Common Combined Sealing Elements for Hydraulic Cylinders
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Author:佚名
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Published time: 2025-06-01
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Bud-shaped Seal
The bud-shaped seal is typically composed of a synthetic rubber O-ring stacked with a fabric-reinforced rubber Y-ring. Similar to self-sealing compression-type and self-sealing tight-type hydraulic seals, as well as lip seals, it generates high initial contact stress on the sealing surface through its own deformation to prevent leakage of non-pressurized fluid. When the hydraulic cylinder operates, the pressure fluid elastically deforms the O-ring to continuously squeeze and expand the sealing lip of the Y-ring, making it closely adhere to the sealing surface. This produces additional contact stress that increases with the pressure fluid's pressure, working together with the initial contact stress to block fluid leakage.
Gland Seal
The gland seal usually consists of a synthetic rubber O-ring combined with a filled polytetrafluoroethylene (PTFE) square seal. It can be divided into bore-type gland seals and shaft-type gland seals, though their sealing functions are identical. They create high initial contact stress on the sealing surface through their own deformation to prevent leakage of non-pressurized fluid. During hydraulic cylinder operation, the pressure fluid elastically deforms the O-ring to maximally squeeze the square seal, pressing it tightly against the sealing surface. This generates additional contact stress that rises with the pressure fluid's pressure, combining with the initial stress to prevent fluid leakage.
Step Seal
The step seal is generally composed of a synthetic rubber O-ring and a filled PTFE seal with a special rectangular-trapezoidal shape. Like the gland seal, it is classified into bore-type and shaft-type step seals. Its sealing function and mechanism are the same as those of the gland seal, but it only provides single-directional sealing.
Lip Seal
Lip seals have a smaller contact area between the lip and the sealing surface, allowing for greater compression deformation to achieve better sealing. However, they are prone to wear, and their sealing performance significantly declines after wear. When combined with an O-ring (i.e., as a combined seal), even if the lip wears, the high elasticity of the synthetic rubber O-ring forces the lip of the lip seal to tightly adhere to the sealing surface, generating sufficient surface contact stress to maintain sealing. Additionally, combined seals offer low friction resistance, stable operation, and ease of assembly and maintenance. Therefore, combined seals such as gland seals and step seals are widely used in hydraulic seals for fully automatic hydraulic brick presses, static pressure forming machines for daily ceramic products (e.g., plates and dishes), and medium/high-pressure grouting machines for sanitary ceramic forming.
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