Hydraulic cylinders are used to perform work in a variety of different situations and applications on a daily basis. In order to contain pressurized fluid and maintain its movement in the hydraulic cylinder system, two basic types of complex configurations of high-performance seals are required: static seals and dynamic seals (supported by guide rings).

There are certain types of seals in each category.

Static seal. A seal that is not subject to any form of movement when pressurized. This includes O-rings, D-rings, backup rings, cover seals, and gaskets.

One of the simplest examples of static seals is the O-ring. O-rings are widely used and available in a variety of sizes. When placed in the cylinder housing and squeezed by the housing, the O-ring forms a physical barrier between the housing and the casing. Normally used with backup rings with pressures exceeding 1500 PSI., O-rings in NBR, FKM and EPDM are suitable for a wide variety of mineral oil, water and water-based liquids and air. Other compounds, such as TPU and silicone, can also be used in static environments.

Dynamic seal. Seals subject to axial and / or radial movement under pressure. This includes piston seals, rod seals, rotary seals, wipers. When system pressure pushes the piston and connecting rod assembly down to the cylinder bore, the piston seal prevents pressurized fluid from leaking through the piston. The rod seal maintains pressure in the cylinder by preventing fluid leakage. Rod seal leakage can degrade equipment performance and, in extreme cases, cause environmental problems. Wipers, also known as scrapers, prevent contaminants such as dirt, dust, and moisture from entering the cylinders when retracted into the system. Pollution will cause serious damage to connecting rod, cylinder wall, seals and other components, which is one of the main reasons for premature seal damage and component failure in hydraulic transmission system.

Guide ring. It is used to guide the piston in the cylinder bore of the hydraulic cylinder and the rod in the cylinder head. Guide rings are used to prevent damage caused by side loads because they prevent metal contact between axial and rotating parts. In addition, the guide ring helps capture contaminants to the sub surface before they reach the most critical sealing elements.

Selecting the correct seals is essential to ensure the best performance of the hydraulic cylinder application.