What's wrong with hydraulic cylinder oil leakage? How to solve the problem of insufficient hydraulic cylinder pressure?

What's wrong with hydraulic cylinder oil leakage?


The reasons for hydraulic cylinder oil leakage may be as follows:
1. Internal leakage
1) The wear-resistant ring on the piston is severely worn, causing friction between the piston and the cylinder liner, and finally straining the cylinder liner, piston and seal;
2) The seal fails after long-term use, and the piston seal (mostly U, V, Y-shaped rings, etc.) ages;
3) The hydraulic oil is dirty, and a large amount of impurities enter the cylinder and wear out the piston seal;
2. External leakage
1) The inlet and outlet pipe joints of the oil cylinder are cracked;(I have seen this quite often in actual work)
2) Damage to the seal between the extended end of the piston rod and the piston rod is mostly caused by the piston cylinder being roughened, or also caused by aging;
3) The seal between the extended end of the piston rod and the cylinder liner is damaged. This is mostly caused by the aging of the seal after long-term use. There are also many cases where the seal is squeezed and damaged by excessive force when the end cover is put on. There are also many domestic manufacturers of hydraulic cylinders. This is caused by the manufacturer's unreasonable design (mostly to save costs).





How to solve the problem of insufficient hydraulic cylinder pressure


Hydraulic cylinder is an actuator in a hydraulic system that converts hydraulic energy into mechanical energy. The faults can be basically summarized as malfunction of the hydraulic cylinder, inability to push the load, and piston slipping or crawling. It is not uncommon for equipment to shut down due to hydraulic cylinder failures. Therefore, attention should be paid to fault diagnosis and use and maintenance of hydraulic cylinders.


1. Fault diagnosis and processing
1. The causes and solutions for malfunction or malfunction are as follows:


(1) The valve core is stuck or the valve hole is blocked. When the flow valve or directional valve spool is stuck or the valve hole is blocked, the hydraulic cylinder is prone to malfunction or malfunction. At this time, you should check the contamination of the oil;check whether dirt or colloid sediments are stuck on the valve core or block the valve hole;check the wear of the valve body, clean and replace the system filter, clean the oil tank, and replace the hydraulic medium.


(2) The piston rod and cylinder tube are stuck or the hydraulic cylinder is blocked. At this time, no matter how you operate it, the hydraulic cylinder will not move or move very little. At this time, you should check whether the piston and piston rod seals are too tight, whether dirt and colloid deposits have entered: whether the axis line of the piston rod and cylinder barrel is aligned, whether wearing parts and seals have failed, and whether the load is too high. big.


(3) The control pressure of the hydraulic system is too low. The throttling resistance in the control pipeline may be too large, the flow valve is improperly adjusted, the control pressure is inappropriate, and the pressure source is interfered with. At this time, the control pressure source should be checked to ensure that the pressure is adjusted to the specified value of the system.


(4) Air enters the hydraulic system. Mainly because there is a leak in the system. At this time, you should check the liquid level of the hydraulic tank, the seals and pipe joints on the suction side of the hydraulic pump, and whether the suction strainer is too dirty. If so, the hydraulic oil should be replenished, seals and pipe joints should be processed, and the coarse filter element should be cleaned or replaced.


(5) The initial movement of the hydraulic cylinder is slow. When the temperature is low, the hydraulic oil has high viscosity and poor fluidity, causing the hydraulic cylinder to move slowly. The improvement method is to replace the hydraulic oil with better viscosity and temperature properties. At low temperatures, you can use a heater or the machine itself to heat up the oil temperature at startup. The normal operating oil temperature of the system should be maintained at around 40°C.



2. The inability to drive the load during operation is mainly manifested by inaccurate parking position of the piston rod, insufficient thrust, reduced speed, unstable work, etc. The reasons are:


(1) Internal leakage of hydraulic cylinder. Internal leakage of the hydraulic cylinder includes leakage caused by excessive wear of the hydraulic cylinder block seal, piston rod and sealing cover seal, and piston seal. The reason for the seal leakage between the piston rod and the sealing cover is that the seal is wrinkled, squeezed, torn, worn, aged, deteriorated, deformed, etc. At this time, the seal should be replaced with a new one. 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. Secondly, foreign matter enters during assembly and the quality of sealing materials is poor. The consequences are slow and weak movements, and in severe cases, damage to the piston and cylinder, resulting in "cylinder pulling". The solution is to adjust the speed control valve and make necessary operations and improvements according to the installation instructions.


(2) Hydraulic circuit leakage. 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 tank through the relief valve. If dirt enters the relief valve and jams the valve core, causing the relief valve to remain open, the hydraulic oil will bypass the relief valve and flow directly back to the tank, 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