NNU4984K bearing: complete specifications & equivalents
The NNU4984K is a ISO 15 radial bearing sized 420 x 560 x 140 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 | 560 mm |
| Width B | 140 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1930 kN |
| Basic static load rating C0 | 4500 kN |
| Fatigue load limit Pu | 340 kN |
| Limiting speed (mechanical) | 900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 87700 g |
| Manufacturer designation | NTN NNU4984K |
| 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 & NNU4900-series range
| Bore d | 16.535 in |
|---|---|
| Outer diameter D | 22.047 in |
| Width B | 5.512 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 70 mm |
| Smallest bore in NNU4900-series | 100 mm |
| Largest outer diameter in NNU4900-series | 650 mm |
| Width range across NNU4900-series | 40–170 mm |
| Bore position in NNU4900-series (smallest first) | 23 of 26 |
| Bore above smallest NNU4900-series size | 320 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNU4984K | 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 NNU4984K model number is decoded
NNU4984K is an NTN NNU 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 420×560×140 mm ISO 15 envelope. Digit by digit, NNU4984K reads as NNU (double row, ribbed outer ring, separable inner), ISO 15 series, and bore 420 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. Double-row NNU precision cylindrical roller bearing: ribbed outer ring with a separable inner ring, two roller rows for high radial stiffness on machine-tool spindles; the K suffix is a 1:12 tapered bore — mounted on a tapered seat or adapter sleeve and driven up to a precise radial clearance/preload; precision classes P5/P4/P2 and clearance are ordered separately. Speed ratio check: limiting 900 r/min is .82 of the 1,100 r/min oil value for NNU4984K; grease-churn heating closes that gap as fill quantity rises. Housing and shaft fillets must clear the ring chamfers of NNU4984K; an oversized radius locks the ring on its face and tilts the 140 mm-wide seat.
Typical equipment & failure modes
Common applications
- precision rotary-table and dividing-head bearings
- high-speed turbine and turbo-blower rotor supports
- coordinate-measuring and semiconductor-equipment drives
- machine-tool main spindles requiring high radial stiffness
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
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- false brinelling on standby machines exposed to external vibration
Selection pitfalls — read before you substitute
- At 420 mm bore, oil-lubricated arrangements toward 1,100 r/min need positive flow and drain design; the 87700 g NNU4984K 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 NNU4900 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 NNU4984K skids at 900 r/min and fails by smearing long before L10 fatigue.
- Open NNU4984K units need application-supplied sealing and a defined lubricant schedule; film thickness is the first failure mode for line contact when viscosity drops at the 420 mm contact.
- The 140 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 420 mm inner ring.
- The 1930/4500 kN ratings, 340 kN Pu and 87700 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU4984K (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 NNU4984K?
NNU4984K is an NTN NNU double-row precision cylindrical roller bearing to ISO 15: 420 mm bore, 560 mm OD and 140 mm width (16.535 × 22.047 × 5.512 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1930 kN, C0 4500 kN, Pu 340 kN, grease limiting speed 900 r/min, oil 1,100 r/min, mass about 87700 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. NNU4984K is the NNU 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. NNU4984K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NNU bearing like NNU4984K?
The K suffix denotes a 1:12 tapered bore. NNU4984K 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 NNU4984 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NNU4984K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 465 mm. The nominal bore/OD remain 420/560 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 900 r/min grease / 1,100 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.