Seals are vital for hydraulic functioning. When the man said, “give me a lever and I’ll move the world” he could have been referring to hydraulic systems. Hydraulic systems can push, pull, lift and move things infinitely heavier than the system itself. It may be the single most important facet to modern building, mining transportation and shipping.
A hydraulic system will not work without a high functioning system of seals. Seals serve several purposes. Dynamic seals operate between to components in motion. For example, cylinder and piston seals are dynamic in nature. It is their job to hold hydraulic fluid behind the piston when it is either at rest or in motion. Both types act as a pressure barrier.
Static seals are used between two nonmoving components. O rings can sometimes be used as either a dynamic or static seal, depending on its location in the system. Some seals are used to prevent dirt and other contaminants from entering the system and damaging vital components.
Seal failure can and often means a failure of the entire system. Since the hydraulic system is based on pressure, a failed seal will necessarily leak fluid, causing a decrease in fluid pressure. If a wiper seal fails, contaminants can erode moving parts. At minimum, the erosion can lead to premature damage. At worse, it can lead to system failure.
Due to the job they are designed to perform, hydraulic cylinder seals and o rings must have several attributes. They must be designed to withstand enormous amounts of pressure. In addition, they must be both heat and cold tolerant. Temperatures can vary between several hundred degrees internally to well below zero in cold climate applications. Dynamic seals must be able to withstand friction and hold up under continuous motion.
Seals are fabricated with a number of materials, including rubber, polyurethane, nylon and other materials. Metals such as nickel or bronze may be incorporated into the material to provide additional strength. When seeking a dealer, it is important to find one with experience in a wide range of applications, but most importantly, with knowledge of the system where seal replacement is necessary.