO 15 envelope. Reading the code: NJ for the one-direction-locating type, then the ISO 15 diameter/width series and the bore code — ×5 = 120 mm (00–03 use the 10/12/15/17 exception table). The separable ring comes off without removing the roller assembly from the other ring, which eases inspection and lets the non-locating arrangement accommodate thermal shaft growth. Selection arithmetic: Pu 51 kN is the fatigue load limit feeding the adjusted-life equation, and the C0/C ratio of 1.02 (510/500 kN) shows the high-static-capacity proportioning of this 120 mm bore. The NJ design locates in one direction only: for two-direction location fit the matching loose rib ring (NUP execution) or pair the bearings back to back on the 120 mm shaft.
Typical equipment & failure modes
Common applications
- mining SAG/ball-mill drive shafts
- offshore drawworks and winch drums
- heavy press and large gearbox main shafts
- rolling-mill work-roll and backup-roll positions
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- cage distortion after a mounting blow carried through the roller set
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- fretting corrosion on a loose rotating shaft seat
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- At 120 mm bore, oil-lubricated arrangements toward 3,200 r/min need positive flow and drain design; the 12500 g NJ324 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 500/510 kN pair here belongs to NJ324 as printed, not to the bare size.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 260 mm race brinells and releases as vibration within hours.
- The 55 mm width and abutment faces must be square to the axis; a tilted spacer concentrates load across the roller set and shows as uneven raceway polish on the 120 mm inner ring.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 500/510 kN pair here belongs to NJ324 as printed, not to the bare size.
- The 500/510 kN ratings, 51 kN Pu and 12500 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NJ324 (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 NJ324?
NJ324 is an NTN NJ single-row cylindrical roller bearing to ISO 15: 120 mm bore, 260 mm OD and 55 mm width (4.724 × 10.236 × 2.165 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 500 kN, C0 510 kN, Pu 51 kN, grease limiting speed 2,700 r/min, oil 3,200 r/min, mass about 12500 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. NJ324 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. NJ324 is supplied in the standard open execution shown in the table.
Can NJ324 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 NJ324?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 154 mm, Ew 226 mm. The nominal bore/OD remain 120/260 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 2,700 r/min grease / 3,200 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.