NU328 bearing: complete specifications & equivalents
The NU328 is a ISO 15 radial bearing sized 140 x 300 x 62 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 140 mm |
| Outer diameter D | 300 mm |
| Width B | 62 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 685 kN |
| Basic static load rating C0 | 745 kN |
| Fatigue load limit Pu | 72 kN |
| Limiting speed (mechanical) | 2300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 20700 g |
| Manufacturer designation | NTN NU328 |
| 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 | 5.512 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 2.441 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 80 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) | 23 of 34 |
| Bore above smallest NU300-series size | 123 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU328-ECM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 140×300×62 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 NU328 model number is decoded
NU328 is the standard section of the NTN NU300 dimension series for a 140 mm shaft — 685 kN of basic dynamic capacity in a 20700 g, open bearing. Digit by digit, NU328 reads as NU (outer ring ribbed, inner ring ribless), ISO 15 series, and bore 140 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. the bare number is the standard-capacity open execution with the normal pressed-steel cage; quote the full NU328 designation when purchasing. Selection arithmetic: Pu 72 kN is the fatigue load limit feeding the adjusted-life equation, and the C0/C ratio of 1.09 (745/685 kN) shows the high-static-capacity proportioning of this 140 mm bore. Heat the inner ring to max 120 °C for the 140 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
- offshore drawworks and winch drums
- heavy press and large gearbox main shafts
- rolling-mill work-roll and backup-roll positions
- large turbine and generator rotor bearings
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
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- rolling-contact fatigue after the catalogue L10 life is exceeded
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
Selection pitfalls — read before you substitute
- At 140 mm bore, oil-lubricated arrangements toward 2,700 r/min need positive flow and drain design; the 20700 g NU328 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The 80.0 mm section at 140 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 62 mm-wide cavity.
- Wide (22/23) and light (10/49) executions at 140 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 62 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 140 mm inner ring.
- The 62 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 140 mm inner ring.
- The 685/745 kN ratings, 72 kN Pu and 20700 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU328 (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 NU328?
NU328 is an NTN NU single-row cylindrical roller bearing to ISO 15: 140 mm bore, 300 mm OD and 62 mm width (5.512 × 11.811 × 2.441 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 685 kN, C0 745 kN, Pu 72 kN, grease limiting speed 2,300 r/min, oil 2,700 r/min, mass about 20700 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. NU328 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. NU328 is supplied in the standard open execution shown in the table.
Can NU328 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 NU328?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 180 mm, Ew 260 mm. The nominal bore/OD remain 140/300 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 2,300 r/min grease / 2,700 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.