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Analysis of typical failure cases of excavators

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First, the main pump cylinder plunger wear

1 Machine information

model operating hours Working condition
LG665 5552 Loose soil


2 Failure phenomenon

The excavator works slowly and weakly, and is accompanied by abnormal noise from the main pump.


3 Troubleshooting and results

3.1 Detecting the overflow pressure of the boom, stick and bucket is 20.8Mpa, the overflow pressure is too small, and the standard pressure range is 23-24Mpa.

3.2 Adjust the pressure of the LS relief valve. The pressure change is small and cannot be adjusted to the standard value.



3.3 Disassembling the oil return filter element, found a large amount of iron filings and copper dust.

3.4 The main pump was disassembled and inspected, and the distribution plate, swash plate, cylinder block and piston were found to be seriously worn.



3.5 Processing results: After the machine was out of warranty, the hydraulic system had not been maintained, causing the main pump to wear early. After that, the cylinder body, the flow plate and the plunger were replaced, the hydraulic oil and the hydraulic oil filter were replaced, and the fault was removed.


Second, the valve rocker arm breaks because the oil is not changed for a long time

1 Machine information

model operating hours Working condition
LG6300 4171 Solid soil


2 Failure phenomenon

The whole machine suddenly shuts down when it is working. There is a strange sound when the engine is restarted and it cannot start.


3 Processing steps and results

3.1 Disassembling the engine, it was found that the fourth, fifth, and sixth cylinder valve rocker arms were broken and the valve push rods were bent.



3.2 It has been verified that the machine has not changed its oil for more than 1000 hours after it is out of warranty. The deterioration of the oil caused the oil passages in the tappets, push rods, and rocker arms to become blocked, which resulted in inability to lubricate and cool, and caused valve shake in long-term work The arm is broken and the valve push rod is bent. Then replace the rocker arm and push rod, clean the oil pan and change the oil, and troubleshoot.


3. Improper maintenance of air filter causes early wear of engine cylinder liner

1 Machine information

model operating hours Working condition
LG6300

4526

mine

2 Failure phenomenon

The engine oil consumption is large. The machine works for 60 hours, consumes 1600L of diesel oil, consumes 18L of oil, the oil consumption is 11.25 ‰, and the exhaust is serious.


3 Processing steps and results

3.1 Disassembly and inspection of the air intake system, the air filter is seriously blocked, as follows:



3.2 Disassembling and inspecting the engine, the air intake is seriously polluted, the pistons and cylinder liners are severely worn, and the 3 and 5 cylinder piston rings are broken, which is due to engine premature wear due to insufficient engine maintenance. Replace the four matching engines and related seals, clean the intake duct, replace the air filter, and troubleshoot.



3.3 Summary: For mining conditions, the working environment of the excavator is harsh and the dust is too large. The air filter element must be maintained every day and replaced if necessary. Because the air inlet after the air filter is directly connected to the engine combustion chamber, if the air filter is not maintained properly, dust will enter the combustion chamber along the air inlet and become an abrasive between the piston ring and the cylinder liner. Abnormal wear.


Fourth, the tool box placed iron debris caused a fire at the battery

1 Machine information

model operating hours Working condition

LG6150

176 Earthwork

2 Failure phenomenon

No electricity


3 Processing steps and results

3.1 Check the toolbox and find that there are wires, wires, and tools in the toolbox placed in disorder.



3.2 Remove the battery cover and check. It was found that the battery positive electrode inside the tool box and the left fixing bolt of the battery fixing plate had ablation marks.



3.3 Remove the battery and measure the voltage. The battery voltage near the tool box is too low at 11V.



3.4 Inspecting the battery, it was found that the battery (near the fixing bolt of the battery fixing plate and the upper frame connection) has ablation marks and the electrolyte is flowing out.



3.5 Check that there are burn marks on the connection between the fixing bolt and the upper frame, and there are traces of grounding on the top of the bolt.



3.6 Comprehensive analysis, the sundries (conductors) placed in the toolbox connected the positive electrode of the battery and the above-mentioned fixing bolts and short-circuited, and the battery was ablated instantly and the electrolyte leaked. Remove the debris from the toolbox and replace the battery.

3.7 Conclusion: Do not place any sundries in the toolbox at random to avoid causing fire.


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