How to repair a leaking, single acting hydraulic ram

There are a lot of different hydraulic rams (cylinders) in the market. Therefore, this article is going to focus on the small, single acting, 10,000 PSI rams, which are common across all sorts of industries. This particular article describes the way you would remove a blown seal from a cylinder like the HSS302 cylinder.


  • The first step is to remove the oil from the cylinder. The way you do this is to remove the quick connect from its port and face the port down to drain out the oil. By removing the quick connect you will also avoid suctions created while removing the rod and piston.


  • The next step is to look for any sort of set screw around the gland nut (stop ring). If you see a set screw there, then remove the set screw and then remove the gland nut.



  • In some situations you will then see a spring under the gland nut. Use a screwdriver to remove the spring. Usually you can rotate the screwdriver in a counter-clockwise direction to “pull” the spring out of the barrel.


  • Once the spring is out you can remove the rod and piston assembly. Once all the parts are out then you will want to inspect the barrel, rod and piston for any rust, scoring or damage. You would also remove the damaged or blown seals at this point. When you have the cylinder apart it is also a good idea to use all the seals from a seal kit. “Never leave a seal behind” is one motto we always use.


  • If you find that the barrel is damaged you may need to send the barrel out for honing or attempt to hone it yourself. Any honing should not exceed 20/1000th of inspected measurement. This is because if you take off too much material you may have a problem with the seal.



  • If everything looks good, then you would replace the seals and reverse the process to reassemble the cylinder. Make sure you keep all surfaces as clean as possible during installation.


As mentioned there are a lot of different models in the market and you may have one where the spring is attached inside. You may also find that the damage to your cylinder is more extensive than just a blown seal. If that is the case please contact us and we are happy to work with you on it.


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