NNU4992K bearing: complete specifications & equivalents
The NNU4992K is a ISO 15 radial bearing sized 460 x 620 x 160 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 460 mm |
| Outer diameter D | 620 mm |
| Width B | 160 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 2460 kN |
| Basic static load rating C0 | 5850 kN |
| Fatigue load limit Pu | 430 kN |
| Limiting speed (mechanical) | 800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 126000 g |
| Manufacturer designation | NTN NNU4992K |
| 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 | 18.11 in |
|---|---|
| Outer diameter D | 24.409 in |
| Width B | 6.299 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 80 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) | 25 of 26 |
| Bore above smallest NNU4900-series size | 360 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNU4992K | 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 NNU4992K model number is decoded
NNU4992K is the extra-light (10/49) section of the NTN NNU4900 dimension series for a 460 mm shaft — 2460 kN of basic dynamic capacity in a 126000 g, open bearing. Digit by digit, NNU4992K reads as NNU (double row, ribbed outer ring, separable inner), ISO 15 series, and bore 460 mm; trailing letters such as EA or E mark the cage/capacity execution and are part of the order number. The 80.0 mm radial section ((620−460)/2) frames the roller complement; capacity per millimetre of bore is about 5.3 kN/mm before application factors. The 460 mm (18.11 in) bore and 620 mm (24.409 in) OD are ISO 15 boundary values; fillet and shoulder dimensions must still come from the NTN mounting table for the 160 mm-wide ring. Keep the open bearing wrapped until fitting: the line-contact raceways of the 460 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 gearbox and indexing-drive shafts
- high-rpm motorised grinding and milling spindles
- CNC lathe and machining-centre spindle radial sets
- precision rotary-table and dividing-head bearings
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
- edge loading from shaft deflection beyond the 3–4 arc-minute alignment limit
- brinelling from static overload or impact during handling
Selection pitfalls — read before you substitute
- At 460 mm bore, oil-lubricated arrangements toward 950 r/min need positive flow and drain design; the 126000 g NNU4992K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- Do not replace NNU4992K with a deep-groove ball bearing on rating alone: line contact gives 2460 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- Grease limiting speed 800 r/min and oil 950 r/min are different limits for NNU4992K: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- Wide (22/23) and light (10/49) executions at 460 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 80.0 mm section at 460 mm bore leaves a narrow oil path; with the standard cage the relubrication groove and oil-level design must keep grease from churning in the 160 mm-wide cavity.
- The 2460/5850 kN ratings, 430 kN Pu and 126000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU4992K (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 NNU4992K?
NNU4992K is an NTN NNU double-row precision cylindrical roller bearing to ISO 15: 460 mm bore, 620 mm OD and 160 mm width (18.11 × 24.409 × 6.299 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 2460 kN, C0 5850 kN, Pu 430 kN, grease limiting speed 800 r/min, oil 950 r/min, mass about 126000 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. NNU4992K 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. NNU4992K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NNU bearing like NNU4992K?
The K suffix denotes a 1:12 tapered bore. NNU4992K 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 NNU4992 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NNU4992K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 512 mm. The nominal bore/OD remain 460/620 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 800 r/min grease / 950 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.