What flexible sealing element is subject to motion in hydraulic systems?

In hydraulic systems, the flexible sealing element that is subject to motion is packing. Packing is specifically designed to create a seal around moving components, such as pistons and rods, to prevent fluid leakage and maintain pressure within the system.

This element is typically made of materials that can withstand high pressure and motion while providing a tight seal. As parts move against each other in hydraulic applications, packing is compressed or deformed to ensure a leak-free operation. It functions effectively in dynamic sealing applications, where there is relative motion between the surfaces.

While O-rings and seal rings are also used for sealing, they are generally employed in static or limited motion applications where the movement is minimal or non-existent. Gaskets are used primarily in static applications between two non-moving surfaces, making them unsuitable for sealing in dynamic environments where motion occurs. Thus, packing is the most appropriate choice for maintaining a seal in areas of hydraulic systems experiencing movement.