How To Solve The Problem of Excavator Powerlessness And Stalling?

Excavator powerlessness is a very common excavator fault. The main reason is the mismatch between the engine, hydraulic pump, distribution valve, and external load. However, there are many specific manifestations of the fault, and it is difficult to troubleshoot and repair.

Excavator powerlessness is closely related to the engine condition, and can generally be divided into two situations:

1. Excavator powerlessness and engine does not stall

The size of the excavation force depends on the output pressure of the main pump, and the engine stalling depends on the relationship between the oil pump absorption torque and the engine output torque. If the engine does not stall, it means that the oil pump absorption torque is small and the engine load is light. The maximum output pressure of the main pump (system overflow pressure) should be checked. If the overflow pressure value is lower than the specified value, it means that the overload overflow valve setting value of the hydraulic circuit of the mechanism is incorrect. At this time, it is necessary to turn the adjustment screw to adjust the machine.

2. The excavator is powerless and the engine is seriously stalled

The engine stalling indicates that the absorption torque of the oil pump is greater than the engine output torque and the engine is overloaded. This fault is mostly caused by an abnormal engine speed sensing system. As long as the engine speed sensing system returns to normal, the stalling fault is eliminated.

According to the specific symptoms, the powerlessness of the excavator can be divided into the following 5 types:

1. The excavator is powerless

(1) If the excavator is powerless when it is cold, you can check the main overflow valve, unloading valve, hydraulic pump, PC-EPC valve, engine speed sensor, distributor oil seal, control valve, pilot valve, regulating valve and other faults. 

(2) If the excavator is powerless when it is hot, in addition to checking the above faults, you should also check the hydraulic oil. If the oil is too dirty, the hydraulic system of the excavator will be contaminated, resulting in internal leakage of the hydraulic system. In addition, the powerlessness after the hot car may be caused by wear of the main pump. As the temperature of the hydraulic oil of the excavator increases, the leakage of the oil will increase, resulting in insufficient pressure of the excavator.

2. The excavator is powerless when walking

(1) The excavator engine has been overloaded for a long time, resulting in insufficient power and powerlessness; 

(2) The PC valve of the excavator is worn and damaged; 

(3) The overflow pressure of the excavator travel motor is incorrect or the overflow valve of the excavator travel motor is worn; 

(4) The adjustment defect of the main overflow valve of the excavator; 

(5) The travel pressure values of the travel motors on the left and right sides of the excavator are inconsistent.

3. The excavator is unable to rotate (swing)

(1) The excavator circuit is faulty. It is necessary to check the excavator wire display and the voltage and resistance values of each joint in detail. 

(2) Hydraulic failure, wear of the internal components of the excavator rotation pump, wear of the excavator oil distribution plate (distribution plate), damage of the excavator pump control valve, high or low pressure values for the left and right rotation of the excavator, internal pressure relief of the rotation pump, seal failure of the excavator rotation motor, improper adjustment of the overflow width, and overload of the rotation motor.

4. The excavator boom is unable to lift

(1) The oil supply line of the large (small) arm is blocked, and the oil supply is not smooth; the filter screen of the oil pump suction port is blocked, and the oil pump cannot absorb oil. 

(2) The large (small) arm cylinder leaks/leakages. 

(3) The large (small) arm holding valve is stuck or the holding valve is damaged. 

(4) The hydraulic oil tank is insufficient. (5) The overflow valve is blocked or damaged.

5. The excavator bucket (arm) is unable to extend or retract

(1) The multi-way valve (main control valve) system is stuck or leaking oil. 

(2) The valve core of the arm oil circuit on the multi-way valve is worn. 

(3) The bucket (arm) cylinder assembly is worn or damaged. 

(4) The valve core of the bucket (arm) sliding valve is stuck or worn. 

(5) The return spring force of the check valve of the bucket (arm) regeneration circuit valve is too weak.