NUP318 bearing: complete specifications & equivalents
The NUP318 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 NUP318 |
| 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 | 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 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) | 15 of 32 |
| Bore above smallest NUP300-series size | 70 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NUP318-ECJ | 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 NUP318 model number is decoded
For pure radial duty on a 90 mm shaft NTN supplies NUP318: the NJ rib arrangement plus a loose L-shaped rib ring on the inner ring; the open execution is rated 3,700 r/min on grease and 4,300 r/min on oil. Numbering ties NUP318 to its envelope: type code NUP, series NUP300, 90 mm bore; the 190×43 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. With C 266 kN and C0 265 kN (C0/C ≈ 1.00) the bearing is proportioned for heavy radial load; the NUP design provides two-direction axial location via its loose rib ring, for light/moderate thrust guidance. The 3.0 kN-per-mm-bore figure (266 kN over 90 mm) lets a NUP318 interchange candidate be screened quickly against the same-envelope ball or roller alternatives. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a NUP318 non-locating position preloads the bearing when the shaft grows.
Typical equipment & failure modes
Common applications
- crusher and vibrating-screen drive shafts
- marine gearbox and deck-machinery shafts
- large electric-motor and generator rotors
- cement and mining conveyor drive pulleys
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
- hard-particle indentation of raceways in unfiltered oil or open arrangements
- brinelling from static overload or impact during handling
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.
- If the shaft must be located both ways, do not use NUP318 alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The NUP rib arrangement is not interchangeable with another prefix on the same 90 mm seat: inner ring two ribs + loose L-ring. Swapping NU for NJ changes axial location behaviour even though the 190×43 mm envelope matches.
- 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 NUP318 as printed, not to the bare size.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NUP318 skids at 3,700 r/min and fails by smearing long before L10 fatigue.
- The 266/265 kN ratings, 29.3 kN Pu and 5180 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NUP318 (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 NUP318?
NUP318 is an NTN NUP 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. NUP318 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. NUP318 is supplied in the standard open execution shown in the table.
Can NUP318 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 NUP318?
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.