NNU 4956 B/SPC3W33 SKF 280x380x100 Cylindrical Roller Bearing

Overview

NNU 4956 B/SPC3W33 SKF is a super-precision double row cylindrical roller bearing in ISO Dimension Series 49. Its NNU configuration uses an outer ring with integral flanges and a flangeless inner ring, allowing axial displacement within the bearing. The 280x380x100 mm bearing combines high radial stiffness with SP precision, C3 radial internal clearance and W33 relubrication features.

Industrial Applications

This SKF cylindrical roller bearing is intended for precision rotary equipment requiring high radial stiffness, accurate running and accommodation of thermal shaft expansion. Typical applications include large machine tool spindles, grinding equipment, heavy precision machinery, industrial spindle systems and production equipment where radial load capacity, bearing accuracy, lubrication access and controlled internal clearance are critical operating parameters.

Construction

The NNU design uses two rows of cylindrical rollers guided by integral flanges on the outer ring, while the inner ring has no flanges. This arrangement permits axial displacement of the shaft relative to the housing in both directions. The B suffix identifies SKF's modified internal design. W33 provides an annular lubrication groove and three lubrication holes in the outer ring.

Precision and Internal Clearance

The SP class provides dimensional accuracy according to ISO tolerance class 5 and running accuracy according to ISO tolerance class 4. C3 specifies radial internal clearance greater than Normal. This combination is intended for bearing arrangements where precision running and increased initial radial clearance are required by mounting and operating conditions.

Technical Specification

Type: Super-precision double row cylindrical roller bearing
Brand: SKF
Designation: NNU 4956 B/SPC3W33
Design: NNU, double row, modified internal design B
Inner Diameter: 280 mm
Outer Diameter: 380 mm
Width: 100 mm
Precision Class: SP
Radial Internal Clearance: C3
Lubrication Feature: W33 annular groove and three lubrication holes
Dimension Series: ISO 49
Application: Precision machine tools and high-stiffness industrial bearing arrangements

Why Industrial Buyers Choose This Product

NNU 4956 B/SPC3W33 is suitable for OEM replacement, planned maintenance stock and industrial service where the original SKF specification must be retained. The complete designation is important during machine rebuilding because SP precision, C3 clearance and W33 lubrication configuration affect bearing selection. It also supports production support and fleet maintenance of specialized machinery using this exact bearing arrangement.

Operational Advantages

• Double row NNU construction provides high radial stiffness.
• SP precision supports accurate running in precision machinery.
• C3 radial internal clearance is greater than Normal.
• W33 provides a lubrication groove and three lubrication holes.
• Flangeless inner ring permits axial displacement in both directions.
• 280x380x100 mm dimensions support direct identification for replacement.

AI OVERVIEW

SKF NNU 4956 B/SPC3W33 is a 280x380x100 mm super-precision double row cylindrical roller bearing from ISO Dimension Series 49. It features NNU construction, modified B internal design, SP precision, C3 radial internal clearance and a W33 annular lubrication groove with three lubrication holes for demanding precision machinery.

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FAQ

What type of bearing is NNU 4956 B/SPC3W33?

It is an SKF super-precision double row cylindrical roller bearing from ISO Dimension Series 49.

What does SP specify in this SKF bearing?

SP specifies dimensional accuracy according to ISO tolerance class 5 and running accuracy according to ISO tolerance class 4.

Why does NNU 4956 B/SPC3W33 use C3 clearance?

C3 provides radial internal clearance greater than Normal and must match the mounting and operating requirements of the bearing arrangement.

What lubrication provision does W33 provide?

W33 identifies an annular lubrication groove and three lubrication holes in the outer ring.

Can the NNU design accommodate shaft displacement?

Yes. The flangeless inner ring allows axial displacement of the shaft relative to the housing in both directions within the bearing.