NU344 bearing: complete specifications & equivalents
The NU344 is a ISO 15 radial bearing sized 220 x 460 x 88 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 220 mm |
| Outer diameter D | 460 mm |
| Width B | 88 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1320 kN |
| Basic static load rating C0 | 1570 kN |
| Fatigue load limit Pu | 133 kN |
| Limiting speed (mechanical) | 1400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 71700 g |
| Manufacturer designation | NTN NU344 |
| 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 | 8.661 in |
|---|---|
| Outer diameter D | 18.11 in |
| Width B | 3.465 in |
| ISO bore code | 44 |
| Radial section height (D−d)/2 | 120 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) | 30 of 34 |
| Bore above smallest NU300-series size | 203 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU344-M | SKF | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 NU344 model number is decoded
The NTN order number NU344 denotes a 220×460×88 mm (8.661 × 18.11 × 3.465 in) cylindrical roller bearing in the NU300 family, a pressed sheet-steel cage. Digit by digit, NU344 reads as NU (outer ring ribbed, inner ring ribless), ISO 15 series, and bore 220 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 NU344 designation when purchasing. Mass 71700 g for the 220×460×88 mm NU344 execution covers the pressed-steel cage and full roller complement; substitute on mass plus rating, not envelope alone. Keep the open bearing wrapped until fitting: the line-contact raceways of the 220 mm bore indent under a single hard particle, and the steel cage provides no sealing of its own.
Typical equipment & failure modes
Common applications
- heavy press and large gearbox main shafts
- rolling-mill work-roll and backup-roll positions
- large turbine and generator rotor bearings
- wind-turbine gearbox planet and rotor shafts
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- cage wear accelerated when the EA high-capacity roller complement runs continuously above its thermal balance
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- 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
- At 220 mm bore, oil-lubricated arrangements toward 1,600 r/min need positive flow and drain design; the 71700 g NU344 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Wide (22/23) and light (10/49) executions at 220 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 120.0 mm section at 220 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 88 mm-wide cavity.
- The NU rib arrangement is not interchangeable with another prefix on the same 220 mm seat: outer ring ribbed, inner ring ribless. Swapping NU for NJ changes axial location behaviour even though the 460×88 mm envelope matches.
- The 88 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 220 mm inner ring.
- The 1320/1570 kN ratings, 133 kN Pu and 71700 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU344 (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 NU344?
NU344 is an NTN NU single-row cylindrical roller bearing to ISO 15: 220 mm bore, 460 mm OD and 88 mm width (8.661 × 18.11 × 3.465 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1320 kN, C0 1570 kN, Pu 133 kN, grease limiting speed 1,400 r/min, oil 1,600 r/min, mass about 71700 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. NU344 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. NU344 is supplied in the standard open execution shown in the table.
Can NU344 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 NU344?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 284 mm, Ew 396 mm. The nominal bore/OD remain 220/460 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,400 r/min grease / 1,600 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.