Common Malfunctions And How To Repair

Common malfunctions

Operation errors, nitrogen leakage, improper maintenance and other phenomena will cause the breaker's working valve to wear, pipeline burst, local overheating of hydraulic oil and other failures. The reason is that the technical configuration is unreasonable, and the on-site management is improper.
The working pressure of the breaker is generally 20MPa and the flow rate is about 170L/min, while the system pressure of the excavator is generally 30MPa and the flow rate of the single main pump is 250L/min. Therefore, the overflow valve needs to undertake the heavy diversion and unloading work. Once the relief valve is damaged but not easily detected, the breaker will work under ultra-high pressure. First, the pipeline bursts, the hydraulic oil is partially overheated, and then the main reversing valve is seriously worn and other parts of the excavator's main working valve group. The hydraulic circuit controlled by the spool (the next spool pointed to by the main oil circuit in the neutral position) is polluted; and because the return oil of the breaker generally does not pass through the cooler, but directly returns to the oil tank through the oil filter, so the circulating oil circuit may The oil temperature of the working oil circuit is too high or even too high, which seriously affects the service life of hydraulic components (especially seals).
The most effective way to prevent the above failures is to improve the hydraulic circuit. One is to add an overload valve at the main reversing valve (the same type of overload valve as the boom or bucket working valve can be used), and its set pressure should be 2~3MPa larger than that of the relief valve, which can effectively Reduce the impact of the system, and at the same time ensure that the system pressure will not be too high when the relief valve is damaged; the second is to connect the oil return line of the working oil circuit to the cooler to ensure that the working oil is cooled in time; the third is when the flow of the main pump exceeds the maximum value of the breaker When the flow rate is 2 times, install a diverter valve before the main reversing valve to reduce the load of the relief valve and prevent overheating caused by a large amount of oil supply passing through the relief valve. Practice has proved that the improved EX300 excavator (old machine) equipped with KRB140 hydraulic breaker has achieved good working results.
Fault cause and correction

Not working

1. The nitrogen pressure in the back head is too high. ------ Adjust to standard pressure.
2. The oil temperature is too low. Especially in the northern winter. ------- Increase heating setting.
3. The stop valve is not opened. ------Open the stop valve.
4. Insufficient hydraulic oil. --------Add hydraulic oil.
5. The pipeline pressure is too low ------- adjust the pressure
6. pipeline connection error ------- correct connection
7. There is a problem with the control pipeline ------ check the control pipeline.
8. The reversing valve is stuck ------- grinding
9. Piston stuck------grinding
10. The chisel and rod pin are stuck
11. The nitrogen pressure is too high------adjust to the standard value

The impact is too low

1. The working pressure is too low. Insufficient flow ------ adjust the pressure
2. The nitrogen pressure of the back head is too low-------adjust the nitrogen pressure
3. Insufficient high pressure nitrogen pressure ------ add to the standard pressure
4. The reversing valve or piston is rough or the gap is too large ------ grinding or replacement
5. Poor oil return ------ check the pipeline

Insufficient number of hits

1. The nitrogen pressure in the back head is too high------adjust to the standard value
2. Reversing valve or piston brushing------grinding
3. Poor oil return ------ check the pipeline
4. The system pressure is too low ------ adjust to normal pressure
5. The frequency regulator is not adjusted properly-----adjust
6. The performance of the hydraulic pump is low ------- adjust oil pump

Abnormal attack

1. It can't be hit when it is crushed to death, but it can be hit when it is lifted up a little---the inner bush is worn. replace
2. Sometime fast and sometime slow-----clean the inside of the hydraulic hammer. sometimes grind the valve or piston
3. This situation will also occur when the performance of the hydraulic pump is low ----- adjust oil pump
4. The chisel is not standard-----replace the standard chisel

Pipeline Over Vibration

1. The high pressure nitrogen pressure is too low ------ add to the standard
2. The diaphragm is damaged------replace
3. The pipeline is not clamped well------re-fixed
4. Oil leakage------replace the relevant oil seal
5. Air leakage------replace the air seal

Post time: Jul-19-2022