NN4928 bearing: complete specifications & equivalents
The NN4928 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 | 3760 g |
| Manufacturer designation | NTN NN4928 |
| 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 | 28 |
| 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 |
|---|---|---|---|
| NN4928 | 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 NN4928 model number is decoded
For pure radial duty on a 140 mm shaft NTN supplies NN4928: 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. On the NTN nameplate NN states which ring carries the ribs, which determines whether NN4928 floats or locates; the numeric remainder is the ISO 15 series and 140 mm bore reference, not a fit or clearance instruction. Double-row NN precision cylindrical roller bearing: ribbed inner ring with a separable outer ring, two roller rows for high radial stiffness on machine-tool spindles; precision classes P5/P4/P2 and clearance are ordered separately. The 140 mm (5.512 in) bore and 190 mm (7.48 in) OD are ISO 15 boundary values; fillet and shoulder dimensions must still come from the NTN mounting table for the 50 mm-wide ring. Keep the open bearing wrapped until fitting: the line-contact raceways of the 140 mm bore indent under a single hard particle, and the steel cage provides no sealing of its own.
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
- inner-ring raceway spalling from overload in the line-contact Hertzian zone
- 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
- fretting corrosion on a loose rotating shaft seat
- rolling-contact fatigue after the catalogue L10 life is exceeded
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 3760 g NN4928 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Open NN4928 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 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.
- Double-row NN precision bearings are typically ordered P5/P4 with specific radial clearance for spindle preloading; a P0/CN NN4928 does not substitute a precision-class execution.
- The 50 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 140 mm inner ring.
- The 251/470 kN ratings, 49 kN Pu and 3760 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN4928 (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 NN4928?
NN4928 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 3760 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. NN4928 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. NN4928 is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN4928?
NN4928 has a cylindrical bore and mounts on a plain machined shaft seat; a K execution (1:12 taper) exists in the NN4900 series when preload must be set by drive-up on a tapered seat.
What do Fw and Ew mean for NN4928?
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.