1) Oil contamination

　　① Air intrusion into the oil: it causes the oil to deteriorate, the hydraulic system to vibrate, and generate noise; Hydraulic components work unstably, moving parts crawl, and there is a large impact during directional changes. Solution: Replace defective seals, check the connections of pipe joints and hydraulic components, and tighten loose bolts in a timely manner.

　　② Water mixed into the oil: The oil turns milky white, causing rusting and accelerated wear of hydraulic components. Solution: Let the oil sit for half an hour, release some oil-water mixture from the bottom of the tank, and replace with new oil if it is severe.

　　③ Impurities (chips, sand, ash, etc.) mixed in the oil: It causes the oil to deteriorate, causing moving parts in pumps, valves, and other components to get stuck, small hole gaps to block, seriously affecting the working performance of the hydraulic system, and accelerating component wear, reducing the service life of components. Solution: Clean the fuel tank before refueling, add a filter screen when refueling, clean the filter in a timely manner, and replace the oil regularly.

　　(2) Hydraulic system generates noise and abnormal operation

　　① Hydraulic pump suction: Poor sealing of the inlet pipe, poor sealing of the pump itself, air leakage, insufficient oil volume, and improper oil viscosity. Solution: Tighten the pipeline nuts, replace poor seals, add sufficient oil, and ensure appropriate oil consistency (this system uses wear-resistant hydraulic oil No. 32 or No. 46).

　　② Hydraulic pump failure: large axial clearance of the pump, insufficient oil delivery, damaged or inaccurate copper sleeves, gears and other components inside the pump, and significant wear on the pressure plate. Solution: It is necessary to promptly inspect or replace parts, and in severe cases, replace the gear pump.

　　③ Insufficient or no pressure in hydraulic pump: reverse connection of motor wires or insufficient motor power, insufficient speed, reverse connection of pump inlet and outlet, poor oil suction. Solution: Replace the motor wires, check the voltage and current, connect the pump inlet and outlet correctly, and ensure smooth oil suction.

　　④ Control valve malfunction: The regulating spring of the control valve is deformed, twisted or damaged, the valve seat is worn, the seal is poor, the valve core is rough and deformed, the movement is not flexible, it is stuck, the damping small hole is blocked, the clearance between the valve core and the valve hole is large, high and low pressure oil are interconnected, the valve opening is small, the flow rate is high, and cavitation occurs. Solution: Timely maintenance, adjustment, replacement of components, and minimizing the pressure difference between the inlet and outlet.

　　⑤ Mechanical vibration: Oil pipe vibration or mutual impact. Solution: Add support pipe clamps.

　　⑥ Hydraulic shock: The hydraulic cylinder buffering fails, and the back pressure valve adjusts the pressure change. Solution: Conduct maintenance, adjust or replace components.