A hydraulic piston pushes the annular element up into a concaved cap which forces the element diameter to decrease in size.

Active stability systems are defined by the need to input energy to the system in the form of a pump, hydraulic piston, or electric actuator.

Hydraulic piston vangs are used on larger sailboats and controlled by manual or electric hydraulic pumps.

They are found as a surface layer on automotive or mechanical components which receive heavy wear such as hydraulic piston pumps.

These disks are then put on a hydraulic piston, forming a pile.