High power motors frequently experience oil leakage during use, which is significantly manifested as oil leakage in the sliding bearing structure. During maintenance and repair, the possible causes of motor oil leakage were analyzed, and the following solutions were proposed.

1. There is a large pressure difference between the inside and outside of the sliding bearing. The forced lubrication of the bearing shell, the lubricating oil itself has a certain pressure, and when the shaft is running, the oil will produce bubbles to generate a certain pressure. During operation, the motor generates a certain negative pressure due to the action of the fan, which increases the pressure difference between the inside and outside of the oil chamber and leads to oil leakage. In order to balance the pressure difference inside and outside the oil chamber, a ventilation pipe is installed between the oil chamber and the outside to balance the pressure difference. However, during use, blockage may occur, causing an increase in pressure inside the oil chamber and resulting in oil leakage.

Solution: Regularly check if the balance pipe is loose and clean the fuel tank vent pipe in a timely manner.

2. Insufficient oil pressure adjustment leads to poor oil return. Excessive or insufficient oil pressure can cause poor oil return. The oil pressure is too low, causing the oil to stay in the oil chamber for too long, resulting in an increase in temperature during the operation of the shaft, leading to oil mist and excessive pressure; Excessive oil pressure can lead to insufficient oil return capacity, resulting in excessive oil storage in the oil chamber and high oil level, thereby increasing internal pressure.

Solution: Adjust the forced lubrication pressure to 0.1-0.8 MPa, so that the oil level in the oil chamber is at 1/2 to 1/3 of the sight glass position, and maintain smooth oil return.

3. Unreasonable design of the oil return pipeline can also lead to poor oil return, resulting in an increase in pressure inside the oil chamber. Impurities in the return oil pipeline or inadequate cleaning of the pipeline can cause filter blockage, resulting in poor oil return.

Solution: The outlet of the oil chamber in the return oil pipeline should be on the same horizontal plane as the inlet, and the entire return oil pipeline should be inclined at a 15 ° angle downwards to the return oil tank, so that the return oil pipe can naturally return oil. At the same time, the filter and the entire lubricating oil pipeline should be cleaned regularly.

4. The contact surface between the floating palace and the shaft is severely worn due to long-term friction, resulting in excessive clearance between the floating palace and the shaft; The change in the elastic coefficient of the fixed spring of the floating palace seal (Figure 1) causes the floating palace seal to loosen, resulting in an increase in the gap.

Figure 1 Floating Palace Seal

Solution: Regular inspection and timely replacement.

5. The wear of the contact surface between the sealing oil stopper and the shaft results in excessive clearance; The return oil hole in the sealed oil stopper is too small or blocked by impurities, which cannot meet the actual return oil volume.

Solution: Replace the sealing oil stopper and modify it. Change the material of the contact surface between the sealing oil stopper and the shaft to wear-resistant material; Increase the oil return hole (Figure 2) to meet the actual oil return needs (not too large).

Figure 2 Sealing oil stopper return oil hole

During the installation of sliding bearings, the sealing treatment between the sealing oil baffle and the oil chamber of the upper and lower bearing covers of the bearing housing is improper; Long term operation leads to loosening of fastening bolts, aging and deterioration of sealant, resulting in poor sealing.

Solution: During the reassembly process, use reliable sealant on the contact surface, and apply it evenly and appropriately. When reassembling, be sure to clean the original sealant before applying new sealant.

7. The change of oil quality causes more and more foam in the oil. In the whole lubrication system, foam occupies more operating space, which leads to the increase of oil pressure in the oil chamber, and the large pressure difference leads to the oil escaping from the shaft gap in contact with the floating palace seal and seal oil baffle.

Solution: Regularly inspect and analyze the lubricating oil, and replace it promptly if there are any problems with the oil quality.

The analysis of the causes and solutions for oil leakage in the sliding bearings of the above-mentioned motor have achieved certain results in practical application, ensuring the safe and stable operation of the unit.

2026 August 1st Week Marginal Product Recommendation

MG-EPB5Z Plastic Plain Bearings：

MG-EPB5Z Plastic Plain Bearings It is a high load material with excellent low friction factor. Marginal load application is acceptable and it is with good wear resistance both for hard and soft shafts. Continuous working temperature: -100℃～250℃; High load capacity; Higher speed is permissible; Marginal pressure is permissible; Best performance for oscillating movement.

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