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How many common hydraulic cylinder seals are there?
Engineering machinery cannot do without hydraulic cylinders, and hydraulic cylinders cannot do without seals. The most common seal is the sealing ring, also called oil seal, which plays the role of isolating oil and preventing oil from overflowing or passing through.
Common seals used in hydraulic cylinders are of the following types: dust rings, piston rod seals, buffer seals, guide support rings, end cover seals and piston seals.
1.Dust ring
The dust ring is installed on the outside of the hydraulic cylinder end cover to prevent external pollutants from entering the cylinder. According to the installation method, it can be divided into snap-in type and press-in type.
The most common type of dust seal is the snap-in dust seal. As the name implies, the dust seal is stuck in the groove on the inner wall of the end cap and is used in less harsh environmental conditions. The material of the snap-in dust seal is usually polyurethane, and there are many variations in the structure, such as the H and K-type sections with double lip structures, but the essence remains unchanged.
Press-in dust seals are used in harsh, heavy-duty conditions. They are not stuck in the groove, but are made of polyurethane with a layer of metal wrapped around it to increase strength and pressed into the end cover of the hydraulic cylinder. Press-in dust seals also come in a variety of forms, including single lip and double lip.
2.Piston rod seal
The piston rod seal, also known as the U-cup, is the main piston rod seal and is installed on the inside of the hydraulic cylinder end cover to prevent hydraulic oil leakage. The piston rod seal is made of polyurethane or nitrile rubber. In some cases, it needs to be used with a support ring (also called a retaining ring) to prevent the seal from being squeezed and deformed under pressure. There are also many variations of piston rod seals.
3.Buffer seal
Buffer seals are used as auxiliary piston rod seals to protect the piston rod when the system pressure suddenly increases. There are three common types of buffer seals. Type A is a single-piece seal made of polyurethane. Types B and C are two-piece seals used to prevent seal extrusion and allow the seal to withstand higher pressures.
4.Guide support ring
The guide support ring is installed on the end cover and piston of the hydraulic cylinder to support the piston rod and piston, guide the piston to make linear motion, and prevent metal-to-metal contact. The materials include plastic, bronze coated with polytetrafluoroethylene, etc.
5.End cover seal
The end cover seal is used to seal the end cover of the hydraulic cylinder and the cylinder wall. It is a static seal used to prevent the hydraulic oil from leaking from the gap between the end cover and the cylinder wall. It is usually composed of a nitrile rubber O-ring and a support ring (retaining ring).
6.Piston seal
The piston seal is used to isolate the two chambers of the hydraulic cylinder and is the main seal in the hydraulic cylinder. It is usually a two-piece type, with the outer ring made of PTFE or nylon and the inner ring made of nitrile rubber. There are also many variations, including bronze coated with PTFE, etc. On single-acting cylinders, polyurethane U-cups are also used.
Contact: Nancy Zhu, Sales manager, JW GROUP.
Email: nancy@jwgroup.cc
Mobile/Whatsapp:+86 15902166721
HYDRAULIC CYLINDER and CNC parts specialist
JW GROUP is an integrated steel product group, products include: hydraulic cylinder, hydraulic cylinder spare parts, drilling forging parts, pneumatic actuator-scotch yoke, CNC machinery parts etc