NNC4976-CV bearing: complete specifications & equivalents
The NNC4976-CV is a ISO 15 radial bearing sized 380 x 520 x 140 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 380 mm |
| Outer diameter D | 520 mm |
| Width B | 140 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 2380 kN |
| Basic static load rating C0 | 5700 kN |
| Fatigue load limit Pu | 500 kN |
| Reference speed (thermal) | 500 rpm |
| Limiting speed (mechanical) | 630 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 92500 g |
| Manufacturer designation | SKF NNC 4976 CV |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.4 double-row full complement cylindrical roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.4 double-row full complement cylindrical roller bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.4 double-row full complement cylindrical roller bearings); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & NNC4900-series range
| Bore d | 14.961 in |
|---|---|
| Outer diameter D | 20.472 in |
| Width B | 5.512 in |
| ISO bore code | 76 |
| Radial section height (D−d)/2 | 70 mm |
| Smallest bore in NNC4900-series | 60 mm |
| Largest outer diameter in NNC4900-series | 540 mm |
| Width range across NNC4900-series | 25–140 mm |
| Bore position in NNC4900-series (smallest first) | 24 of 25 |
| Bore above smallest NNC4900-series size | 320 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NNCF4976-CV | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 380×520×140 mm and equivalent catalogue ratings; the NNCF execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NNCL4976-CV | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 380×520×140 mm and equivalent catalogue ratings; the NNCL execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
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 NNC4976-CV model number is decoded
NNC4976-CV is the 380 mm bore entry in the NNC4900 range: a 380×520×140 mm double-row full-complement cylindrical roller bearing with a full complement of extra rollers fitted in place of a cage, rated C 2380 kN / C0 5700 kN. Reading the NNC prefix: a non-separable double-row full complement bearing with three integral inner-ring flanges and two retaining rings holding the outer ring on both sides. This makes the execution two-direction locating — the retaining-ring configuration closes both axial escape paths. Suffix CV identifies the full-complement execution: the space a cage would occupy is filled with extra rollers, trading speed for maximum radial capacity and stiffness. Load-per-bore for the 380 mm seat is about 6.26 kN/mm, typical of dimension series 49 (compact heavy section); use C0 5700 kN for static checks such as crane hook blocks standing under load. Fit practice for NNC4976-CV: check both retaining rings are seated in their grooves before installation; axial guidance in both directions makes this the locating pair member, so the mating bearing must float. Single-row cylindrical rollers tolerate only about 3–4 minutes of arc misalignment, so verify shaft and housing alignment.
Typical equipment & failure modes
Common applications
- large offshore winch and hook blocks
- mining shovel and dragline pivots
- steelmaking and heavy crane sheaves
Known failure patterns
- inner-ring raceway spalling from overload or contamination in the line-contact hertz zone
- outer-ring raceway fatigue after extended service at loads above the catalogue L10 rating
- roller smearing between the uncaged rollers during slow skidding starts under heavy static load
- cage pocket wear from roller skidding at insufficient radial load or during start-up before oil film build-up
- roller-end scoring from inadequate oil flow in the roller-raceway contact
- uneven row loading from misalignment, concentrating fatigue on one row of the double complement
- smearing (microwelding) on roller surfaces during skid starts with insufficient minimum load
Selection pitfalls — read before you substitute
- The NNCF/NNCL/NNC triplet shares the envelope and ratings but differs in outer-ring retention — one retaining ring, none, or two; selecting the wrong one changes the axial-locating scheme.
- Relubrication must reach both roller rows through the annular groove; blocked lube holes starve one row silently and show later as asymmetric raceway wear.
- Shaft and housing fillets must clear the bearing chamfers; an oversized radius tilts the 140 mm-wide ring and concentrates load.
- Shaft and housing fillets must clear the bearing chamfers; an oversized radius tilts the 140 mm-wide ring and concentrates load.
- The 2380/5700 kN ratings are SKF catalogue 17000 (2018) values for the CV execution; re-verify against the current catalogue for critical drives and keep the catalogue version with the specification.
Frequently asked questions
What are the dimensions and catalogue data of NNC4976-CV?
SKF NNC 4976 CV is a double-row full-complement cylindrical roller bearing with 380 mm bore, 520 mm OD and 140 mm width per ISO 15. SKF lists C 2380 kN, C0 5700 kN, Pu 500 kN, reference speed 500 r/min and limiting speed 630 r/min, mass about 92500 g.
What does the NNC designation and CV suffix mean?
Suffix CV identifies the full-complement execution: the space a cage would occupy is filled with extra rollers, trading speed for maximum radial capacity and stiffness. Structurally this execution has a non-separable double-row full complement bearing with three integral inner-ring flanges and two retaining rings holding the outer ring on both sides.
Can NNC4976-CV take axial load and locate the shaft?
Yes, in both directions, because retaining rings close both sides of the outer ring; the paired bearing must then float.
How does NNC4976-CV compare with the other executions in the same envelope?
NNCF (one outer retaining ring, one-direction guidance), NNCL (no retaining ring, floating outer ring) and NNC (retaining rings both sides, two-direction location) share the ISO envelope and ratings but are not interchangeable in a locating arrangement.
What limits the service life of this bearing most often?
On full-complement bearings the dominant risks are roller smearing from skidding below minimum load and contamination; maintain minimum radial load, keep lubricant film thick and accelerate gently.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.4 double-row full complement cylindrical roller bearings on 2026-09-26. Read our editorial & correction policy.