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Is the hydraulic oil black at high temperature and abnormal noise from the big pump? Who is to blame!

Is the hydraulic oil black at high temperature and abnormal noise from the big pump? Who is to blame!

2021-08-03

     For excavators, the hydraulic oil is not allowed to have any discoloration, impurities, and even the brand and quality of the oil must be guaranteed when changing the oil. Otherwise, the high temperature of the hydraulic oil, abnormal noise of the excavator, etc. will be easy to come to your door.If your excavator has black hydraulic oil, abnormal noise during machine operation, then take a look at this article!


一、Source of hazard-bubbles

  According to most situations, when the above-mentioned failures appear almost simultaneously, it can basically be locked as a bubble! Moreover, the appearance of bubbles in the hydraulic oil is not a sudden problem, and it is definitely not accidental. You can first refer to the following reasons:

1. Water enters the hydraulic oil during filling or use of the machine;

2. The owner is careless or cheap in maintenance, and mixes hydraulic oils of different manufacturers, brands and labels for a long time.

3. Due to the long use time, there are problems such as aging, air leakage or leakage in the tubing and joints, or seals.

4. The maintenance time has come, but the hydraulic oil is not replaced in time due to various reasons, resulting in insufficient oil.

5. When the excavator stops working, the oil in the oil return cavity will flow back into the oil tank through the oil return pipe. During the whole process, a partial vacuum area will be formed, and air can easily invade.

6. There is also a rather complicated reason. If the hydraulic oil pressure drops rapidly during the construction process, the cross section will suddenly become larger, so the air in the oil will be released at an accelerated rate, and cavitation will be formed.


二、The hazard of air bubbles in hydraulic oil

1. Abnormal machine action: Simply speaking, if there are air bubbles in the hydraulic oil, the first impact is the transmission efficiency. To put it more bluntly, the construction action of the whole machine will be abnormal!

2. Abnormal sound of the hydraulic system: If the operator can clearly hear the abnormal sound of the large pump in the cab that is different from the normal construction, then it is very likely that the air bubbles have increased the vibration and noise generated by the system!

3. The hydraulic oil temperature is high: Many owners have wondered why the sudden high temperature failure of the hydraulic oil at the end of the machine? In fact, what makes the mess is the air bubbles in the hydraulic oil! When these bubbles travel through the high-pressure area, they will quickly be compressed from the normal pressure state, resulting in a sudden increase in local temperature. Over time, the oil will deteriorate under high temperature conditions, that is, our common hydraulic oil will turn black!

三、How to check if there are air bubbles in the hydraulic oil?


    

 

Now that we know that the cause of the fault is air bubbles, and we also understand the harm caused by air bubbles to the machine, what we need to understand right away is how to quickly check and remove these air bubbles?

1. First check whether the oil level of the hydraulic oil tank is lower than the oil inlet of the variable double pump or the control oil pump. If the oil level of the fuel tank is low, then the air must be coming in from the oil inlet, so at this time everyone should add hydraulic oil to the standard oil level immediately, and exhaust air through the exhaust valve in time

2. If the oil level is within the standard range, but there is still air in the oil, consider that the seal is leaking. You can install an air pressure gauge on the top of the oil tank, and then inject 0.3~0.4MPa air pressure into the hydraulic oil tank, which is also variable Observe the air leakage points at the oil inlet pipe of the pump, the oil inlet pipe of the pilot gear pump and the shells of the two pumps.

3. If there is an air leak, you can observe that bubbles of different sizes are discharged from the air leak when the air pressure is injected. Find out where the air is leaking, and you can solve it symptomatically according to different situations.

If there are air bubbles in the hydraulic oil, the oil pollution will turn black, the hydraulic system will have abnormal noise, and the operation of the whole machine will be seriously affected! Therefore, you must do a good job of inspection in daily situations. Once you find a problem, immediately follow the above suggestions to solve the problem, so as not to cause worse effects.


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