Bearings, as the main components of locomotives, especially traction motors and axle box bearings, play a crucial role in safe transportation. When locomotives run online, if bearings fail, it will cause the entire train to be unable to operate, block the main transportation line, especially for passenger trains. The negative impact is even greater. At the same time, once locomotive bearings fail, it is also very difficult to repair the locomotive. Therefore, preventing and reducing the occurrence of locomotive bearing failures is very important for the safe transportation of locomotives. The focus of this article is whether bearings with hidden faults can be detected before installing deep groove ball bearings to ensure that qualified bearing accessories are loaded onto the train.

1. Contact fatigue failure

Contact fatigue failure refers to the failure of the working surface of a bearing under alternating stress. Contact fatigue peeling occurs on the working surface of bearings, often accompanied by fatigue cracks. It first occurs at the maximum alternating shear stress below the contact surface, and then extends to the surface to form different peeling shapes, such as pitting or pitting peeling, and peeling into small flakes is called shallow peeling. Due to the gradual expansion of the peeling surface, it often extends to deeper layers, forming deep peeling. Deep peeling is the fatigue source of contact fatigue failure.

2. Wear and tear failure

Wear failure refers to the failure caused by the continuous wear of the working surface metal due to the relative sliding friction between surfaces. Continuous wear will cause gradual damage to bearing components, ultimately leading to loss of dimensional accuracy and other related issues in deep groove ball bearings. Wear and tear may affect shape changes, increase clearance, and alter the morphology of the working surface, which may affect the lubricant or contaminate it to a certain extent, resulting in complete loss of lubrication function, thus causing the bearing to lose rotational accuracy and even malfunction. Wear failure is one of the common failure modes of various types of bearings, which can usually be divided into the most common abrasive wear and adhesive wear according to the form of wear.

The serious damage of deep groove ball bearings is often not caused by a single factor, but by the combined effects of several factors, a vicious cycle occurs under harsh operating conditions, resulting in severe bearing burnout. Therefore, after an accident occurs, it is often difficult to determine the cause, which brings certain difficulties to us in formulating relevant measures. For the convenience of discussion, we will first analyze the reasons for bearing failure from several aspects.

After a period of use, certain defects and scars may occur in the inner ring, rolling elements, cage, outer ring, raceway, etc. of the bearing, causing poor lubrication and heating of the bearing. Prolonged heating can lead to:

1. Dilution of bearing lubricating oil.

2. Accelerate material fatigue and reduce hardness.

Due to the above reasons, a vicious cycle is further formed, accelerating overheating and causing bearing burnout. Severe displacement of the inner ring of deep groove ball bearings, loss of roundness of rolling elements, collision induced heat generation, and ultimately fusion together. Therefore, when running online, if the bearings are severely overheating or smoking, do not stop the machine. Instead, maintain operation until the front station, as the overheated bearings are in a molten state. Once the machine is stopped and cooled down, it can no longer move and block the main line.