Suddenly all the movements of a Carter excavator are slow. Check the monitoring items on the instrument screen of the excavator on the spot, as shown in the following figure:
Check the maintenance manual, the historical fault code shows "69: 581-06", indicating that the pump controller power shift pressure proportional pressure relief valve current is higher than normal, it is suspected that the proportional pressure relief valve is shorted to ground, the actual measurement of the proportional pressure relief valve There is no voltage on the terminal, and the obvious line is faulty. After searching, the line of the proportional pressure relief valve is found. The clip of the harness is fixed at the bottom next to the hydraulic pump. Due to long-term action friction and high temperature, the inner line of the braid layer is seriously aging and melting causing short circuit , Re-handle the dressing fault resolution.
Summary: The Carter proportional pressure reducing solenoid valve is to convert the electrical signal of the controller into the hydraulic signal of the hydraulic oil pump. The hydraulic signal (power shift pressure) is used to adjust the output of the hydraulic oil pump. The controller changes the current (PWM signal) to the solenoid, and the solenoid adjusts the power shift pressure. The controller changes the current to the solenoid according to the selected power mode and engine speed. The position of the proportional pressure reducing solenoid valve is as shown in the figure below
The Carter excavator computer controller will adjust the current for driving the proportional solenoid valve solenoid according to the position of the engine speed knob, the actual speed of the engine, the delivery pressure of the pump and the pressure of the power shift circuit. , Slow down the operation speed and increase the work intensity under heavy load. This is the principle of proportional control of the excavator. It is recommended that the excavator be handled by professional maintenance personnel to maximize the ability of the excavator.
