Abstract: An improved door closing device has a door closer main body for exerting a closing force on a door, a guide rail for guiding a slider, a tension spring provided in the guide rail and a releasably connecting device for releasably connecting the tension spring with the slider at a certain angular position of the door whereby a closing force can be additionally exerted near a position where the door is completely opened.

Abstract: An improved door closer which prevents overly rapid closing due to an external force, such as wind pressure, being exerted on the door. A pair of oil holes are formed communicating with a first pressure chamber and a non-pressure chamber formed in the main cylinder of the closer. A slide valve is disposed in a communicating hole communicating with the oil holes and extending generally perpendicular to the cylinder. A head portion and a braking valve portion are formed on the valve rod of the slide valve at positions corresponding to the oil holes. An elastic member urges the slide valve in the direction opposite to the normal flow direction of the operating oil when the door is closing. An adjusting screw controls the position of the slide valve.