Cause Analysis and Maintenance Method of Bridge Crane’s “Rail Gnawing” Phenomenon

In reality, a type of mechanical failure that often occurs in the operation of overhead cranes is “rail gnawing”, which will cause many unfavorable factors to the operating stability and safety of the crane. When the crane is in normal operation, there is a gap between the wheel and the side of the track, that is, there will be no direct contact, but in fact, due to the influence of various factors, the two may have direct contact, which is the so-called “track gnawing”. In order to ensure the operation quality of overhead cranes and fully reflect their role and value in industrial production, it is necessary to take timely measures to effectively deal with the problem of “track gnawing” to ensure their safe operation.

crane rail gnawing

Of course, in order to achieve accurate judgment, further measurement and testing are needed, and the specific causes of “rail gnawing” should be identified based on the test results, so as to provide a scientific basis for adjustment and maintenance.

If the bridge crane “gnaws on the rail” during its work, it will inevitably cause serious adverse effects on the safety and stability of its operation. The harm is mainly reflected in the following aspects: First, the “rail gnawing” first It will aggravate the wear of the wheel rim and the side of the track, which will reduce the service life of the two. In severe cases, it will even cause the deformation of the wheel rim or the metal peeling on the side of the track, causing the wheel and the track to be scrapped. Second, “track gnawing” means that the wheel slips laterally on the track, and therefore, a lateral force is associated with it. On the one hand, this lateral force will increase the positive pressure between the rim and the side of the track, which will increase friction and wear; on the other hand, it will also cause gauge deviation during operation, making the track unable to be used normally. Third, the “rail gnawing” will cause the operating resistance of the bridge crane to increase abnormally due to the increased friction, which acts on the drive motor and transmission system, causing it to withstand abnormally large loads and increase the working temperature. , in the long run, it may cause the key components of the motor and transmission system to burn out or be damaged.

In actual work, the factors that cause the “rail gnawing” failure of bridge cranes are often multi-faceted, which may be the cause of the wheel or the track. The main factors will be analyzed below.

1. The reason for the wheel

For the wheels of bridge cranes, if there are large manufacturing and processing errors, uneven wear during use, or replacement of unilateral parts during maintenance, these may cause the geometry of the wheels on both sides. Sizes vary. And this difference will cause the wheels on both sides to run out of sync when the speed is the same, and the car body will slip sideways, resulting in the phenomenon of “track gnawing”. In addition, if there are installation errors in the wheels, for example, the four wheels are not accurately installed at the four corners of the rectangle, or the centers of the wheels on the same side are not in a straight line, then the center line of the wheels will also be skewed, which will lead to “gnawing” track” phenomenon. At the same time, if the center line of the wheel on the same side and the top surface of the track do not maintain a strict mutual vertical relationship, then the contact area between the wheel tread and the top surface of the track will decrease, and the pressure per unit area will increase, which will cause The uneven wear of the wheels can easily cause the wheels to skew, and then the phenomenon of “track gnawing” occurs. Finally, if the bridge crane is operated unreasonably or cannot be used correctly, it may cause structural deformation and even diagonal errors, thereby causing the problem of “track gnawing”.

2. Rail track reasons

In addition to the wheel factors, the problem of the bridge crane track is also one of the important factors leading to the phenomenon of “track gnawing”, which is embodied in the following aspects: First, if the track laying is not standardized, for example, horizontal bending If the straightness error is too large or the straightness error exceeds the allowable value, it will cause the “track gnawing” problem in some fixed line segments. Second, the gauge of the track is not suitable. If the gauge is too large, it is easy to cause the outer rim to “gnaw the rail”; otherwise, it is easy to cause the inner rim to “gnaw the rail”. Third, in actual work, if the relevant installation and maintenance operations are not standardized, or when the columns of the factory building sink, it may lead to a large difference in the vertical height of the tread between the two rails, which will lead to “track gnawing”. . Finally, if there is a parallelism error between the two tracks when they are laid, for example, when they are in the shape of a “figure of eight”, then “track gnawing” will also occur.

crane rail track Maintenace

3. Reasons for the transmission system

In addition to the above introduction, if the two sets of transmission systems of the crane are out of synchronization, the car body will also be tilted, and then “track gnawing” will occur. For example, assembly differences will produce different resistances. If two sets of power and transmission systems are used separately, then the drive motor will run out of synchronization, which will lead to the skewed running of the car body and the phenomenon of “track gnawing”. In addition, if the rotational speeds of the two drive motors are out of sync, it will also cause the car body to tilt, which will then cause “track gnawing”.

Discussion on processing methods

The above has carried out a more detailed analysis of the reasons for the “track gnawing” of the bridge crane. It can be seen from this that there are many reasons for the “track gnawing”, and this requires the handling of the “track gnawing”. When it is necessary to sort out the relevant factors and determine the specific reasons, and then formulate scientific and reasonable treatment methods on this basis.

rail lubrication

1. Check the wheels

Regarding the factors of the wheel, the first thing to do is to check the appearance of the wheel for defects such as cracks, tread peeling and indentation. Further, it is necessary to judge whether the standards are met through relevant inspections. Whether the rim thickness and tread wear are within the warning values, and whether there are pits on the tread are important criteria for judging whether the wheel meets the standard. In addition, through relevant inspection and measurement, if it is found that the diameter size deviation of the driving wheel or the driven wheel exceeds the specified allowable value, it will easily cause “rail gnawing”. At the same time, the diameter difference between the driving wheel and the driven wheel is controlled.

2. Check the crane rail track

The installation and laying of the track are not standardized, for example, the deviation of the track span and the deviation of the elevation of the same span of the two tracks exceeding the standard, etc., may cause the “track gnawing” of the cart. Therefore, it must be ensured that the installation of the rails is up to standard. Generally speaking, the relative elevation of the two rails should be controlled within 10mm, the straightness deviation of the rails should be controlled within ±3mm, and the gauge deviation should not exceed 15mm. If it is found that the relevant measurement value exceeds the above-specified value, it should be dealt with by adjusting the height difference and orbital moment.

As for the “rail gnawing” phenomenon caused by factors of the drive and transmission system, it generally occurs less in reality and can be dealt with by adjusting the rotational speed of the drive motor, the braking torque of the brake, and the transmission accuracy.

To sum up, the key to the prevention and treatment of the crane “track gnawing” phenomenon is to do a good job in the inspection of wheels and tracks. After the occurrence of the “track gnawing” problem, the cause of the “track gnawing” should also be identified through testing, so as to provide a scientific basis for taking targeted measures.