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How to Rebuild a Hydraulic Cylinder

Hydraulic cylinders are a critical component of certain hydraulic systems. They help provide the necessary force to accomplish the desired work. When one fails, it affects your productivity. You’ll need to repair it as soon as possible.
Fortunately, hydraulic cylinders are one of the least complex components of hydraulic systems that you can repair. However, it is important you have the right tools, knowledge, and expertise needed for hydraulic cylinder repair.

hydraulics piston

Types of Hydraulic Cylinders

The repair process used will depend on the type of hydraulic cylinder your hydraulic system uses. There are two general types of cylinders—threaded head and wire ring. You will need to know what type of cylinder your system uses before you begin repairing it.

Preparing to Rebuild the Cylinder

Regardless of the type of cylinder you are repairing, the first thing you will need to do is to clean the exterior of the cylinder housing and any hoses connected to the cylinder. This helps prevent dust, dirt, sludge, and debris from getting inside the cylinder.
When you disconnect hoses from the cylinder, you need to plug the openings to keep dirt and debris from getting inside the hoses. The next step is to disconnect and remove the cylinder from the hydraulic system. 

Rebuilding a Threaded Head Cylinder

Threaded head cylinders will have a set screw and end cap that holds the internal parts and components in place. Before removing the set screw, open the ports on the cylinder and drain out any hydraulic fluid.
Once the set screw is removed, you can remove the end cap, gland, and rod assembly. You should remove all O-rings and seals. Anytime you rebuild a cylinder, these parts should be replaced and never reused.
Pay attention to the order and placement of the O-rings and seals as you remove them. It can be beneficial to take a picture using your smartphone for reference to make reassembly easier.
If you need to replace the piston, rod, gland, or end cap, there will be a lock nut on the end of the rod assembly. Loosen the lock nut to remove the components that need to be replaced.
You will want to rebuild the cylinder by replacing the O-rings and seals first. Make sure to lubricate these with some clean hydraulic fluid.
Next, put the rod assembly back together, making sure the end cap and gland are in the proper locations. Then, carefully slide the cylinder rod assembly back into the cylinder housing. You may need to use a rocking motion to get everything slid back inside.
Now, slide the end cap back in place and reinstall the set screw to the right torque using a torque wrench. To finish up, reinstall the cylinder back into the hydraulic system and reconnect the hoses.

Rebuilding a Wire Ring Cylinder

A wire ring cylinder has a steel wire ring that will need to be removed before you can remove the rod assembly. With this type of cylinder, it is vital to have a new seal kit on hand, as you will need to replace the O-rings and seals during the rebuild process.
Additionally, the seal kit contains a special plastic removal ring required to get the rod assembly out of the cylinder houses. In general, the rebuild steps are as follows:
  • Step 1: Retract the .
  • Step 2: Remove the wire ring.
  • Step 3: Wipe off any dirt or debris under the ring.
  • Step 4: Using a punch and , carefully tap the head into the cylinder housing until you can see the internal tube groove.
  • Step 5: Insert the special plastic removal ring into the internal groove tube.
  • Step 6: Pull the out of the cylinder housing.
  • Step 7: Remove the locknut from the bottom of the to replace the , or gland.
  • Step 8: Remove all O-rings and seals and replace them with new ones.
  • Step 9: Remove the special plastic ring from inside the cylinder housing.
  • Step 10: Reassemble the .
  • Step 11: Lubricate the cylinder housing, seals, and O-rings.
  • Step 12: Use a band clamp to compress the interior wire ring found on the gland.
  • Step 13: Slide the back into the cylinder until the band clamp slides over the interior wire ring.
  • Step 14: Remove the band clamp.
  • Step 15: Install the dual seal O-ring and lubricate it.
  • Step 16: Slide the all the way back into the cylinder housing.
  • Step 17: Verify the inner wire ring has snapped back into place and that the is flush with the cylinder housing.
  • Step 18: Reinstall the wire ring.
As you can see, rebuilding a wire ring cylinder is a bit more complicated than rebuilding a threaded head cylinder. Therefore, you should always double-check your work, no matter what type of cylinder you rebuild.
Otherwise, when you reapply pressure to the system, the rod assembly could come out of the cylinder housing, along with hydraulic fluid.

hydraulic cylinder

White House Products Has the Parts You Need

For all your hydraulic cylinder parts and components, including rod seals, rods, piston seals, rods, pistons, and O-rings, and other hydraulic system parts and components, please feel free to contact White House Products Ltd. at  +44 (0) 1475 742500 today!

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