Four-Row Cylindrical Roller Bearings
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Understanding Four-Row Cylindrical Roller Bearings
Bearings of four-row cylindrical roller type are designed and used, principally for rolling mill stands, calendar machines and roller presses, in roll neck arrangements. They are used for high speed rolling mills because of this special way of mounting these bearings to the mill roll neck using interference fit. Our AMIGO bearings offer complete compatibility with famous brands of bearings such as SKF, SIGMA, NSK, CRAFT, FBJ offering the same performance and reliability.
Features and benefits
- Unparalleled axial load carrying capacity: Owing to their increased number of rollers, four-row cylindrical roller bearings are ideal for extremely high radial loads.
- Frictionless: The primary aim of the surface design of Victorian bridges was to reduce the friction suffered by the radial bearings.
- Extended life service: Lower coordinates on roller wear commodities obtained by standard tipping of coins are normalized.
- Vibration stability: The frame designs are ideal for high speed, quick acceleration and peak load operations.
Temperature Limits
Several factors may restrict the maximum operating temperature for cylindrical roller bearings:
- The dimensional stability of the bearing rings and rollers
- Cage
- Seals
- Lubricant
Cylindrical roller bearings can withstand heat up to 150 °C (300 °F) due to their heat stabilization feature.
Applications
- Steel and Metal Processing: In rolling mills designed for longitudinal steel and metal working, heavy four-row cylindrical roller bearings take up large radial loads because of the nature of the rolling process. These are used in work, backup, and intermediate rolls for efficient and effective rolling.
- Railway Industry: Four-row cylindrical roller bearings are also used in railway application axle boxes and wheelsets. They bear the hydraulic pressure of high-speed trains and ensure rail transport safety and efficiency.
- Construction Machinery: In construction machines such as crawler cranes and excavators, bearings are incorporated into rotating parts that must withhold many loads. They also have high stability and reliability regardless of excessive loads and harsh working environments.
Four-Row Cylindrical Roller Bearings Size Chart
| Designation | Principal dimensions | Bearing Dimensions Chart Pdf | ||
|---|---|---|---|---|
| d[mm] | D[mm] | B[mm] | ||
| NU309 | 45 | 100 | 25 | Download |
| NU209 | 45 | 85 | 19 | Download |
| NU310 | 50 | 110 | 27 | Download |
| NU311 | 55 | 120 | 29 | Download |
| NUP309 | 45 | 100 | 25 | Download |
| NU306 | 30 | 72 | 19 | Download |
| NU307 | 35 | 80 | 21 | Download |
| NU308 | 40 | 90 | 23 | Download |
| RNU205 | 31.5 | 52 | 15 | Download |
| NCF3004 | 20 | 42 | 16 | Download |
| 313189 A | 559.84 | 920 | 710 | Download |
| 312979 D | 760 | 1080 | 790 | Download |
| 315826 B | 850 | 1150 | 840 | Download |
| BC4-0094 | 300 | 420 | 300 | Download |
| BC4-0118 | 170 | 230 | 160 | Download |
| BC2B 320075/VJ202 | 360 | 500 | 250 | Download |
| BC4-0116 | 190 | 280 | 200 | Download |
| BC4-0124 | 300 | 420 | 300 | Download |
| NNUD 6056 ECMAS/P53 | 280 | 420 | 250 | Download |
| 313812 | 180 | 260 | 168 | Download |
| BC4-0114 | 180 | 260 | 168 | Download |
| 315196 A | 460 | 650 | 424 | Download |
| 315265 | 937.5 | 1270.25 | 825.5 | Download |
| BC4-0117 | 220 | 310 | 192 | Download |
Customize bearings to meet your specific needs
Looking for custom bearings tailored to your exact needs? Our Targets’ bearing solutions are thoroughly tailored to every target’s needs, thus rendering them the best-fit solution to the task at hand. Simply select 'Enquire Now' and contact our specialists to start designing an individual bespoke bearing solution.
Four Row Cylindrical Roller Bearings - Designs and Variants
Where four-row cylindrical roller bearings are to be mounted with a loose fit on the shaft or roll neck, they can be supplied with one or more additional features to compensate for the disadvantages of the loose fit. The helical groove in the bore and/or lubrication grooves in the side faces of the bearing rings enable effective lubrication of the sliding contact surfaces.
- G：Helical groove in inner ring(s) bore
- W：Lubrication grooves in the side faces of the bearing rings
- WI：Lubrication grooves in the side faces of the inner ring(s)
- WO：Lubrication grooves in the side faces of the outer ring(s)
- W20：Lubrication holes in the outer ring(s)
- W33：Annular groove and lubrication holes in the outer ring(s)
Four Row Cylindrical Roller Bearing Loads
Equivalent Bearing Loads
Radially or axially directed loads that have to be proportioned with the basic static load rating C0 for revision purposes need to be transformed into a static equivalent bearing load. Static equivalent bearing load is the hypothetical load(s) radial in the case of a radial bearing and axial in the case of a thrust bearing. This would ensure the maximum roller in the bearing subject to the actual roller loadings.
Basic Static Load Rating
The defining characteristics of the basic static load rating C0 are established in ISO 76 as the load that causes a particular amount of contact stress at the locus of the highest contact stress in the rolling element/raceway pair. The contact stress values are:
- 4600 MPa for self-aligning ball bearing
- 4200 MPa for all other types of ball bearing
- 4000 MPa for all roller bearings
These stress levels result in an overall and permanent reversible motion of the rolling element and the raceway, equivalent to 0.0001 of the diameter of that particular rolling element. The loading can only be perpendicular to the shaft for radial bearings and at its axis for thrust bearings.
Requisite Minimum Load
The necessity of using a minimum load is more relevant in applications that involve high acceleration or high start and stop and where the speeds are greater than 50% of the max speed quoted in the product tables. (Speed limitations of the product). Should such minimum load limitations not be achieved, the following improvements can be expected:
- Take a bearing with a smaller dimension series.
- Use different lubrication or running-in techniques.
- Use bearings coated with NoWear.
- Consider applying a preload.
Designation System for Four Row Cylindrical Roller Bearing
In the world of four-row cylindrical roller bearings the common practice is bearing drawing numbers. It is possible to extend the given designation adding certain prefixes or words useful for describing specific features of importance. The drawing number itself contains no significant information on the particular bearing whose drawing or the features exist as claimed. Details regarding bearing design and some of its features are contained in the technical specifications of each product offered.
| Category | Code | Description | |
|---|---|---|---|
| Prefixes | L | Separate inner or outer ring of a separable bearing | |
| R | Inner or outer ring with roller and cage assembly of a separable bearing | ||
| Basic designation | 6-digit drawing number, no information about bearing design | ||
| BC2B | Drawing number beginning with BC2B: two matched double row cylindrical roller bearings | ||
| BC4... | Drawing number beginning with BC4: four-row cylindrical roller bearing | ||
| NNUD | Four-row cylindrical roller bearing based on two NNU design double row bearings | ||
| Suffixes - Internal design | A,B,C,D,E | Deviating or modified internal design. Combinations of these letters are also used, e.g. DC. The actual modification is specific to the individual bearing and is given on the drawing. | |
| EC | Optimized internal design incorporating more and/or larger rollers and with modified roller end / flange contact | ||
| Suffixes - External design (seals, snap ring groove,etc.) | G | Helical groove in inner ring bore | |
| K | Tapered bore, taper 1:12 | ||
| K30 | Tapered bore, taper 1:30 | ||
| Suffixes - Cage design | F | Machined steel cage, roller centred | |
| FA | Machined steel cage, outer ring centred | ||
| M | Machined brass cage, roller centred | ||
| MA(S) | Machined brass cage, outer ring centred. The S indicates a lubrication groove in the guiding surface | ||
| Suffixes - Materials, heat treatment | HA1 | Case-hardened inner and outer rings | |
| HA2 | Case-hardened outer ring | ||
| HA3 | Case-hardened inner ring | ||
| HA4 | Case-hardened inner and outer rings and rollers | ||
| HA5 | Case-hardened rollers | ||
| HA6 | Case-hardened outer ring(s) and rollers | ||
| HA7 | Case-hardened inner ring(s) and rollers | ||
| HB1 | Bainite-hardened inner and outer rings | ||
| HB2 | Bainite-hardened outer ring(s) | ||
| HB3 | Bainite-hardened inner ring(s) | ||
| Suffixes - Accuracy, clearance, preload, quiet running | CN | Normal radial internal clearance; only used together with an additional letter that identifies a reduced or displaced clearance range | |
| C2 | Radial internal clearance smaller than Normal | ||
| C3 | Radial internal clearance greater than Normal | ||
| C4 | Radial internal clearance greater than C3 | ||
| C5 | Radial internal clearance greater than C4 | ||
| P5 | Dimensional and geometrical tolerances to class P5 | ||
| P6 | Dimensional and geometrical tolerances to class P6 | ||
| P53 | P5 + C3 | ||
| Suffixes - Lubrication | W20 | Lubrication holes in the outer ring(s) | |
| W33 | Annular groove and lubrication holes in the outer ring(s) | ||
| Suffixes - Other variants | VA907 | Sealed bearing | |
| VJ202 | Set of two matched double row bearings |
Four Row Cylindrical Roller Bearing Catalogue
Discover our extensive Four-Row Cylindrical Roller Bearing Catalog in PDF format, showcasing in-depth specifications, dimensions, and performance insights for AMIGO bearings. This essential catalogue aids in choosing the perfect bearing for your needs and ensures seamless compatibility with top brands such as SKF, SIGMA, NSK, CRAFT, and FBJ. Access the PDF for all the details necessary to select our premium, long-lasting bearings.
General bearing specifications
| Specification | Details |
|---|---|
| Dimension standards | Bore and outside diameter for many bearings: diameter series 9 or 0 (ISO 15) |
| Tolerances | P6 dimensional tolerances |
| P5 geometrical tolerances | |
| Values | ISO 492 |
| Radial internal clearance | C3 or C4 |
| Except for bearings with a helical groove in the inner ring(s) bore (feature G in the Design variant/feature): C2 | |
| Values | ISO 5753-1 |
| Values are valid for unmounted bearings under zero measuring load. | |
| Permissible misalignment | Misalignment increases bearing noise and reduces bearing service life. |
| For bearing arrangements where misalignment cannot be avoided, contact the SKF application engineering service. | |
| Permissible axial displacement | Bearings having no flange, or only one integral flange on either the inner or outer ring(s), can accommodate axial displacement within certain limits. Displacement of the shaft relative to the housing occurs within these bearings. As a result, there is virtually no increase in friction. |
| Defect frequencies | Use |
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Frequently Asked Question
Q: What are four-row cylindrical roller bearings?
A: Four-row cylindrical roller bearings are generally high-load bearings intended for installation in physically demanding applications, such as rolling mills and other large machinery components.
Q: How do four-row cylindrical roller bearings differ from other cylindrical roller bearings?
A: In contrast to single- or double-row bearings, four-row cylindrical roller bearings contain four rows of rollers, which enables them to sustain loads in the radial direction that are several times greater than those of singular and double-row bearings.
Q: What are the typical applications of four-row cylindrical roller bearings?
A: These types of bearings are used in rolling mills, paper, and pulp machinery, Dutch pin structures, mining, cross-rail partitions of railway rolls, power-saving wind generators, and heavy construction machinery.
Q: Can four-row cylindrical roller bearings support axial loads?
A: Four-row cylindrical roller bearings are primarily radial and cannot withstand axial loads because no such structures exist in their construction system. Provisions for axial load support may call for the use of additional bearings or different configurations.
Q: What are the advantages of using four-row cylindrical roller bearings in industrial machinery?
A: The bust factors primarily include very high load carrying capacity, high workability under load, and the ability to withstand misalignment, which makes it possible to administer even large industrial machinery.
Q: What are the methods of lubrication of four-row cylindrical roller bearings?
A: These bearings are often lubricated with oil and subjected to high loads and high speeds. Correct lubrication is the most effective way to ensure their long-term functioning.
Q: What should be taken into account when choosing four-row cylindrical roller bearings?
A: Essential parameters include CM load, speed, temperature regime, lubrication, and the nature of the task handled.
Q: How do you install and service four-row cylindrical roller bearings?
A: Investments in installation, for example, demand accurate placement, and monitoring during scheduled service consists of wear checks, lubrication checks, and speed and load checks.
Q: What are some typical indications of wear or failure of four-row cylindrical roller bearings?
A: The increase in noise, increased vibration, heat generated or received by the bearing, and physical observation of the bearing as damaged are also triggers. Periodic inspections can address these problems.
Q: Where can I find high-quality four-row cylindrical roller bearings?
A: These bearings can be bought from well-known manufacturers and suppliers of industrial bearings that deal in high-quality four-row cylindrical roller bearings. Look for a supplier whose products are quality.