It is necessary to check from three aspects: pump, hydraulic lock and pilot system.
1. First determine whether there is really no action. Shut the engine off, restart it, and try again, still nothing.
2. After starting the car, check the pump pressure on the monitoring panel and find that the left and right pump pressures are both above 4000kpa, which temporarily eliminates the pump problem.
3. A spring piece at the hydraulic opening and stopping lever of the excavator is broken. I wonder if the switch at the opening and stopping lever cannot be turned in place. I short-circuit the switch directly and make an action, but there is still no response. Check the circuit and use a multimeter to directly measure the hydraulic lock solenoid valve. The voltage of the two wires is more than 25V, and the resistance of the solenoid valve is normal when measured. After directly removing the solenoid valve and energizing it, it was found that the solenoid valve core moved in place, thus eliminating the problem of the hydraulic lock solenoid valve.
4. Check the pilot system and measure the pilot pressure to be about 40,000kpa, which is normal and eliminate the problem of the pilot pump.
5. Test drive again, still no action. Suspecting a pilot line problem, I directly disassembled the pilot line of the bucket control valve on the main control valve and moved the bucket arm. No hydraulic oil flowed out. It was determined that the pilot line problem caused the excavator to have no movement after repairing the pump. , there is no problem when walking.
6. The following work is to check the pilot oil line section by section starting from the pilot pump and find that a pilot oil pipe behind the pilot multi-way valve is blocked. After clearing it, the fault is eliminated.
When the hydraulic excavator fails to operate, it is often necessary to follow the following sequence to diagnose and troubleshoot the fault.
1 Check the hydraulic oil level
Blockage of the oil suction filter element in the hydraulic oil circuit, empty suction of the oil circuit (including low oil level in the hydraulic oil tank), etc. will cause the hydraulic pump to insufficiently absorb oil or even fail to absorb oil, which will directly lead to insufficient oil pressure in the hydraulic oil circuit. , causing the excavator to have no movement. The diagnosis of this kind of fault can be eliminated by checking the hydraulic oil tank page and the degree of contamination of the hydraulic oil.
2 Check whether the hydraulic pump is faulty
Hydraulic excavators generally use two or more main pumps to provide pressure oil to the system. You can first determine whether the power of the engine output shaft can be transmitted to each hydraulic pump. If it cannot be transmitted, then the problem occurs in the power output of the engine. If it can be transmitted, the fault may occur on the hydraulic pump. In this case, you can install an oil pressure gauge with a suitable range at the output port of each hydraulic pump to measure the output pressure of the pump, and compare it with the theoretical output pressure value of each pump to determine whether the hydraulic pump is faulty.
3 Check whether the safety locking valve is faulty
The safety locking valve is a mechanical switch located in the cab. It can control the opening and closing of the low-pressure oil circuit and the three sets of proportional pressure control valves in the cab, namely the left and right control handles and the travel push-pull rod. When the safety locking valve is stuck or blocked, the oil cannot push the main control valve through the proportional pressure control valve, resulting in the failure of the entire machine to operate. Replacement method can be used to troubleshoot this fault.
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Post time: Jul-16-2024