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Three Sealing Methods of Hydraulic Cylinders

1. The Importance of Hydraulic Cylinder Seals

The reason why the hydraulic cylinder needs to be sealed is that it has problems of internal leakage and external leakage. When there are internal leakage and external leakage in the hydraulic cylinder, it will reduce the volume of the cavity, the working efficiency and performance of the hydraulic cylinder. When the situation is serious, the system pressure cannot go up and it will not work. From the perspective of environmental protection, leakage should be avoided as much as possible, so it is very important to take necessary sealing measures.

2. Three Sealing Methods of Hydraulic Cylinders

The main sealing parts in hydraulic cylinder are piston, piston rod, end cover, etc. Here are three sealing methods commonly used in hydraulic cylinders.

(1) Gap Seal

Its working principle is that there will be a little gap between two moving parts. The liquid friction resistance generated in the gap is used to prevent leakage. This prevents the piston axis from shifting, which is beneficial to maintain the fit clearance, ensure the lubrication effect, reduce the wear between the piston and the cylinder wall and increase the clearance sealing performance.

(2) Rubber Sealing Rings

Because of the different types of sealing rings in hydraulic cylinders, the sealing principles are different. Among them, O-ring mainly relies on pre-compression to offset the gap to realize sealing. Y, YX, V-shape, etc. depend on the deformation of the lip of the sealing ring under the action of hydraulic pressure, so that the lip adheres to the sealing surface for sealing. The higher the hydraulic pressure, the tighter the lip adheres. They also have the ability to compensate automatically after wear and tear.

(3) Rubber Seal Assembly

Generally, this kind of seal is a combination type and has the characteristics of two kinds of seals, which play the role of sealing together in work. For example, the Gray Ring is composed of rubber O-ring and polytetrafluoroethylene Gray Ring. In the work, the good elasticity of rubber O-ring is used to produce pre-wetting and self-wetting, so that its service life in hydraulic cylinder seal is longer.