NNU4926K bearing: complete specifications & equivalents
The NNU4926K is a ISO 15 radial bearing sized 130 x 180 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 | 130 mm |
| Outer diameter D | 180 mm |
| Width B | 50 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 244 kN |
| Basic static load rating C0 | 440 kN |
| Fatigue load limit Pu | 47 kN |
| Limiting speed (mechanical) | 3300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3520 g |
| Manufacturer designation | NTN NNU4926K |
| 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 | 5.118 in |
|---|---|
| Outer diameter D | 7.087 in |
| Width B | 1.969 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 25 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) | 5 of 26 |
| Bore above smallest NNU4900-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNU4926K | 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 NNU4926K model number is decoded
NNU4926K belongs to the NTN cylindrical roller range in NTN Ball and Roller Bearings CAT.No.2203E: line-contact rollers between ground raceways for a 244 kN dynamic rating in the 130 mm bore. The leading NNU defines the rib arrangement (double row, ribbed outer ring, separable inner); the dimension-series digits and the two-digit bore code resolve to 130 mm, with 180 mm OD and 50 mm width from the ISO 15 general plan. Line contact between rollers and raceways gives NNU4926K high radial capacity but no tolerance for misalignment: beyond roughly 3–4 arc-minutes the roller ends edge-load and fatigue accelerates. Rating life at 244 kN C assumes clean oil and adequate film; the 47 kN Pu floor means contamination derating — not the C rating alone — governs adjusted life in dusty gearboxes. Keep the open bearing wrapped until fitting: the line-contact raceways of the 130 mm bore indent under a single hard particle, and the steel cage provides no sealing of its own.
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
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- pressed-steel cage pocket wear when rollers skid at light load or too-thin lubricant
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- false brinelling on standby machines exposed to external vibration
- false brinelling on standby machines exposed to external vibration
Selection pitfalls — read before you substitute
- At 130 mm bore, oil-lubricated arrangements toward 3,900 r/min need positive flow and drain design; the 3520 g NNU4926K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- 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 130 mm inner ring.
- The K tapered bore of NNU4926K 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.
- Open NNU4926K 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 130 mm contact.
- Wide (22/23) and light (10/49) executions at 130 mm bore share bore but not OD/width; check the full NNU4900 series code before substituting, because housing and shoulder geometry will not interchange.
- The 244/440 kN ratings, 47 kN Pu and 3520 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU4926K (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 NNU4926K?
NNU4926K is an NTN NNU double-row precision cylindrical roller bearing to ISO 15: 130 mm bore, 180 mm OD and 50 mm width (5.118 × 7.087 × 1.969 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 244 kN, C0 440 kN, Pu 47 kN, grease limiting speed 3,300 r/min, oil 3,900 r/min, mass about 3520 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. NNU4926K 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. NNU4926K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NNU bearing like NNU4926K?
The K suffix denotes a 1:12 tapered bore. NNU4926K 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 NNU4926 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NNU4926K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 146 mm. The nominal bore/OD remain 130/180 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 3,300 r/min grease / 3,900 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.