The main reason for the heavy load extinction of the excavator is that the engine is automatically shut down due to excessive load due to the excessive displacement of the working pump. It can be seen from the hydraulic system diagram that the servo piston that searches for the displacement of the working pump should be controlled first, and then the inspection should be performed according to the complexity of each control valve according to the function.
You can first check whether the connection of the LS-EPC solenoid valve and PC-EPC solenoid valve is reversed. If the line is reversed, it will cause a signal transmission error of the pump controller, and the machine will lose the displacement due to the pump during heavy load Control causes the engine to stall. If there is no error, then check the working condition of the PC-EPC solenoid valve. The main technical indicator is that the resistance of the PC-EPC solenoid valve coil should be 7~14 ohms. If the PC-EPC solenoid valve is damaged, the machine should The valve cannot receive the pump displacement command issued by the pump controller, which prevents the PC-EPC solenoid valve from adjusting the pump displacement, causing the engine to stall due to excessive load.
If the solenoid valve is not faulty, then check the pressure control valve (PC valve). The role of the PC valve is that when the change in external load reflects the change in working pressure, the PC valve senses this pressure change, and then according to the pump and engine. The principle of "best match" automatically adjusts the displacement of the working pump. If the valve core is stuck, the pressure at the end of the rodless chamber of the servo piston will not change with the change of the external load pressure, making the displacement of the working pump too large. This causes the engine to stall. If there is a fault, replace the hydraulic oil and clean the PC valve to solve the problem.
