Piston Sealing System in Cylinder Mechanisms

As the core component of cylinder sealing systems, piston seals undertake the critical task of ​pressure isolation. Their performance directly determines ​output efficiency, speed stability, energy consumption, and service life​ of cylinders. This article analyzes the system’s functions, seal composition, and failure impacts.

​I. Core Functions​

1. ​Establishing Pressure Differential:

   Dividing the cylinder into two isolated chambers enables effective pressure separation. The stable pressure differential acts on the piston’s effective area to generate driving force. Seal failure causes air leakage, insufficient force, speed fluctuation (crawling), etc.

2. ​Withstanding Pressure & Wear:

   Maintains sealing integrity under ​pressures ranging from several to hundreds of Bar​ while enduring severe friction from reciprocating motion.

3. ​Location:

   Mounted in circumferential grooves on the piston’s outer periphery.

​II. Key Seal Types & Functions​

1. ​Wiper Seal (Scraper)​:

   • ​Location: Outermost position (right side)

   • ​Feature: Sharp scraping lip contacting the rod surface

   • ​Function: Scrapes contaminants (dust, debris, moisture) off the rod during retraction, acting as the ​primary barrier​ against internal component damage.

   • ​Material: Polyurethane (PU) or hard rubber (dark blue in figure)

   • ​Failure Impact: Accelerated internal wear, premature rod seal failure

2. ​Rod Seal (Primary Seal)​:

   • ​Location: Between wiper seal and guide ring/end cover (inner side)

   • ​Feature: U/Y-shaped profile with pressure-activated lip (black in figure)

   • ​Function:

     • Primary: Prevents leakage of pressure media (air/hydraulic fluid) along the rod

     • Low pressure: Sealing via elastic preload

     • High pressure: ​Pressure intensification​ forces lip against rod

     • Secondary: Limits contaminant ingress (minor role)

   • ​Material: PU, NBR, FKM, or composite seals (e.g., Stepseal)

   • ​Failure Impact: Pressure loss, efficiency decline, environmental contamination

​III. Conclusion​

Modern piston seals adopt ​elastomer + wear-resistant ring combinations​ (e.g., Glyd Ring, Stepseal). The ​preload at low pressure + pressure-energized sealing at high pressure​ efficiently isolates chamber pressure to convert differentials into linear thrust. Performance hinges on materials science, precision engineering, and proper maintenance. Optimal selection is paramount for cylinder reliability and operational efficiency.

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