Static sealing is described as:

• A. A stationary seal on a moving component such as a head gland seal on a hydraulic cylinder.
• B. A moving seal on a moving component.
• C. A seal that seals the hydraulic reservoir.
• D. A decorative seal used during maintenance.

Answer: (B)

Static sealing means the sealing surfaces stay fixed relative to each other; there is no sliding contact between the seal faces during operation. In a hydraulic cylinder, the seal sits in a gland that is attached to the cylinder body, so the seal itself remains stationary while the moving part (the rod) passes by or through it. This is why describing static sealing as a stationary seal on a moving component fits: the seal’s surfaces don’t move against each other even though another part of the assembly is moving.

This is different from dynamic sealing, where the sealing surfaces slide against each other as components move. The other options describe seals that aren’t about a stationary interface (or are not relevant to this concept), so they aren’t the correct way to define static sealing.