Common sealing rings for hydraulic cylinders are divided into the following types: dust ring, piston rod sealing ring, buffer sealing ring, guide support ring, end cover sealing ring and piston sealing ring.
1. Dust ring
The dust ring is installed on the outside of the end cover of the hydraulic cylinder to prevent external pollutants from entering the oil cylinder. It can be divided into Snap-on type and press-in type according to the installation method.
2. Snap-on type dust ring
Snap-on type dust ring is the most common. The dust ring is stuck in the groove on the inner wall of the end cover for less harsh environmental conditions. The material of Snap-on type dust ring is usually polyurethane, and there are many variations in its structural form.
3. Press-in dust ring
The press-in dust ring is used under harsh and heavy load conditions, not stuck in the groove, but wrapped with a layer of metal outside the polyurethane material to increase the strength and pressed into the end cover of the hydraulic cylinder. Push-In dust ring also has many forms, including single lip and double lip.
4. Piston rod seal ring
Piston rod seal ring, also known as U-cup bra, is the main piston rod seal, which is installed inside the end cover of the hydraulic cylinder to prevent hydraulic oil leakage. The piston rod seal ring is made of polyurethane or Nitrile Rubber. In some occasions, it needs to be used with the support ring (also called closing ring). The support ring is used to prevent the seal ring from being extruded and deformed under pressure. There are also many variations of piston rod seals.
5. Buffer seal ring
As an auxiliary piston rod seal ring, the buffer seal ring is used to protect the piston rod when the system pressure suddenly increases. Three common types of buffer seals. Type A is a single sealing ring made of polyurethane. Type B and Type C are two-piece, which are used to prevent seal extrusion and allow seals to bear higher pressure.