• What are hydraulic cylinders?

What are hydraulic cylinders?

Hydraulic cylinders, also known as linear hydraulic actuators, are hydraulic devices which, thanks to the action of a fluid (in this case oil), create movement. The work of hydraulic cylinders is generated by the application of a force along the direction of their extension.

Hydraulic cylinders are made up of:

  • tube or barrel or liner;
  • rod;
  • head bush;
  • piston;
  • seals.

The operation of hydraulic cylinders is obtained by the sliding of the rod within the barrel thanks to the fluid contained in the cylinder itself. The pressure created by the fluid is the origin of the piston movement of hydraulic cylinders.


Single acting cylinders are cylinders where the movement can be controlled only in one axial direction. The oil goes into the cylinder only from one side and, pushing the piston, moves the rod: to go back to the original position, the single acting cylinder needs either gravity or an integrated spring return system.
The single acting cylinder can be pushing or pulling depending on the oil action, pushing towards the inside or the outside of the cylinder.