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Analysis of Oil Leakage Failure of Fast Hydraulic Retarder

Jun 1, 2022 | Operation and Maintenance | 0 comments

Share some oil leakage faults of Fast FHB400 hydraulic retarder.

1. Oil leakage at the muffler part of the working chamber

The function of the working cavity muffler is that when the retarder is opened, the oil enters the working cavity, the gas in the working cavity is discharged from the working cavity muffler through the float valve, and the oil is sealed in the working cavity by the float valve.

Possible causes of oil leaks in this area are:
The float valve fails to seal, including damaged float, scratched float cover, float offset, etc.
If the amount of oil is too small, the amount of refueling is less than 2L, and the float valve cannot be completely closed, resulting in oil discharge;
The float valve is only related to the oil discharge in this place. If the oil is not discharged from this place, please do not disassemble, clean and replace the float.

2. Oil leakage at the muffler of the oil pool shell

The function of the muffler of the oil pool shell is to discharge the pressure gas in the oil pool shell to the atmosphere through the proportional valve through the muffler of the oil pool shell when the retarder is closed, and the muffler can reduce the working noise.
Possible reasons for the leak here are:

If the amount of refueling is too much, the FHB400 refuels 6.5L, and if the refueling amount exceeds 6.5L, the excess oil will be discharged from the oil drain hole. At this time, the oil drain operation should be carried out. When the FHB400 is draining oil, all the oil can be drained through the oil drain hole at the bottom (the heat exchanger oil drain plug is not required when the FHB400 is draining oil)

Heat exchanger oil-water mixing. After the internal communication of the heat exchanger, the oil and water are mixed together into the working chamber of the retarder. Due to the low boiling point of the water, the temperature of the working chamber is very high, causing the oil-water mixture to boil and be discharged from the muffler. During maintenance, you can judge whether oil and water are mixed by observing whether there is oil in the antifreeze, and at the same time releasing part of the retarder oil to observe whether it is emulsified.

The air source contains a lot of water, and the water in the intake air will also cause the oil and water to mix and drain the oil. In particular, it is necessary to observe whether the customer’s vehicle is equipped with a water spray tank. The intake air of the water tank and the intake air of the retarder cannot be taken from the same air path.

Excessive working pressure will also cause oil leakage in this part. When the vehicle is stationary, enter the retarder service mode, and use a barometer or “Falun Gong” to test the working pressure of 5th gear. When the pressure is greater than 3.3bar, it will cause oil to drain. When it is necessary to replace or let professionals adjust the controller or proportional valve.


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