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Dec 12 2024
Structural Characteristics of the Pilot Valve Seal Kit
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Common sealing components are sealing rings, also known as oil seals, which serve the function of isolating hydraulic oil and preventing leakage or passage of oil. The sealing rings commonly used in hydraulic cylinders include the following types: dust seals, piston rod seals, hydraulic cylinder buffer seals, guide support rings, end cap seals, and piston seals.
Dust seals are installed on the outer side of the hydraulic cylinder end cap and are used to prevent external contaminants from entering the cylinder. Depending on the installation method, they can be categorized into snap-in and press-in types.
The snap-in dust seal is the most common type, and as the name suggests, it snaps into a groove on the inner wall of the end cap, typically used in less demanding environments. Snap-in dust seals are usually made from polyurethane and come in various structural variations, such as the H and K types, which feature a double-lip structure but are fundamentally similar.
Press-in dust seals are used in harsh, heavy-duty conditions and do not snap into grooves. Instead, the polyurethane material is wrapped with a metal layer to increase strength and is pressed into the hydraulic cylinder end cap. Press-in dust seals also come in various forms, including single-lip and double-lip types.
Piston rod seals, also known as U-cups, are the primary sealing components for piston rods. They are installed on the inside of the hydraulic cylinder end cap and prevent hydraulic oil from leaking out. Piston rod seals are typically made from polyurethane or nitrile rubber. In some cases, they need to be used with support rings (also called retaining rings), which help prevent the seals from being deformed under pressure. There are several variations of piston rod seals available.
The hydraulic cylinder buffer seal, as an auxiliary piston rod seal, is used to protect the piston rod when there is a sudden increase in system pressure.
There are three common types of hydraulic cylinder buffer seals:
Type A is a single-piece hydraulic cylinder buffer seal made from polyurethane.
Types B and C are two-piece designs that prevent seal extrusion and allow the seals to withstand higher pressure.
The guide support ring is installed on the hydraulic cylinder end cap and piston and is used to support the piston rod and piston, guiding the piston to move in a straight line while preventing metal-to-metal contact. Materials used for guide support rings include plastic and bronze coated with polytetrafluoroethylene (PTFE).
End cap seals are used to seal the gap between the cylinder wall and the cylinder end cap, serving as static seals to prevent hydraulic oil from leaking through the gap between the end cap and the cylinder wall.
Typically, they consist of nitrile rubber O-rings and support rings (retaining rings).
Piston seals are used to isolate the two chambers of a hydraulic cylinder and are the main sealing components within the hydraulic cylinder.
They are usually two-piece designs, with the outer ring made from PTFE or nylon, and the inner ring made from nitrile rubber.
