Harbour Portal Crane Slewing Bearing: Causes of Failure and Effective Repair Solutions

No matter what type of crane it is, there will be harbour portal crane slewing bearing. It is an important part of the crane structure. harbour portal crane slewing bearing can not only keep the crane stable and safe during operation but also improve its work efficiency. Naturally, there will inevitably be failures. To ensure the performance of the crane during use, it is necessary to analyze the cause of the failure and propose targeted modification methods.

Gantry cranes are a type of crane equipment that is more used in crane equipment, and their application fields are very wide. Of course, harbour portal crane slewing bearing bearings are also a particularly critical structure. There are two common forms of harbour portal crane slewing bearing bearings for gantry cranes, one is rotary type and the other is rotary column type, and the former is more stable and the mechanical structure is simpler. Therefore, when there are certain influences from the outside world, it is particularly prone to failure, which is bound to affect the work of the crane.

The operating principle of harbour portal crane slewing bearing 

There are many structures in the harbour portal crane, and harbour portal crane slewing bearing bearings are a particularly critical structure. There are different types and specifications of harbour portal crane slewing bearing bearings, so the installation methods are also different. Even if the selected bearing type and specifications are the same, it still needs to be analyzed in advance during installation. The two parameters of mechanical bearing capacity and axial size are usually carefully examined to ensure the smooth installation of the bearing and meet the actual production needs.

According to the type and arrangement of rolling elements, harbour portal crane slewing bearing bearings can be divided into double-row roller type, single-row cross-roller type, etc. Due to the large load, the harbour portal crane slewing bearing required for crane operation have higher requirements, so generally, three rows of roller slewing bearings are selected for port operations (Figure 1). This is because the inner ring and outer ring of the harbour portal crane slewing bearing of this method are fixed at the bottom of the turntable and the upper part of the cylindrical gantry, respectively. When compared with the axial size, the radial direction of the slewing bearing is much larger, and the impact capacity and dynamic load resistance are significantly stronger so that the safety of the crane can be guaranteed when working.

In a harbour portal crane, the part connected to the upper support is the internal rotating part, and the part connected to the lower support is the large ring gear, which is usually bolted. It is the use of bolts to fix it, and it will not rotate while working.

Common faults of harbour portal crane slewing bearing

Improper design

Gantry cranes often fail due to improper operation during operation or lack of normal maintenance after operation. The bearing part of the harbour portal crane slewing bearing is particularly prone to failure. Due to the particularly large load it has, once a failure occurs, it will affect the operation process. To solve these problems, analysis and research are generally carried out from the design of the components, such as the installation quality is not high enough during the installation process, the production is too rough, etc., which will cause deformation of certain parts of the raceway of the equipment in actual operation.

Improper late maintenance

The reason for the failure of most harbour portal crane slewing bearing is due to the failure of the standardized operation and the failure to carry out timely maintenance after the end of the operation, which gradually expands the hidden dangers that existed at the beginning. The hidden dangers mentioned here may be that there are small gaps in the connection structure of the slewing bearing, or it may be that the connection bolts are cracked, etc. These small hidden dangers are difficult to truly detect at the beginning. However, with the continuous growth of the use time, these gaps and cracks continue to be hit hard, which eventually leads to the complete fracture or partial deformation of the support structure, failing.

Structural deformation

There are generally two situations of structural deformation. One is that during the initial design, the stiffness of the support frame it possesses is not enough, and it is particularly prone to deformation over a long period (of course, there are not many such situations); the other is caused by abnormal forces during work, usually due to the huge gap in the height of the tracks on both sides, which makes the door machine tilt. If the vibration is caused by the second situation, it has something to do with the change value of stiffness.

If the speed of rotation of the device is uniform, it means that this kind of vibration has certainty. When the signal has an impact after some time, these can be visually seen in the time acceleration diagram of the vibration.

Harbour portal crane slewing bearing replacement scheme

Replacing harbour portal crane slewing bearing bearings is not a simple task, it needs to be carried out in the following 6 steps.

The first step is to use jack bearings. A total of 4 jack bearings need to be prepared, and then they are directly welded to the upper part of the cylinder. There needs to be a larger spacing between the two bearings placed in front. Usually, this spacing is larger than the outer diameter of the large ring gear. At the same time, many pads need to be prepared. These pads do not need to be of the same size and thickness. The boom should be placed where the amplitude is greatest. At this time, you need to use the amplitude indicator to measure the weight of the maximum load required at this time, and then use the hook to lift it.

The second step is to lift the hook that hooks the counterweight to ensure that there is a distance of about 10 cm between it and the ground, and then let it no longer move. This requires the turntable windproof anchoring device to be directly locked, lift the rotating gearbox and rotating pinions that have been removed from the foot screws, and put them all on the turntable.  Be careful not to let it rotate at this time, and keep it stable.

In the third step, 16# channel steel needs to be used, mainly to play a supporting role in the future, because it needs to let the newly welded jack support lean on the channel steel. At this time, it is necessary to decide whether to remove the central slip ring based on the actual situation. To facilitate the flexible sliding of the large ring gear, there is also a need for a small platform, which is generally built directly in front of the turntable. Then you have to directly remove the large ring gear bolts, and after opening the jack, you will find that the turntable is slowly rising. After removing all the bolts owned by the large ring gear, the chain hoist needs to be installed laterally so that the large gear will appear directly on the small platform.

In the fourth step, the previous large ring gear can be directly removed by a car crane, and then its plane is tested, and a laser instrument is required for testing. If the unevenness exceeds the standard, repair measures need to be used immediately to repair it. The new large ring gear needs to be filled with lubricating oil, of course, this step needs to be carried out on the ground.

The fifth step is to install the new ring gear. All the installation steps are exactly the opposite of the previous one. Of course, all the high-strength bolts that need to be installed need to be updated to ensure safety, and the installation steps must strictly abide by the specifications. After everything is installed, acceptance needs to be carried out, and the struts need to be removed after the results are determined to be qualified.

The sixth step is to put the entire machine into production and reload, so that after 4 hours, you need to check all the high-strength bolts again, and make sure that there are no signs of loosening before you can officially hand over the machine.

Konklusjon

In summary, in crane equipment, slewing bearing bearings have a particularly important role and can be said to be a key component. If it fails, it will definitely affect the operation of the crane. Only by analyzing and understanding the causes of the failure and finding solutions to these causes can the gantry crane be guaranteed to be safe enough in future work.

Cindy

Hva skjer: +86-19137386654

E-post: cindywang@hndfcrane.com

Jeg er Cindy, med 10 års arbeidserfaring i kranindustrien og samlet et vell av faglig kunnskap. Jeg har valgt de tilfredsstillende kranene for 500+ kunder. Hvis du har behov eller spørsmål om kraner, ta gjerne kontakt med meg, jeg vil bruke min ekspertise og praktiske erfaring til å hjelpe deg med å løse problemet!