Two-row or double row cylindrical roller bearings have high radial rigidity and are used primarily for precision machine tools. They provide a high load-carrying capacity and are suitable for heavy radial loads.

The maximum rolling force at the horizontal rolls is 4,200 kN. Depending on the type of rolled stock, thrust loads of up to 2,000 kN have to be accommodated. Speeds range from two to 60 min–1.

Double-row cylindrical roller bearings have been provided to accommodate the radial forces because of their high load-carrying capacity.

The higher loaded cylindrical roller bearing, situated directly beside the roll, was specially developed to support the straightening rolls (dimensions 530 x 780 x 285/475 mm).

The less loaded cylindrical roller bearing has the dimensions 300 x 460 x 180 mm.
The cylindrical roller bearings are fitted with bored rollers, which are evenly spaced by pins and cage side
washers.

As this design allows the distance between the rollers to be indefinitely small, the most significant possible number of rollers can be fitted and adapted to the mounting space, and the highest possible load carrying capacity can be obtained for the bearing.

double row cylindrical roller bearing

Double Row Cylindrical Roller Bearing Size Chart

Here’s a size chart for double row cylindrical roller bearings:

(Note: This is a sample size chart. Actual sizes may vary based on manufacturer and model.)

What Is Double Row Cylindrical Roller Bearing?

A double row cylindrical roller bearing is a type of rolling element bearing designed to provide support for radial loads, which act perpendicular to the axis of rotation.

Unlike single row cylindrical roller bearings that consist of one set of cylindrical rollers, double row cylindrical roller bearings have two sets of cylindrical rollers arranged in parallel.

The design of double row cylindrical roller bearings allows them to handle higher radial loads and provide increased radial rigidity compared to single row bearings. These bearings are commonly used in applications where there are heavy radial loads, such as in machine tools, gearboxes, rolling mills, and other industrial machinery.

Double row cylindrical roller bearings typically consist of inner and outer rings with cylindrical rolling elements between them. The rollers are guided by integral flanges on the inner and outer rings, and they can operate at high speeds while maintaining high load-carrying capacity. The configuration of the two rows of rollers enables these bearings to distribute loads evenly, improving their overall performance in various applications.

Double Row Cylindrical Roller Bearing Features

Cylindrical roller bearings (CRBs) feature a straightforward design with cylindrical rollers in direct contact with the raceways, providing substantial load capacity, particularly under radial loads. The minimal friction between the rollers and ring ribs makes them well-suited for applications involving high-speed rotation.

Designations for single-row bearings include NU, NJ, NUP, N, or NF, while double-row bearings are labeled as NNU or NN, depending on the presence of side ribs. All variations allow for the separation of inner and outer rings.

In certain CRBs functioning as free-end bearings, the absence of ribs enables axial movement between the rings. When one ring has ribs on both sides and the other has a single-side rib, these bearings can accommodate axial loads in a specific direction.

Double-row cylindrical roller bearings exhibit heightened radial rigidity and find application primarily in the main shafts of precision machine tools. Cages for these bearings are commonly constructed from pressed steel or machined brass, although some models employ molded polyamide resin cages.

What are double roller bearings used for?

Double row roller bearings are used in various applications where there is a need for robust radial load support and increased radial rigidity.

Some common uses of double row roller bearings include:

1. Precision Machine Tools: Double row cylindrical roller bearings are often employed in the main shafts of precision machine tools. Their ability to handle high radial loads and provide enhanced rigidity makes them suitable for applications where precision and accuracy are crucial.
2. Gearboxes: In gearbox assemblies, double row roller bearings are utilized to support radial loads generated by gears and other rotating components. Their durable design helps ensure the smooth and reliable operation of the gearbox.
3. Rolling Mills: Double row roller bearings play a vital role in rolling mills where heavy loads and continuous operation are common. They provide the necessary support to withstand the forces involved in metal rolling processes.
4. Mining Equipment: The robust nature of double row roller bearings makes them suitable for use in various mining equipment, such as crushers and screens, where they can handle the heavy radial loads encountered in these applications.
5. Industrial Machinery: Double row roller bearings are widely used in various industrial machinery, including pumps, fans, and compressors. Their ability to accommodate high radial loads makes them valuable in applications where heavy-duty performance is required.
6. Railway Applications: In the railway industry, double row roller bearings are utilized in wheelsets and axleboxes. Their capacity to handle radial loads efficiently contributes to the reliable and smooth operation of trains.
7. Construction Machinery: Double row roller bearings find application in construction equipment such as excavators, cranes, and loaders. These bearings contribute to the equipment’s durability and performance under heavy loads.
8. Wind Turbines: In wind turbine generators, where there are varying and sometimes substantial loads, double row roller bearings are used to support the main shaft. Their robust construction helps ensure reliable performance in challenging wind conditions.

Double row roller bearings are chosen for applications that demand strength, durability, and the ability to withstand significant radial loads. Their versatility makes them a crucial component in a wide range of industrial and machinery settings.

What are the advantages of double row bearings?

Double row bearings offer several advantages that make them suitable for various applications:

1. Increased Load Capacity: One of the primary advantages of double row bearings is their ability to accommodate higher radial loads compared to single row bearings. The presence of two rows of rolling elements distributes the load more effectively, enhancing the overall load-carrying capacity.
2. Enhanced Radial Rigidity: Double row bearings provide greater radial rigidity, making them suitable for applications where rigidity is crucial, such as in precision machinery and heavy-duty industrial equipment.
3. Axial Load Capability: Depending on the bearing design, double row bearings can have the ability to handle axial loads in addition to radial loads. This makes them versatile in applications where both types of loads are present.
4. Improved Speed Capability: The design of double row bearings, with multiple rolling elements, often results in lower friction and heat generation. This characteristic makes them well-suited for applications involving high-speed rotation.
5. Versatility in Designations: Double row bearings are designated differently based on their configuration, such as NNU or NN for cylindrical roller bearings. This allows for easy identification and selection of the appropriate bearing for specific applications.
6. Redundancy and Reliability: Having two rows of rolling elements provides redundancy, enhancing the reliability of the bearing. In the event of damage or wear to one row, the second row can continue to provide support, extending the overall bearing life.
7. Axial Displacement Capability: Some double row bearings, especially cylindrical roller bearings used as free-end bearings, allow axial displacement between the inner and outer rings. This feature provides flexibility in certain applications where axial movement is required.
8. Suitability for Oscillating Movements: Double row bearings are often suitable for applications involving oscillating or vibrating movements due to their robust design and ability to handle dynamic loads.
9. Wide Range of Applications: The versatility of double row bearings makes them applicable in various industries, including machine tools, automotive, mining, construction, and more. They are used in applications where durability, reliability, and load-carrying capacity are essential.

The advantages of double row bearings, including increased load capacity, enhanced rigidity, and versatility, make them a preferred choice in a wide range of industrial and mechanical applications.

What is the difference between single and double roller bearings?

The primary difference between single and double row roller bearings lies in the number of rows of rolling elements they contain. Here are some key distinctions:

Number of Rows:

• Single Row Bearings: Have a single set of rolling elements, either balls or rollers, arranged in a linear fashion between the inner and outer rings.
• Double Row Bearings: Feature two sets of rolling elements, arranged in parallel, with two rows between the inner and outer rings.

Load Capacity:

• Single Row Bearings: Generally have a lower load-carrying capacity compared to double row bearings, making them suitable for applications with lighter radial loads.
• Double Row Bearings: Offer increased load capacity, making them well-suited for applications with heavier radial loads.

Radial Rigidity:

• Single Row Bearings: Provide less radial rigidity compared to double row bearings.
• Double Row Bearings: Exhibit higher radial rigidity, making them suitable for applications where rigidity is crucial, such as in precision machinery.

Axial Load Capability:

• Single Row Bearings: Primarily designed for radial loads but may have limited axial load capacity depending on the specific design.
• Double Row Bearings: Can handle both radial and axial loads, offering greater versatility in load-carrying capabilities.

Speed Capability:

• Single Row Bearings: Generally suitable for high-speed applications, but speed may be limited by factors like friction and heat generation.
• Double Row Bearings: With multiple rolling elements, often exhibit improved speed capability due to reduced friction and heat generation.

Designations:

• Single Row Bearings: Designated with letters such as NU, NJ, NUP, N, or NF, depending on the specific type and application.
• Double Row Bearings: Designated with NNU or NN, with variations based on the presence of side ribs.

To further illustrate the differences, here’s a simplified table:

This table provides a concise overview of the key differences between single and double row roller bearings.

What are the components of a cylindrical roller bearing?

A cylindrical roller bearing consists of several essential components that work together to enable smooth rotation and support radial loads. The main components of a cylindrical roller bearing include:

1. Inner Ring: Also known as the inner race or cone, the inner ring is the part that is mounted onto the shaft. It provides the surface on which the rolling elements, in this case, cylindrical rollers, move.
2. Outer Ring: Also called the outer race or cup, the outer ring is the stationary part of the bearing that houses the rolling elements. It provides a surface for the bearing to be mounted in the housing.
3. Cylindrical Rollers: These are the rolling elements that facilitate the rotation of the bearing. Cylindrical rollers are positioned between the inner and outer rings and are designed to distribute the load evenly.
4. Cage or Separator: The cage, also referred to as the separator, is a component that retains and spaces the cylindrical rollers within the bearing. It prevents the rollers from coming into direct contact with each other, reducing friction and wear.
5. Flanges: Some cylindrical roller bearings have flanges on either the inner or outer rings, or both. Flanges help in guiding the rollers and can improve the axial stability of the bearing.
6. Ribs: Ribs are raised features on the inner or outer rings that guide and retain the cylindrical rollers. They can be present on one or both rings, depending on the specific design of the bearing.
7. Bearing Width: The width of the bearing is the distance between the inner and outer rings. It influences the load-carrying capacity of the bearing and provides stability.
8. Bearing Bore: The bore is the inner diameter of the bearing, and it corresponds to the size of the shaft onto which the bearing is mounted.

Understanding the interaction and arrangement of these components is crucial for selecting the right cylindrical roller bearing for a particular application. The combination of these elements allows cylindrical roller bearings to provide efficient support for radial loads in various industrial and machinery settings.