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Reasons and treatment methods for oil leakage of reducer bearing end cover

Reasons and treatment methods for oil leakage of reducer bearing end cover

2022-05-31

Oil leakage at the bearing end cover of the reducer is also a common phenomenon. Causes of oil leakage: Most of the reducers used on the crane are ZG series reducers, and most of their end covers are embedded bearing covers. The bearing cover is divided into shaft extension end cover and non-shaft extension end cover. For the oil leakage of the non-shaft extension cover, the main reason is that the matching gap between the end cover and the box body is large. The main reasons for the oil leakage of the shaft extension end cover are the large matching gap between the end cover and the box body, the lack of seals or damage to the inner holes of the input or output shaft and the end cover, the blockage of the vent plug, and the oil level is too high.


The specific processing method is as follows:


1. Reprocess the end cover of the non-shaft extension bearing so that the gap between the end cover and each joint surface of the box body is less than 0.1mm. When installing, it is advisable to lightly tap the stop groove embedded in the box with a hand hammer. Before installation, apply a uniform sealant to each joint surface, which can effectively prevent leakage after pressing.


2. For the shaft extension bearing cover, in addition to ensuring the clearance between the end cover and the joint surface of the box body according to the first article, sealing elements and oil drainage plates should be added to the end cover.


3. The peripheral speed of the large gear in the crane reducer is generally not large. Usually, the gear teeth of the large gear are immersed in the oil pool for lubrication, so that when the gear rotates, the lubricating oil is brought to the meshing tooth surface, and the oil is also thrown away. to the box wall. In this way, part of the oil flows back to the oil pool, and part of the oil leaks out of the box through the bearing along the shaft. In order to prevent the leakage of oil, the inner side of the bearing is close to the wall of the box, and a guide plate is added to the shaft. Drain the oil thrown on the drainage plate into the oil pool in time.


4. The inner hole of the drainage plate is interfered with the shaft to make it rotate together with the shaft. The inner side of the drainage plate is inclined to facilitate drainage. The deflector is as large as possible within its range of rotation to allow the least amount of oil to break into the bearing. To further prevent leakage, a felt seal is added to the end cap. And a drainage hole communicated with the felt groove is opened on the end cover. Even if the oil leaks into the felt ring, it can be drained into the box through the drainage hole under the action of centrifugal force, thus effectively cutting off the leakage channel.


5. When using the felt ring, it should be noted that the number of felt ring joints must exceed one. The joint sections should be closely connected to each other, and the surface of the felt ring should be clean. The dimensions of the felt ring and felt groove is selected from the standard according to the diameter of the shaft. In particular, attention should be paid to ensuring the fit tolerance of the shaft and the inner hole of the felt ring.


6. The reducer is equipped with a ventilator in the structure. However, when the reducer is painted on-site, the vent hole is not carefully blocked, which aggravates the leakage. When the gearbox is working, the temperature inside the box rises, the gas expands and the pressure increases, causing a pressure difference inside and outside, resulting in accelerated leakage of lubricating oil along the sub-box surface and the input and output shafts. Therefore, to ensure that the ventilation holes are unblocked, the internal and external pressures of the reduction box can be balanced, which can effectively prevent leakage.


7. The crane reducer is usually lubricated by immersing the large gear in the oil pool. The depth of the gear immersed in the oil should not exceed one tooth height, otherwise, it will accelerate the leakage due to the violent agitation of the oil and the rise of the oil temperature, and also reduce the mechanical efficiency due to the increase of oil resistance. , but never more.


8. In field use, it is found that the oil leakage along the input shaft of the reducer is more serious. In addition to the influencing factors mentioned above, the misalignment of the input shaft of the reducer and the motor shaft is also an important factor affecting the leakage. Due to the misalignment, the input shaft of the reducer will jump, which will increase the circular jump. In this way, a convergent wedge-shaped space is formed between the shaft surface and the inner hole surface of the end cover, and there is relative movement between the shaft and the end cover, which forms the condition of hydrodynamic lubrication. thereby exacerbating the leak. Therefore, when installing the reducer and the motor, be sure to align and level them to ensure that they are concentric.

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