NN3084K bearing: complete specifications & equivalents
The NN3084K is a ISO 15 radial bearing sized 420 x 620 x 150 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 420 mm |
| Outer diameter D | 620 mm |
| Width B | 150 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 2300 kN |
| Basic static load rating C0 | 4300 kN |
| Fatigue load limit Pu | 320 kN |
| Limiting speed (mechanical) | 840 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 148000 g |
| Manufacturer designation | NTN NN3084K |
| 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 & NN3000-series range
| Bore d | 16.535 in |
|---|---|
| Outer diameter D | 24.409 in |
| Width B | 5.906 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 100 mm |
| Smallest bore in NN3000-series | 25 mm |
| Largest outer diameter in NN3000-series | 680 mm |
| Width range across NN3000-series | 16–163 mm |
| Bore position in NN3000-series (smallest first) | 38 of 40 |
| Bore above smallest NN3000-series size | 395 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN3084K | 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 NN3084K model number is decoded
NTN lists NN3084K on the 420×620 mm envelope, 150 mm wide: a line-contact radial bearing with a machined or stamped steel cage per the precision execution and a grease limiting speed of 840 r/min. The leading NN defines the rib arrangement (double row, ribbed inner ring, separable outer); the dimension-series digits and the two-digit bore code resolve to 420 mm, with 620 mm OD and 150 mm width from the ISO 15 general plan. With C 2300 kN and C0 4300 kN (C0/C ≈ 1.87) the bearing is proportioned for heavy radial load; the NU design carries no axial load and floats axially on both sides. With the inner ring rotating, catalogue practice is a m6/n6 shaft seat and an H7/H6 housing; the outer ring must remain free to creep slightly axially in non-locating NN arrangements. Housing and shaft fillets must clear the ring chamfers of NN3084K; an oversized radius locks the ring on its face and tilts the 150 mm-wide seat.
Typical equipment & failure modes
Common applications
- high-rpm motorised grinding and milling spindles
- CNC lathe and machining-centre spindle radial sets
- precision rotary-table and dividing-head bearings
- high-speed turbine and turbo-blower rotor supports
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
- 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
- false brinelling on standby machines exposed to external vibration
Selection pitfalls — read before you substitute
- At 420 mm bore, oil-lubricated arrangements toward 990 r/min need positive flow and drain design; the 148000 g NN3084K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Wide (22/23) and light (10/49) executions at 420 mm bore share bore but not OD/width; check the full NN3000 series code before substituting, because housing and shoulder geometry will not interchange.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NN3084K skids at 840 r/min and fails by smearing long before L10 fatigue.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NN3084K skids at 840 r/min and fails by smearing long before L10 fatigue.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NN3084K skids at 840 r/min and fails by smearing long before L10 fatigue.
- The 2300/4300 kN ratings, 320 kN Pu and 148000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN3084K (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 NN3084K?
NN3084K is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 420 mm bore, 620 mm OD and 150 mm width (16.535 × 24.409 × 5.906 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 2300 kN, C0 4300 kN, Pu 320 kN, grease limiting speed 840 r/min, oil 990 r/min, mass about 148000 g. It is open, with a machined or stamped steel cage per the precision execution.
What is the difference between NU, NJ, NUP, N and NF cylindrical roller bearings?
NN and NNU are double-row precision designs rather than single-row rib variants: NN has a ribbed inner ring and separable outer ring, NNU the reverse; both give high radial stiffness for spindles and are commonly ordered with P5/P4 precision and a K 1:12 tapered bore for preload setting. NN3084K is the NN execution.
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. NN3084K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN3084K?
The K suffix denotes a 1:12 tapered bore. NN3084K mounts on a tapered shaft seat or adapter sleeve and is driven up to a measured residual clearance or preload — this is how precision spindle bearings achieve stiffness without locknut guesswork; the cylindrical-bore NN3084 execution of the same envelope mounts on a plain seat.
What speeds and lubrication apply to NN3084K?
NTN rates NN3084K at 840 r/min with grease and 990 r/min with oil. The grease figure is the cage/film mechanical ceiling; the oil figure assumes circulating or carefully supplied oil that removes heat from the line-contact zone.
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.