NN4928K bearing: complete specifications & equivalents
The NN4928K is a ISO 15 radial bearing sized 140 x 190 x 50 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 140 mm |
| Outer diameter D | 190 mm |
| Width B | 50 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 251 kN |
| Basic static load rating C0 | 470 kN |
| Fatigue load limit Pu | 49 kN |
| Limiting speed (mechanical) | 3000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3580 g |
| Manufacturer designation | NTN NN4928K |
| 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 & NN4900-series range
| Bore d | 5.512 in |
|---|---|
| Outer diameter D | 7.48 in |
| Width B | 1.969 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in NN4900-series | 100 mm |
| Largest outer diameter in NN4900-series | 440 mm |
| Width range across NN4900-series | 40–118 mm |
| Bore position in NN4900-series (smallest first) | 6 of 18 |
| Bore above smallest NN4900-series size | 40 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN4928K | 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 NN4928K model number is decoded
For pure radial duty on a 140 mm shaft NTN supplies NN4928K: two integral ribs on the outer ring and a ribless, separable inner ring; the open execution is rated 3,000 r/min on grease and 3,600 r/min on oil. 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 140 mm, with 190 mm OD and 50 mm width from the ISO 15 general plan. NTN prints two speed ceilings: 3,000 r/min grease and 3,600 r/min oil — the pressed-steel cage and lubricant film set the real limit at the 140 mm bore. Thermal planning around the 3,000 r/min grease ceiling should include the cage type (a machined or stamped steel cage per the precision execution) and oil-flow option to 3,600 r/min for continuously high-duty 140 mm positions. On NN arrangements confirm which ring is separable before heating: forcing the ribbed ring off over the roller complement damages the cage and rib faces.
Typical equipment & failure modes
Common applications
- high-speed turbine and turbo-blower rotor supports
- coordinate-measuring and semiconductor-equipment drives
- machine-tool main spindles requiring high radial stiffness
- precision gearbox and indexing-drive shafts
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
- roller-end and raceway scoring from inadequate oil flow under heavy radial load
- false brinelling on standby machines exposed to external vibration
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- At 140 mm bore, oil-lubricated arrangements toward 3,600 r/min need positive flow and drain design; the 3580 g NN4928K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The K tapered bore of NN4928K is driven up to a measured clearance: skipping the drive-up procedure in favour of a normal press fit leaves the precision spindle set either preloaded hot or loose under load.
- The NN rib arrangement is not interchangeable with another prefix on the same 140 mm seat: double row, ribbed inner ring, separable outer. Swapping NU for NJ changes axial location behaviour even though the 190×50 mm envelope matches.
- Open NN4928K 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 140 mm contact.
- The K tapered bore of NN4928K is driven up to a measured clearance: skipping the drive-up procedure in favour of a normal press fit leaves the precision spindle set either preloaded hot or loose under load.
- The 251/470 kN ratings, 49 kN Pu and 3580 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN4928K (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 NN4928K?
NN4928K is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 140 mm bore, 190 mm OD and 50 mm width (5.512 × 7.48 × 1.969 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 251 kN, C0 470 kN, Pu 49 kN, grease limiting speed 3,000 r/min, oil 3,600 r/min, mass about 3580 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. NN4928K 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. NN4928K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN4928K?
The K suffix denotes a 1:12 tapered bore. NN4928K 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 NN4928 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NN4928K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 156 mm. The nominal bore/OD remain 140/190 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 3,000 r/min grease / 3,600 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.