Editing Piston (section)

=== Hydraulic cylinders ===
[[File:Hydraulic cylinders used in a particle board machine.jpg|alt=Pistons of Hydraulic cylinders used in a hot press|left|thumb|Pistons of Hydraulic cylinders used in a hot press]]
Hydraulic cylinders can be both [[Single- and double-acting cylinders|single-acting]] or [[Double acting/differential cylinder|double-acting]]. A hydraulic actuator controls the movement of the piston back and/or forth. Guide rings guides the piston and rod and absorb the radial forces that act perpendicularly to the cylinder and prevent contact between sliding the metal parts.