NNU4952K bearing: complete specifications & equivalents
The NNU4952K is a ISO 15 radial bearing sized 260 x 360 x 100 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | NTN |
| Bore diameter d | 260 mm |
| Outer diameter D | 360 mm |
| Width B | 100 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1000 kN |
| Basic static load rating C0 | 2070 kN |
| Fatigue load limit Pu | 179 kN |
| Limiting speed (mechanical) | 1600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 28300 g |
| Manufacturer designation | NTN NNU4952K |
| 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 | 10.236 in |
|---|---|
| Outer diameter D | 14.173 in |
| Width B | 3.937 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 50 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) | 15 of 26 |
| Bore above smallest NNU4900-series size | 160 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNU4952K | 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 NNU4952K model number is decoded
NNU4952K is an NTN NNU 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 260×360×100 mm ISO 15 envelope. On the NTN nameplate NNU states which ring carries the ribs, which determines whether NNU4952K floats or locates; the numeric remainder is the ISO 15 series and 260 mm bore reference, not a fit or clearance instruction. NTN prints two speed ceilings: 1,600 r/min grease and 1,800 r/min oil — the pressed-steel cage and lubricant film set the real limit at the 260 mm bore. With the inner ring rotating, catalogue practice is a m6/n6 shaft seat and an H7/H6 housing; the outer ring must remain free to creep slightly axially in non-locating NNU arrangements. On NNU arrangements confirm which ring is separable before heating: forcing the ribbed ring off over the roller complement damages the cage and rib faces.
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
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- 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
- brinelling from static overload or impact during handling
- false brinelling on standby machines exposed to external vibration
Selection pitfalls — read before you substitute
- At 260 mm bore, oil-lubricated arrangements toward 1,800 r/min need positive flow and drain design; the 28300 g NNU4952K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The 50.0 mm section at 260 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 100 mm-wide cavity.
- Wide (22/23) and light (10/49) executions at 260 mm bore share bore but not OD/width; check the full NNU4900 series code before substituting, because housing and shoulder geometry will not interchange.
- Do not replace NNU4952K with a deep-groove ball bearing on rating alone: line contact gives 1000 kN radial capacity but the bearing cannot carry the thrust duty a ball bearing can and misalignment tolerance is only 3–4 arc-minutes.
- The K tapered bore of NNU4952K 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.
- The 1000/2070 kN ratings, 179 kN Pu and 28300 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NNU4952K (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 NNU4952K?
NNU4952K is an NTN NNU double-row precision cylindrical roller bearing to ISO 15: 260 mm bore, 360 mm OD and 100 mm width (10.236 × 14.173 × 3.937 in). From NTN Ball and Roller Bearings CAT.No.2203E: C 1000 kN, C0 2070 kN, Pu 179 kN, grease limiting speed 1,600 r/min, oil 1,800 r/min, mass about 28300 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. NNU4952K 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. NNU4952K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NNU bearing like NNU4952K?
The K suffix denotes a 1:12 tapered bore. NNU4952K 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 NNU4952 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NNU4952K?
Fw is the inner sub-assembly raceway/roller-set envelope diameter and Ew the outer-ring raceway diameter printed for geometric checks: Fw 292 mm. The nominal bore/OD remain 260/360 mm; Fw/Ew describe the rolling-contact path, and speeds still run to 1,600 r/min grease / 1,800 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.