NNU4972K bearing: complete specifications & equivalents
The NNU4972K is a ISO 15 radial bearing sized 360 x 480 x 118 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 360 mm |
| Outer diameter D | 480 mm |
| Width B | 118 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1430 kN |
| Basic static load rating C0 | 3250 kN |
| Fatigue load limit Pu | 255 kN |
| Limiting speed (mechanical) | 1100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 54400 g |
| Manufacturer designation | NTN NNU4972K |
| 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 | 14.173 in |
|---|---|
| Outer diameter D | 18.898 in |
| Width B | 4.646 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 60 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) | 20 of 26 |
| Bore above smallest NNU4900-series size | 260 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNU4972K | 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 NNU4972K model number is decoded
NNU4972K belongs to the NTN cylindrical roller range in NTN Ball and Roller Bearings CAT.No.2203E: line-contact rollers between ground raceways for a 1430 kN dynamic rating in the 360 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 360 mm, with 480 mm OD and 118 mm width from the ISO 15 general plan. Double-row NNU precision cylindrical roller bearing: ribbed outer ring with a separable inner ring, two roller rows for high radial stiffness on machine-tool spindles; the K suffix is a 1:12 tapered bore — mounted on a tapered seat or adapter sleeve and driven up to a precise radial clearance/preload; precision classes P5/P4/P2 and clearance are ordered separately. Mass 54400 g for the 360×480×118 mm NNU4972K execution covers the pressed-steel cage and full roller complement; substitute on mass plus rating, not envelope alone. 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 NNU4972K.
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
- 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
- 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
- At 360 mm bore, oil-lubricated arrangements toward 1,300 r/min need positive flow and drain design; the 54400 g NNU4972K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NNU4972K skids at 1,100 r/min and fails by smearing long before L10 fatigue.
- Minimum radial load is frequently missed in oversized motor and fan selections: an underloaded NNU4972K skids at 1,100 r/min and fails by smearing long before L10 fatigue.
- Open NNU4972K 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 360 mm contact.
- The 118 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 360 mm inner ring.
- The 1430/3250 kN ratings, 255 kN Pu and 54400 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU4972K (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 NNU4972K?
NNU4972K is an NTN NNU double-row precision cylindrical roller bearing to ISO 15: 360 mm bore, 480 mm OD and 118 mm width (14.173 × 18.898 × 4.646 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1430 kN, C0 3250 kN, Pu 255 kN, grease limiting speed 1,100 r/min, oil 1,300 r/min, mass about 54400 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. NNU4972K 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. NNU4972K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NNU bearing like NNU4972K?
The K suffix denotes a 1:12 tapered bore. NNU4972K 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 NNU4972 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NNU4972K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 398 mm. The nominal bore/OD remain 360/480 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,100 r/min grease / 1,300 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.