Reasons and Solutions for Leakage of the Slewing Bearing

No matter what kind of equipment it is, oil leakage in bearings lubrication is a headache. After lubricating oil or grease leaks, it will leave grease on the bearing surface. When the bearing surface is contaminated by dust or dirt, it will corrode the surface of the bearing, causing a decrease in the bearing's service life. Take the slewing bearing as an example. Today, we will introduce the reasons for the oil leakage in slewing bearings and the methods of dealing with it. Let's take a look together.

Reasons for the oil leakage in the slewing bearing

Oil filling too frequently

The oil filling cycle of slewing bearings should be between 150-250 hours. The manufacturer's maintenance cycle is 250 hours, but in practical work, it can be appropriately shortened according to the working intensity and frequency of the slewing part. If filling is too frequent, it will cause a large amount of grease leakage.

Lubricating oil or grease becomes thinner

Whether the hydraulic oil or gear oil of the slewing motor has invaded the cavity of the slewing ring. If there is a leak, after opening the inspection cover of the lubricating grease of the slewing ring, it will be found that the lubricating grease has become thinner. This thinning is a characteristic of the mixture of hydraulic oil or gear oil.

Incorrect selection of grease

Due to the possibility that the grease added by the original equipment may be incorrect, it is possible to encounter a situation where the temperature of the slewing support or the slewing ring rises, causing the grease to become thinner. If the thinner grease is pushed onto the upper section of the slewing ring through the active gear of the slewing motor during meshing, it will flow into the bearing cavity through the inner oil seal and then drip out from the outer oil seal.

Damage to the outer oil seal

Carefully check along the slewing oil seal to determine whether it is a local or a segment leakage, or a uniform peripheral leakage, and check whether there is any missing phenomenon in the entire slewing oil seal.

Loose outer oil seal

The outer oil seal should be relatively fixed with the sealing groove of the lower frame. It should be observed when the excavator is rotating. If the oil seal rotates at the same time as the equipment rotation, it indicates that the existing oil seal has been loosened in the sealing groove and the outer oil seal must be replaced. Adopting this method has a certain degree of danger, so safety should be taken into consideration. However, this is one of the important methods to check whether the slewing oil seal plays a sealing role.

Damage to the inner oil seal

After opening the inspection cover of the lubricating grease of the slewing ring, check whether there is a large amount of grease reduction or broken pieces of oil seal in the oil cavity of the ring. If a significant reduction in the amount of grease is found, it indicates that the grease has leaked.

Excessive bearing clearance

If there is abnormal noise or instability during equipment rotation, it may be caused by excessive and uneven clearance of the slewing bearing, causing the oil to be squeezed out from the external oil seal during the rotation process.

Solutions to the oil leakage in the slewing bearing

• If it is caused by sealing problems, the old seal needs to be removed, and the sealing groove needs to be cleaned with diesel or gasoline. Then, the new seal can be completely inserted into the sealing groove. It should be noted that after the sealing strip becomes a ring, there is a joint, and double-sided tape should be used to stick both sides of the joint together.

• If the deterioration of lubricating oil is caused by leakage of the slewing motor, it is necessary to repair the slewing motor fundamentally, and then replace the lubricating grease of the entire slewing ring.
  

• If it is caused by improper grease selection, all the grease of the slewing ring needs to be replaced. At the same time, it should also be noted that the same brand of grease should be used in the slewing bearing chamber. Lithium-molybdenum-based grease can be used. This grease basically does not reduce its viscosity at high temperatures.
  

• Control the maintenance cycle of the slewing bearing correctly. Lubricating oil or grease needs to be added once every 150-250 working hours. The oil can be added in multiple times. Each time the excavator rotates 90 degrees, add oil once. The amount of oil added should be limited to the grease overflowing from the outer oil seal.
  

• If there are no problems elsewhere, check whether the slewing bearing is damaged. If the slewing bearing is damaged, the entire slewing bearing needs to be replaced.
  

After knowing the reasons for the oil leakage in slewing bearings, preventive measures and maintenance can be taken based on the reasons for the grease leakage. Of course, slewing bearings are also a type of bearings. Different types of bearings encountering lubricating oil or grease leakage can also deal with different situations of grease leakage.