NUP324 bearing: complete specifications & equivalents
The NUP324 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 NUP324 |
| 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 & NUP300-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 NUP300-series | 20 mm |
| Largest outer diameter in NUP300-series | 580 mm |
| Width range across NUP300-series | 15–108 mm |
| Bore position in NUP300-series (smallest first) | 20 of 32 |
| Bore above smallest NUP300-series size | 100 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NUP324-ECP | 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 NUP324 model number is decoded
NUP324 is the standard section of the NTN NUP300 dimension series for a 120 mm shaft — 500 kN of basic dynamic capacity in a 12500 g, open bearing. Digit by digit, NUP324 reads as NUP (inner ring two ribs + loose L-ring), ISO 15 series, and bore 120 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. At 3,200 r/min with oil versus 2,700 r/min with grease (a 500 r/min band), lubrication choice for NUP324 is a thermal decision, not just a sealing one. The 4.2 kN-per-mm-bore figure (500 kN over 120 mm) lets a NUP324 interchange candidate be screened quickly against the same-envelope ball or roller alternatives. Heat the inner ring to max 120 °C for the 120 mm interference fit and support the ring face square during fitting; cocking over a keyway brinells the raceway before first rotation.
Typical equipment & failure modes
Common applications
- ship propulsion line shafts and reduction gears
- mining SAG/ball-mill drive shafts
- offshore drawworks and winch drums
- heavy press and large gearbox main 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
- 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
- At 120 mm bore, oil-lubricated arrangements toward 3,200 r/min need positive flow and drain design; the 12500 g NUP324 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- If the shaft must be located both ways, do not use NUP324 alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- Grease limiting speed 2,700 r/min and oil 3,200 r/min are different limits for NUP324: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NUP324 skids at 2,700 r/min and fails by smearing long before L10 fatigue.
- Grease limiting speed 2,700 r/min and oil 3,200 r/min are different limits for NUP324: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The 500/510 kN ratings, 51 kN Pu and 12500 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NUP324 (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 NUP324?
NUP324 is an NTN NUP 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. NUP324 is the NJ rib arrangement plus a loose L-shaped rib ring on the inner ring — it locates the shaft in both axial directions.
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. NUP324 is supplied in the standard open execution shown in the table.
Can NUP324 take axial load and locate a shaft?
the NUP design provides two-direction axial location via its loose rib ring, for light/moderate thrust guidance. 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 NUP324?
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.