NU320-NTN bearing: complete specifications & equivalents
The NU320-NTN is a ISO 15 radial bearing sized 100 x 215 x 47 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 100 mm |
| Outer diameter D | 215 mm |
| Width B | 47 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 330 kN |
| Basic static load rating C0 | 335 kN |
| Fatigue load limit Pu | 36 kN |
| Limiting speed (mechanical) | 3300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 7320 g |
| Manufacturer designation | NTN NU320 |
| 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 & NU300-series range
| Bore d | 3.937 in |
|---|---|
| Outer diameter D | 8.465 in |
| Width B | 1.85 in |
| ISO bore code | 20 |
| Radial section height (D−d)/2 | 57.5 mm |
| Smallest bore in NU300-series | 17 mm |
| Largest outer diameter in NU300-series | 620 mm |
| Width range across NU300-series | 14–109 mm |
| Bore position in NU300-series (smallest first) | 18 of 34 |
| Bore above smallest NU300-series size | 83 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU320 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 100×215×47 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 NU320-NTN model number is decoded
NU320 belongs to the NTN cylindrical roller range in NTN Ball and Roller Bearings CAT.No.2203E: line-contact rollers between ground raceways for a 330 kN dynamic rating in the 100 mm bore. On the NTN nameplate NU states which ring carries the ribs, which determines whether NU320 floats or locates; the numeric remainder is the ISO 15 series and 100 mm bore reference, not a fit or clearance instruction. With C 330 kN and C0 335 kN (C0/C ≈ 1.02) the bearing is proportioned for heavy radial load; the NU design carries no axial load and floats axially on both sides. Equivalent-load planning treats NU320 as a pure radial bearing: keep P below 330 kN at the required L10, and let a paired angular-contact or thrust part carry any sustained axial component. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a NU320 non-locating position preloads the bearing when the shaft grows.
Typical equipment & failure modes
Common applications
- rolling-mill auxiliary drive shafts
- crusher and vibrating-screen drive shafts
- marine gearbox and deck-machinery shafts
- large electric-motor and generator rotors
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
- electrical pitting on VFD-driven motor shafts without grounding protection
- electrical pitting on VFD-driven motor shafts without grounding protection
Selection pitfalls — read before you substitute
- Induction-heat the 100 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 215 mm raceway.
- The 57.5 mm section at 100 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 47 mm-wide cavity.
- Wide (22/23) and light (10/49) executions at 100 mm bore share bore but not OD/width; check the full NU300 series code before substituting, because housing and shoulder geometry will not interchange.
- The 57.5 mm section at 100 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 47 mm-wide cavity.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NU320 skids at 3,300 r/min and fails by smearing long before L10 fatigue.
- The 330/335 kN ratings, 36 kN Pu and 7320 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU320 (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 NU320?
NU320 is an NTN NU single-row cylindrical roller bearing to ISO 15: 100 mm bore, 215 mm OD and 47 mm width (3.937 × 8.465 × 1.85 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 330 kN, C0 335 kN, Pu 36 kN, grease limiting speed 3,300 r/min, oil 3,800 r/min, mass about 7320 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. NU320 is two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially.
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. NU320 is supplied in the standard open execution shown in the table.
Can NU320 take axial load and locate a shaft?
the NU design carries no axial load and floats axially on both sides. Provide axial location with an adjacent locating bearing (angular-contact, deep-groove or a paired NJ/NUP set).
What do Fw and Ew mean for NU320?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 129.5 mm, Ew 185.5 mm. The nominal bore/OD remain 100/215 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 3,300 r/min grease / 3,800 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.