Classification Of Hydraulic Dynamic Seals
Factors to be considered in the selection process also cover all aspects, including materials, compliance with cylinder conditions, quality, cost, etc. We have encountered many customers due to the wrong selection of seals, resulting in oil leakage and seal failure. We hope to provide you with useful seal information by sharing some easy-to-understand seal knowledge.
The sealing element has a decisive influence on the design, function and service life of the hydraulic system. Hydraulic seals are typically made of rubber, polytetrafluoroethylene (PTFE) and polyurethane (PU). The choice of materials will depend on the particular operating medium or limitations due to pressure, media, temperature or chemical compatibility.
Hydraulic seals are typically piston seals and piston rod seals.
The piston rod seal is installed in the groove of the hydraulic cylinder, and the inner diameter thereof is opposite to the piston rod or the shaft; the piston seal is installed in the groove of the piston, and the outer diameter is opposite to the hole or the cylinder of the hydraulic cylinder.
Therefore, the piston rod seal is also commonly referred to as a shaft seal, and the piston seal is also referred to as a piston seal.
What are the types of hydraulic seals? According to the action, the hydraulic dynamic seals can be divided into five categories. They are piston seals, piston rod seals, wiper seals, rotary seals and wear rings (guide rings).
1. Piston seals
The role of the piston seal is to ensure that the liquid working medium in the hydraulic cylinder does not leak through the piston tip. Piston seals typically include a one-way seal and a two-way seal.
One-way sealing, that is, pressure only acts in a single direction; in two-way sealing, pressure acts in both directions of reciprocating motion.
2. Piston rod seal
The piston rod seal is considered to be the most important component of the hydraulic cylinder seal configuration. When the piston rod is linearly reciprocated, the rod seal can effectively prevent the working medium from leaking from the inside of the hydraulic cylinder to the outside (dynamic pressure seal). The rod seal is used in conjunction with the dust seal to prevent external dust and dirt from entering the cylinder.
3. Wiper seals
In addition to the cylinder sealing function, the dust seal is mainly used to prevent foreign matter such as dust and dirt from entering the cylinder. Dust seals are often used with other seal assemblies to create a tight fit while still allowing the piston to reciprocate linearly.
4. Rotary seals
Rotary seal is a two-way action seal that can withstand the pressure of two sides or alternating pressure. It is used to seal rods, shafts, rotary joints and other components with rotating or oscillating motion.
5. Wear rings (guide rings)
The wear ring mainly helps to determine the relative position of the piston and the piston rod in the hydraulic cylinder and plays a supporting role.
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