Disassembly Hydraulic cylinder Prepare in advance. First, depressurize the hydraulic circuit; otherwise, if the hose fitting connected to the hydraulic cylinder becomes loose, the high-pressure oil in the control circuit will rapidly spray out. After the hydraulic circuit has been depressurized, loosen the handwheel or adjusting screw of the relief valve to release the pressurized oil, then disconnect the power supply to bring the hydraulic system to a stop.

　　Steps for removing the hydraulic cylinder:

　　First, to prevent slender components (such as piston rods) from bending or deforming, support and balance them with shims during placement. During disassembly, take care to avoid damaging the piston rod’s top threads, the oil‑port threads, the piston rod surface, and the cylinder liner’s inner wall.

　　Secondly, disassembly should be carried out in a prescribed sequence. Because hydraulic cylinders vary in design and dimensions, the specific sequence may differ slightly. Generally, the fluid should be drained from both chambers of the cylinder, after which the cylinder head is removed, followed by the piston and piston rod. When removing the cylinder head, keys or circlips that are engaged with internal splines must be extracted using specialized tools; flat chisels are prohibited. Flanged end caps should be pushed off with screws—hammering or prying with force is not permitted. If the piston and piston rod cannot be withdrawn, do not attempt to pull them out forcefully; first identify the underlying cause before proceeding with disassembly.

　　Third, before and after disassembly, take every possible measure to prevent the hydraulic cylinder components from becoming severely contaminated by ambient dust and foreign particles. For example, disassembly should be carried out in a clean environment whenever feasible; after disassembly, all parts should be covered with plastic sheeting rather than cotton cloth or other work cloths.

　　Fourth, after disassembly, carefully inspect the hydraulic cylinder to determine which components can be reused, which can be repaired and reused, and which must be replaced.

　　Fifth, before assembly, all components must be thoroughly cleaned; care should be taken to ensure that sealing elements are correctly installed in all locations. For example, when installing O-rings, avoid stretching them to the point of deformation or rolling them as you fit them, as such actions can lead to oil leakage due to distortion. All removed O-rings and dust seals should be replaced with new ones. When installing Y‑type and V‑type seals, pay close attention to the correct installation orientation to prevent leaks. The lip of a Y‑type seal must face the pressurized oil chamber; additionally, be sure to distinguish whether a YX‑type seal is intended for a shaft or a bore, and do not install it incorrectly. A V‑type seal consists of a support ring, a sealing ring, and a pressure ring of distinct shapes. As the pressure ring compresses the sealing ring, the support ring helps shape the sealing ring and provides the sealing function. During installation, the opening of the seal should face the pressurized oil chamber. When adjusting the pressure ring, ensure that no leakage occurs, but avoid over‑tightening to prevent excessive sealing resistance.

　　Sixth, when tightening threaded connections, a dedicated wrench must be used, and the torque must comply with the specified standards.

　　Seventh, after assembling the piston and piston rod, verify that their coaxiality and straightness do not exceed the specified tolerances over the entire length.

　　Eighth, after assembly, the piston assembly shall move without binding or uneven resistance.

　　Ninth, when the hydraulic cylinder is mounted on the main machine, the inlet and outlet fittings must be sealed and tightened to prevent oil leakage.