NU340 bearing: complete specifications & equivalents
The NU340 is a ISO 15 radial bearing sized 200 x 420 x 80 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 200 mm |
| Outer diameter D | 420 mm |
| Width B | 80 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1080 kN |
| Basic static load rating C0 | 1270 kN |
| Fatigue load limit Pu | 111 kN |
| Limiting speed (mechanical) | 1500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 54500 g |
| Manufacturer designation | NTN NU340 |
| 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 | 7.874 in |
|---|---|
| Outer diameter D | 16.535 in |
| Width B | 3.15 in |
| ISO bore code | 40 |
| Radial section height (D−d)/2 | 110 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) | 29 of 34 |
| Bore above smallest NU300-series size | 183 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU340-ECML | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 200×420×80 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 NU340 model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, NU340 appears as a 200 mm bore single-row cylindrical roller bearing (1080 kN C / 1270 kN C0) with a pressed sheet-steel cage, listed to the ISO 15 boundary plan. On the NTN nameplate NU states which ring carries the ribs, which determines whether NU340 floats or locates; the numeric remainder is the ISO 15 series and 200 mm bore reference, not a fit or clearance instruction. NTN prints the raceway diameters for this size — Fw 260 mm and Ew 360 mm — the envelope inside the 200/420 mm bore/OD where the rollers actually run. Selection arithmetic: Pu 111 kN is the fatigue load limit feeding the adjusted-life equation, and the C0/C ratio of 1.18 (1270/1080 kN) shows the high-static-capacity proportioning of this 200 mm bore. Mount the separable inner ring + roller assembly on the shaft first and slide the outer ring into the housing; never press the outer ring through the rollers of NU340.
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
- electrical pitting on VFD-driven motor shafts without grounding protection
- false brinelling on standby machines exposed to external vibration
Selection pitfalls — read before you substitute
- At 200 mm bore, oil-lubricated arrangements toward 1,800 r/min need positive flow and drain design; the 54500 g NU340 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The 110.0 mm section at 200 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 80 mm-wide cavity.
- The 80 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 200 mm inner ring.
- Wide (22/23) and light (10/49) executions at 200 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 NU rib arrangement is not interchangeable with another prefix on the same 200 mm seat: outer ring ribbed, inner ring ribless. Swapping NU for NJ changes axial location behaviour even though the 420×80 mm envelope matches.
- The 1080/1270 kN ratings, 111 kN Pu and 54500 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU340 (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 NU340?
NU340 is an NTN NU single-row cylindrical roller bearing to ISO 15: 200 mm bore, 420 mm OD and 80 mm width (7.874 × 16.535 × 3.15 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1080 kN, C0 1270 kN, Pu 111 kN, grease limiting speed 1,500 r/min, oil 1,800 r/min, mass about 54500 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. NU340 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. NU340 is supplied in the standard open execution shown in the table.
Can NU340 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 NU340?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 260 mm, Ew 360 mm. The nominal bore/OD remain 200/420 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,500 r/min grease / 1,800 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.