Hydraulic seals Introduction

2024-04-01

Hydraulic seals are used in cylinders to seal the opening areas between various components in the hydraulic cylinder.

Some seals are moulded, some are machines, and they are carefully designed and manufactured precisely. There are dynamic and static seals. Hydraulic seals include various types of seals, such as piston seals, rod seals, buffer seals, wiper seals, guide rings, o rings, and backup seals.

Piston Seals

Sealing systems are important because they keep the fluid media and the system operating pressure in and contaminants out of the cylinders.

Materials play a major role in the performance and lifetime of seals. Generally, hydraulic seals are exposed to a variety of applications and working conditions, such as a wide temperature range, contact with various hydraulic fluids and the outside environment as well as high pressures and contact forces. The appropriate seal materials must be selected to achieve a reasonable service life and service intervals.

Piston seals maintain sealing contact between a piston and cylinder bore. The moving piston rod generates high pressure on the piston seal, increasing contact forces between the seal and the cylinder surface. Thus the surface properties of the sealing surfaces are critical to proper seal performance. Piston seals can be classified into single-acting(pressure acting on one side only) and double-acting(pressure acting on both sides) seals.

Rod and buffer seals maintain sealing contact in a sliding motion between the cylinder head and the piston rod. Depending on the application, a rod sealing system can consist of a rod seal and a buffer seal or only a rod seal.

Wiper seals or dust seals are fitted on the external side of the cylinder head to prevent contaminants from entering the cylinder assembly and hydraulic system. Because cylinders operate in a variety of applications and environmental conditions, including exposure to dust. Without a wiper seal, the retracting piston rod could transport contaminants into the cylinder.

The commonly used guides in hydraulic cylinders are guide rings(wear rings) and guide strips. Guides are made of polymer materials and prevent metal-to-metal contact between moving parts in a working hydraulic cylinder.

O rings are used in most applications, it is the common sealing solution, it maintains sealing contact force by radial or axial deformation in the seal between two components.

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