GQZ Technology Knowledge: High Performance Spherical Roller Bearing

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Design features and performance of E series spherical roller bearings and the application of E series spherical roller bearings.




Spherical roller bearings have high bearing capacity and can withstand high running speed. Their raceways are spherical and have automatic spherical function, which can compensate for bearing eccentricity caused by different installation centrality and shaft deflection. These advantages make the spherical roller bearing very suitable for heavy load, impact and eccentric applications. It is one of the most widely used bearings in the market.


Timken has a history of more than 60 years in the field of design and manufacturing of spherical roller bearings. Timken spherical roller bearings are widely used in gearbox, metallurgy, mining, cement aggregate, papermaking, thermal power generation, oil and gas, fluid machinery and other industries, and have been widely recognized by our customers. In recent years, combined with the progress in material technology, design capability and manufacturing process, Timken Company has upgraded the design of spherical roller bearings and launched a new generation of E-series spherical roller bearings.


1. Design features and performance of E series spherical roller bearings

1.1 Design features of cage

Cage is an important part of bearing. During the operation of bearing, cage mainly plays the role of separating rolling elements, preventing direct contact between rolling elements, reducing friction and heating, improving lubrication effect, and correctly guiding rolling elements in the non-bearing area of bearing to prevent rolling elements from slipping and skewing. In addition, during the installation and disassembly of the bearing, the cage plays a role in preventing the rolling element from falling off from the ferrule. Therefore, the material and design of bearing cage play an important role in the reliability and overall performance of bearing.


E series spherical roller bearings have two types of cage design, one is EJ type pressed steel cage (Fig. 1), which is commonly used for small spherical roller bearings, and the other is EM or EMB type machined brass cage (Fig. 2), which is mostly used for medium and large spherical roller bearings.



Fig. 1 EJ type pressed steel cage      


Fig. 2 machined brass cage type EM or EMB


1.1.1 EJ type pressed steel cage

EJ type pressed steel cage adopts a unique and innovative design, which has the following main features:


(1) The EJ type pressed steel cage is guided by the inner ring, which reduces the load of the rolling element. The support beam of the cage is designed above the diameter of the center line of the rolling element. This design allows the cage beam to have a wider design width, which can improve the strength and stiffness of the cage and reduce the internal stress of the cage under high impact load or frequent acceleration and deceleration conditions.


(2) EJ cage adopts advanced stamping process to ensure good manufacturing accuracy control. The cage pocket integrates the roller guide function, which can guide the rollers into and out of the bearing area. Since the guide ring is not required for centering and guiding, the friction between the roller and the inner ring is reduced. At the same time, this also leaves more space for designing longer rollers, improving load capacity and reducing bearing stress. In addition, more internal space also improves the fluidity of the lubricant, which is conducive to taking away the heat generated by the work of the bearing.


(3) The surface of EJ type pressed steel cage is treated by nitriding and hardening process, which improves the strength and wear resistance of the cage, so that the bearing can operate normally in worse application conditions.


(4) The end face of EJ type pressed steel cage has a unique slotting treatment, which is conducive to improving the fluidity of lubricant, reducing the working temperature of bearing and prolonging the service life of bearing. At the same time, this innovative design makes the cage have lighter weight and less centrifugal force, which is more conducive to the operation of the bearing in high-speed application conditions.


1.1.2 EM or EMB type brass cage

This type of cage is a precision machined open finger cage, as shown in Figure 3 and Figure 4 respectively. Both EM and EMB cages adopt one-piece design. The difference between them lies in the different guiding modes of cages. EM type cage is often used in the design of small and medium-sized spherical roller bearings. The cage is light and guided by rolling elements; The EMB cage is often used in the design of medium and large size spherical roller bearings. The cage is heavy and guided by the inner ring of the bearing. The precision machined brass cage has precise overall dimensions, which can better guide the rolling element. The open finger design can make the lubricating oil reach all the working surfaces that need lubrication easily, so as to ensure full lubrication of the bearing and reduce the working temperature of the bearing. In addition, brass cage has high strength, good high temperature stability and low friction coefficient. These characteristics make EM type and EMB type spherical roller bearings commonly used in harsh working conditions such as high temperature, high speed, impact load and insufficient lubrication.



Fig. 3 EM type brass cage         


Fig. 4 EMB type brass cage


1.2 Other improvements and their effects

In addition to the design improvement and innovation of cage, e series spherical roller bearings also optimize the internal geometry: optimize the coincidence of raceway and rolling element contact surface, optimize the modification of raceway surface and rolling element, and improve the surface roughness and surface texture of raceway surface and rolling element in manufacturing process. These improvements and innovations have greatly improved the overall performance of E series spherical roller bearings, which are mainly reflected in the following aspects:


(1) Higher bearing capacity the bearing capacity of E series spherical roller bearings has increased by 18% on average compared with the previous bearing design. Therefore, under the same application conditions, the bearing design life can be increased by nearly 75%. In the case of limited design space, the use of E series spherical roller bearings can achieve a more compact structural design.


(2) Lower operating temperature compared with traditional products, the new generation of E series products can reduce friction torque, reduce the operating temperature of bearings, prolong the service life of lubricants and bearings, and have higher bearing reliability by virtue of improved surface treatment and design innovation.


(3) Higher thermal speed grade the bearing operates at a lower temperature due to the innovative cage design, optimized internal geometric design and better surface roughness and surface texture, and the thermal speed grade of the bearing is correspondingly improved. Compared with the previous Timken spherical roller bearing products, under the same working conditions, the average reference speed of E series spherical roller bearings is increased by 17%.


2. Application of E series spherical roller bearings

In the granulator of a well-known customer in Europe, the original bearings are spherical roller bearings of other well-known brands. Under the severe working conditions of impact, heavy load and vibration when the maximum working temperature reaches 150 ℃, the spherical roller bearings need to be replaced every 500h on average. Frequent downtime resulted in expensive bearing replacement, and the supplier failed to solve this problem after the customer replaced two bearings. Finally, customers have to ask their equipment suppliers to find more reliable bearing products that can be replaced. The final equipment supplier selected Timken E series spherical roller bearings. The test after installation shows that under the same operating conditions, the actual service life of E series spherical roller bearings reaches 2500h, which is 5 times that of the original bearings. In addition, the customer's temperature monitoring found that the operating temperature of E series spherical bearings was 5%~8% lower than that of similar products. In this application, e series spherical roller bearings have lower operating temperature, which improves the lubrication condition and prolongs the service life of lubricants and bearings.


Another case is the application of crushers in the cement industry. Crusher application is one of the most challenging bearing applications. In crusher application, the bearing is often in the working environment of extreme load and impurity intrusion. In the crusher pulley of a European customer, the original design is the configuration of cylindrical roller bearings and ball bearings. In practical application, the bearings will be damaged every three months or so, bringing expensive downtime maintenance costs and bearing replacement costs to customers. In view of the application of eccentricity, deformation and impact load in the process of stone crushing, Timken engineers selected E-Series spherical roller bearings to replace the original bearing scheme, carried out lubrication analysis on the application, and recommended appropriate grease and grease change cycle to customers. After installing the spherical roller bearing according to the design change, the crusher has operated for one and a half years and the bearing has not been damaged.


3. Conclusion

To sum up, by virtue of technical improvement and innovation, Timken e series spherical roller bearings have higher bearing capacity, lower operating temperature and higher thermal speed grade, providing customers with spherical roller bearing solutions that meet stringent application requirements. These products and solutions can help OEMs design more compact and reliable equipment, help end users reduce downtime and reduce operating costs.


More about GQZ Spherical Roller Bearing:

GQZ precious-quality spherical roller bearing with reasonable price for customers all over the world and first-class service and unrivaled products.


Dealing with very heavy radial and axial loads in applications prone to misalignment or shaft deflections? Meet the challenge with GQZ spherical roller bearings, whose high load carrying capacity and ability to accommodate misalignment help you obtain low maintenance costs and long bearing service life. Our range is the widest in the industry today – both open and sealed. Our assortment includes spherical roller bearings designed for many applications, including wind turbine main shafts, continuous casters, vibratory applications and high-speed applications, as well as bearings with Solid Oil, split bearings, GQZ Con-Central roller bearing units, and, for the harshest operating environments, our GQZ three-barrier solution.


 Spherical Roller Bearing