NNU4930K bearing: complete specifications & equivalents
The NNU4930K is a ISO 15 radial bearing sized 150 x 210 x 60 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 150 mm |
| Outer diameter D | 210 mm |
| Width B | 60 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 380 kN |
| Basic static load rating C0 | 690 kN |
| Fatigue load limit Pu | 70.5 kN |
| Limiting speed (mechanical) | 2800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5900 g |
| Manufacturer designation | NTN NNU4930K |
| 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 | 5.906 in |
|---|---|
| Outer diameter D | 8.268 in |
| Width B | 2.362 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 30 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) | 7 of 26 |
| Bore above smallest NNU4900-series size | 50 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNU4930K | 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 NNU4930K model number is decoded
For pure radial duty on a 150 mm shaft NTN supplies NNU4930K: two integral ribs on the outer ring and a ribless, separable inner ring; the open execution is rated 2,800 r/min on grease and 3,300 r/min on oil. On the NTN nameplate NNU states which ring carries the ribs, which determines whether NNU4930K floats or locates; the numeric remainder is the ISO 15 series and 150 mm bore reference, not a fit or clearance instruction. The 30.0 mm radial section ((210−150)/2) frames the roller complement; capacity per millimetre of bore is about 2.5 kN/mm before application factors. Equivalent-load planning treats NNU4930K as a pure radial bearing: keep P below 380 kN at the required L10, and let a paired angular-contact or thrust part carry any sustained axial component. Heat the inner ring to max 120 °C for the 150 mm interference fit and support the ring face square during fitting; cocking over a keyway brinells the raceway before first rotation.
Typical equipment & failure modes
Common applications
- CNC lathe and machining-centre spindle radial sets
- precision rotary-table and dividing-head bearings
- high-speed turbine and turbo-blower rotor supports
- coordinate-measuring and semiconductor-equipment drives
Known failure patterns
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- 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
- brinelling from static overload or impact during handling
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- At 150 mm bore, oil-lubricated arrangements toward 3,300 r/min need positive flow and drain design; the 5900 g NNU4930K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Do not replace NNU4930K with a deep-groove ball bearing on rating alone: line contact gives 380 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 210 mm race brinells and releases as vibration within hours.
- The NNU rib arrangement is not interchangeable with another prefix on the same 150 mm seat: double row, ribbed outer ring, separable inner. Swapping NU for NJ changes axial location behaviour even though the 210×60 mm envelope matches.
- The 30.0 mm section at 150 mm bore leaves a narrow oil path; with the standard cage the relubrication groove and oil-level design must keep grease from churning in the 60 mm-wide cavity.
- The 380/690 kN ratings, 70.5 kN Pu and 5900 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU4930K (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 NNU4930K?
NNU4930K is an NTN NNU double-row precision cylindrical roller bearing to ISO 15: 150 mm bore, 210 mm OD and 60 mm width (5.906 × 8.268 × 2.362 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 380 kN, C0 690 kN, Pu 70.5 kN, grease limiting speed 2,800 r/min, oil 3,300 r/min, mass about 5900 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. NNU4930K 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. NNU4930K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NNU bearing like NNU4930K?
The K suffix denotes a 1:12 tapered bore. NNU4930K 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 NNU4930 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NNU4930K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 168.5 mm, Ew 196.5159 mm. The nominal bore/OD remain 150/210 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 2,800 r/min grease / 3,300 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.