① Adjust the working pressure according to the specified value; Cleaning oil change; Replace the oil pump and check the tightness of the system according to the natural settlement; Replace the multiway valve. 

②  Change the working oil; Clean the oil circuit system and tank; Clean or replace the oil filter; Remove air from the system. 

③ Remove the lifting boom after the spontaneous sinking. Remove and repair the cylinder and replace the sealing ring; Remove or replace multi-way stem. 

④ The oil temperature is too high. Downtime or load reduction; Fuel to the specified oil level. 

⑤  Remove, repair and replace steering gear; Remove steering gear and repair. 

⑥ Replace the pump oil seal; Eliminate the air in the hydraulic pipeline; Replace the main pump leather bowl; Add full total pump oil; Adjust the stroke of the push rod; Replace the brake friction plate.