Displacement cylinders have a single port and are load returned. They function by displacing the cylinder rod which may or may not have bearings but does not have a piston seal.
The oil is contained within the cylinder by gland or rod seals only. When oil enters the cylinder the rod is displaced and when the oil is released from the cylinder the force of the load returns the rod into the cylinder.
|Cannot be hydraulically retracted
|Oil filled bore – no corrosion issues
|Requires external force to retract
|Only one feed required
|Force generated relates to rod diameter not tube diameter