Which statement describes Dynamic Sealing?

• A. A stationary seal on a moving component.
• B. A moving seal such as a piston seal on a hydraulic cylinder.
• C. A seal that seals the air around the platform.
• D. A decorative seal used for branding.

Answer: (B)

Dynamic sealing means keeping fluid contained where surfaces are moving relative to each other. A piston seal on a hydraulic cylinder is a classic example because the piston slides inside the cylinder while the seal maintains a tight seal against leakage under pressure and motion. This is exactly what a dynamic seal is designed to handle—motion plus pressure—unlike seals that stay stationary while the parts move or seals used for nonfunctional branding. So the moving seal on a hydraulic cylinder best describes dynamic sealing.