Precautions for Disassembling and Assembling Hydraulic Cylinder Barrels

(1) Release Hydraulic Pressure Before Disassembly

Before disassembling a hydraulic cylinder, the hydraulic circuit must be depressurized. Otherwise, high-pressure oil may spray out rapidly when loosening the pipe joints. To depressurize the system, first loosen the handwheel or pressure adjustment screw of the relief valve to release pressure oil, then cut off the power or shut down the power source to stop the hydraulic system.

(2) Prevent Damage During Disassembly

Be careful not to damage the piston rod threads, port threads, piston rod surface, or inner wall of the cylinder barrel. Use wooden blocks to support slender parts like the piston rod to avoid bending or deformation during placement.

(3) Disassemble in Proper Sequence

The disassembly sequence varies depending on the type and size of the hydraulic cylinder. Typically, the oil in both chambers should be drained first, followed by removal of the cylinder head, then the piston and piston rod assembly.

For cylinder heads with snap rings or retaining rings, use special tools instead of chisels. For flange-type end caps, they must be pushed out with screws rather than hammered or pried. If the piston and rod cannot be removed easily, do not force them—investigate the cause before proceeding.

(4) Prevent Contamination

To prevent contamination of parts by dust and debris, disassembly should be done in a clean environment. After disassembly, cover all parts with plastic sheets—avoid using cotton or cloth rags.

(5) Inspect Components Carefully

After disassembly, inspect all parts to determine which can be reused, which can be repaired, and which must be replaced.

(6) Clean All Parts Thoroughly Before Reassembly

(7) Correct Installation of Seals

• When installing O-rings, avoid over-stretching or twisting them, as this may cause deformation and leakage.

• When installing Y-type or V-type seals, pay attention to the correct orientation. For Y-rings, the lip should face the pressure chamber. For YX-type seals, distinguish between those used for shafts and for bores.

• V-ring seals are composed of support rings, sealing rings, and pressure rings. When the pressure ring is tightened, the sealing ring deforms and seals effectively. The open side of the V-ring should face the pressure side. Tighten only enough to prevent leakage—avoid over-tightening.

• Apply a thin layer of hydraulic oil to sliding surfaces during seal installation.

• All used O-rings and dust seals should be replaced with new ones.

(8) Use Proper Tools and Torque Values

Use torque wrenches for threaded connections and follow the specified torque values.

(9) Check Alignment After Assembly

After installing the piston and rod, check their coaxiality and straightness along the entire length.

(10) Ensure Smooth Piston Movement

After assembly, piston movement should be smooth without binding or uneven resistance.

(11) Proper Sealing on Installation to Main Equipment

When installing the hydraulic cylinder to the main machine, ensure that sealing rings are properly installed between oil port joints and tightened to prevent leakage.

(12) Perform Test Runs at Low Pressure

After final assembly, run the cylinder through several reciprocating cycles at low pressure to remove any trapped air inside the cylinder.