NN4952K bearing: complete specifications & equivalents
The NN4952K 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 | 27000 g |
| Manufacturer designation | NTN NN4952K |
| 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 | 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 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) | 15 of 18 |
| Bore above smallest NN4900-series size | 160 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NN4952K | 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 NN4952K model number is decoded
NN4952K belongs to the NTN cylindrical roller range in NTN Ball and Roller Bearings CAT.No.2203E: line-contact rollers between ground raceways for a 1000 kN dynamic rating in the 260 mm bore. The leading NN defines the rib arrangement (double row, ribbed inner ring, separable outer); the dimension-series digits and the two-digit bore code resolve to 260 mm, with 360 mm OD and 100 mm width from the ISO 15 general plan. At 1,800 r/min with oil versus 1,600 r/min with grease (a 200 r/min band), lubrication choice for NN4952K is a thermal decision, not just a sealing one. Speed ratio check: limiting 1,600 r/min is .89 of the 1,800 r/min oil value for NN4952K; grease-churn heating closes that gap as fill quantity rises. After mounting verify the outer ring slides axially by hand at ambient temperature; a stuck float ring in a NN4952K non-locating position preloads the bearing when the shaft grows.
Typical equipment & failure modes
Common applications
- high-rpm motorised grinding and milling spindles
- CNC lathe and machining-centre spindle radial sets
- precision rotary-table and dividing-head bearings
- high-speed turbine and turbo-blower rotor supports
Known failure patterns
- roller smearing (microwelding) at start-up before the oil film builds under insufficient radial load
- cage distortion after a mounting blow carried through the roller set
- micro-pitting when the EHL film falls below the composite roughness at high specific load
- electrical pitting on VFD-driven motor shafts without grounding protection
- electrical pitting on VFD-driven motor shafts without grounding protection
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 27000 g NN4952K ring stores enough heat that grease-only duty needs a careful relubrication calculation.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 1000/2070 kN pair here belongs to NN4952K as printed, not to the bare size.
- The EA high-capacity roller complement changes the load figure versus the basic execution of the same number; the 1000/2070 kN pair here belongs to NN4952K as printed, not to the bare size.
- Never press either ring through the roller complement when fitting: mounting force goes through the ring faces, or the 360 mm race brinells and releases as vibration within hours.
- Grease limiting speed 1,600 r/min and oil 1,800 r/min are different limits for NN4952K: the first is the cage/lubricant mechanical ceiling, the second assumes real oil flow rather than an oil bath.
- The 1000/2070 kN ratings, 179 kN Pu and 27000 g mass are NTN Ball and Roller Bearings CAT.No.2203E values for NN4952K (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 NN4952K?
NN4952K is an NTN NN 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 27000 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. NN4952K 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. NN4952K is supplied in the standard open execution shown in the table.
What does the K tapered bore mean on a precision NN bearing like NN4952K?
The K suffix denotes a 1:12 tapered bore. NN4952K 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 NN4952 execution of the same envelope mounts on a plain seat.
What do Fw and Ew mean for NN4952K?
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.