Excavator Swing Motor Leak



Swing drives are essential for excavators working for logging, mining, construction projects, and more complicated conditions. If they malfunction, your whole operation will stop within seconds. That is why people choose a high-quality swing motor. However, even high-quality swing motors can break down after a time if one didn’t take care of it. Many industrialists face this problem quite often. One of the reasons behind the breakdown is the excavator swing motor leak. Sometimes, a swing motor leak directly causes malfunction. On the other hand, leak causes other problems which result in malfunction. In simple words, motor breakdown occurs indirectly or directly because of the leakage.

Output pinion is the most commonplace for the leak. For large excavators, this is the place where the shaft fades up into the gearbox. One of the most frequently asked questions is the reasons behind the excavator swing motors leak, let’s talk about that.


Common Reasons Behind Excavator Swing Motors Leak


Please do note that the below reasons are common reasons behind excavator swing motors leak. This doesn’t mean that your case will be one of these. There is a possibility that your case might be something that isn’t common. Although, you can consider these points for troubleshooting, as mentioned above, don’t rely 100% on them. Below are the common reasons why this happens:


Enormous Amount of Case Drain from The Motor


In the swing motor, the rotating group is the most frequently used. It is the most hardworking component in the excavator. Over time, it can wear out. However, quality can increase the time but still, it will wear out. When the swing motor is in action, it creates a lot of heat which can create a problem of overheating. This overheating problem can increase the rate of wear.

If the motor is operating at a sluggish rate that indicates the rotating group is wearing out. In addition, if you pulled the cab control lever yet your machine takes a long time to stop, that also indicates a rotating group wearing out. In any of these cases, the excavator’s motor is producing a lot of case drain.

You need to transfer the case drain to the hydraulic tank with the help of the return line filter. In many cases, the return line can’t handle the volume, the pressure will back up into the case. This will result in a breach of the seal between the gearbox and motor and hence the motor leaking starts to begin.



If this happens, you need to replace the oil seals as well as the rotating group. At first, you need to replace the oil seals to avoid leaking. If this doesn’t work then replace the rotating group as well.


Output Bearing Failure

There are many ways a bearing can fail for example through abuse, fatigue, etc. The most common reason for the failure is the lack of lubrication. To avoid it, we have collected three different ways through which you can lubricate the output bearing.

1, When the gears are been assembled in the factory, the bearings are filled with greases. They remain like this throughout the lifespan of the motor.

2, Lubrication of the bearings can be done with the help of the grease nipple.

3, Even with the sealing, some bearings will be off from the gearbox. You can use gear oil as a lubricant to avoid bearing failure.

Bearing failure can cause misalignment of the shaft. This will allow the motor oil to leak from the output seal. In addition, if the leaking is too much then it can cause the swing motor breakdown as well. To avoid this, you must replace the oil seal as well as output bearing at the first sight.


Seal Failure

Last but not least, if none of the above are the reasons behind oil leaking then it might be the seal failure. Although the seal doesn’t fail that easily but, time by time, the output shaft seal gets weak. If the usage of excavators is too much, this can lead to overheating. Overheating accelerates this process. These things will make the seal brittle and a time will come that it will allow oil to leak past.


What Shall I Do to Avoid These Problems?

The motor leak might be one of the most common problems faced by many excavator owners, however, there are some things that excavator owners can do to avoid this problem. Below are some points that you can do to increase the service life of your excavator’s swing motor.

When there is a leak, that is for sure that the hydraulic oil level starts to decrease.

1. Keep a record on that level. In case, if there is a big change in oil levels that indicates the swing motor leak.

2. In a few cases, the condition of hydraulic oil can also cause this problem. Make sure you check the condition of hydraulic oil once a week.

3. Lubrication of the output bearing (at least once a week if your excavator using is high).

4. Clean the oil cooler.

What if the Swing Motor Started to Leak?


If the swing motor starts to leak that means either you can replace it or get it repaired. Repairing depends on the condition of the leaking. In some cases, it can work but the best solution is to get it replaced. You might not need to change the whole swing motor, maybe, all you need is to replace a few parts. So, the question is from where to buy for a reasonable cost? Fortunately, you are standing in the right place.

KS XUGONG provides high-quality excavator equipment with the same quality of OE parts. We supply almost everything, from swing drive assembly to swing drive parts. The unique part of us is pricing. We charge a reasonable amount for our equipment that you won’t find them elsewhere. Last but not least, we value your time and that is why we provide fast delivery and amazing communication.

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