The harm of rolling bearing burning shaft, the cause of hot shaft and how to judge whether hot shaft failure has occurred.

Abstract: Whether the rolling bearing works normally or not directly affects the vehicle operation safety, and the fault occurs quickly, develops rapidly, and does great harm. Once the hot box occurs, the consequences are unimaginable. It is an important part of the train inspection work to find and handle the hot box fault in time and prevent the occurrence of the shaft burning accident. The harm of burning shaft of rolling bearing, the cause of hot shaft and how to judge whether hot shaft failure occurs are analyzed.

Keyword: Rolling bearing; Hot shaft; judge

Hot box is a common fault in the operation of railway vehicles, which seriously threatens the safety of train operation. If the hot box fault of the vehicle is not found in time and properly handled, it will cause the vehicle to cut the shaft due to burning the shaft, which will lead to serious accidents such as train derailment and overturning, causing heavy losses to the country and people's lives and property. In order to improve the economic benefits of railway transportation, a series of measures and countermeasures must be taken accordingly, and the hot box fault of vehicles must be controlled first.

The normal temperature of rolling bearing during operation is generally 15-30 ℃ higher than the external temperature, which may be caused by too small radial clearance of bearing or too much grease filled, and it is not fault heat, so it can not be treated. If the shaft temperature rises sharply, especially when the shaft temperature exceeds the external temperature by more than 40 degrees, the expansion of the bearing inner race may be greater than the interference during assembly. If the inner race loosens, it should be treated as a fault shaft temperature.

The main reasons for rolling bearing hot shaft are as follows: poor bearing assembly, poor lubrication, bearing internal damage, bearing external damage, poor vehicle bogie status, and lack of vehicle technical inspection.

For the inspection method of rolling bearing hot shaft, the inspection method of "one listening, two looking, three twisting, four measuring, five touching, six comparing, seven probing, eight turning and nine diagnosing" shall be applied in combination with the working characteristics of each link.

One listening: pay attention to the abnormal sound inspection when receiving the vehicle, and listen to the friction sound of the bearing;

Second, stop to check the appearance characteristics of wheels and bearings. Check whether the wheel tread is scratched and whether the bearing bolt is loose or missing.

Three twists: Hand twist the grease leaked from the bearing to judge the internal problems. Normal grease is light yellow, black when the shaft temperature is too high, white when water is mixed, and gray when the roller is damaged. It can be preliminarily judged whether it is normal according to the color of grease.

Four measurements: measure temperature with a point thermometer. Generally, the temperature of the bearing outer sleeve shall not exceed 40 ° C of the external temperature, the temperature of the RD2 bearing outer sleeve shall not exceed 40 ° C of the external temperature, and the temperature of the seal shall not exceed 60 ° C. If the temperature exceeds 30 degrees, the vehicle must be detained.

Five touch: Touch the bearing to identify the place with abnormal temperature. Touch the upper or bottom outer casing of the bearing with your hand. If you find any temperature difference, touch the front and back of the bearing for 5-7 seconds in winter and 3-5 seconds in other seasons to find the temperature difference.

Six ratios: through the comparison of shaft temperature, find out the different temperature bearing and the different temperature place. The eight axle ratio of the same vehicle, the four axle ratio of the same side, the two ends ratio of the same axle, and the front rear ratio of the same bearing can accurately determine the fault location.

Seven probes: Use flaw detection hooks to detect the edges of the jacket from the left and right sides of the lower part of the bearing saddle to identify whether there is a catch. If there is, and it is obvious, it is likely that the lower jacket is broken.

Eight turns: further set up and turn the bearing with fault characteristics to judge the fault. Use a hydraulic pick to jack up the side frame end, and check the bearing with fault characteristics by 360 ° rotation. During rotation, listen carefully for abnormal sound and feel abnormal vibration.

Nine diagnosis: The abnormal bearing must be collectively diagnosed to determine the fault before further treatment.

There are generally three treatment methods for rolling bearing hot shaft:

1. Bearings with oil leakage symptoms that can still maintain normal operation can be released, but attention should be paid.

2. For the bearings newly subject to regular inspection, due to excessive grease and large internal shade of grease rotation, when the hot shaft leaks oil or throws oil, it is generally shown that the top surface of the bearing is evenly heated. If no continuous rise of the shaft temperature is found within 600km after regular inspection, the bearings can be released. However, if the axle temperature continues to rise, there may be a fault and the vehicle should be detained for repair.

3. For the confirmed hot box fault, the vehicle must be detained for repair, but watering or sanding on site is prohibited. The vehicle department with a train inspection station shall be handled by the vehicle inspector. For the vehicle department without a train inspection station, the vehicle inspector shall cooperate with the driver to inspect and handle. In case of serious hot axle failure, it shall be thrown out of the train set and the depot shall be notified to send personnel to deal with it.

Vehicle shaft burning has been an inertial accident affecting the normal railway transportation for many years. Reducing and eliminating hot axles is not only the responsibility of the vehicle department, but also the responsibility and obligation of all personnel in the transportation department. It is of great significance to prevent burning of the axle, and the responsibility of the vehicle inspector lies on the shoulders.

More about WSW Tapered Roller Bearings： 

Tapered roller bearings are rolling element bearings that can support axial forces (i.e., they are good thrust bearings) as well as radial forces. Tapered roller bearings feature a cup and cone assembly. The cup is comprised of the outer ring and the cone assembly consists of inner ring, rollers, and cage. This bearing construction accommodates combined loads and provides low friction during operation. By adjusting one single row tapered roller bearing against a second tapered roller bearing and applying a preload, a rigid bearing application can be achieved.

Tapered roller bearings are also made to Explorer class. Explorer combines our expertise in bearing design, tribology, metallurgy, lubrication and manufacturing. Explorer tapered roller bearings are typically used in bearing solutions where there is a need to increase performance, reduce friction or increase power density in applications.

We promise that WSW only provides excellent quality products with the best price and the most professional service! We sincerely invite all of you to cooperate with us.