Before disassembling the hydraulic cylinder, the hydraulic circuit should be depressurized, otherwise, when the oil pipe joint connected with the cylinder is loosened, the high-pressure oil in the circuit will be ejected rapidly. When the hydraulic circuit is depressurized, first loosen the hand wheel or high-pressure screw at the overflow valve to unload the pressure oil, then cut off the power supply or cut off the power source to stop the operation of the hydraulic device.
During disassembly, the top thread of the piston rod, the oil port thread, the surface of the piston rod and the inner wall of the cylinder liner shall be prevented from being operated. In order to prevent the piston rod and other slender parts from bending or deformation, the skids shall be used to support the balance when they are placed.
Disassembling the hydraulic cylinder in sequence. Due to the different structures and sizes of various hydraulic cylinders, the disassembly sequence is slightly different. Generally, drain the oil in the two cavities of the cylinder, then remove the cylinder head, and finally remove the piston and piston rod. When disassembling the cylinder head of hydraulic cylinder, special tools shall be used for the key or snap ring of internal key type connection, flat spade is forbidden to be used, and the flange end cover must be pushed out with screws, and hammering or hard prying is not allowed. When the piston and piston rod are difficult to be pulled out, they shall not be forced out. The reason shall be found out before disassembly.
Before and after disassembly, try to create conditions to prevent the parts of hydraulic cylinder from being polluted by surrounding dust and impurities. For example, when disassembling the hydraulic cylinder, it should be carried out in a clean environment as far as possible. After disassembling, all parts should be covered with plastic cloth instead of cotton cloth or other working cloth.
After the cylinder is disassembled, it shall be carefully inspected to determine which parts can be used continuously, which parts can be used after repair, and which parts must be replaced.
All parts must be cleaned carefully before assembly.
All sealing devices shall be installed correctly. When installing the O-ring, do not pull it to the extent of permanent deformation, and do not roll the package at the same time, otherwise it may cause oil leakage due to the formation of twist off. When installing Y-ring and V-ring, pay attention to the installation direction to avoid oil leakage. For the Y-ring, its lip should face the oil cavity with pressure. In addition, the YX ring should be distinguished from the shaft ring or the hole ring. Do not install it wrong. The V-ring is composed of support ring, seal ring and pressure ring with different shapes. When the pressure ring is pressed tightly, the support ring can make the seal ring produce sealing effect. During installation, the opening of the seal ring should face the pressure oil cavity and adjust When pressing the ring, it shall be limited to no oil leakage and shall not be pressed too tight to prevent excessive sealing resistance. If the sealing device is matched with the sliding surface, an appropriate amount of hydraulic oil shall be applied during assembly. The O-ring and dust ring shall be replaced with new ones after removal.
Special spanner shall be used when tightening the threaded connection, and the torque shall meet the standard requirements.
After the piston and piston rod are assembled, it is necessary to measure whether their coaxiality and straightness over the whole length are out of tolerance.
After assembly, the piston assembly shall move without any negative hysteresis and uneven resistance.
When the main engine of the hydraulic cylinder is installed, a sealing ring must be added between the inlet and outlet joints and fastened to prevent oil leakage. After assembly as required, several reciprocating movements shall be carried out under the condition of low pressure to remove the gas in the cylinder.