NU306EA bearing: complete specifications & equivalents
The NU306EA is a ISO 15 radial bearing sized 30 x 72 x 19 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 30 mm |
| Outer diameter D | 72 mm |
| Width B | 19 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 63 kN |
| Basic static load rating C0 | 50 kN |
| Fatigue load limit Pu | 6.15 kN |
| Limiting speed (mechanical) | 9300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 353 g |
| Manufacturer designation | NTN NU306EA |
| 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 | 1.181 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 0.748 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 21 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) | 4 of 34 |
| Bore above smallest NU300-series size | 13 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NU306EA | 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 NU306EA model number is decoded
NU306EA is an NTN NU cylindrical roller bearing: two integral ribs on the outer ring and a ribless, separable inner ring — a non-locating bearing that lets the shaft float axially, inside the 30×72×19 mm ISO 15 envelope. On the NTN nameplate NU states which ring carries the ribs, which determines whether NU306EA floats or locates; the numeric remainder is the ISO 15 series and 30 mm bore reference, not a fit or clearance instruction. EA marks the high-capacity design: optimised roller complement in a pressed (stamped) sheet-steel cage for more load capacity than the basic number in the same ISO 15 envelope; the ＊ symbol printed before the number in 2203E marks the ULTAGE new-generation specification — upgraded material/geometry and longer rating life, not part of the order code; quote the full NU306EA designation when purchasing. The 2.1 kN-per-mm-bore figure (63 kN over 30 mm) lets a NU306EA interchange candidate be screened quickly against the same-envelope ball or roller alternatives. Housing and shaft fillets must clear the ring chamfers of NU306EA; an oversized radius locks the ring on its face and tilts the 19 mm-wide seat.
Typical equipment & failure modes
Common applications
- medium electric-motor and generator shafts
- pump and compressor crankshafts and rotors
- machine-tool gearbox and spindle radial sets
- material-handling drum and wheel shafts
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- On this 30 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 NU306EA.
- If the shaft must be located both ways, do not use NU306EA alone: pair it with a locating bearing or specify the NUP execution with the matching loose rib ring from the 2203E table.
- The 21.0 mm section at 30 mm bore leaves a narrow oil path; with the EA pressed-steel-cage cage the relubrication groove and oil-level design must keep grease from churning in the 19 mm-wide cavity.
- The NU rib arrangement is not interchangeable with another prefix on the same 30 mm seat: outer ring ribbed, inner ring ribless. Swapping NU for NJ changes axial location behaviour even though the 72×19 mm envelope matches.
- The 19 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 30 mm inner ring.
- The 63/50 kN ratings, 6.15 kN Pu and 353 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NU306EA (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 NU306EA?
NU306EA is an NTN NU single-row cylindrical roller bearing to ISO 15: 30 mm bore, 72 mm OD and 19 mm width (1.181 × 2.835 × 0.748 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 63 kN, C0 50 kN, Pu 6.15 kN, grease limiting speed 9,300 r/min, oil 13,200 r/min, mass about 353 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. NU306EA 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 NU306EA 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 NU306EA?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 40.5 mm, Ew 62.5 mm. The nominal bore/OD remain 30/72 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 9,300 r/min grease / 13,200 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.