Repacking your Hydraulic Cylinder

Published: August 22, 2016 Last Updated: June 2, 2021 How To Series ,

Repacking your hydraulic cylinder doesn’t have to be a mystery. It can become a part of your standard annual preventative maintenance routine. Correct preventative maintenance will ensure you get the most life out of your hydraulic cylinders.

It’s always best to ensure you have the correct parts on hand before you begin the break down of the hydraulic cylinder. Different hydraulic cylinders have different glands and seal kits. You’ll be able to confirm the old parts are the same size, shape, and type as the new. If the equipment will be used for raising and lowering heavy objects or weight-bearing purposes, brace the supported weight with jacks or blocks to prevent any accidental injury not just to yourself, but the equipment.

Steps to Repack a Hydraulic Cylinder

  1. Release all pressure from the cylinder.
  2. Loosen and remove the hydraulic lines from the cylinder.
    • This will allow the last bit of pressure to escape the cylinder.
  3. Ensure the hydraulic cylinder is supported and won’t drop.
    • Then remove the pin from the rod end of the cylinder.
  4. Remove the gland from the cylinder.
    • This will be different for each cylinder manufacturer. Some are bolted on and some will require a special tool to be inserted into small holes to turn the gland where the rod exits the cylinder. It may require a small tap or bump with a hammer to break it loose, however once loose, it should easily unscrew and pull away onto the piston rod.
  5. Remove the piston rod from the cylinder.
    • Make sure to keep the piston rod from contacting other metal objects or falling into the dirt. We want to prevent contamination and scratches and dings to its surface. We also want to ensure the fine threads inside the cylinder do not become damaged by the rod being removed. Damage to these components could be costly.
  6. There are different ways to hold the rod to the piston.
    • A threaded rod can have the piston directly attached, or a nut, or a nut and bolt can hold the piston in place on the rod. When the rod is free from the cylinder housing, remove the piston from the rod. Keep the parts in order and take a photo to use later for reference if needed.
  7. Replace seals and o-rings on the piston and gland one at a time.
    • This will help to minimize confusion and correct placement. Be careful to identify and use the right seal. Some seals are very thin and can be easily damaged if not installed evenly. Ensure each groove is clean and debris free before replacing with the new part.
  8. Reverse the process and reassemble the piston to the rod.
    • Make sure to use a thread locking adhesive when replacing the piston rod bolt. Oil and clean all parts well before reassembly.
  9. Reinsert the gland into the cylinder.
    • Do not use a thread locking substance on the gland threads.
  10. Replace all hydraulic lines and test for leaks around the new seals.

This procedure should work well for most cylinder types. Remember, when handling heavy parts and dealing with hydraulic repairs, be careful to avoid injury to yourself and the expensive cylinder piston assemblies. Take it slow and be careful and you will have a new leak-free hydraulic cylinder in a short amount of time. Check out our Seal Kit Catalog for diagrams and more information on your particular cylinder type. If you still have questions, contact one of the Hydraulic Cylinders Inc. experts at 888-771-1894.