Hydraulic systems run the world by providing unidirectional force to move or hold loads. These can be as simple as the small cylinders and arms holding your screen door open or as complex as the multiple telescoping units controlling the arms of excavator equipment. No matter what type of system you have, the seals inside of it do a lot of the work. There are many different seals at various points inside a hydraulic motor including the piston seal and the rod seal.
When They Work
When your hydraulic seals work, the fluid in your system can be moved into and out of various chambers in the cylinder to provide the force necessary to move and hold a load. There are probably more seals than you might initially think because engineers have designed these systems to fail as infrequently and as little as possible. For instance, it can be possible for the wiper seal at the end of the rod to crack and break without a huge fluid leak because there is usually a rod seal behind it a bit in the assembly.
When They Fail
Depending on the type of seal to fail, you will see different signs. The seal around the piston is what keeps the fluid pushing against it instead of flowing around it, so if this seal fails, your rod arm will not move as forcefully or will not hold under a load. When the wiper seal fails, contaminants can get into the hydraulic fluid and create pocking or erosion. It is a good idea to check the seals you have easy access to visually for signs of hardening or cracks as well as keep an eye on how strong the system is.
Checking your hydraulics, particularly the seals, can help you keep your heavy machinery running better for longer. It can also help you understand why the door to your vehicle trunk no longer stays open and what you need to do to fix it. It is a good idea to have a supply of the seals needed for your equipment on hand for repairs.