A ventilation device for a hydraulic cylinder providing a housing having a fluid passageway with an inlet and an outlet, and a closure member disposed in said passageway displaceable in obstructing relation with such inlet upon application of a first fluid force in such inlet, obstructing relation with such outlet upon application of a second fluid force on such inlet and in nonobstructing relation with either of such inlet and outlet upon application of a third fluid force between such first and second fluid forces.