Mainly manifested as inaccurate piston rod parking, insufficient thrust, speed drop, unstable work, etc. The reasons are:
(1) Internal leakage of hydraulic cylinder. The internal leakage of the hydraulic cylinder includes the leakage caused by the excessive wear of the hydraulic cylinder block seal, the piston rod and the sealing cover seal and the piston seal.
The reason for the leakage of the seal between the piston rod and the sealing cover is that the seal is wrinkled, squeezed, torn, worn, aged, deteriorated, deformed, etc. At this time, a new seal should be replaced.
The main causes of excessive piston seal wear are improper adjustment of the speed control valve, resulting in excessive back pressure and improper seal installation or hydraulic oil contamination. The second is the entry of foreign objects during assembly and the poor quality of the sealing material. The consequence is that the action is slow and powerless, and in severe cases, the piston and cylinder can be damaged, and the phenomenon of "pulling the cylinder" occurs. The treatment method is to adjust the speed control valve, and make necessary operations and improvements according to the installation instructions.
(2) The hydraulic circuit leaks. Including leaks in valves and hydraulic lines. The maintenance method is to check and eliminate the leakage of the hydraulic connection pipeline by operating the reversing valve.
(3) The hydraulic oil is bypassed back to the oil tank through the relief valve. If the overflow valve enters the dirt and jams the valve core, the overflow valve is normally open, and the hydraulic oil will flow directly back to the oil tank through the bypass of the overflow valve, resulting in no oil entering the hydraulic cylinder. If the load is too large, although the regulating pressure of the relief valve has reached the maximum rated value, the hydraulic cylinder still cannot get the thrust required for continuous action and will not act. If the adjustment pressure is low, the vertebral force required for still loading cannot be achieved due to insufficient pressure, which is manifested as insufficient thrust. At this time, the relief valve should be checked and adjusted.
