NN4920K bearing: complete specifications & equivalents
The NN4920K is a ISO 15 radial bearing sized 100 x 140 x 40 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 100 mm |
| Outer diameter D | 140 mm |
| Width B | 40 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 145 kN |
| Basic static load rating C0 | 260 kN |
| Fatigue load limit Pu | 30 kN |
| Limiting speed (mechanical) | 4300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1670 g |
| Manufacturer designation | NTN NN4920K |
| 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 | 3.937 in |
|---|---|
| Outer diameter D | 5.512 in |
| Width B | 1.575 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 20 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) | 1 of 18 |
| Bore above smallest NN4900-series size | 0 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN4920K | 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 NN4920K model number is decoded
In NTN Ball and Roller Bearings CAT.No.2203E, NN4920K appears as a 100 mm bore single-row cylindrical roller bearing (145 kN C / 260 kN C0) with a machined or stamped steel cage per the precision execution, listed to the ISO 15 boundary plan. Reading the code: NN for the double-row precision type, then the ISO 15 diameter/width series and the bore code — ×5 = 100 mm (00–03 use the 10/12/15/17 exception table). Line contact between rollers and raceways gives NN4920K high radial capacity but no tolerance for misalignment: beyond roughly 3–4 arc-minutes the roller ends edge-load and fatigue accelerates. Selection arithmetic: Pu 30 kN is the fatigue load limit feeding the adjusted-life equation, and the C0/C ratio of 1.79 (260/145 kN) shows the high-static-capacity proportioning of this 100 mm bore. Provide axial location with an adjacent locating bearing rather than expecting the float cylindrical set to hold thrust on the 100 mm shaft.
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
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- hard-particle indentation of raceways in unfiltered oil or open arrangements
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
Selection pitfalls — read before you substitute
- Induction-heat the 100 mm inner ring (max 120 °C) and mount it before fitting the outer ring; the ring mass makes square guidance essential — driving through the rollers brinells the 140 mm raceway.
- The NN rib arrangement is not interchangeable with another prefix on the same 100 mm seat: double row, ribbed inner ring, separable outer. Swapping NU for NJ changes axial location behaviour even though the 140×40 mm envelope matches.
- Grease limiting speed 4,300 r/min and oil 5,100 r/min are different limits for NN4920K: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Do not replace NN4920K with a deep-groove ball bearing on rating alone: line contact gives 145 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- Wide (22/23) and light (10/49) executions at 100 mm bore share bore but not OD/width; check the full NN4900 series code before substituting, because housing and shoulder geometry will not interchange.
- The 145/260 kN ratings, 30 kN Pu and 1670 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN4920K (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 NN4920K?
NN4920K is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 100 mm bore, 140 mm OD and 40 mm width (3.937 × 5.512 × 1.575 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 145 kN, C0 260 kN, Pu 30 kN, grease limiting speed 4,300 r/min, oil 5,100 r/min, mass about 1670 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. NN4920K 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. NN4920K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN4920K?
The K suffix denotes a 1:12 tapered bore. NN4920K 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 NN4920 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NN4920K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 113 mm. The nominal bore/OD remain 100/140 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 4,300 r/min grease / 5,100 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.