N306EA bearing: complete specifications & equivalents
The N306EA 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 N306EA |
| 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 & N300-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 N300-series | 17 mm |
| Largest outer diameter in N300-series | 580 mm |
| Width range across N300-series | 14–108 mm |
| Bore position in N300-series (smallest first) | 4 of 33 |
| Bore above smallest N300-series size | 13 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| N306EA | 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 N306EA model number is decoded
For pure radial duty on a 30 mm shaft NTN supplies N306EA: two integral ribs on the inner ring and a ribless separable outer ring; the open execution is rated 9,300 r/min on grease and 13,200 r/min on oil. The leading N defines the rib arrangement (inner ring ribbed, outer ring ribless); the dimension-series digits and the two-digit bore code resolve to 30 mm, with 72 mm OD and 19 mm width from the ISO 15 general plan. The 21.0 mm radial section ((72−30)/2) frames the roller complement; capacity per millimetre of bore is about 2.1 kN/mm before application factors. Selection arithmetic: Pu 6.15 kN is the fatigue load limit feeding the adjusted-life equation, and the C0/C ratio of 0.79 (50/63 kN) shows the high-static-capacity proportioning of this 30 mm bore. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a N306EA non-locating position preloads the bearing when the shaft grows.
Typical equipment & failure modes
Common applications
- fan and blower rotor positions
- industrial gearbox input and output shafts
- medium electric-motor and generator shafts
- pump and compressor crankshafts and rotors
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- grease starvation and cage drag when relubrication intervals are extended past the grease life
- 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 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 N306EA.
- Do not replace N306EA with a deep-groove ball bearing on rating alone: line contact gives 63 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 9,300 r/min and oil 13,200 r/min are different limits for N306EA: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Wide (22/23) and light (10/49) executions at 30 mm bore share bore but not OD/width; check the full N300 series code before substituting, because housing and shoulder geometry will not interchange.
- 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 63/50 kN ratings, 6.15 kN Pu and 353 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for N306EA (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 N306EA?
N306EA is an NTN N 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. N306EA is two integral ribs on the inner ring and a ribless separable outer ring — equivalent float behaviour with the separable ring on the housing side.
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 N306EA take axial load and locate a shaft?
the N design is non-locating like NU but floats with the separable outer ring in the housing. 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 N306EA?
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.