NN4924 bearing: complete specifications & equivalents
The NN4924 is a ISO 15 radial bearing sized 120 x 165 x 45 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 120 mm |
| Outer diameter D | 165 mm |
| Width B | 45 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 203 kN |
| Basic static load rating C0 | 360 kN |
| Fatigue load limit Pu | 39.5 kN |
| Limiting speed (mechanical) | 3600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2630 g |
| Manufacturer designation | NTN NN4924 |
| 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 | 4.724 in |
|---|---|
| Outer diameter D | 6.496 in |
| Width B | 1.772 in |
| ISO bore code | 24 |
| Radial section height (D−d)/2 | 22.5 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) | 4 of 18 |
| Bore above smallest NN4900-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN4924 | 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 NN4924 model number is decoded
NN4924 is an NTN NN 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 120×165×45 mm ISO 15 envelope. Numbering ties NN4924 to its envelope: type code NN, series NN4900, 120 mm bore; the 165×45 mm outline therefore swaps dimensionally with other ISO 15 bearings of the same code, though rib arrangements differ by prefix. NTN prints the raceway diameters for this size — Fw 134.5 mm — the envelope inside the 120/165 mm bore/OD where the rollers actually run. Equivalent-load planning treats NN4924 as a pure radial bearing: keep P below 203 kN at the required L10, and let a paired angular-contact or thrust part carry any sustained axial component. Mount the separable inner ring + roller assembly on the shaft first and slide the outer ring into the housing; never press the outer ring through the rollers of NN4924.
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
- false brinelling on standby machines exposed to external vibration
- hard-particle indentation of raceways in unfiltered oil or open arrangements
Selection pitfalls — read before you substitute
- At 120 mm bore, oil-lubricated arrangements toward 4,200 r/min need positive flow and drain design; the 2630 g NN4924 ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Wide (22/23) and light (10/49) executions at 120 mm bore share bore but not OD/width; check the full NN4900 series code before substituting, because housing and shoulder geometry will not interchange.
- Wide (22/23) and light (10/49) executions at 120 mm bore share bore but not OD/width; check the full NN4900 series code before substituting, because housing and shoulder geometry will not interchange.
- Grease limiting speed 3,600 r/min and oil 4,200 r/min are different limits for NN4924: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The NN rib arrangement is not interchangeable with another prefix on the same 120 mm seat: double row, ribbed inner ring, separable outer. Swapping NU for NJ changes axial location behaviour even though the 165×45 mm envelope matches.
- The 203/360 kN ratings, 39.5 kN Pu and 2630 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN4924 (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 NN4924?
NN4924 is an NTN NN double-row precision cylindrical roller bearing to ISO 15: 120 mm bore, 165 mm OD and 45 mm width (4.724 × 6.496 × 1.772 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 203 kN, C0 360 kN, Pu 39.5 kN, grease limiting speed 3,600 r/min, oil 4,200 r/min, mass about 2630 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. NN4924 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. NN4924 is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN4924?
NN4924 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 NN4924?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 134.5 mm. The nominal bore/OD remain 120/165 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 3,600 r/min grease / 4,200 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.