Engineering machinery cannot do without oil cylinders, and oil cylinders cannot do without seals. Common seals are sealing rings, also called oil seals, which play the role of isolating oil and preventing oil from overflowing or passing through. Here are some common types and forms of oil cylinder sealing rings for everyone.
Common sealing rings for hydraulic oil cylinders are the following types: dust rings, piston rod sealing rings, buffer sealing rings, guide support rings, end cover sealing rings and piston sealing rings.
Dust rings
The dust rings are installed on the outside of the end cover of the hydraulic cylinder to prevent external pollutants from entering the oil cylinder. According to the installation method, they can be divided into snap-in type and press-in type.
Basic form of snap-in dust rings
The snap-in dust ring is the most common. As the name suggests, the dust ring is stuck in the groove on the inner wall of the end cover and is used under less harsh environmental conditions. The material of the snap-in dust ring is usually polyurethane, and there are many variations in the structural form, such as the H and K-type sections are double-lip structures, but the essence remains unchanged.
Some variations of snap-in wipers
Press-in wipers are used in harsh, heavy-duty conditions. They are not stuck in a groove, but are made of polyurethane wrapped with a layer of metal to increase strength and pressed into the end cover of the hydraulic cylinder. Press-in wipers also come in a variety of forms, and are also divided into single-lip and double-lip.
Press-in wipers and some variations
Rod seals
Rod seals, also known as U-cups, are the main piston rod seals and are installed on the inside of the hydraulic cylinder end cover to prevent hydraulic oil from leaking out. Piston rod seals are made of polyurethane or nitrile rubber. In some cases, they need to be used with support rings (also called retaining rings) to prevent the seals from being squeezed and deformed under pressure. There are also many variations of piston rod seals.
Common forms of piston rod seals
Some variations of piston rod seals
Buffer seals
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. Type B and C are two-piece, used to prevent seal extrusion, allowing seals to withstand higher pressures.
Several common forms of buffer seals
Guide support ring
Guide support rings are 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 PTFE, etc.
Guide support rings used on the end cover and piston of the hydraulic cylinder respectively
End cover seal ring
The end cover seal ring is used to seal the end cover of the cylinder with the cylinder wall. It is a static seal used to prevent hydraulic oil from leaking from the gap between the end cover and the cylinder wall. It usually consists of a nitrile rubber O-ring and a support ring (retaining ring).
End cover seal ring
Piston seal ring
The piston seal ring 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 an outer ring made of PTFE or nylon and an inner ring made of nitrile rubber. There are also many variations, including bronze coated with PTFE, etc. Polyurethane U-cups are also used on single-acting cylinders.
