Generally, it is normal for the outer oil seal to have a small amount of oil leakage under working conditions. The so-called normal means that the amount of grease leaked through the outer seal of the rotary bearing is roughly equal to the amount of grease filled into the rotary bearing. However, when a large amount of grease leakage occurs on Caterpillar excavator, it must be checked. Due to the particularity of the lubrication structure of the rotating part, it is necessary to analyze whether there is leakage and determine the problem, so as to finally solve the problem. The specific inspection steps and methods are as follows:
(1) Is the maintenance correct
The grease filling cycle of the slewing bearing cavity shall be between 150 ~ 250h (the maintenance cycle recommended by the manufacturer is 250h, but it can be appropriately shortened according to the working intensity and frequency of the slewing part in actual work). If the filling is too frequent, a large amount of grease will leak out.
(2) Is the hydraulic oil or gear oil of the swing motor channeled into the cavity of the swing ring gear
In case of leakage in this case, after opening the inspection cover of the lubricating grease of the rotary gear ring, it will be found that the lubricating grease has become thin. This thinning is characteristic of mixing hydraulic oil or gear oil.
(3) Is the grease used for the original filling of the equipment correct
Since the grease filled in the original equipment may be incorrect, the grease will become thinner as soon as the temperature of the rotary bearing or rotary gear ring increases slightly. If the diluted grease is pushed to the upper end face of the inner gear ring by the driving gear of the rotary motor during meshing, it will flow into the bearing cavity through the inner oil seal, and finally the grease drips out from the outer oil seal.
(4) Is the outer oil seal missing
Carefully check along the rotary oil seal to determine whether it is local and section leakage or uniform peripheral leakage. Check whether the whole rotary oil seal is missing.
(5) Is the outer oil seal fixed
The outer oil seal shall be fixed relative to the sealing groove of the lower frame. The key to inspection is to observe when the excavator rotates. If the oil seal rotates at the same time when the equipment rotates, it indicates that the existing oil seal has become loose in the sealing groove, and the outer oil seal must be replaced. This method is dangerous, so pay attention to safety, but it is one of the important methods to check whether the rotary oil seal really plays a sealing role.
(6) Check whether the inner oil seal is obviously damaged
Open the lubricating grease inspection cover of the rotary gear ring, and check whether there is a large reduction of grease in the oil chamber of the gear ring and whether there are fragments with broken oil seal. If the grease is greatly reduced, it indicates that the grease has been leaked.
(7) It is determined that the leakage is the grease in the bearing cavity
Or the grease in the rotary gear ring cavity. Add the grease of different colors into the bearing cavity. After a period of use (such as about 150h), after the oil in the bearing cavity has been basically replaced with the injected grease, determine whether it is the grease of the rotary gear ring or the grease in the bearing cavity according to the surrounding leaked grease color. This is one of the methods to preliminarily judge whether the internal seal fails from the outside.
(8) Observe whether the rotation of the equipment is abnormal
If the equipment makes abnormal noise or is unstable during the rotation, the bearing clearance may be too large and uneven, resulting in the extrusion of oil from the outer oil seal during the rotation of the bearing.
(9) Check the inner oil seal
After the above inspections have been completed and the existing problems have been eliminated, the problems can be concentrated on the oil seal in the bearing. Take out the peripheral bolts of the rotating part, remove the oil pipe of the traveling part, and lift the upper frame part with a crane. Since this method requires a crane and the work volume of the whole process is relatively large, this is the last step to check and solve the problems. Therefore, it is recommended to use the above method All steps have been completed and other possibilities are excluded before using this method.
