NNU4900 Series Cylindrical Roller Bearings
NNU4900 / NNU4900K / NNU4900W / JTEKT Corporation (Official website)
Double-row cylindrical roller bearings with flange on outer ring. Dimension tables for bore diameters of 120 to 190 mm are included.
Last verified: (date the content was verified against the source document)
Specifications
| Inner diameter d | 120〜190 mm |
|---|---|
| Outer diameter D | 165〜260 mm |
How to choose Rolling Bearings
Points to check when selecting, with the values for this product (NNU4900 Series Cylindrical Roller Bearings).
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1. Bore and housing bore dimensions
This product: Inner diameter d 120〜190 mmSelect the bore diameter d to match the shaft seat, the outside diameter D to match the housing bore, and the width B to suit the installation space. Main dimensions are standardized in ISO and JIS dimension series, so interchangeable products can be found by boundary dimension designation. For tapered roller bearings, also check the assembled width T; for thrust bearings, also check the height H.
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2. Dynamic load rating based on life calculation
The basic dynamic load rating Cr is the reference value for calculating rated life. Verify that the required life is met using the equivalent load during operation and the rotational speed. For ball bearings, life is proportional to the cube of the load ratio, so providing load margin greatly extends life.
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3. Margin for static and shock loads
The basic static load rating C0r is the allowable standard for permanent deformation generated at the rolling elements and raceways under stationary or low-speed conditions. For applications with oscillating motion or shock loads, confirm that a static safety factor against the maximum load is secured using C0r.
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4. Operating speed and lubrication method
The limiting speed differs by lubrication method, and separate values are given for grease lubrication and oil lubrication. Confirm that the normal operating speed does not exceed the limiting value, and in high-speed ranges also consider cage material and precision grade. The reference speed can also be consulted as a thermal guideline.
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5. Precision grade and internal clearance
Precision grades (P0, P6, P5, etc.) indicate rotational accuracy and dimensional accuracy; for high-precision applications such as machine tool spindles, select higher grades. Internal clearance (C2, CN, C3, etc.) is selected to allow for changes caused by interference fit and temperature differences during operation.
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6. Materials and lubrication suited to the environment
For corrosive, high-temperature, vacuum, or clean environments, select specifications such as rings and rolling elements made of stainless steel or ceramics, or solid lubricants and fluorine grease for vacuum use. Check the operating temperature range, low dust generation, and whether food-grade grease registration applies against the application conditions.
This guide was written by AI based on the listed products' documents and specification items.
Description
Double-row cylindrical roller bearings with flange on outer ring, available in cylindrical bore and tapered bore types. W specification with oil holes and oil grooves is also available.
Features
- Double-row design with flange on outer ring
- Two types: cylindrical bore and tapered bore
- W specification with oil holes and oil grooves available
Applications
- Machine tool spindles
FAQ
- Q. What types of NNU4900 series cylindrical roller bearings are available?
- A. They are double-row cylindrical roller bearings with flange on outer ring, available in cylindrical bore and tapered bore types. W specification with oil holes and oil grooves is also available.
- Q. What is the range of bore and outside diameters for the NNU4900 series?
- A. Bore diameter d is 120 to 190 mm and outside diameter D is 165 to 260 mm. Dimension tables for bore diameters of 120 to 190 mm are included.
- Q. What applications is the NNU4900 series suitable for?
- A. It is intended for use in machine tool spindles.
Written by AI based on the content of the source documents.
Source documents
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