A gearbox, as the name implies, is a mechanical device that primarily functions through gear transmission.
In industrial production, different types of energy are transformed into rotational mechanical energy that satisfies demand through mechanical devices.
There is a need to convert unstable potential energy from water, or kinetic energy from wind, into the required source of power. This led to the birth of the earliest gearboxes. Through gearboxes, the unstable rotational speed is increased or decreased to harness the necessary energy.
With the advancement of science and technology, human industrial civilization entered the era of steam turbines and electricity. We have learned to convert natural energy into forms that are easier to transmit and utilize. The process of energy transformation underwent stages from natural energy to heat energy and electric energy, and then from heat energy to mechanical energy.
Gearboxes played a critical role in both energy conversion processes.
In mechanical systems, gearboxes achieve energy transmission through adjusting the rotational speed and torque of the shaft. The meshing of internal gears of different sizes results in changes in transmission speed and corresponding transmission torque. Therefore, it is sometimes also referred to as a transmission.
Gearboxes belong to a category of rotating equipment, transmitting energy through their shafts, making the rotation of the shaft crucial.
The rotational axis of the gearbox moves relative to the gearbox casing, and the components connecting them are bearings. Acting as supports and rotational components for the shaft, bearings play a critical role in ensuring the stable operation of the gearbox and the realization of its intended functions.
Although a bearing is a single, standard part, it is internally composed of several corresponding components. During operation, there is relative motion between these internal components. Compared to other parts, a bearing is akin to a “miniature device”, embodying its own complexity.
In contrast to bearings, the gearbox housing bears the load, with no relative motion occurring between its individual components. The rotating shaft is responsible for bearing the torque and rotates at a specific speed.
The gear is a critical component of the gearbox. When two gears mesh, the meshing point not only bears the load but also undergoes relative motion, adding to its complexity. However, this motion occurs within a pair of gears and a single gear does not exhibit relative motion.
In summary, the components in a gearbox that both bear and rotate include gears and bearings. These two types of components are the most critical parts in the design, application, maintenance, and fault diagnosis of gearboxes.
They are also the parts most prone to failure. Among these, bearings are components that operate intrinsically. Therefore, considering individual components, they can be said to be more complex.
During the design phase of a gearbox, the design and selection of bearings is one of the challenges. When a gearbox fails, bearings are among the components most prone to failure. Thus, a bearing is a vital component for a gearbox, and its selection, assembly, use, and maintenance are quite complex.
From the standpoint of engineering technicians’ knowledge base, the core technology of a gearbox is the design, production, and manufacturing of gears. Therefore, gearbox engineers have a limited grasp of bearing technology.
For gearbox manufacturers and users, a bearing is a component, and engineers and end users seldom participate in the design of bearings. They generally choose from a variety of standard bearing types. Therefore, there is not much investment in learning and understanding bearing technology.
After years of accumulated application experience, many bearing manufacturers might develop special bearing models specifically for gearboxes based on their unique operating conditions. Alternatively, bearing manufacturers may also make special designs for specific requirements, producing bearings for particular applications.
Whether it’s for generic standard bearings or specialized bearings for gearbox applications, or even special bearings developed for unique conditions, for gearbox engineers, a bearing remains a “plug-and-play” component, with many complex application requirements.
In most gearbox design processes, gearbox engineers partake in discussions about bearing requirements. However, they merely delegate tasks to the bearing manufacturers, without gaining a deeper understanding of bearing knowledge or applications.
These tasks ultimately require bearing application engineers to translate and fulfill during the bearing selection and application design process.
The frequency of custom orders is much lower compared to the selection of standard bearings. The most crucial skill in the day-to-day work of bearing application is to select the appropriate bearing based on requirements, transform unsuitable demands, choose the right bearing, and use it correctly.
The above-mentioned points constitute what we refer to as “gearbox bearing application technology”.
The application of gearbox bearings, a cross-disciplinary field of gearbox technology and bearing technology, presents numerous challenges to engineering technicians.
Firstly, it requires engineers to have a deep understanding of the application technology of gearbox bearings, including the design and manufacturing of gearboxes, as well as their application environment and operational conditions.
Additionally, it necessitates some knowledge of the features and operational requirements of components such as bearings and gears. Thus, for both gearbox engineers and bearing engineers, it is a test of comprehensive abilities and a field requiring cumulative experience.
We can easily identify a contradiction in practical engineering: on one hand, bearings are a critical component with frequent failures in gearboxes, causing numerous problems with significant impact in practical applications.
On the other hand, the application technology of bearings in gearboxes is neither the core technology of gearbox engineers nor that of bearing engineers. This “crucial but not core” technical status creates difficulties for both types of engineers in resolving issues related to gearbox bearing applications.
For this reason, we aim to share our past experiences and lessons learned with you all. Of course, our capabilities and experience are limited, and we hope that our readers will provide us with more knowledge and experience, allowing us all to grow together.