Crossed roller bearings

Product structure of Crossed Cylindrical Roller Bearings:
The internal structure of the cross roller bearing adopts rollers arranged perpendicularly at 90 degrees to each other. The structure is compact and can withstand radial loads, bidirectional thrust loads and overturning moments at the same time. At the same time, cross roller bearings have high rigidity, so they are suitable for joints or rotating parts of industrial robots, rotary tables of machining centers, rotating parts of manipulators, precision rotary tables, medical equipment, measuring instruments, IC manufacturing equipment and other equipment. Crossed roller bearings have three structural types: with cage, with spacer and with full complement rollers. The bearings with cage and spacer are suitable for working conditions with small friction torque and high speed, while the bearings with full complement rollers are suitable for working conditions with low speed and heavy load.

Product features of Crossed Cylindrical Roller Bearings:
1. High load carrying capacity: Compared with the traditional cage, the spacer retainer of the cross roller bearing can increase the effective contact length of the roller, thereby greatly improving the load carrying capacity; at the same time, the spacer retainer guides the full length of each roller, which effectively prevents the roller from tilting. In addition, the spacer retainer keeps the load area symmetrically distributed, preventing end-face contact caused by the asymmetry of the load area, reducing friction and wear, and improving bearing life.
2. High precision: The inner or outer ring of the cross roller bearing can be separated, and the bearing gap can be adjusted, so that it can still obtain higher rotation accuracy under load.
3. High stiffness: Compared with double row angular contact ball bearings, cross roller bearings can bear the load in all directions with only one row of crossed cylindrical rollers, greatly reducing the width of the bearing, and meeting the requirements of compact structure. Because the roller is loaded, the stiffness of the cross roller bearings can also be increased by 3-4 times when the rigidity of the installed components remains unchanged.
4. Simple operation: The crossed roller bearing has a divided inner ring or outer ring. After the rollers and the spacer cage are installed, they are fixed together with the other undivided part to prevent separation from each other, so the installation operation is very simple.

Types of Crossed Cylindrical Roller Bearings:
Precision crossed cylindrical roller bearings are available in seven structural series: RB, RE, RU, RA, RA-C, CRB, and CRBH-A.
1. RB Series Crossed Cylindrical Roller Bearings
The RB series crossed cylindrical roller bearing is the basic type of crossed cylindrical roller bearing. Both the inner ring and outer ring dimensions are compactly designed. Its structure features a separable outer ring and an integrated inner ring, making it suitable for applications requiring high rotational accuracy of the inner ring.
The RB series crossed roller bearings are available in two structural types: RB (open type) and RB...UU (double-side sealed type).

2. RE Series Crossed Cylindrical Roller Bearings
The main dimensions of the RE series crossed cylindrical roller bearings are the same as those of the RB series. Its structure features a separable inner ring and an integrated outer ring, making it most suitable for applications requiring high rotational accuracy of the outer ring.
The RE series crossed roller bearings are available in two structural types: RE (open type) and RE...UU (double-side sealed type).

3. RU Series Crossed Cylindrical Roller Bearings
The RU series crossed cylindrical roller bearings are provided with mounting holes, eliminating the need for fixing flanges and support housings. In addition, since both the inner ring and outer ring adopt an integrated structure with housing, installation has almost no effect on performance, enabling stable rotational accuracy and torque to be achieved. These bearings are suitable for both outer ring and inner ring rotation.
The RU series crossed roller bearings are available in two structural types: RU (open type) and RU...UU (double-side sealed type). Our company can also provide RU...U (single-side sealed type) according to customer requirements.

4. RA Series Crossed Cylindrical Roller Bearings
The RA series crossed cylindrical roller bearings are a compact design derived from the RB series, with the thickness of both the inner ring and outer ring reduced to the minimum. They are suitable for applications requiring light loads and compact designs, such as the rotating sections of robots and manipulators.
The RA series crossed roller bearings are available in two structural types: RA (open type) and RA...UU (double-side sealed type).

5. RA-C Series Crossed Cylindrical Roller Bearings
The main dimensions of the RA-C series crossed cylindrical roller bearings are the same as those of the RA series. Since this series features a slotted outer ring structure, the outer ring also maintains high rigidity, making it suitable for outer ring rotation applications as well.
The RA-C series crossed roller bearings are available in two structural types: RA...C (open type) and RA...CUU (double-side sealed type).

6. CRB Series Crossed Cylindrical Roller Bearings
The CRB series crossed cylindrical roller bearings feature a separable outer ring and an integrated inner ring, and are full-complement crossed cylindrical roller bearings without cages. They are suitable for applications requiring high rotational accuracy of the inner ring and heavy load capacity.
The CRB series crossed roller bearings are available in two structural types: CRB (open type) and CRB...UU (double-side sealed type).

7. CRBH-A Series Crossed Cylindrical Roller Bearings
The CRBH-A series crossed cylindrical roller bearings feature integrated inner and outer ring structures, making them suitable for both outer ring and inner ring rotation.
The CRBH-A series crossed roller bearings are available in two structural types: CRBH...A (open type) and CRBH...AUU (double-side sealed type).

Technical parameters of Crossed Cylindrical Roller Bearings:

Lubrication of Crossed Roller Bearings:
Crossed roller bearings are typically pre-lubricated with grease before leaving the factory, allowing customers to use them immediately upon receipt. However, compared to standard roller bearings, crossed roller bearings have a smaller internal volume and a rolling contact structure that is more demanding on the lubricant. After operating for a certain period, grease depletion is inevitable, leading to increased frictional resistance and reduced service life. Therefore, periodic replenishment of the grease is essential.
Depending on the specific operating conditions, the replenishment interval is approximately 1 to 6 months. When replenishing, the same type of grease must be used to fill and evenly distribute throughout the internal structure of the bearing; avoid mixing different types of grease. After lubrication, a temporary increase in frictional torque may occur during the initial stage of operation. As operation continues, excess grease will be expelled, and the frictional torque will return to normal levels.

Installation of Crossed Roller Bearings:
1.  Installation Precautions
The inner or outer rings, which are divided into two parts, are secured with special rivets or bolts and nuts and must not be separated; they should be installed directly into the bearing housing. Furthermore, incorrect assembly of the spacers significantly impacts the rotational performance of the bearing; therefore, do not disassemble the bearing under any circumstances.
Occasionally, the joints of the inner or outer rings may deviate slightly. Before mounting into the housing, please loosen the bolts securing the inner or outer ring, correct the alignment using a plastic mallet, and then proceed with the installation (as the fixing rivets will deform along with the housing).
During installation or removal, do not apply external force to the fixing rivets or bolts. Please pay close attention to the dimensional tolerances of the mounting components. Securely press the inner or outer ring by tightening the side flange; however, avoid excessive pressure that could cause bearing deformation and prevent normal rotation.
2. Installation Sequence
1) Inspection of Components Before Installation 
Clean the bearing housing and other mounting components to remove dirt and debris, and ensure that all burrs have been removed from each part.
2) Installation into the Housing or onto the Shaft 
Because these are thin-walled bearings, they are prone to tilting during installation. Please maintain a horizontal alignment and tap uniformly around the circumference with a plastic mallet, installing the bearing bit by bit until the sound confirms that the contact surfaces are firmly seated.
3) Installation of the Side Clamping Flange 
After placing the side clamping flange into position, rock it back and forth several times in the circumferential direction to align the positions of the mounting bolts. 
When installing the clamping bolts, tighten them by hand first to ensure there is no resistance caused by misalignment of the bolt holes. 
The tightening process for the clamping bolts should be divided into 3 to 4 stages, following a diagonal sequence as shown in the diagram below. When tightening the clamping bolts for a split inner or outer ring, slightly rotate the integral ring (the non-split side) frequently during the process to correct any misalignment of the two-piece ring.