NF344 bearing: complete specifications & equivalents
The NF344 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 NF344 |
| 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 & NF300-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 NF300-series | 20 mm |
| Largest outer diameter in NF300-series | 580 mm |
| Width range across NF300-series | 15–108 mm |
| Bore position in NF300-series (smallest first) | 29 of 32 |
| Bore above smallest NF300-series size | 200 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NF344 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 NF344 model number is decoded
NF344 is an NTN NF cylindrical roller bearing: one integral rib on each ring — separable inner ring with single-direction axial guidance and a defined shaft position, inside the 220×460×88 mm ISO 15 envelope. Digit by digit, NF344 reads as NF (one rib on each ring), 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. With C 1320 kN and C0 1570 kN (C0/C ≈ 1.19) the bearing is proportioned for heavy radial load; the NF design gives one-direction axial guidance via its single outer-ring rib. Mass 71700 g for the 220×460×88 mm NF344 execution covers the pressed-steel cage and full roller complement; substitute on mass plus rating, not envelope alone. Heat the inner ring to max 120 °C for the 220 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
- large turbine and generator rotor bearings
- wind-turbine gearbox planet and rotor shafts
- ship propulsion line shafts and reduction gears
- mining SAG/ball-mill drive shafts
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- 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
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
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 NF344 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 460 mm race brinells and releases as vibration within hours.
- Grease limiting speed 1,400 r/min and oil 1,600 r/min are different limits for NF344: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 460 mm race brinells and releases as vibration within hours.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NF344 skids at 1,400 r/min and fails by smearing long before L10 fatigue.
- The 1320/1570 kN ratings, 133 kN Pu and 71700 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NF344 (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 NF344?
NF344 is an NTN NF 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. NF344 is one integral rib on each ring — separable inner ring with single-direction axial guidance and a defined shaft position.
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. NF344 is supplied in the standard open execution shown in the table.
Can NF344 take axial load and locate a shaft?
the NF design gives one-direction axial guidance via its single outer-ring rib. 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 NF344?
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.