Hydraulic Cylinder Disassembly and Reassembly

When conducting hydraulic cylinder disassembly and reassembly, it is crucial to know the operation order and use correct tools in a safe manner, keep you safe and prevent the hydraulic cylinder from being damaged.

How to disassemble a hydraulic cylinder

  • Before hydraulic cylinder disassembly, the hydraulic circuit should be used to relieve pressure. Otherwise, when the oil pipe joint connected with the hydraulic cylinder is loosened, the high pressure oil in the circuit will spray out quickly. When depressurizing the hydraulic circuit, loosen the handwheel or pressure regulating screw at the relief valve, etc., to unload the pressure oil, and then cut off the power or power source to stop the hydraulic device.
  • When disassembling, prevent damage to the thread on the top of the piston rod and the oil port, the surface of the piston rod, and the inner wall of the cylinder barrel. In order to prevent slender parts such as piston rods from bending or deforming, you should use cushioned wooden support to balance them when placed.
  • The disassembly must be carried out in order. Due to the different structures and sizes of various hydraulic cylinders, the disassembly sequence is also slightly different. Generally, drain the oil in the two chambers of the cylinder at first, then remove the cylinder head, and finally remove the piston and piston rod. When disassembling the cylinder head, use special tools for the key or the snap ring connected by the inner snap key, but prohibit to use flat shovel. For flange type end caps, use screws to push out, but don’t hammer or hard pry. When the piston and piston rod are difficult to withdraw, don’t forced them out but to find out the reason before disassembly.
  • Before and after disassembly, try to create conditions to prevent the parts of the hydraulic cylinder from being contaminated by surrounding dust and impurities. For example, to carry out the disassemly in a clean environment as much as possible. After disassembly, to cover all the parts with plastic cloth, but not cotton cloth or other working cloth.
  • After the hydraulic cylinder is disassembled, check carefully to determine which parts can continue to be used, which parts can be used after repair, and which parts must be replaced.

How to reassemble a hydraulic cylinder

  • To clean all parts carefully before assembly.
  1. To properly install the sealing devices everywhere.
  2. When installing the O-ring, do not pull it to the extent that it is easily deformed, and do not roll it while rolling it, otherwise it may leak oil due to the twisted stroke.
  3. When installing Y-ring and V-ring, pay attention to the installation direction to avoid oil leakage due to installation. As for the Y-type sealing ring, its lip should correspond to the pressure oil cavity. In addition, the YX type sealing ring should be distinguished between shaft and hole use, and don’t install it wrongly. The V-shaped sealing ring is composed of a supporting ring, a sealing ring and a pressure ring of different shapes. When the pressure ring compresses the sealing ring, the supporting ring can make the sealing ring produce a sealing effect. The opening of the sealing ring should face the pressure oil chamber during installation. When adjusting the pressure ring, the oil leakage should be the limit, and the pressure should not be too tight to prevent excessive sealing resistance.
  4. If the sealing device is matched with the sliding surface, a proper amount of hydraulic oil should be applied during assembly.
  5. Replace all O-rings and dust-proof rings with new ones after disassembly.
  • Special wrench should be used when tightening the threaded connection, and the torque should meet the standard requirements.
  • After the piston and piston rod are assembled, try to measure their coaxiality and straightness over the full length.
  • After completing the assembly, there should be no sense of blocking and uneven resistance when the piston moves.
  • When install the hydraulic cylinder on the main engine, add a sealing ring and tighten between the inlet and outlet oil buckle joints to prevent oil leakage.
  • After assembling as required, perform several reciprocating movements under low pressure to remove the gas in the cylinder.

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