NU307EA bearing: complete specifications & equivalents
The NU307EA is a ISO 15 radial bearing sized 35 x 80 x 21 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 35 mm |
| Outer diameter D | 80 mm |
| Width B | 21 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 83.5 kN |
| Basic static load rating C0 | 71 kN |
| Fatigue load limit Pu | 8.65 kN |
| Limiting speed (mechanical) | 8100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 483 g |
| Manufacturer designation | NTN NU307EA |
| 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 | 1.378 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.827 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 22.5 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) | 5 of 34 |
| Bore above smallest NU300-series size | 18 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU307EA | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; standard interchange — confirm clearance class and precision with the 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 NU307EA model number is decoded
NTN lists NU307EA on the 35×80 mm envelope, 21 mm wide: a line-contact radial bearing with the EA high-capacity pressed sheet-steel cage and a grease limiting speed of 8,100 r/min. Digit by digit, NU307EA reads as NU (outer ring ribbed, inner ring ribless), ISO 15 series, and bore 35 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. At 11,500 r/min with oil versus 8,100 r/min with grease (a 3,400 r/min band), lubrication choice for NU307EA is a thermal decision, not just a sealing one. The 35 mm (1.378 in) bore and 80 mm (3.15 in) OD are ISO 15 boundary values; fillet and shoulder dimensions must still come from the NTN mounting table for the 21 mm-wide ring. Housing and shaft fillets must clear the ring chamfers of NU307EA; an oversized radius locks the ring on its face and tilts the 21 mm-wide seat.
Typical equipment & failure modes
Common applications
- industrial gearbox input and output shafts
- medium electric-motor and generator shafts
- pump and compressor crankshafts and rotors
- machine-tool gearbox and spindle radial sets
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
- micro-pitting when the EHL film falls below the composite roughness at high specific 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
- On this 35 mm bore, shaft thermal growth can preload the inner ring if the fit is too tight; verify residual interference at temperature and confirm the float ring still slides after mounting NU307EA.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NU307EA skids at 8,100 r/min and fails by smearing long before L10 fatigue.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 80 mm race brinells and releases as vibration within hours.
- Do not replace NU307EA with a deep-groove ball bearing on rating alone: line contact gives 83.5 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- Grease limiting speed 8,100 r/min and oil 11,500 r/min are different limits for NU307EA: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The 83.5/71 kN ratings, 8.65 kN Pu and 483 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU307EA (EA pressed-steel-cage 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 NU307EA?
NU307EA is an NTN NU single-row cylindrical roller bearing to ISO 15: 35 mm bore, 80 mm OD and 21 mm width (1.378 × 3.15 × 0.827 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 83.5 kN, C0 71 kN, Pu 8.65 kN, grease limiting speed 8,100 r/min, oil 11,500 r/min, mass about 483 g. It is open, with the EA high-capacity 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. NU307EA 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. This page's bearing carries the EA pressed-steel-cage execution.
Can NU307EA 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 NU307EA?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 46.2 mm, Ew 70.2 mm. The nominal bore/OD remain 35/80 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 8,100 r/min grease / 11,500 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.