Dynamic–Static Thrust Bearing Structures and their Applications
Abstract
Dynamic–Static Thrust Bearingsare special type of bearings that are designed to support the axial loads or thrusts from one direction and are usually used in all types of rotary machinery. This paper covers a detailed overview of dynamic–static thrust bearing structures and their different applications. The three categories of dynamic–static thrust bearings – hydrodynamic, hydrostatic and non-contacting – are discussed along with their advantages and disadvantages. The paper also outlines the different types of dynamic–static thrust bearings and the situations in which these bearings are used. Finally, the paper describes the advantages of using the dynamic–static thrust bearings and presents an overview of the recent advancements in this technology.
1. Introduction
Dynamic–Static Thrust Bearings are special type of bearings that are designed to support the axial loads or thrusts from one direction and are usually used in all types of rotary machinery. The most common dynamic–static thrust bearing are of the rolling-element type, such as cylindrical, tapered, and spherical roller bearings (TRBs). However, the non-rolling-element type dynamic–static thrust bearing, such as fluid film, hydrostatic and non-contacting bearings are also suitable for use in some applications.
A dynamic–static thrust bearing consists of a stationary outer race, and movable inner race, and a cushion or thrust race, or element, whose decoupling by rotary movement limits the dynamic load of the bearing. The cushion or thrust race provides a counterforce to prevent the dynamic thrust loads from being applied directly to the stationary outer race.
2. Types of Dynamic–Static Thrust Bearings
Dynamic–static thrust bearings can be divided into three categories - hydrodynamic, hydrostatic and non-contacting.
2.1 Hydrodynamic Dynamic–Static Thrust Bearings
Hydrodynamic dynamic–static thrust bearings rely on a thin layer of oil to provide the cushioning force that prevents the dynamic thrust loads from being applied directly to the stationary outer race. The hydrodynamic dynamic–static thrust bearings can support extremely high dynamic thrust loads, however, they require a large amount of oil to be supplied to the bearing during its operation. In addition, the bearing can produce excessive whirring noises during its operation.
2.2 Hydrostatic Dynamic–Static Thrust Bearings
In hydrostatic dynamic–static thrust bearings, a thin film of pressurized gas is used to create the cushioning force that prevents the dynamic thrust loads from being applied directly to the stationary outer race. Hydrostatic dynamic–static thrust bearings are capable of supporting extremely high dynamic thrust loads, and require negligible amounts of oil to be supplied to the bearing duringl its operation. In addition, the bearings are much quieter than hydrodynamic bearings.
2.3 Non-contact Dynamic–Static Thrust Bearings
Non-contact dynamic–static thrust bearings rely on a thin layer of non-metallic material such as plastic or ceramic to create the cushioning force that prevents the dynamic thrust loads from being applied directly to the stationary outer race. The non-contact dynamic–static thrust bearings can support extremely high dynamic thrust loads and require negligible amounts of oil to be supplied to the bearing during its operation. However, the bearings can be prone to fretting and other surface degradation over time.
3. Applications of Dynamic–Static Thrust Bearings
Dynamic–static thrust bearings are used in a variety of applications including, but not limited to, compressors, pumps, fans, turbines, and other rotary machinery. Several types of dynamic–static thrust bearing designs can be used depending on the application and environment.
The cylindrical roller bearing is one of the most commonly used dynamic–static thrust bearings. It is characterized by its ability to support high loads and has excellent of performance in dynamic thrust applications.
The tapered roller bearing is another commonly used dynamic–static thrust bearing. It is characterized by its ability to support high shock loads and has an excellent coefficient of friction.
The spherical roller bearing is used in dynamic thrust applications which require high shock loads and misalignment of the load. It has good shock absorbing qualities and has a low coefficient of friction.
The fluid film bearing is used in dynamic thrust applications which require a large radial or thrust surface. It is characterized by its low coefficient of friction and its ability to precisely control the motion of the bearing on the shaft.
The hydrostatic bearing is used in dynamic thrust applications which require low friction and low shock loads. It is characterized by its ability to precisely regulate the motion of the bearing on the shaft due to its hydrostatic cushioning effect.
Finally, the non-contacting bearing is used in dynamic thrust applications which require a low coefficient of friction, a high load capacity and low shock loads. It is characterized by its low coefficient of friction, its ability to accurately control the bearing’s motion on the shaft and its self-compensating properties.
4. Advantages of using Dynamic–Static Thrust Bearings
Dynamic–static thrust bearings are primarily used in applications which require high shock load capacity and/or high radial or thrust surfaces. They have several advantages compared to traditional ball bearings. Firstly, they offer greater load carrying capacity and are often less prone to wear and tear. Secondly, they can be used in applications where misalignment of the load and/or directions of thrust force applications are likely to occur. Thirdly, they are quieter and require less maintenance than traditional ball bearings. Finally, due to their hydrostatic or hydrodynamic cushioning effect, they are capable of providing a smooth and reliable rotation.
5. Recent Advances in Dynamic–Static Thrust Bearing Technology
Recent advances in dynamic–static thrust bearing technology have included the development of new materials, such as ceramics, that have improved the performance of dynamic–static thrust bearings. New hydrostatic and hydrodynamic bearing designs have also been developed that are capable of supporting higher loads and are much quieter in operation. High tech coatings and lubricants specifically designed for dynamic–static thrust bearings are now being used to improve their performance and reliability.
6. Conclusion
Dynamic–static thrust bearings are special type of bearings that are designed to support the axial loads or thrusts from one direction and are usually used in all types of rotary machinery. This paper has presented a detailed overview of dynamic–static thrust bearing structures and their different applications. Three categories of dynamic–static thrust bearings – hydrodynamic, hydrostatic and non-contacting – were discussed along with their advantages and disadvantages. Several types of dynamic–static thrust bearings were also outlined and the situations in which these bearings are used. The advantages of using the dynamic–static thrust bearings were also described, along with an overview of the recent advancements in this technology.
