NJ304EA bearing: complete specifications & equivalents
The NJ304EA is a ISO 15 radial bearing sized 20 x 52 x 15 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 20 mm |
| Outer diameter D | 52 mm |
| Width B | 15 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 37.5 kN |
| Basic static load rating C0 | 26.9 kN |
| Fatigue load limit Pu | 3.25 kN |
| Limiting speed (mechanical) | 13000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 147 g |
| Manufacturer designation | NTN NJ304EA |
| 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 & NJ300-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.591 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 16 mm |
| Smallest bore in NJ300-series | 17 mm |
| Largest outer diameter in NJ300-series | 580 mm |
| Width range across NJ300-series | 14–108 mm |
| Bore position in NJ300-series (smallest first) | 2 of 33 |
| Bore above smallest NJ300-series size | 3 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ304EA | 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 NJ304EA model number is decoded
NTN lists NJ304EA on the 20×52 mm envelope, 15 mm wide: a line-contact radial bearing with the EA high-capacity pressed sheet-steel cage and a grease limiting speed of 13,000 r/min. The leading NJ defines the rib arrangement (inner ring two ribs + one outer rib); the dimension-series digits and the two-digit bore code resolve to 20 mm, with 52 mm OD and 15 mm width from the ISO 15 general plan. At 18,000 r/min with oil versus 13,000 r/min with grease (a 5,000 r/min band), lubrication choice for NJ304EA is a thermal decision, not just a sealing one. With the inner ring rotating, catalogue practice is a k5/m5 shaft seat and an H7/H6 housing; the outer ring must remain free to creep slightly axially in non-locating NJ arrangements. Mount the separable inner ring + roller assembly on the shaft first and slide the outer ring into the housing; never press the outer ring through the rollers of NJ304EA.
Typical equipment & failure modes
Common applications
- light gearbox layshaft and pinion positions
- two-wheeler and small-engine transmission shafts
- small pump and compressor rotor shafts
- appliance and office-machine drives
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
- rolling-contact fatigue after the catalogue L10 life is exceeded
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- Small 20 mm-bore cylindrical rollers are skid-sensitive: ensure the radial load exceeds the minimum-load floor at operating speed, or the NJ304EA rollers smear even with correct grease.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NJ304EA skids at 13,000 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 52 mm race brinells and releases as vibration within hours.
- Do not replace NJ304EA with a deep-groove ball bearing on rating alone: line contact gives 37.5 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 13,000 r/min and oil 18,000 r/min are different limits for NJ304EA: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The 37.5/26.9 kN ratings, 3.25 kN Pu and 147 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NJ304EA (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 NJ304EA?
NJ304EA is an NTN NJ single-row cylindrical roller bearing to ISO 15: 20 mm bore, 52 mm OD and 15 mm width (0.787 × 2.047 × 0.591 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 37.5 kN, C0 26.9 kN, Pu 3.25 kN, grease limiting speed 13,000 r/min, oil 18,000 r/min, mass about 147 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. NJ304EA is two integral ribs on the inner ring and one rib on the outer ring — it locates the shaft in one axial direction.
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 NJ304EA take axial load and locate a shaft?
the NJ design accepts axial load in one direction and provides one-way shaft location. For two-direction location use an NUP execution or an NJ pair with loose rib rings.
What do Fw and Ew mean for NJ304EA?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 27.5 mm, Ew 45.5 mm. The nominal bore/OD remain 20/52 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 13,000 r/min grease / 18,000 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.