Causes and diagnosis methods of locomotive rolling bearing faults

Causes and diagnosis methods of locomotive rolling bearing faults

This paper introduces the simple diagnosis and precise diagnosis of rolling imported bearings of locomotives, and lists the detection examples.

Keywords: Fault detection of rolling imported bearings of locomotives

1 Introduction

Imported bearings, as the main components of locomotives, especially traction motors and axle box bearings, play an important role in safe transportation. When locomotives are running online, once the bearings fail, the whole train will be unable to run and the main transportation line will be blocked, especially when passenger trains fail, which will have a greater negative impact. At the same time, once the locomotive bearings fail, it is very difficult to repair the locomotive. Therefore, it is very difficult to prevent and reduce the occurrence of locomotive bearing failures. It is very important for the safe transportation of locomotives. The key point of this paper is whether the bearings with hidden trouble can be detected before loading the bearings to ensure the qualified bearing parts to get on the train.

2 bearing failure

The serious damage of bearings is often not caused by a single reason, but by the comprehensive action of several aspects, a vicious circle is generated under bad operating conditions, which leads to serious burning of bearings. Therefore, after the accident, it is often difficult to judge what causes it, which brings us some difficulties in formulating relevant measures. For the convenience of discussion, the reasons for bearing failure are analyzed from several aspects.

2.1 Abnormal wear of bearings

2.1.1 When the bearing is used for a period of time, certain defects and scars are produced in the inner ring, rolling body, cage, outer ring and raceway of the bearing, resulting in poor lubrication of the bearing and heating of the bearing, which will lead to:

(1) Dilution of bearing lubricating oil.

(2) Accelerate the fatigue of materials and decrease the hardness. Due to the above reasons, a vicious circle is further formed, which accelerates overheating and causes bearing burning. Serious bearing inner ring displacement, rolling body out of round, collision and heat generation, and finally welded together. Therefore, when running on the line, if the bearing is found to be seriously hot and smoking, do not stop, but keep running to the front station, because the overheated bearing is in a melting state at the moment, and once it is stopped and cooled, it can no longer walk, blocking the main line.

2.1.2 It is very important for locomotive bearings to be oiled and maintained, especially proper oiling can ensure good lubrication of bearings. Lack of oil and excessive oiling can easily lead to bearing failures. Adding less oil can easily lead to poor lubrication of bearings and heating, and adding more oil can easily lead to overheating of mixing. Therefore, proper oiling is required in maintenance, and the cleaning of lubricating grease of bearings is also very important. Once other impurities and moisture fall into grease, it will affect normal clearance and establish necessary oil film.

2.1.3 The service life of the bearing is too long, which will easily lead to the fatigue of the material. In addition, the strong impact will deform the material, which will cause peeling and grinding of the roller and raceway surface, resulting in poor lubrication and increased vibration.

2.2 Influence of Installation on Bearing

2.2.1 The fit clearance between the bearing inner ring and the shaft does not match the interference amount, which is easy to cause bearing failure. The interference amount is large, which is easy to cause the bearing inner ring to crack due to excessive tensile stress, and the interference amount is too small, which is also easy to cause the bearing inner ring to "relax".

2.2.2 Improper clearance fit in bearing assembly will easily lead to bearing failure, and small clearance will easily lead to friction and heat generation between roller and raceway. With the rising temperature, the temperatures of bearing inner ring, rolling body, cage, outer ring and end cover are different, and there is a temperature difference between them, so the expansion amount is slightly different, which will further reduce the fit clearance and increase the heat generation of bearing. If the gap is too large, the vibration of the roller will increase, which will aggravate the impact of the roller and raceway, and at the same time, it will easily cause uneven internal load distribution, less bearing rollers and excessive load of the central roller.

2.2.3 When assembling the bearing, a copper hammer is used to impact the bearing, resulting in deformation of the cage, incorrect installation of the inner and outer rings of the traction motor bearing or other reasons, which makes the axial transverse momentum disappear, causing the bearing shaft to be squeezed to death.